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Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2015	Oct. 16, 2015
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q3
Trading Symbol	AA
Entity Registrant Name	ALCOA INC.
Entity Central Index Key	0000004281
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		1,310,128,840

Statement of Consolidated Operations (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Statement [Abstract]
Sales (I)	$ 5,573	$ 6,239	$ 17,289	$ 17,529
Cost of goods sold (exclusive of expenses below)	4,559	4,904	13,665	14,164
Selling, general administrative, and other expenses	261	243	717	724
Research and development expenses	55	57	178	158
Provision for depreciation, depletion, and amortization	318	347	958	1,036
Restructuring and other charges (D)	66	209	460	780
Interest expense	123	126	369	351
Other (income) expenses, net (H)	(15)	23	(27)	53
Total costs and expenses	5,367	5,909	16,320	17,266
Income before income taxes	206	330	969	263
Provision for income taxes (K)	100	199	401	200
Net income	106	131	568	63
Less: Net income (loss) attributable to noncontrolling interests	62	(18)	189	(46)
Consolidated net income attributable to Alcoa	44	149	379	109
AMOUNTS ATTRIBUTABLE TO ALCOA COMMON SHAREHOLDERS (J):
Net income	$ 26	$ 149	$ 327	$ 108
Earnings per share:
Basic	$ 0.02	$ 0.13	$ 0.26	$ 0.09
Diluted	0.02	0.12	0.26	0.09
Dividends paid per share	$ 0.03	$ 0.03	$ 0.09	$ 0.09

Statement of Consolidated Comprehensive Loss (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Net income (loss)	$ 106	$ 131	$ 568	$ 63
Other comprehensive loss, net of tax (C):
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	120	122	226	214
Foreign currency translation adjustments	(1,188)	(1,000)	(2,166)	(464)
Net change in unrealized gains on available-for-sale securities	(2)	(1)	(2)
Net change in unrecognized gains (losses) on cash flow hedges	215	(14)	581	(11)
Total Other comprehensive loss, net of tax	(855)	(893)	(1,361)	(261)
Comprehensive loss	(749)	(762)	(793)	(198)
Alcoa [Member]
Net income (loss)	44	149	379	109
Other comprehensive loss, net of tax (C):
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	111	126	212	217
Foreign currency translation adjustments	(889)	(774)	(1,649)	(384)
Net change in unrealized gains on available-for-sale securities	(2)	(1)	(2)
Net change in unrecognized gains (losses) on cash flow hedges	214	(19)	584	(10)
Total Other comprehensive loss, net of tax	(566)	(668)	(855)	(177)
Comprehensive loss	(522)	(519)	(476)	(68)
Noncontrolling Interests [Member]
Net income (loss)	62	(18)	189	(46)
Other comprehensive loss, net of tax (C):
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	9	(4)	14	(3)
Foreign currency translation adjustments	(299)	(226)	(517)	(80)
Net change in unrecognized gains (losses) on cash flow hedges	1	5	(3)	(1)
Total Other comprehensive loss, net of tax	(289)	(225)	(506)	(84)
Comprehensive loss	$ (227)	$ (243)	$ (317)	$ (130)

Consolidated Balance Sheet (Unaudited) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 1,739	$ 1,877
Receivables from customers, less allowances of $12 in 2015 and $14 in 2014 (L)	1,525	1,395
Other receivables (L)	669	733
Inventories (F)	3,559	3,082
Prepaid expenses and other current assets	1,100	1,182
Total current assets	8,592	8,269
Properties, plants, and equipment	33,237	35,517
Less: accumulated depreciation, depletion, and amortization	18,485	19,091
Properties, plants, and equipment, net	14,752	16,426
Goodwill (E)	5,443	5,247
Investments	1,647	1,944
Deferred income taxes	2,265	2,754
Other noncurrent assets (E & G)	3,888	2,759
Total assets	36,587	37,399
Current liabilities:
Short-term borrowings	50	54
Accounts payable, trade	2,734	3,152
Accrued compensation and retirement costs	825	937
Taxes, including income taxes	421	348
Other current liabilities	981	1,021
Long-term debt due within one year	136	29
Total current liabilities	5,147	5,541
Long-term debt, less amount due within one year	9,091	8,769
Accrued pension benefits	2,968	3,291
Accrued other postretirement benefits	2,110	2,155
Other noncurrent liabilities and deferred credits	2,580	2,849
Total liabilities	21,896	22,605
CONTINGENCIES AND COMMITMENTS (G)
Alcoa shareholders' equity:
Preferred stock	55	55
Mandatory convertible preferred stock	3	3
Common stock (E)	1,391	1,304
Additional capital (E)	9,954	9,284
Retained earnings	9,553	9,379
Treasury stock, at cost	(2,830)	(3,042)
Accumulated other comprehensive loss (C)	(5,532)	(4,677)
Total Alcoa shareholders' equity	12,594	12,306
Noncontrolling interests	2,097	2,488
Total equity	14,691	14,794
Total liabilities and equity	$ 36,587	$ 37,399

Consolidated Balance Sheet (Unaudited) (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Receivables from customers, allowance	$ 12	$ 14

Statement of Consolidated Cash Flows (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
CASH FROM OPERATIONS
Net income	$ 568	$ 63
Adjustments to reconcile net income to cash from operations:
Depreciation, depletion, and amortization	959	1,036
Deferred income taxes	(18)	2
Equity income, net of dividends	137	88
Restructuring and other charges (D)	460	780
Net gain from investing activities - asset sales (H)	(69)	(44)
Net periodic pension benefit cost (M)	365	321
Stock-based compensation	78	71
Excess tax benefits from stock-based payment arrangements	(9)	(7)
Other	(65)	67
Changes in assets and liabilities, excluding effects of acquisitions, divestitures, and foreign currency translation adjustments:
(Increase) in receivables	(97)	(665)
(Increase) in inventories	(176)	(485)
Decrease (increase) in prepaid expenses and other current assets	31	(28)
(Decrease) increase in accounts payable, trade	(240)	83
(Decrease) in accrued expenses	(424)	(456)
Increase (decrease) in taxes, including income taxes	135	(51)
Pension contributions	(363)	(446)
(Increase) decrease in noncurrent assets (G)	(348)	5
(Decrease) in noncurrent liabilities	(207)	(118)
CASH PROVIDED FROM OPERATIONS	717	216
FINANCING ACTIVITIES
Net change in short-term borrowings (original maturities of three months or less)	(6)
Net change in commercial paper		99
Additions to debt (original maturities greater than three months)	1,534	2,881
Debt issuance costs	(2)	(16)
Payments on debt (original maturities greater than three months)	(1,551)	(1,717)
Proceeds from exercise of employee stock options	26	128
Excess tax benefits from stock-based payment arrangements	9	7
Issuance of mandatory convertible preferred stock		1,213
Dividends paid to shareholders	(149)	(105)
Distributions to noncontrolling interests	(72)	(75)
Contributions from noncontrolling interests		44
Acquisitions of noncontrolling interests		(28)
CASH (USED FOR) PROVIDED FROM FINANCING ACTIVITIES	(211)	2,431
INVESTING ACTIVITIES
Capital expenditures	(782)	(750)
Acquisitions, net of cash acquired (E)	97
Proceeds from the sale of assets and businesses (E)	112	6
Additions to investments	(86)	(137)
Sales of investments	40	49
Net change in restricted cash	(7)
Other	23	25
CASH USED FOR INVESTING ACTIVITIES	(603)	(807)
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	(41)	(5)
Net change in cash and cash equivalents	(138)	1,835
Cash and cash equivalents at beginning of year	1,877	1,437
CASH AND CASH EQUIVALENTS AT END OF PERIOD	$ 1,739	$ 3,272

Statement of Changes in Consolidated Equity (Unaudited) - USD ($) $ in Millions	Total	Preferred Class A [Member]	Preferred Class B [Member]	Preferred Stock [Member]	Mandatory Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Capital [Member]	Retained Earnings [Member]	Retained Earnings [Member] Preferred Class A [Member]	Retained Earnings [Member] Preferred Class B [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Loss [Member]	Noncontrolling Interests [Member]
Balance at Dec. 31, 2013	$ 13,522			$ 55		$ 1,178	$ 7,509	$ 9,272			$ (3,762)	$ (3,659)	$ 2,929
Net income (loss)	63							109					(46)
Other comprehensive loss (C)	(261)											(177)	(84)
Cash dividends declared:
Preferred share, value		$ (1)							$ (1)
Common share, value	(104)							(104)
Stock-based compensation	71						71
Common stock issued: compensation plans	114						(519)				633
Issuance of mandatory convertible preferred stock	1,213				$ 3		1,210
Issuance of common stock (E)	575					89	486
Distributions	(75)												(75)
Contributions	44												44
Purchase of equity from noncontrolling interest	(28)						3						(31)
Other	2												2
Balance at Sep. 30, 2014	15,135			55	3	1,267	8,760	9,276			(3,129)	(3,836)	2,739
Balance at Jun. 30, 2014	14,706			55		1,267	7,635	9,163			(3,275)	(3,168)	3,029
Net income (loss)	131							149					(18)
Other comprehensive loss (C)	(893)											(668)	(225)
Cash dividends declared:
Common share, value	(36)							(36)
Stock-based compensation	22						22
Common stock issued: compensation plans	36						(110)				146
Issuance of mandatory convertible preferred stock	1,213				3		1,210
Distributions	(20)												(20)
Purchase of equity from noncontrolling interest	(28)						3						(31)
Other	4												4
Balance at Sep. 30, 2014	15,135			55	3	1,267	8,760	9,276			(3,129)	(3,836)	2,739
Balance at Dec. 31, 2014	14,794			55	3	1,304	9,284	9,379			(3,042)	(4,677)	2,488
Net income (loss)	568							379					189
Other comprehensive loss (C)	(1,361)											(855)	(506)
Cash dividends declared:
Preferred share, value		(2)	$ (50)						(2)	$ (50)
Common share, value	(153)							(153)
Stock-based compensation	78						78
Common stock issued: compensation plans	21						(191)				212
Issuance of common stock (E)	870					87	783
Distributions	(72)												(72)
Other	(2)												(2)
Balance at Sep. 30, 2015	14,691			55	3	1,391	9,954	9,553			(2,830)	(5,532)	2,097
Balance at Jun. 30, 2015	14,638			55	3	1,304	9,147	9,605			(2,834)	(4,966)	2,324
Net income (loss)	106							44					62
Other comprehensive loss (C)	(855)											(566)	(289)
Cash dividends declared:
Preferred share, value		$ (1)	$ (16)						$ (1)	$ (16)
Common share, value	(79)							(79)
Stock-based compensation	23						23
Common stock issued: compensation plans	5						1				4
Issuance of common stock (E)	870					87	783
Distributions	(1)												(1)
Other	1												1
Balance at Sep. 30, 2015	$ 14,691			$ 55	$ 3	$ 1,391	$ 9,954	$ 9,553			$ (2,830)	$ (5,532)	$ 2,097

Statement of Changes in Consolidated Equity (Unaudited) (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Common stock, dividends per share	$ 0.06	$ 0.03	$ 0.12	$ 0.09
Preferred Class A [Member]
Preferred, dividends per share	1.875	$ 0.9375	3.75	$ 2.8125
Preferred Class B [Member]
Preferred, dividends per share	$ 6.71875		$ 20.15625

Basis of Presentation	9 Months Ended
Basis of Presentation	Sep. 30, 2015
Accounting Policies [Abstract]
Basis of Presentation	A. Basis of Presentation – The interim Consolidated Financial Statements of Alcoa Inc. and its subsidiaries (“Alcoa” or the “Company”) are unaudited. These Consolidated Financial Statements include all adjustments, consisting of normal recurring adjustments, considered necessary by management to fairly state the Company’s results of operations, financial position, and cash flows. The results reported in these Consolidated Financial Statements are not necessarily indicative of the results that may be expected for the entire year. The 2014 year-end balance sheet data was derived from audited financial statements but does not include all disclosures required by accounting principles generally accepted in the United States of America (GAAP). This Form 10-Q report should be read in conjunction with Alcoa’s Annual Report on Form 10-K for the year ended December 31, 2014, which includes all disclosures required by GAAP. Certain amounts in previously issued financial statements were reclassified to conform to the current period presentation.

Recently Adopted and Recently Issued Accounting Guidance	9 Months Ended
	Sep. 30, 2015
Accounting Changes and Error Corrections [Abstract]
Recently Adopted and Recently Issued Accounting Guidance	B. Recently Adopted and Recently Issued Accounting Guidance Adopted On January 1, 2015, Alcoa adopted changes issued by the Financial Accounting Standards Board (FASB) to reporting discontinued operations and disclosures of disposals of components of an entity. These changes require a disposal of a component to meet a higher threshold in order to be reported as a discontinued operation in an entity’s financial statements. The threshold is defined as a strategic shift that has, or will have, a major effect on an entity’s operations and financial results such as a disposal of a major geographical area or a major line of business. Additionally, the following two criteria have been removed from consideration of whether a component meets the requirements for discontinued operations presentation: (i) the operations and cash flows of a disposal component have been or will be eliminated from the ongoing operations of an entity as a result of the disposal transaction, and (ii) an entity will not have any significant continuing involvement in the operations of the disposal component after the disposal transaction. Furthermore, equity method investments now may qualify for discontinued operations presentation. These changes also require expanded disclosures for all disposals of components of an entity, whether or not the threshold for reporting as a discontinued operation is met, related to profit or loss information and/or asset and liability information of the component. The adoption of these changes had no impact on the Consolidated Financial Statements. This guidance will need to be considered in the event Alcoa initiates a disposal of a component. In September 2015, the FASB issued changes to the accounting for measurement-period adjustments related to business combinations. Currently, an acquiring entity is required to retrospectively adjust the balance sheet amounts of the acquiree recognized at the acquisition date with a corresponding adjustment to goodwill during the measurement period, as well as revise comparative information for prior periods presented within financial statements as needed, including revising income effects, such as depreciation and amortization, as a result of changes made to the balance sheet amounts of the acquiree. Such adjustments are required when new information is obtained about facts and circumstances that existed as of the acquisition date that, if known, would have affected the measurement of the amounts initially recognized or would have resulted in the recognition of additional assets or liabilities. The measurement period is the period after the acquisition date during which the acquirer may adjust the balance sheet amounts recognized for a business combination (generally up to one year from the date of acquisition). The changes eliminate the requirement to make such retrospective adjustments, and, instead require the acquiring entity to record these adjustments in the reporting period they are determined. Additionally, the changes require the acquiring entity to present separately on the face of the income statement or disclose in the notes to the financial statements the portion of the amount recorded in current-period income by line item that would have been recorded in previous reporting periods if the adjustment to the balance sheet amounts had been recognized as of the acquisition date. These changes were to become effective for Alcoa on January 1, 2016; however, early adoption is permitted. As such, Alcoa elected to early adopt these changes upon issuance and applied the new requirements to two acquisitions (Firth Rixson and TITAL – see Note E) that are in the midst of their respective measurement period. At September 30, 2015, Alcoa recognized adjustments to the original balance sheet amounts of these two acquisitions, resulting in the recognition of amounts in current period income that would have been recorded in previous reporting periods had the adjustments to the balance sheet amounts been recognized as of the respective acquisition date. Such amounts recorded in current period income were not material to the Statement of Consolidated Operations for the third quarter and nine months ended September 30, 2015. Issued In January 2015, the FASB issued changes to the presentation of extraordinary items. Such items are defined as transactions or events that are both unusual in nature and infrequent in occurrence, and, currently, are required to be presented separately in an entity’s income statement, net of income tax, after income from continuing operations. The changes eliminate the concept of an extraordinary item and, therefore, the presentation of such items will no longer be required. Notwithstanding this change, an entity will still be required to present and disclose a transaction or event that is both unusual in nature and infrequent in occurrence in the notes to the financial statements. These changes become effective for Alcoa on January 1, 2016. Management has determined that the adoption of these changes will not have an impact on the Consolidated Financial Statements. In February 2015, the FASB issued changes to the analysis that an entity must perform to determine whether it should consolidate certain types of legal entities. These changes (i) modify the evaluation of whether limited partnerships and similar legal entities are variable interest entities or voting interest entities, (ii) eliminate the presumption that a general partner should consolidate a limited partnership, (iii) affect the consolidation analysis of reporting entities that are involved with variable interest entities, particularly those that have fee arrangements and related party relationships, and (iv) provide a scope exception from consolidation guidance for reporting entities with interests in legal entities that are required to comply with or operate in accordance with requirements that are similar to those in Rule 2a-7 of the Investment Company Act of 1940 for registered money market funds. These changes become effective for Alcoa on January 1, 2016. Management is currently evaluating the potential impact of these changes on the Consolidated Financial Statements. In April 2015, the FASB issued changes to the presentation of debt issuance costs. Currently, such costs are required to be presented as a noncurrent asset in an entity’s balance sheet and amortized into interest expense over the term of the related debt instrument. The changes require that debt issuance costs be presented in an entity’s balance sheet as a direct deduction from the carrying value of the related debt liability. The amortization of debt issuance costs remains unchanged. These changes become effective for Alcoa on January 1, 2016. In August 2015, the FASB issued an update to these changes based on an announcement of the staff of the U.S. Securities and Exchange Commission. This change provides an exception to the April 2015 FASB changes allowing debt issuance costs related to line-of-credit arrangements to continue to be presented as an asset regardless of whether there are any outstanding borrowings under such arrangement. This additional change also becomes effective for Alcoa on January 1, 2016. Management has determined that the adoption of all of these changes will result in a decrease of approximately $60 to both Other noncurrent assets and Long-term debt, less amount due within one year on the accompanying Consolidated Balance Sheet. In July 2015, the FASB issued changes to the subsequent measurement of inventory. Currently, an entity is required to measure its inventory at the lower of cost or market, whereby market can be replacement cost, net realizable value, or net realizable value less an approximately normal profit margin. The changes require that inventory be measured at the lower of cost and net realizable value, thereby eliminating the use of the other two market methodologies. Net realizable value is defined as the estimated selling prices in the ordinary course of business less reasonably predictable costs of completion, disposal, and transportation. These changes do not apply to inventories measured using LIFO (last-in, first-out) or the retail inventory method. Currently, Alcoa applies the net realizable value market option to measure non-LIFO inventories at the lower of cost or market. These changes become effective for Alcoa on January 1, 2017. Management has determined that the adoption of these changes will not have an impact on the Consolidated Financial Statements.

- Definition

The entire disclosure of changes in accounting principles, including adoption of new accounting pronouncements, that describes the new methods, amount and effects on financial statement line items.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Change in Accounting Principle
-URI http://asc.fasb.org/extlink&oid=6507316

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Direct Effects of a Change in Accounting Principle
-URI http://asc.fasb.org/extlink&oid=6510796

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=56949863&loc=d3e22583-107794

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Indirect Effects of a Change in Accounting Principle
-URI http://asc.fasb.org/extlink&oid=6515603

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=56949863&loc=d3e22580-107794

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 270
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.10-01.(b)(6))
-URI http://asc.fasb.org/extlink&oid=27015980&loc=d3e46468-122699

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Accounting Change
-URI http://asc.fasb.org/extlink&oid=6503790

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=56949863&loc=d3e22499-107794

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Retrospective Application
-URI http://asc.fasb.org/extlink&oid=6523989

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 270
-SubTopic 10
-Section 45
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=51655806&loc=d3e765-108305

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 270
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=51655806&loc=d3e725-108305

+ Details

Accumulated Other Comprehensive Loss

9 Months Ended

Sep. 30, 2015

Equity [Abstract]

Accumulated Other Comprehensive Loss

C. Accumulated Other Comprehensive Loss

The following table details the activity of the four components that comprise Accumulated other comprehensive loss for both Alcoa’s shareholders and noncontrolling interests:


	Alcoa						Noncontrolling Interests
	Third quarter ended September 30,						Third quarter ended September 30,
	2015			2014			2015			2014
Pension and other postretirement benefits (M)
Balance at beginning of period	$	(3,500	)	$	(3,441	)	$	(59	)	$	(50	)
Other comprehensive income (loss):
Unrecognized net actuarial loss and prior service cost/benefit		46			96			10			(9	)
Tax (expense) benefit		(10	)		(33	)		(1	)		3

Total Other comprehensive income (loss) before reclassifications, net of tax		36			63			9			(6	)

Amortization of net actuarial loss and prior service cost/benefit⁽¹⁾		116			97			—			3
Tax expense⁽²⁾		(41	)		(34	)		—			(1	)

Total amount reclassified from Accumulated other comprehensive loss, net of tax⁽⁸⁾		75			63			—			2

Total Other comprehensive income (loss)		111			126			9			(4	)

Balance at end of period	$	(3,389	)	$	(3,315	)	$	(50	)	$	(54	)


Foreign currency translation
Balance at beginning of period	$	(1,606	)	$	569		$	(569	)	$	36
Other comprehensive loss⁽³⁾		(889	)		(774	)		(299	)		(226	)

Balance at end of period	$	(2,495	)	$	(205	)	$	(868	)	$	(190	)


Available-for-sale securities
Balance at beginning of period	$	—		$	3		$	—		$	—
Other comprehensive (loss) income⁽⁴⁾		(2	)		(1	)		—			—

Balance at end of period	$	(2	)	$	2		$	—		$	—


Cash flow hedges (N)
Balance at beginning of period	$	140		$	(299	)	$	(6	)	$	(8	)
Other comprehensive income (loss):
Net change from periodic revaluations		288			(35	)		1			7
Tax (expense) benefit		(79	)		11			—			(2	)

Total Other comprehensive income (loss) before reclassifications, net of tax		209			(24	)		1			5

Net amount reclassified to earnings:
Aluminum contracts⁽⁵⁾		3			7			—			—
Foreign exchange contracts⁽⁵⁾		2			(1	)		—			—
Nickel contracts⁽⁶⁾		1			—			—			—

Sub-total		6			6			—			—
Tax expense⁽²⁾		(1	)		(1	)		—			—

Total amount reclassified from Accumulated other comprehensive income (loss), net of tax⁽⁸⁾		5			5			—			—

Total Other comprehensive income (loss)		214			(19	)		1			5

Balance at end of period	$	354		$	(318	)	$	(5	)	$	(3	)


	Alcoa						Noncontrolling Interests
	Nine months ended September 30,						Nine months ended September 30,
	2015			2014			2015			2014
Pension and other postretirement benefits (M)
Balance at beginning of period	$	(3,601	)	$	(3,532	)	$	(64	)	$	(51	)
Other comprehensive income (loss):
Unrecognized net actuarial loss and prior service cost/benefit		(30	)		33			13			(9	)
Tax benefit (expense)		18			(8	)		(1	)		3

Total Other comprehensive (loss) income before reclassifications, net of tax		(12	)		25			12			(6	)

Amortization of net actuarial loss and prior service cost/benefit⁽¹⁾		345			296			4			5
Tax expense⁽²⁾		(121	)		(104	)		(2	)		(2	)

Total amount reclassified from Accumulated other comprehensive loss, net of tax⁽⁸⁾		224			192			2			3

Total Other comprehensive income (loss)		212			217			14			(3	)

Balance at end of period	$	(3,389	)	$	(3,315	)	$	(50	)	$	(54	)


Foreign currency translation
Balance at beginning of period	$	(846	)	$	179		$	(351	)	$	(110	)
Other comprehensive loss⁽³⁾		(1,649	)		(384	)		(517	)		(80	)

Balance at end of period	$	(2,495	)	$	(205	)	$	(868	)	$	(190	)


Available-for-sale securities
Balance at beginning of period	$	—		$	2		$	—		$	—
Other comprehensive loss⁽⁴⁾		(2	)		—			—			—

Balance at end of period	$	(2	)	$	2		$	—		$	—


Cash flow hedges (N)
Balance at beginning of period	$	(230	)	$	(308	)	$	(2	)	$	(2	)
Other comprehensive income (loss):
Net change from periodic revaluations		792			(31	)		(4	)		(2	)
Tax (expense) benefit		(235	)		7			1			1

Total Other comprehensive income (loss) before reclassifications, net of tax		557			(24	)		(3	)		(1	)

Net amount reclassified to earnings:
Aluminum contracts⁽⁵⁾		26			18			—			—
Energy contracts⁽⁶⁾		4			—			—			—
Foreign exchange contracts⁽⁵⁾		3			(2	)		—			—
Interest rate contracts⁽⁷⁾		1			1			—			—
Nickel contracts⁽⁶⁾		1			—			—			—

Sub-total		35			17			—			—
Tax expense⁽²⁾		(8	)		(3	)		—			—

Total amount reclassified from Accumulated other comprehensive loss, net of tax⁽⁸⁾		27			14			—			—

Total Other comprehensive income (loss)		584			(10	)		(3	)		(1	)

Balance at end of period	$	354		$	(318	)	$	(5	)	$	(3	)

⁽¹⁾	These amounts were included in the computation of net periodic benefit cost for pension and other postretirement benefits (see Note M).

⁽²⁾	These amounts were included in Provision for income taxes on the accompanying Statement of Consolidated Operations.

⁽³⁾	In all periods presented, there were no tax impacts related to rate changes and no amounts were reclassified to earnings.

⁽⁴⁾	In all periods presented, unrealized and realized gains and losses related to these securities were immaterial. Realized gains and losses were included in Other (income) expenses, net on the accompanying Statement of Consolidated Operations.

⁽⁵⁾	These amounts were included in Sales on the accompanying Statement of Consolidated Operations.

⁽⁶⁾	These amounts were included in Cost of goods sold on the accompanying Statement of Consolidated Operations.

⁽⁷⁾	These amounts were included in Interest expense on the accompanying Statement of Consolidated Operations.

⁽⁸⁾	A positive amount indicates a corresponding charge to earnings and a negative amount indicates a corresponding benefit to earnings. These amounts were reflected on the accompanying Statement of Consolidated Operations in the line items indicated in footnotes 1 through 7.

- Definition

The entire disclosure for comprehensive income, which includes, but is not limited to, 1) the amount of income tax expense or benefit allocated to each component of other comprehensive income, including reclassification adjustments, 2) the reclassification adjustments for each classification of other comprehensive income and 3) the ending accumulated balances for each component of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=36458714&loc=d3e689-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=36458714&loc=SL7669619-108580

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=36458714&loc=d3e640-108580

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=36458714&loc=d3e716-108580

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=36458714&loc=d3e709-108580

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=36458714&loc=d3e637-108580

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=36458714&loc=d3e681-108580

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Reclassification Adjustments
-URI http://asc.fasb.org/extlink&oid=6522872

+ Details

Restructuring and Other Charges

9 Months Ended

Sep. 30, 2015

Restructuring and Related Activities [Abstract]

Restructuring and Other Charges

D. Restructuring and Other Charges – In the third quarter and nine-month period of 2015, Alcoa recorded Restructuring and other charges of $66 ($30 after-tax and noncontrolling interest) and $460 ($329 after-tax and noncontrolling interest), respectively.

Restructuring and other charges in the 2015 third quarter included $42 ($20 after-tax and noncontrolling interest) for charges related to the decision to curtail the remaining capacity (887,000 metric-tons-per-year) at the refinery in Suriname; $33 ($29 after-tax) for layoff costs, including the separation of approximately 370 employees (355 in the Transportation and Construction Solutions segment and a combined 15 in three other segments and Corporate); an $18 ($13 after-tax) gain on the sale of land related to one of the rolling mills in Australia that was permanently closed in December 2014; $11 ($5 after-tax and noncontrolling interest) for exit costs related to the decision to permanently shut down and demolish a power station (see below); a net charge of $2 (a net credit of $9 after-tax and noncontrolling interest) for other miscellaneous items; and $4 ($2 after-tax and noncontrolling interest) for the reversal of a few layoff reserves related to prior periods.

In the 2015 nine-month period, Restructuring and other charges included $190 ($120 after-tax and noncontrolling interest) for exit costs related to decisions to permanently shut down and demolish a smelter and a power station (see below); $161 ($151 after-tax and noncontrolling interest) related to the March 2015 divestiture of a rolling mill in Russia and post-closing adjustments associated with three December 2014 divestitures (see Note E); $80 ($43 after-tax and noncontrolling interest) for the separation of approximately 800 employees (680 in the Primary Metals segment and 120 in the Alumina segment), supplier contract-related costs, and other charges associated with the decisions to curtail the remaining capacity at both the refinery in Suriname (1,330,000 metric-tons-per-year) and the São Luís smelter (74,000 metric-tons-per-year); $62 ($50 after-tax and noncontrolling interest) for layoff costs, including the separation of approximately 970 employees (410 in the Transportation and Construction Solutions segment, 275 in the Engineered Products and Solutions segment, 165 in the Primary Metals segment, 70 in the Global Rolled Products segment, and 50 in Corporate); the previously mentioned $18 ($13 after-tax) gain on a land sale; a net credit of $3 ($13 after-tax and noncontrolling interest) for other miscellaneous items; and $12 ($9 after-tax and noncontrolling interest) for the reversal of a number of small layoff reserves related to prior periods.

In the second quarter of 2015, management approved the permanent shutdown and demolition of the Poços de Caldas smelter (capacity of 96,000 metric-tons-per-year) in Brazil and the Anglesea power station (includes the closure of a related coal mine) in Australia. The entire capacity at Poços de Caldas had been temporarily idled since May 2014 and the Anglesea power station was shut down at the end of August 2015. Demolition and remediation activities related to the Poços de Caldas smelter and the Anglesea power station will begin in late 2015 and are expected to be completed by the end of 2026 and 2020, respectively.

The decision on the Poços de Caldas smelter was due to management’s conclusion that the smelter was no longer competitive as a result of challenging global market conditions for primary aluminum, which led to the initial curtailment, that have not dissipated and higher costs. For the Anglesea power station, the decision was made because a sale process did not result in a sale and there would have been imminent operating costs and financial constraints related to this site in the remainder of 2015 and beyond, including significant costs to source coal from available resources, necessary maintenance costs, and a depressed outlook for forward electricity prices. The Anglesea power station previously supplied approximately 40 percent of the power needs for the Point Henry smelter, which was closed in August 2014.

In the 2015 nine-month period, costs related to the shutdown actions included asset impairments of $86, representing the write-off of the remaining book value of all related properties, plants, and equipment; $22 ($11 in the 2015 third quarter) for the layoff of approximately 90 employees (Primary Metals segment), including $11 in pension costs (see Note M); and $82 in other exit costs. Additionally in the 2015 nine-month period, remaining inventories, mostly operating supplies and raw materials, were written down to their net realizable value, resulting in a charge of $4 ($2 after-tax and noncontrolling interest), which was recorded in Cost of goods sold on the accompanying Statement of Consolidated Operations. The other exit costs of $82 represent $45 in asset retirement obligations and $29 in environmental remediation, both of which were triggered by the decisions to permanently shut down and demolish the aforementioned structures in Brazil and Australia (includes the rehabilitation of a related coal mine), and $8 in other related costs, including supplier and customer contract-related costs.

In the third quarter and nine-month period of 2014, Alcoa recorded Restructuring and other charges of $209 ($175 after-tax and noncontrolling interest) and $780 ($503 after-tax and noncontrolling interest), respectively.

Restructuring and other charges in the 2014 third quarter included $220 ($186 after-tax and noncontrolling interest) for exit costs related to decisions to permanently shut down and demolish two smelters and two rolling mills (see below); $5 ($4 after-tax) for a gain on the sale of assets related to a previously shutdown location; a charge of $4 ($2 after-tax and noncontrolling interest) for other miscellaneous items; and $10 ($9 after-tax and noncontrolling interest) for the reversal of a number of layoff reserves related to prior periods, including those associated with a smelter in Italy due to changes in facts and circumstances (see below).

In the 2014 nine-month period, Restructuring and other charges included $663 ($426 after-tax and noncontrolling interest) for exit costs related to decisions to permanently shut down and demolish three smelters and two rolling mills (see below); $67 ($44 after-tax and noncontrolling interest) for the temporary curtailment of two smelters and a related production slowdown at one refinery (see below); $33 ($26 after-tax) for asset impairments related to prior capitalized costs for a modernization project at a smelter in Canada that is no longer being pursued; $18 ($11 after-tax and noncontrolling interest) for layoff costs, including the separation of approximately 245 employees (65 in the Engineered Products and Solutions segment, 50 in the Transportation and Construction Solutions segment, 30 in the Global Rolled Products segment,10 in the Alumina and Primary Metals segments combined, and 90 in Corporate); a charge of $16 ($9 after-tax and noncontrolling interest) for other miscellaneous items; and $17 ($13 after-tax and noncontrolling interest) for the reversal of a number of layoff reserves related to prior periods, including those associated with a smelter in Italy due to changes in facts and circumstances (see below).

In the 2014 first quarter, management approved the permanent shutdown and demolition of the remaining capacity (84,000 metric-tons-per-year) at the Massena East smelter in New York and the full capacity (190,000 metric-tons-per-year) at the Point Henry smelter in Australia. The capacity at Massena East was fully shut down by the end March 2014 and the Point Henry smelter was fully shut down in August 2014. Demolition and remediation activities related to both the Massena East and Point Henry smelters began in late 2014 and are expected to be completed by the end of 2020 and 2018, respectively.

The decisions on the Massena East and Point Henry smelters were part of a 15-month review of 460,000 metric tons of smelting capacity initiated by management in May 2013 for possible curtailment. Through this review, management determined that the remaining capacity of the Massena East smelter was no longer competitive and the Point Henry smelter had no prospect of becoming financially viable. Management also initiated the temporary curtailment of the remaining capacity (62,000 metric-tons-per-year) at the Poços de Caldas smelter and additional capacity (85,000 metric-tons-per-year) at the São Luís smelter, both in Brazil. These curtailments were completed by the end of May 2014. As a result of these curtailments, 200,000 metric-tons-per-year of production at the Poços de Caldas refinery was reduced by the end of June 2014.

Also in the 2014 first quarter, management approved the permanent shutdown of Alcoa’s two rolling mills in Australia, Point Henry and Yennora. This decision was made due to the significant impact of excess can sheet capacity in both Australia and Asia. The two rolling mills had a combined can sheet capacity of 200,000 metric-tons-per-year and were closed at the end of 2014. Demolition and remediation activities related to the two rolling mills began in mid 2015 and are expected to be completed by the end of 2018.

In the 2014 third quarter, management approved the permanent shutdown and demolition of the capacity (150,000 metric-tons-per-year) at the Portovesme smelter in Italy, which had been idle since November 2012. This decision was made because the fundamental reasons that made the Portovesme smelter uncompetitive remain unchanged, including the lack of a viable long-term power solution. Demolition and remediation activities related to the Portovesme smelter will begin in 2016 (delayed due to discussions with the Italian government and other stakeholders) and are expected to be completed by the end of 2020.

In the third quarter and nine-month period of 2014, costs related to the shutdown and curtailment actions included $60 and $197, respectively, for the layoff of approximately 1,780 employees (1,200 in the Primary Metals segment, 470 in the Global Rolled Products segment, 80 in the Alumina segment, and 30 in Corporate), including $18 in pension costs (see Note M); accelerated depreciation of $40 and $190, respectively, related to the three facilities in Australia as they continued to operate during 2014 (the smelter operated for one month in the 2014 third quarter); asset impairments of $74 and $165, respectively, representing the write-off of the remaining book value of all related properties, plants, and equipment; and $45 and $178, respectively, in other exit costs (see below). Additionally in the third quarter and nine-month period of 2014, remaining inventories, mostly operating supplies and raw materials, were written down to their net realizable value, resulting in a charge of $33 ($27 after-tax and noncontrolling interest) and $67 ($47 after-tax and noncontrolling interest), respectively, which was recorded in Cost of goods sold on the accompanying Statement of Consolidated Operations. The other exit costs in the 2014 third quarter and nine-month period represent $40 and $95, respectively, in asset retirement obligations and $4 and $42, respectively, in environmental remediation, both of which were triggered by the decisions to permanently shut down and demolish the aforementioned structures in the United States, Australia, and Italy, and $1 and $41, respectively, in other related costs, including supplier and customer contract-related costs.

Alcoa does not include Restructuring and other charges in the results of its reportable segments. The pretax impact of allocating such charges to segment results would have been as follows:


	Third quarter ended September 30,					Nine months ended September 30,
	2015			2014		2015		2014
Alumina	$	38		$	1	$	55	$	8
Primary Metals		11			193		209		608
Global Rolled Products		(17	)		13		119		126
Engineered Products and Solutions		22			—		33		1
Transportation and Construction Solutions		3			—		6		3

Segment total		57			207		422		746
Corporate		9			2		38		34

Total restructuring and other charges	$	66		$	209	$	460	$	780

As of September 30, 2015, approximately 1,240 of the 1,860 employees associated with 2015 restructuring programs, approximately 2,500 of the 2,870 employees (previously 2,910 – updated to reflect employees accepting other positions within Alcoa and natural attrition) associated with 2014 restructuring programs, and approximately 1,480 of the 1,530 employees associated with 2013 restructuring programs were separated. Most of the remaining separations for the 2015 restructuring programs and all of the remaining separations for the 2014 and 2013 restructuring programs are expected to be completed by the end of 2015.

In the 2015 third quarter and nine-month period, cash payments of $19 and $34, respectively, were made against the layoff reserves related to the 2015 restructuring programs, $4 and $60, respectively, were made against the layoff reserves related to the 2014 restructuring programs, and $1 and $6, respectively, were made against the layoff reserves related to the 2013 restructuring programs.

Activity and reserve balances for restructuring charges were as follows:


	Layoff costs			Other exit costs			Total
Reserve balances at December 31, 2013	$	96		$	42		$	138

2014:
Cash payments		(191	)		(22	)		(213	)
Restructuring charges		259			194			453
Other*		(66	)		(180	)		(246	)

Reserve balances at December 31, 2014		98			34			132

2015:
Cash payments		(100	)		(9	)		(109	)
Restructuring charges		111			89			200
Other*		(52	)		(90	)		(142	)

Reserve balances at September 30, 2015	$	57		$	24		$	81

Other includes reversals of previously recorded restructuring charges and the effects of foreign currency translation. In the 2015 nine-month period, Other for layoff costs also included a reclassification of $28 in pension and other postretirement benefits costs, as this obligation was included in Alcoa’s separate liability for pension and other postretirement benefit obligations (see Note M). Additionally in the 2015 nine-month period, Other for other exit costs also included a reclassification of the following restructuring charges: $45 in asset retirement and $29 in environmental obligations, as these liabilities were included in Alcoa’s separate reserves for asset retirement obligations and environmental remediation (see Note G). In 2014, Other for layoff costs also included a reclassification of $26 in pension costs, as this obligation was included in Alcoa’s separate liability for pension obligations. Additionally in 2014, Other for other exit costs also included a reclassification of the following restructuring charges: $95 in asset retirement and $47 in environmental obligations, as these liabilities were included in Alcoa’s separate reserves for asset retirement obligations and environmental remediation.

The remaining reserves are expected to be paid in cash during the remainder of 2015, with the exception of approximately $50 to $55, which is expected to be paid over the next several years for special separation benefit payments, ongoing site remediation work, and lease termination costs.

Acquisitions and Divestitures

9 Months Ended

Sep. 30, 2015

Business Combinations [Abstract]

Acquisitions and Divestitures

E. Acquisitions and Divestitures – In November 2014, Alcoa completed the acquisition of an aerospace jet engine components company, Firth Rixson, for $2,995 plus $130 in contingent consideration. The preliminary allocation of the purchase price at that time resulted in total assets of $3,470, including $1,898 in goodwill and $398 in intangibles, and $475 in total liabilities, including the $130 of contingent consideration. In the 2015 nine-month period, Alcoa updated the estimated beginning balances of certain assets acquired, including a decrease to properties, plants, and equipment of $166, an increase to intangible assets of $393, and a decrease to goodwill of $94. These changes were based, in part, on management’s review of information from a completed third-party valuation. The intangible assets of $791 consist primarily of customer relationships and contracts, backlog, qualifications, and technology. These amounts, which will be finalized in the fourth quarter of 2015, are subject to change upon further review by management.

In March 2015, Alcoa completed the acquisition of an aerospace structural castings company, TITAL, for $204 (€188) in cash (an additional $1 (€1) was paid in the 2015 third quarter to settle working capital in accordance with the purchase agreement). This transaction is no longer subject to post-closing adjustments. TITAL, a privately held company with approximately 650 employees based in Germany, produces aluminum and titanium investment casting products for the aerospace and defense end markets. The purpose of this acquisition is to capture increasing demand for advanced jet engine components made of titanium, establish titanium-casting capabilities in Europe, and expand existing aluminum casting capacity. The assets, including the associated goodwill, and liabilities of this business were included within Alcoa’s Engineered Products and Solutions segment since the date of acquisition. Based on the preliminary allocation of the purchase price, goodwill of $123 was recorded for this transaction, none of which is estimated to be deductible for income tax purposes. The final allocation of the purchase price will be based on management’s best estimates, including a valuation of the assets acquired and liabilities assumed, which may result in the identification of other intangible assets, and other studies related to potential environmental and contingent liabilities.

Also in March 2015, Alcoa signed a definitive agreement to acquire RTI International Metals, Inc. (RTI), a U.S. company that was publicly traded on the New York Stock Exchange under the ticker symbol “RTI.” On July 23, 2015, after satisfying all customary closing conditions and receiving the required regulatory and RTI shareholder approvals, Alcoa completed the acquisition of RTI. Alcoa purchased all outstanding shares of RTI common stock in a stock-for-stock transaction valued at $870 (based on the $9.96 per share July 23, 2015 closing price of Alcoa’s common stock). Each issued and outstanding share of RTI common stock prior to the completion of the transaction was converted into the right to receive 2.8315 shares of Alcoa common stock. In total, Alcoa issued 87,397,414 shares of its common stock to consummate this transaction, which was not reflected in the accompanying Statement of Consolidated Cash Flows as it represents a noncash financing activity. The exchange ratio was the quotient of a $41 per RTI common share acquisition price and the $14.48 per share March 6, 2015 closing price of Alcoa’s common stock. In addition to the transaction price, Alcoa also paid $25 ($19 after-tax) in professional fees and costs related to this acquisition. This amount was recorded in Selling, general administrative, and other expenses on the accompanying Statement of Consolidated Operations.

RTI is a global supplier of titanium and specialty metal products and services for the commercial aerospace, defense, energy, and medical device end markets. The purpose of this acquisition is to expand Alcoa’s range of titanium offerings and add advanced technologies and materials, primarily related to the aerospace end market. In 2014, RTI generated net sales of $794 and had approximately 2,600 employees. The operating results and assets and liabilities of RTI were included within Alcoa’s Engineered Products and Solutions segment since the date of acquisition. Third-party sales and after-tax operating income (Alcoa’s primary segment performance measure – see Note I) of RTI from the acquisition date through September 30, 2015 were $127 and $(7), respectively.

The following table represents the preliminary allocation of the purchase price by major asset acquired and liability assumed, as well as the amount of goodwill recognized:


Assets:
Cash and cash equivalents	$	302
Receivables from customers		103
Inventories		538
Other current assets		68
Properties, plants, and equipment, net		436
Goodwill		209
Other noncurrent assets		91

Total assets	$	1,747


Liabilities:
Accounts payable	$	90
Long-term debt due within one year		115
Other current liabilities		93
Long-term debt		440
Other noncurrent liabilities		139

Total liabilities	$	877

The amounts in the table above are subject to change upon completion of a third-party valuation of the assets acquired and liabilities assumed. This valuation is expected to be completed in 2016.

As reflected in the table above, Alcoa recognized goodwill of $209, which represents the earnings growth potential of RTI, Alcoa’s ability to expand its titanium capabilities in the aerospace market, and expected synergies from combining the operations of the two companies. This goodwill will be allocated to a new Alcoa reporting unit associated with the Engineered Products and Solutions segment, Alcoa Titanium and Engineered Products, which consists solely of the acquired RTI business. None of this goodwill is deductible for income tax purposes.

The other noncurrent assets in the table above include an estimate for intangible assets of $73, most of which were included in Alcoa’s other intangibles class. The specific identification and weighted-average amortization period for these intangible assets is dependent on the final valuation.

As part of this acquisition, Alcoa also assumed the obligation to repay two tranches of convertible debt; one tranche is due on December 1, 2015 and the other tranche is due in 2019. Alcoa may elect to settle these convertible notes either in cash or shares of common stock (up to 37,009,898 shares combined).

In the 2015 nine-month period, Alcoa completed the divestiture of an operation in Russia (see below) and had post-closing adjustments, as provided for in the respective purchase agreements, related to three divestitures completed in December 2014. The divestiture and post-closing adjustments combined resulted in net cash received of $30 and a net loss of $161 ($151 after-tax and noncontrolling interest), which was recorded in Restructuring and other charges (see Note D) on the accompanying Statement of Consolidated Operations. One of these four divestitures remains subject to certain post-closing adjustments as defined in the respective purchase agreement.

In March 2015, Alcoa completed the sale of a rolling mill located in Belaya Kalitva, Russia to a wholly-owned subsidiary of Stupino Titanium Company. While owned by Alcoa, the operating results and assets and liabilities of the rolling mill were included in the Global Rolled Products segment. The rolling mill generated sales of approximately $130 in 2014 and, at the time of divestiture, had approximately 1,870 employees.

Inventories

9 Months Ended

Sep. 30, 2015

Inventory Disclosure [Abstract]

Inventories

F. Inventories


	September 30, 2015		December 31, 2014
Finished goods	$	850	$	768
Work-in-process		1,233		1,035
Bauxite and alumina		493		578
Purchased raw materials		790		508
Operating supplies		193		193

	$	3,559	$	3,082

At September 30, 2015 and December 31, 2014, the total amount of inventories valued on a LIFO basis was $1,507 and $1,514, respectively. If valued on an average-cost basis, total inventories would have been $625 and $767 higher at September 30, 2015 and December 31, 2014, respectively.

Contingencies and Commitments	9 Months Ended
Contingencies and Commitments	Sep. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Contingencies and Commitments	G. Contingencies and Commitments Contingencies Litigation On June 5, 2015, Alcoa World Alumina LLC (“AWA”) and St. Croix Alumina, L.L.C. (“SCA”) filed a complaint in Delaware Chancery Court for a declaratory judgment and injunctive relief to resolve a dispute between Alcoa and Glencore Ltd. (“Glencore”) with respect to claimed obligations under a 1995 asset purchase agreement between Alcoa and Glencore. The dispute arose from Glencore’s demand that Alcoa indemnify it for liabilities it may have to pay to Lockheed Martin (“Lockheed”) related to the St. Croix alumina refinery. Lockheed had earlier filed suit against Glencore in federal court in New York seeking indemnity for liabilities it had incurred and would incur to the U.S. Virgin Islands to remediate certain properties at the refinery property and claimed that Glencore was required by an earlier, 1989 purchase agreement to indemnity it. Glencore had demanded that Alcoa indemnify and defend it in the Lockheed case and threatened to claim over against Alcoa in the New York action despite exclusive jurisdiction for resolution of disputes under the 1995 purchase agreement being in Delaware. After Glencore conceded that it was not seeking to add Alcoa to the New York action, AWA and SCA dismissed their complaint in the Chancery Court case and on August 6, 2015 filed a complaint for declaratory judgment in Delaware Superior Court. AWA and SCA filed a motion for judgment on the pleadings on September 16, 2015. If AWA’s and SCA’s motion is granted, it will be determined that Alcoa is not liable to Glencore for any Glencore liabilities arising out of its contractual indemnity of Lockheed in the 1989 agreement. Glencore answered AWA’s and SCA’s complaint and asserted counterclaims on August 27, 2015, and on October 2, 2015 filed its own motion for judgment on the pleadings. Should Glencore’s motion for judgment be upheld, Alcoa could be required to defend against Lockheed’s claims in the action that Lockheed brought against Glencore, as to which Glencore seeks indemnification from Alcoa, estimated to be up to $76, which represents the high end of the range of reasonably possible loss associated with this matter of $0 to $76. Further briefing on the motions will continue through October 23, 2015. At this time, the Company is unable to reasonably predict an outcome for this matter. Before 2002, Alcoa purchased power in Italy in the regulated energy market and received a drawback of a portion of the price of power under a special tariff in an amount calculated in accordance with a published resolution of the Italian Energy Authority, Energy Authority Resolution n. 204/1999 (“204/1999”). In 2001, the Energy Authority published another resolution, which clarified that the drawback would be calculated in the same manner, and in the same amount, in either the regulated or unregulated market. At the beginning of 2002, Alcoa left the regulated energy market to purchase energy in the unregulated market. Subsequently, in 2004, the Energy Authority introduced regulation no. 148/2004 which set forth a different method for calculating the special tariff that would result in a different drawback for the regulated and unregulated markets. Alcoa challenged the new regulation in the Administrative Court of Milan and received a favorable judgment in 2006. Following this ruling, Alcoa continued to receive the power price drawback in accordance with the original calculation method, through 2009, when the European Commission declared all such special tariffs to be impermissible “state aid.” In 2010, the Energy Authority appealed the 2006 ruling to the Consiglio di Stato (final court of appeal). On December 2, 2011, the Consiglio di Stato ruled in favor of the Energy Authority and against Alcoa, thus presenting the opportunity for the energy regulators to seek reimbursement from Alcoa of an amount equal to the difference between the actual drawback amounts received over the relevant time period, and the drawback as it would have been calculated in accordance with regulation 148/2004. On February 23, 2012, Alcoa filed its appeal of the decision of the Consiglio di Stato (this appeal was subsequently withdrawn in March 2013). On March 26, 2012, Alcoa received a letter from the agency (Cassa Conguaglio per il Settore Eletrico (CCSE)) responsible for making and collecting payments on behalf of the Energy Authority demanding payment in the amount of approximately $110 (€85), including interest. By letter dated April 5, 2012, Alcoa informed CCSE that it disputes the payment demand of CCSE since (i) CCSE was not authorized by the Consiglio di Stato decisions to seek payment of any amount, (ii) the decision of the Consiglio di Stato has been appealed (see above), and (iii) in any event, no interest should be payable. On April 29, 2012, Law No. 44 of 2012 (“44/2012”) came into effect, changing the method to calculate the drawback. On February 21, 2013, Alcoa received a revised request letter from CSSE demanding Alcoa’s subsidiary, Alcoa Trasformazioni S.r.l., make a payment in the amount of $97 (€76), including interest, which reflects a revised calculation methodology by CCSE and represents the high end of the range of reasonably possible loss associated with this matter of $0 to $97 (€76). Alcoa has rejected that demand and has formally challenged it through an appeal before the Administrative Court on April 5, 2013. The Administrative Court scheduled a hearing for December 19, 2013, which was subsequently postponed until April 17, 2014, and further postponed until June 19, 2014. On this date, the Administrative Court listened to Alcoa’s oral argument, and on September 2, 2014, rendered its decision. The Administrative Court declared the payment request of CCSE and the Energy Authority to Alcoa to be unsubstantiated based on the 148/2004 resolution with respect to the January 19, 2007 through November 19, 2009 timeframe. On December 18, 2014, the CCSE and the Energy Authority appealed the Administrative Court’s September 2, 2014 decision; however, a date for the hearing has not been scheduled. At this time, the Company is unable to reasonably predict an outcome for this matter. European Commission Matters In July 2006, the European Commission (EC) announced that it had opened an investigation to establish whether an extension of the regulated electricity tariff granted by Italy to some energy-intensive industries complied with European Union (EU) state aid rules. The Italian power tariff extended the tariff that was in force until December 31, 2005 through November 19, 2009 (Alcoa had been incurring higher power costs at its smelters in Italy subsequent to the tariff end date through the end of 2012). The extension was originally through 2010, but the date was changed by legislation adopted by the Italian Parliament effective on August 15, 2009. Prior to expiration of the tariff in 2005, Alcoa had been operating in Italy for more than 10 years under a power supply structure approved by the EC in 1996. That measure provided a competitive power supply to the primary aluminum industry and was not considered state aid from the Italian Government. The EC’s announcement expressed concerns about whether Italy’s extension of the tariff beyond 2005 was compatible with EU legislation and potentially distorted competition in the European market of primary aluminum, where energy is an important part of the production costs. On November 19, 2009, the EC announced a decision in this matter stating that the extension of the tariff by Italy constituted unlawful state aid, in part, and, therefore, the Italian Government is to recover a portion of the benefit Alcoa received since January 2006 (including interest). The amount of this recovery was to be based on a calculation prepared by the Italian Government (see below). In late 2009, after discussions with legal counsel and reviewing the bases on which the EC decided, including the different considerations cited in the EC decision regarding Alcoa’s two smelters in Italy, Alcoa recorded a charge of $250 (€173), which included $20 (€14) to write off a receivable from the Italian Government for amounts due under the now expired tariff structure and $230 (€159) to establish a reserve. On April 19, 2010, Alcoa filed an appeal of this decision with the General Court of the EU (see below). Prior to 2012, Alcoa was involved in other legal proceedings related to this matter that separately sought the annulment of the EC’s July 2006 decision to open an investigation alleging that such decision did not follow the applicable procedural rules and requested injunctive relief to suspend the effectiveness of the EC’s November 19, 2009 decision. However, the decisions by the General Court, and subsequent appeals to the European Court of Justice, resulted in the denial of these remedies. In June 2012, Alcoa received formal notification from the Italian Government with a calculated recovery amount of $375 (€303); this amount was reduced by $65 (€53) for amounts owed by the Italian Government to Alcoa, resulting in a net payment request of $310 (€250). In a notice published in the Official Journal of the European Union on September 22, 2012, the EC announced that it had filed an action against the Italian Government on July 18, 2012 to compel it to collect the recovery amount (on October 17, 2013, the European Court of Justice ordered Italy to so collect). On September 27, 2012, Alcoa received a request for payment in full of the $310 (€250) by October 31, 2012. Following discussions with the Italian Government regarding the timing of such payment, Alcoa paid the requested amount in five quarterly installments of $69 (€50) beginning in October 2012 through December 2013. Notwithstanding the payments made, Alcoa’s estimate of the most probable loss of the ultimate outcome of this matter and the low end of the range of reasonably possible loss, which is $178 (€159) to $340 (€303), remains the $178 (€159) recorded in 2009 (the U.S. dollar amount reflects the effects of foreign currency movements since 2009). Alcoa no longer has a reserve for this matter; instead, Alcoa has a noncurrent asset reflecting the excess of the total of the five payments made to the Italian Government over the reserve recorded in 2009. At September 30, 2015, the noncurrent asset was $103 (€91) (this does not include the $59 (€53) for amounts owed by the Italian Government to Alcoa mentioned above). On October 16, 2014, Alcoa received notice from the General Court of the EU that its April 19, 2010 appeal of the EC’s November 19, 2009 decision was denied. On December 27, 2014, Alcoa filed an appeal of the General Court’s October 16, 2014 ruling to the European Court of Justice. Following submission of the EC’s response to the appeal, on June 10, 2015, Alcoa filed a request for an oral hearing before the European Court of Justice. No decision on that request has been received. A final decision by the European Court of Justice in this matter could take a year or more. As a result of the EC’s November 19, 2009 decision, management had contemplated ceasing operations at its Italian smelters due to uneconomical power costs. In February 2010, management agreed to continue to operate its smelters in Italy for up to six months while a long-term solution to address increased power costs could be negotiated. Over a portion of this time, a long-term solution was not able to be reached related to the Fusina smelter, therefore, in May 2010, Alcoa and the Italian Government agreed to a temporary idling of the Fusina smelter. As of September 30, 2010, the Fusina smelter was fully curtailed (44,000 metric-tons-per-year). For the Portovesme smelter, Alcoa executed a new power agreement effective September 1, 2010 through December 31, 2012, replacing the short-term, market-based power contract that was in effect since early 2010. This new agreement along with interruptibility rights (i.e. compensation for power interruptions when grids are overloaded) granted to Alcoa for the Portovesme smelter provided additional time to negotiate a long-term solution (the EC had previously determined that the interruptibility rights were not considered state aid). At the end of 2011, as part of a restructuring of Alcoa’s global smelting system, management decided to curtail operations at the Portovesme smelter during 2012 due to the uncertain prospects for viable, long-term power, along with rising raw materials costs and falling global aluminum prices (mid-2011 to late 2011). As of December 31, 2012, the Portovesme smelter was fully curtailed (150,000 metric-tons-per-year). In June 2013 and August 2014, Alcoa decided to permanently shut down and demolish the Fusina and Portovesme smelters, respectively, due to persistent uneconomical conditions. Environmental Matters Alcoa participates in environmental assessments and cleanups at more than 100 locations. These include owned or operating facilities and adjoining properties, previously owned or operating facilities and adjoining properties, and waste sites, including Superfund (Comprehensive Environmental Response, Compensation and Liability Act (CERCLA)) sites. A liability is recorded for environmental remediation when a cleanup program becomes probable and the costs can be reasonably estimated. As assessments and cleanups proceed, the liability is adjusted based on progress made in determining the extent of remedial actions and related costs. The liability can change substantially due to factors such as the nature and extent of contamination, changes in remedial requirements, and technological changes, among others. Alcoa’s remediation reserve balance was $558 and $543 at September 30, 2015 and December 31, 2014 (of which $63 and $70 was classified as a current liability), respectively, and reflects the most probable costs to remediate identified environmental conditions for which costs can be reasonably estimated. In the 2015 third quarter and nine-month period, the remediation reserve was increased by $3 and $56, respectively. The change in the third quarter of 2015 was due to a charge of $1 related to the Mosjøen location (see below) and a net charge of $2 associated with a number of other sites. In the 2015 nine-month period, the change was due to a charge of $29 related to the planned demolition of the Poços de Caldas smelter and the Anglesea power station (see Note D), a charge of $12 related to the Mosjøen location (see below), a charge of $7 related to the Portovesme location (see below), and a net charge of $8 associated with a number of other sites. The changes to the remediation reserve in the 2015 third quarter and nine-month period, except for the charge of $29, were recorded in Cost of goods sold on the accompanying Statement of Consolidated Operations. Payments related to remediation expenses applied against the reserve were $14 and $30 in the third quarter and nine-month period, respectively. These amounts include expenditures currently mandated, as well as those not required by any regulatory authority or third party. In the 2015 third quarter and nine-month period, the change in the reserve also reflects a decrease of $10 and $16, respectively, due to the effects of foreign currency translation and an increase of $5 related to the acquisition of Firth Rixson (see Note E). Included in annual operating expenses are the recurring costs of managing hazardous substances and environmental programs. These costs are estimated to be approximately 2% of cost of goods sold. The following discussion provides details regarding the current status of certain significant reserves related to current or former Alcoa sites. Massena West, NY—Alcoa has an ongoing remediation project related to the Grasse River, which is adjacent to Alcoa’s Massena plant site. Many years ago, it was determined that sediments and fish in the river contain varying levels of polychlorinated biphenyls (PCBs). The project, which was selected by the U.S. Environmental Protection Agency (EPA) in a Record of Decision (ROD) issued in April 2013, is aimed at capping PCB contaminated sediments with concentration in excess of one part per million in the main channel of the river and dredging PCB contaminated sediments in the near-shore areas where total PCBs exceed one part per million. At September 30, 2015 and December 31, 2014, the reserve balance associated with this matter was $235 and $239, respectively. Alcoa is in the planning and design phase, which is expected to take approximately three years from mid-2013, followed by the actual remediation fieldwork that is expected to take approximately four years. The majority of the project funding is expected to be spent between 2016 and 2020. Sherwin, TX—In connection with the sale of the Sherwin alumina refinery, which was required to be divested as part of the Reynolds merger in 2000, Alcoa agreed to retain responsibility for the remediation of the then existing environmental conditions, as well as a pro rata share of the final closure of the active bauxite residue waste disposal areas (known as the Copano facility). Alcoa’s share of the closure costs is proportional to the total period of operation of the active waste disposal areas. At September 30, 2015 and December 31, 2014, the reserve balance associated with Sherwin was $31 and $32, respectively. Approximately half of the project funding is expected to be spent through 2019. The remainder is not expected to be spent in the foreseeable future as it is dependent upon the operating life of the active waste disposal areas. East St. Louis, IL—Alcoa has an ongoing remediation project related to an area used for the disposal of bauxite residue from former alumina refining operations. The project, which was selected by the EPA in a ROD issued in July 2012, is aimed at implementing a soil cover over the affected area. On November 1, 2013, the U.S. Department of Justice lodged a consent decree on behalf of the EPA for Alcoa to conduct the work outlined in the ROD. This consent decree was entered as final in February 2014 by the U.S. Department of Justice. As a result, Alcoa began construction in March 2014; this project is expected to be completed by the end of 2015 (Alcoa has a second project in East St. Louis that is separate from the matter presented herein on which Alcoa is expecting an EPA decision in 2016—any resulting liability is not expected to be material). At September 30, 2015 and December 31, 2014, the reserve balance associated with this matter was $11 and $15, respectively. Fusina and Portovesme, Italy—In 1996, Alcoa acquired the Fusina smelter and rolling operations and the Portovesme smelter, both of which are owned by Alcoa’s subsidiary Alcoa Trasformazioni S.r.l. (“Trasformazioni”), from Alumix, an entity owned by the Italian Government. At the time of the acquisition, Alumix indemnified Alcoa for pre-existing environmental contamination at the sites. In 2004, the Italian Ministry of Environment and Protection of Land and Sea (MOE) issued orders to Trasformazioni and Alumix for the development of a clean-up plan related to soil contamination in excess of allowable limits under legislative decree and to institute emergency actions and pay natural resource damages. Trasformazioni appealed the orders and filed suit against Alumix, among others, seeking indemnification for these liabilities under the provisions of the acquisition agreement. In 2009, Ligestra S.r.l. (“Ligestra”), Alumix’s successor, and Trasformazioni agreed to a stay of the court proceedings while investigations were conducted and negotiations advanced towards a possible settlement. In December 2009, Trasformazioni and Ligestra reached an initial agreement for settlement of the liabilities related to Fusina while negotiations continued related to Portovesme (see below). The agreement outlined an allocation of payments to the MOE for emergency action and natural resource damages and the scope and costs for a proposed soil remediation project, which was formally presented to the MOE in mid-2010. The agreement was contingent upon final acceptance of the remediation project by the MOE. As a result of entering into this agreement, Alcoa increased the reserve by $12 in 2009 for Fusina. Based on comments received from the MOE and local and regional environmental authorities, Trasformazioni submitted a revised remediation plan in the first half of 2012; however, such revisions did not require any change to the existing reserve. In October 2013, the MOE approved the project submitted by Alcoa, resulting in no adjustment to the reserve. In January 2014, in anticipation of Alcoa reaching a final administrative agreement with the MOE, Alcoa and Ligestra entered into a final agreement related to Fusina for allocation of payments to the MOE for emergency action and natural resource damages and the costs for the approved soil remediation project. The agreement resulted in Ligestra assuming 50% to 80% of all payments and remediation costs. On February 27, 2014, Alcoa and the MOE reached a final administrative agreement for conduct of work. This agreement includes both a soil and groundwater remediation project estimated to cost $33 (€24) and requires payments of $25 (€18) to the MOE for emergency action and natural resource damages. The remediation projects are slated to begin as soon as Alcoa receives final approval from the Ministry of Infrastructure. Based on the final agreement with Ligestra, Alcoa’s share of all costs and payments is $17 (€12), of which $9 (€6) related to the damages will be paid annually over a 10-year period, which began in April 2014, and was previously fully reserved. Separately, in 2009, due to additional information derived from the site investigations conducted at Portovesme, Alcoa increased the reserve by $3. In November 2011, Trasformazioni and Ligestra reached an agreement for settlement of the liabilities related to Portovesme, similar to the one for Fusina. A proposed soil remediation project for Portovesme was formally presented to the MOE in June 2012. Neither the agreement with Ligestra nor the proposal to the MOE resulted in a change to the reserve for Portovesme. In November 2013, the MOE rejected the proposed soil remediation project and requested a revised project be submitted. In May 2014, Trasformazioni and Ligestra submitted a revised soil remediation project that addressed certain stakeholders’ concerns. Alcoa increased the reserve by $3 in 2014 to reflect the estimated higher costs associated with the revised soil remediation project, as well as current operating and maintenance costs of the Portovesme site. In October 2014, the MOE required a further revised project be submitted to reflect the removal of a larger volume of contaminated soil than what had been proposed, as well as design changes for the cap related to the remaining contaminated soil left in place and the expansion of an emergency containment groundwater pump and treatment system that was previously installed. Trasformazioni and Ligestra submitted the further revised soil remediation project in February 2015. As a result, Alcoa increased the reserve by $7 in the 2015 first quarter to reflect the increase in the estimated costs of the project. The ultimate outcome of this matter may result in a change to the existing reserve for Portovesme. Baie Comeau, Quebec, Canada—In August 2012, Alcoa presented an analysis of remediation alternatives to the Quebec Ministry of Sustainable Development, Environment, Wildlife and Parks (MDDEP), in response to a previous request, related to known PCBs and polycyclic aromatic hydrocarbons (PAHs) contained in sediments of the Anse du Moulin bay. As such, Alcoa increased the reserve for Baie Comeau by $25 in 2012 to reflect the estimated cost of Alcoa’s recommended alternative, consisting of both dredging and capping of the contaminated sediments. In July 2013, Alcoa submitted the Environmental Impact Assessment for the project to the MDDEP. The MDDEP notified Alcoa that the project as it was submitted was approved and a final ministerial decree was issued in July 2015. As a result, no further adjustment to the reserve was required in the 2015 third quarter. The decree provides final approval for the project and allows Alcoa to start work on the final project design, which is expected to be completed in 2016 with construction on the project expected to begin in 2017. Completion of the final project design and bidding of the project may result in additional liability in a future period. Mosjøen, Norway—In September 2012, Alcoa presented an analysis of remediation alternatives to the Norwegian Environmental Agency (NEA) (formerly the Norwegian Climate and Pollution Agency, or “Klif”), in response to a previous request, related to known PAHs in the sediments located in the harbor and extending out into the fjord. As such, Alcoa increased the reserve for Mosjøen by $20 in 2012 to reflect the estimated cost of the baseline alternative for dredging of the contaminated sediments. A proposed project reflecting this alternative was formally presented to the NEA in June 2014, and was resubmitted in the fourth quarter of 2014 to reflect changes by the NEA. The revised proposal did not result in a change to the reserve for Mosjøen. In the second quarter of 2015, the NEA notified Alcoa that the revised project was approved and required submission of the final project design before issuing a final order. Alcoa completed and submitted the final project design, which identified a need to stabilize the related wharf structure to allow for the sediment dredging in the harbor. As a result, Alcoa increased the reserve for Mosjøen by $11 in the 2015 second quarter to reflect the estimated cost of the wharf stabilization. In June 2015, the NEA issued a final order approving the project as well as the final project design. In the 2015 third quarter, Alcoa increased the reserve by $1 to reflect the potential need (based on prior experience with similar projects) to perform additional dredging if the results of sampling, which is required by the order, don’t achieve the required cleanup levels. Project construction is expected to begin in late 2015 and be completed by the end of 2017. Other In September 2010, following a corporate income tax audit covering the 2003 through 2005 tax years, an assessment was received as a result of Spain’s tax authorities disallowing certain interest deductions claimed by a Spanish consolidated tax group owned by the Company. An appeal of this assessment in Spain’s Central Tax Administrative Court by the Company was denied in October 2013. In December 2013, the Company filed an appeal of the assessment in Spain’s National Court. Additionally, following a corporate income tax audit of the same Spanish tax group for the 2006 through 2009 tax years, Spain’s tax authorities issued an assessment in July 2013 similarly disallowing certain interest deductions. In August 2013, the Company filed an appeal of this second assessment in Spain’s Central Tax Administrative Court, which was denied in January 2015. The Company filed an appeal of this second assessment in Spain’s National Court in March 2015. The combined assessments (remeasured for a tax rate change enacted in November 2014) total $268 (€239), including interest. The Company believes it has meritorious arguments to support its tax position and intends to vigorously litigate the assessments through Spain’s court system. However, in the event the Company is unsuccessful, a portion of the assessments may be offset with existing net operating losses available to the Spanish consolidated tax group. Additionally, it is possible that the Company may receive similar assessments for tax years subsequent to 2009. At this time, the Company is unable to reasonably predict an outcome for this matter. In March 2013, Alcoa’s subsidiary, Alcoa World Alumina Brasil (AWAB), was notified by the Brazilian Federal Revenue Office (RFB) that approximately $110 (R$220) of value added tax credits previously claimed are being disallowed and a penalty of 50% assessed. Of this amount, AWAB received $41 (R$82) in cash in May 2012. The value added tax credits were claimed by AWAB for both fixed assets and export sales related to the Juruti bauxite mine and São Luís refinery expansion. The RFB has disallowed credits they allege belong to the consortium in which AWAB owns an interest and should not have been claimed by AWAB. Credits have also been disallowed as a result of challenges to apportionment methods used, questions about the use of the credits, and an alleged lack of documented proof. AWAB presented defense of its claim to the RFB on April 8, 2013. If AWAB is successful in this administrative process, the RFB would have no further recourse. If unsuccessful in this process, AWAB has the option to litigate at a judicial level. Separately from AWAB’s administrative appeal, in June 2015, new tax law was enacted repealing the provisions in the tax code that were the basis for the RFB assessing a 50% penalty in this matter. As such, the estimated range of reasonably possible loss is $0 to $25 (R$103), whereby the maximum end of the range represents the portion of the disallowed credits applicable to the export sales and excludes the 50% penalty. Additionally, the estimated range of disallowed credits related to AWAB’s fixed assets is $0 to $28 (R$117), which would increase the net carrying value of AWAB’s fixed assets if ultimately disallowed. It is management’s opinion that the allegations have no basis; however, at this time, management is unable to reasonably predict an outcome for this matter. Between 2000 and 2002, Alcoa Alumínio (Alumínio) sold approximately 2,000 metric tons of metal per month from its Poços de Caldas facility, located in the State of Minas Gerais (the “State”), to Alfio, a customer also located in the State. Sales in the State were exempted from value-added tax (VAT) requirements. Alfio subsequently sold metal to customers outside of the State, but did not pay the required VAT on those transactions. In July 2002, Alumínio received an assessment from State auditors on the theory that Alumínio should be jointly and severally liable with Alfio for the unpaid VAT. In June 2003, the administrative tribunal found Alumínio liable, and Alumínio filed a judicial case in the State in February 2004 contesting the finding. In May 2005, the Court of First Instance found Alumínio solely liable, and a panel of a State appeals court confirmed this finding in April 2006. Alumínio filed a special appeal to the Superior Tribunal of Justice (STJ) in Brasilia (the federal capital of Brazil) later in 2006. In 2011, the STJ (through one of its judges) reversed the judgment of the lower courts, finding that Alumínio should neither be solely nor jointly and severally liable with Alfio for the VAT, which ruling was then appealed by the State. In August 2012, the STJ agreed to have the case reheard before a five-judge panel. A decision from this panel is pending, but additional appeals are likely. At September 30, 2015, the assessment totaled $32 (R$133), including penalties and interest. While the Company believes it has meritorious defenses, the Company is unable to reasonably predict an outcome. In addition to the matters discussed above, various other lawsuits, claims, and proceedings have been or may be instituted or asserted against Alcoa, including those pertaining to environmental, product liability, safety and health, and tax matters. While the amounts claimed in these other matters may be substantial, the ultimate liability cannot now be determined because of the considerable uncertainties that exist. Therefore, it is possible that the Company’s liquidity or results of operations in a particular period could be materially affected by one or more of these other matters. However, based on facts currently available, management believes that the disposition of these other matters that are pending or asserted will not have a material adverse effect, individually or in the aggregate, on the financial position of the Company. Commitments Investments Alcoa has an investment in a joint venture for the development, construction, ownership, and operation of an integrated aluminum complex (bauxite mine, alumina refinery, aluminum smelter, and rolling mill) in Saudi Arabia. The joint venture is owned 74.9% by the Saudi Arabian Mining Company (known as “Ma’aden”) and 25.1% by Alcoa and consists of three separate companies as follows: one each for the mine and refinery, the smelter, and the rolling mill. Alcoa accounts for its investment in the joint venture under the equity method. Capital investment in the project is expected to total approximately $10,800 (SAR 40.5 billion) and has been funded through a combination of equity contributions by the joint venture partners and project financing by the joint venture, which has been guaranteed by both partners (see below). Both the equity contributions and the guarantees of the project financing are based on the joint venture’s partners’ ownership interests. Originally, it was estimated that Alcoa’s total equity investment in the joint venture would be approximately $1,100, of which Alcoa has contributed $967, including $6 and $15 in the 2015 third quarter and nine-month period, respectively. Based on changes to both the project’s capital investment and equity and debt structure from the initial plans, the estimated $1,100 equity contribution may be reduced. As of September 30, 2015 and December 31, 2014, the carrying value of Alcoa’s investment in this project was $935 and $983, respectively. The smelting and rolling mill companies have project financing totaling $4,374 (reflects principal repayments made through September 30, 2015), of which $1,098 represents Alcoa’s share (the equivalent of Alcoa’s 25.1% interest in the smelting and rolling mill companies). In conjunction with the financings, Alcoa issued guarantees on behalf of the smelting and rolling mill companies to the lenders in the event that such companies default on their debt service requirements through 2017 and 2020 for the smelting company and 2018 and 2021 for the rolling mill company (Ma’aden issued similar guarantees for its 74.9% interest). Alcoa’s guarantees for the smelting and rolling mill companies cover total debt service requirements of $176 in principal and up to a maximum of approximately $50 in interest per year (based on projected interest rates). At September 30, 2015 and December 31, 2014, the combined fair value of the guarantees was $7 and $8, respectively, which was included in Other noncurrent liabilities and deferred credits on the accompanying Consolidated Balance Sheet. The mining and refining company has project financing totaling $2,232, of which $560 represents Alcoa World Alumina and Chemical’s (AWAC) 25.1% interest in the mining and refining company. In conjunction with the financings, Alcoa, on behalf of AWAC, issued guarantees to the lenders in the event that the mining and refining company defaults on its debt service requirements through 2019 and 2024 (Ma’aden issued similar guarantees for its 74.9% interest). Alcoa’s guarantees for the mining and refining company cover total debt service requirements of $120 in principal and up to a maximum of approximately $30 in interest per year (based on projected interest rates). At September 30, 2015 and December 31, 2014, the combined fair value of the guarantees was $3 and $4, respectively, which was included in Other noncurrent liabilities and deferred credits on the accompanying Consolidated Balance Sheet. In the event Alcoa would be required to make payments under the guarantees, 40% of such amount would be contributed to Alcoa by Alumina Limited, consistent with its ownership interest in AWAC. Alumínio, a wholly-owned subsidiary of Alcoa, is a participant in four consortia that each owns a hydroelectric power project in Brazil. One of these projects is known as Estreito, which reached full capacity in March 2013. Alumínio’s investment in this project is 25.49%, which entitles Alumínio to approximately 150 megawatts of assured power. The Estreito consortium is an unincorporated joint venture, and, therefore, Alumínio’s share of the assets and liabilities of the consortium are reflected in the respective lines on the accompanying Consolidated Balance Sheet. Total estimated project costs are approximately $1,260 (R$5,170) and Alumínio’s share is approximately $320 (R$1,320). As of September 30, 2015, approximately $310 (R$1,270) of Alumínio’s commitment was expended on the project. In 2004, Alcoa acquired a 20% interest in a consortium, which subsequently purchased the Dampier to Bunbury Natural Gas Pipeline (DBNGP) in Western Australia, in exchange for an initial cash investment of $17 (A$24). The investment in the DBNGP, which is classified as an equity investment, was made in order to secure a competitively priced long-term supply of natural gas to Alcoa’s refineries in Western Australia. Alcoa made additional contributions of $141 (A$176) for its share of the pipeline capacity expansion and other operational purposes of the consortium through September 2011. No further expansion of the pipeline’s capacity is planned at this time. In late 2011, the consortium initiated a three-year equity call plan to improve its capitalization structure. This plan required Alcoa to contribute $39 (A$40), all of which was made through December 2014. Following the completion of the three-year equity call plan in December 2014, the consortium initiated a new equity call plan to further improve its capitalization structure. This plan requires Alcoa to contribute $30 (A$36) through mid 2016, of which $12 (A$16) was made through September 30, 2015, including $3 (A$4) and $11 (A$15) in the 2015 third quarter and nine-month period, respectively. In addition to its equity ownership, Alcoa has an agreement to purchase gas transmission services from the DBNGP. At September 30, 2015, Alcoa has an asset of $256 (A$366) representing prepayments made under the agreement for future gas transmission services. Alcoa’s maximum exposure to loss on the investment and the related contract is approximately $370 (A$520) as of September 30, 2015. On April 8, 2015, Alcoa’s majority-owned subsidiary, Alcoa of Australia Limited (AofA), which is part of AWAC, secured a new 12-year gas supply agreement to power its three alumina refineries in Western Australia beginning in July 2020. This agreement was conditional on the completion of a third-party acquisition of the related energy assets from the current owner, which occurred in the 2015 second quarter. The terms of AofA’s gas supply agreement require a prepayment of $500 to be made in two installments. The first installment of $300 was made at the time of the completion of the third-party acquisition in June 2015 and was reflected in Other noncurrent assets on the accompanying Consolidated Balance Sheet. The second installment of $200 will be made in January 2016.

Other (Income) Expenses, Net

9 Months Ended

Sep. 30, 2015

Other Income and Expenses [Abstract]

Other (Income) Expenses, Net

H. Other (Income) Expenses, Net


	Third quarter ended September 30,						Nine months ended September 30,
	2015			2014			2015			2014
Equity loss	$	24		$	16		$	68		$	84
Interest income		(4	)		(3	)		(11	)		(13	)
Foreign currency gains, net		(17	)		(5	)		(27	)		—
Net gain from asset sales		(41	)		(15	)		(69	)		(44	)
Net loss on mark-to-market derivative contracts (N)		16			20			19			17
Other, net		7			10			(7	)		9

	$	(15	)	$	23		$	(27	)	$	53

Segment Information

9 Months Ended

Sep. 30, 2015

Segment Reporting [Abstract]

Segment Information

I. Segment Information – In the third quarter of 2015, management approved a realignment of Alcoa’s Engineered Products and Solutions segment due to the expansion of this part of Alcoa’s business portfolio through both organic and inorganic growth. This realignment consisted of moving both the Alcoa Wheel and Transportation Products and Building and Construction Systems business units to a new reportable segment named Transportation and Construction Solutions. Additionally, the Latin American soft alloy extrusions business previously included in Corporate was moved into the new Transportation and Construction Solutions segment. The remaining Engineered Products and Solutions segment consists of the Alcoa Fastening Systems and Rings (renamed to include portions of the Firth Rixson business acquired in November 2014), Alcoa Power and Propulsion (includes the TITAL business acquired in March 2015), Alcoa Forgings and Extrusions (includes the other portions of Firth Rixson), and Alcoa Titanium and Engineered Products (a new business unit that represents the RTI International Metals business acquired in July 2015) business units. Segment information for all prior periods presented was updated to reflect the new segment structure.

Effective in the second quarter of 2015, management removed the impact of metal price lag from the results of the Global Rolled Products and Engineered Products and Solutions (now Engineered Products and Solutions and Transportation and Construction Solutions – see above) segments in order to enhance the visibility of the underlying operating performance of these businesses. Metal price lag describes the timing difference created when the average price of metal sold differs from the average cost of the metal when purchased by the respective segment. In general, when the price of metal increases, metal price lag is favorable, and when the price of metal decreases, metal price lag is unfavorable. The impact of metal price lag is now reported as a separate line item in Alcoa’s reconciliation of total segment ATOI to consolidated net income attributable to Alcoa. As a result, this change does not impact the consolidated results of Alcoa. Segment information for all prior periods presented was updated to reflect this change.

The operating results of Alcoa’s reportable segments were as follows (differences between segment totals and consolidated totals are in Corporate):


	Alumina			Primary Metals			Global Rolled Products			Engineered Products and Solutions		Transportation and Construction Solutions		Total
Third quarter ended September 30, 2015
Sales:
Third-party sales	$	912		$	1,249		$	1,527		$	1,397	$	475	$	5,560
Intersegment sales		391			479			29			—		—		899

Total sales	$	1,303		$	1,728		$	1,556		$	1,397	$	475	$	6,459

Profit and loss:
Equity loss	$	(9	)	$	(7	)	$	(8	)	$	—	$	—	$	(24	)
Depreciation, depletion, and amortization		71			106			56			61		11		305
Income taxes		85			(49	)		28			71		18		153
After-tax operating income (ATOI)		212			(59	)		62			151		44		410
Third quarter ended September 30, 2014
Sales:
Third-party sales	$	886		$	1,865		$	1,926		$	1,034	$	523	$	6,234
Intersegment sales		482			730			52			—		—		1,264

Total sales	$	1,368		$	2,595		$	1,978		$	1,034	$	523	$	7,498

Profit and loss:
Equity loss	$	(7	)	$	—		$	(8	)	$	—	$	—	$	(15	)
Depreciation, depletion, and amortization		100			124			62			32		10		328
Income taxes		26			95			26			78		20		245
ATOI		62			245			69			155		50		581


	Alumina			Primary Metals			Global Rolled Products			Engineered Products and Solutions		Transportation and Construction Solutions		Total
Nine months ended September 30, 2015
Sales:
Third-party sales	$	2,723		$	4,355		$	4,816		$	3,933	$	1,438	$	17,265
Intersegment sales		1,323			1,733			99			—		—		3,155

Total sales	$	4,046		$	6,088		$	4,915		$	3,933	$	1,438	$	20,420

Profit and loss:
Equity loss	$	(27	)	$	(15	)	$	(24	)	$	—	$	—	$	(66	)
Depreciation, depletion, and amortization		228			324			168			166		32		918
Income taxes		264			14			89			228		49		644
ATOI		648			195			192			472		126		1,633
Nine months ended September 30, 2014
Sales:
Third-party sales	$	2,492		$	4,948		$	5,463		$	3,103	$	1,521	$	17,527
Intersegment sales		1,472			2,182			139			—		—		3,793

Total sales	$	3,964		$	7,130		$	5,602		$	3,103	$	1,521	$	21,320

Profit and loss:
Equity loss	$	(19	)	$	(45	)	$	(19	)	$	—	$	—	$	(83	)
Depreciation, depletion, and amortization		297			377			178			95		31		978
Income taxes		78			114			73			234		55		554
ATOI		192			327			193			455		142		1,309

The following table reconciles total segment ATOI to consolidated net income attributable to Alcoa:


	Third quarter ended September 30,						Nine months ended September 30,
	2015			2014			2015			2014
Total segment ATOI	$	410		$	581		$	1,633		$	1,309
Unallocated amounts (net of tax):
Impact of LIFO		50			(18	)		93			(33	)
Metal price lag		(48	)		38			(110	)		56
Interest expense		(80	)		(81	)		(240	)		(228	)
Noncontrolling interests		(62	)		18			(189	)		46
Corporate expense		(72	)		(72	)		(199	)		(204	)
Restructuring and other charges		(48	)		(189	)		(368	)		(587	)
Other		(106	)		(128	)		(241	)		(250	)

Consolidated net income attributable to Alcoa	$	44		$	149		$	379		$	109

Items required to reconcile total segment ATOI to consolidated net income attributable to Alcoa include: the impact of LIFO inventory accounting and metal price lag; interest expense; noncontrolling interests; corporate expense (general administrative and selling expenses of operating the corporate headquarters and other global administrative facilities, along with depreciation and amortization on corporate-owned assets); restructuring and other charges; and other items, including intersegment profit eliminations, differences between tax rates applicable to the segments and the consolidated effective tax rate, and other nonoperating items such as foreign currency transaction gains/losses and interest income.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
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-Paragraph 41
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
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-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8933-108599

Reference 7: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-SubTopic 10
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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+ Details

Earnings Per Share

9 Months Ended

Sep. 30, 2015

Earnings Per Share [Abstract]

Earnings Per Share

J. Earnings Per Share – Basic earnings per share (EPS) amounts are computed by dividing earnings, after the deduction of preferred stock dividends declared, by the average number of common shares outstanding. Diluted EPS amounts assume the issuance of common stock for all potentially dilutive share equivalents outstanding.

The information used to compute basic and diluted EPS attributable to Alcoa common shareholders was as follows (shares in millions):


	Third quarter ended September 30,				Nine months ended September 30,
	2015		2014		2015		2014
Net income attributable to Alcoa	$	44	$	149	$	379	$	109
Less: preferred stock dividends declared		18		—		52		1

Net income available to Alcoa common shareholders – basic		26		149		327		108
Add: dividends related to mandatory convertible preferred stock		—		—		—		—
Add: interest expense related to convertible notes		—		—		—		—

Net income available to Alcoa common shareholders – diluted	$	26	$	149	$	327	$	108

Average shares outstanding – basic		1,281		1,177		1,241		1,150
Effect of dilutive securities:
Stock options		1		8		4		6
Stock and performance awards		12		12		12		11
Mandatory convertible preferred stock		—		8		—		3
Convertible notes		—		—		—		—

Average shares outstanding – diluted		1,294		1,205		1,257		1,170

In the 2015 third quarter and nine-month period, 77 million share equivalents related to mandatory convertible preferred stock and 25 million and 8 million (weighted-average), respectively, share equivalents related to convertible debt (acquired through RTI – see Note E) were not included in the computation of diluted EPS because their effect was anti-dilutive.

In the first quarter of 2014, holders of convertible notes exercised their option to convert the notes into 89 million shares of Alcoa common stock. As a result, for the 2014 third quarter, these 89 million shares were outstanding for the entire period and were included in both basic and diluted average shares outstanding. For the 2014 nine-month period, these 89 million shares were outstanding for a portion of the period equivalent to a weighted average of 67 million shares. The 67 million shares were included in both basic and diluted average shares outstanding for the 2014 nine-month period. For the portion of the 2014 nine-month period that the notes were still outstanding debt, a weighted average of the 89 million share equivalents (22 million) would have been included only in the diluted average shares outstanding if their effect was dilutive.

Options to purchase 26 million and 3 million shares of common stock at a weighted average exercise price of $12.76 and $16.24 per share were outstanding as of September 30, 2015 and 2014, respectively, but were not included in the computation of diluted EPS because they were anti-dilutive, as the exercise prices of the options were greater than the average market price of Alcoa’s common stock.

In July 2015, Alcoa issued 87 million shares of its common stock to acquire RTI (see Note E). As a result, the basic average number of shares in the 2015 third quarter and nine-month period includes 58 million and 20 million, respectively, representing the weighted average number of shares for the length of time the 87 million shares were outstanding during the respective periods.

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Income Taxes	K. Income Taxes – The effective tax rate for the third quarter of 2015 and 2014 was 48.5% and 60.3%, respectively. The rate for the 2015 third quarter differs from the U.S. federal statutory rate of 35% primarily due to restructuring charges related to the curtailment of a refinery in Suriname (see Note D), a portion for which no tax benefit was recognized. The rate for the 2014 third quarter differs from the U.S. federal statutory rate of 35% primarily due to a $56 discrete income tax charge related to a tax rate change in Brazil, restructuring charges related to operations in Italy for which no tax benefit was recognized (see Note D), and an $8 unfavorable impact related to the interim period treatment of operational losses in certain foreign jurisdictions for which no tax benefit was recognized (impact reversed by the end of 2014), slightly offset by a $9 discrete income tax benefit for the release of a valuation allowance related to operations in Germany due to the initiation of a tax planning strategy. The effective tax rate for the 2015 and 2014 nine-month periods was 41.4% and 76.0%, respectively. The rate for the 2015 nine-month period differs from the U.S. federal statutory rate of 35% primarily due to a loss on the sale of a rolling mill in Russia (see Note E) for which no tax benefit was recognized, a $34 net discrete income tax charge as described below, and restructuring charges related to the curtailment of a refinery in Suriname (see Note D), a portion for which no tax benefit was recognized. These items were partially offset by foreign income taxed in lower rate jurisdictions. In the first quarter of 2015, AWAC, a joint venture owned 60% by Alcoa and 40% by Alumina Limited (Alcoa consolidates AWAC for financial reporting purposes), recognized an $83 discrete income tax charge (increased to $85 in the 2015 second quarter) for a valuation allowance on certain deferred tax assets, which were related mostly to employee benefits and tax loss carryforwards. Alcoa also had a $50 deferred tax liability (increased to $51 in the 2015 second quarter) related to its 60%-share of these deferred tax assets that was written off as a result of the valuation allowance recognized by AWAC. The rate for the 2014 nine-month period differs from the U.S. federal statutory rate of 35% primarily due to the previously mentioned $56 discrete income tax charge and a $44 unfavorable impact related to the interim period treatment of operational losses in certain foreign jurisdictions for which no tax benefit was recognized (impact reversed by the end of 2014).

Receivables	9 Months Ended
Receivables	Sep. 30, 2015
Transfers and Servicing [Abstract]
Receivables	L. Receivables – Alcoa has an arrangement with three financial institutions to sell certain customer receivables without recourse on a revolving basis. The sale of such receivables is completed through the use of a bankruptcy remote special purpose entity, which is a consolidated subsidiary of Alcoa. This arrangement provides for minimum funding of $200 up to a maximum of $500 for receivables sold. The initial sale of receivables in March 2012 resulted in the setup of a deferred purchase price of $254. Alcoa has received net cash funding of $250 ($1,308 in draws and $1,058 in repayments) since the program’s inception (no draws or repayments occurred in the 2015 nine-month period). As of September 30, 2015 and December 31, 2014, the deferred purchase price receivable was $361 and $356, respectively, which was included in Other receivables on the accompanying Consolidated Balance Sheet. The deferred purchase price receivable is reduced as collections of the underlying receivables occur; however, as this is a revolving program, the sale of new receivables will result in an increase in the deferred purchase price receivable. The net change in the deferred purchase price receivable was reflected in the (Increase) in receivables line item on the accompanying Statement of Consolidated Cash Flows. This activity is reflected as an operating cash flow because the related customer receivables are the result of an operating activity with an insignificant, short-term interest rate risk. The gross amount of receivables sold and total cash collected under this program since its inception was $22,990 and $22,379, respectively. Alcoa services the customer receivables for the financial institutions at market rates; therefore, no servicing asset or liability was recorded.

- Definition

The entire disclosure for a transferor's continuing involvement in financial assets that it has transferred in a securitization or asset-backed financing arrangement, the nature of any restrictions on assets reported by an entity in its statement of financial position that relate to a transferred financial asset (including the carrying amounts of such assets), how servicing assets and servicing liabilities are reported, and (for securitization or asset-backed financing arrangements accounted for as sales) when a transferor has continuing involvement with the transferred financial assets and transfers of financial assets accounted for as secured borrowings, how the transfer of financial assets affects an entity's financial position, financial performance, and cash flows.

+ References + Details

Pension and Other Postretirement Benefits

9 Months Ended

Sep. 30, 2015

Compensation and Retirement Disclosure [Abstract]

Pension and Other Postretirement Benefits

M. Pension and Other Postretirement Benefits – The components of net periodic benefit cost were as follows:


	Third quarter ended September 30,						Nine months ended September 30,
Pension benefits	2015			2014			2015			2014
Service cost	$	44		$	42		$	132		$	125
Interest cost		144			157			433			476
Expected return on plan assets		(189	)		(198	)		(566	)		(586	)
Recognized net actuarial loss		117			97			352			292
Amortization of prior service cost		4			5			12			14
Settlements*		13			18			14			18
Curtailments*		9			—			9			—
Special termination benefits*		—			—			12			—

Net periodic benefit cost	$	142		$	121		$	398		$	339

*	Except for Settlements of $2 in both the third quarter and nine months ended September 30, 2015, these amounts were recorded in Restructuring and other charges on the accompanying Statement of Consolidated Operations (see Note D).


	Third quarter ended September 30,						Nine months ended September 30,
Other postretirement benefits	2015			2014			2015			2014
Service cost	$	4		$	4		$	11		$	12
Interest cost		23			28			69			86
Recognized net actuarial loss		4			4			13			10
Amortization of prior service benefit		(9	)		(6	)		(28	)		(15	)
Curtailments*		(5	)		—			(6	)		—
Special termination benefits*		—			—			1			—

Net periodic benefit cost	$	17		$	30		$	60		$	93

*	These amounts were recorded in Restructuring and other charges on the accompanying Statement of Consolidated Operations (see Note D).

Derivatives and Other Financial Instruments

9 Months Ended

Sep. 30, 2015

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivatives and Other Financial Instruments

N. Derivatives and Other Financial Instruments

Fair Value

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The fair value hierarchy distinguishes between (i) market participant assumptions developed based on market data obtained from independent sources (observable inputs) and (ii) an entity’s own assumptions about market participant assumptions developed based on the best information available in the circumstances (unobservable inputs). The fair value hierarchy consists of three broad levels, which gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). The three levels of the fair value hierarchy are described below:

•

Level 1 - Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities.

•

Level 2 - Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly, including quoted prices for similar assets or liabilities in active markets; quoted prices for identical or similar assets or liabilities in markets that are not active; inputs other than quoted prices that are observable for the asset or liability (e.g., interest rates); and inputs that are derived principally from or corroborated by observable market data by correlation or other means.

•

Level 3 - Inputs that are both significant to the fair value measurement and unobservable.

Derivatives

Alcoa is exposed to certain risks relating to its ongoing business operations, including financial, market, political, and economic risks. The following discussion provides information regarding Alcoa’s exposure to the risks of changing commodity prices, interest rates, and foreign currency exchange rates.

Alcoa’s commodity and derivative activities are subject to the management, direction, and control of the Strategic Risk Management Committee (SRMC), which is composed of the chief executive officer, the chief financial officer, and other officers and employees that the chief executive officer selects. The SRMC meets on a periodic basis to review derivative positions and strategy and reports to Alcoa’s Board of Directors on the scope of its activities.

The aluminum, energy, interest rate, and foreign exchange contracts are held for purposes other than trading. They are used primarily to mitigate uncertainty and volatility, and to cover underlying exposures. Alcoa is not involved in trading activities for energy, weather derivatives, or other nonexchange commodity trading activities.

A number of Alcoa’s aluminum, energy, and foreign exchange contracts are classified as Level 1 and an interest rate contract is classified as Level 2 under the fair value hierarchy. These energy, foreign exchange, and interest rate contracts are not material to Alcoa’s Consolidated Financial Statements for all periods presented except as follows for a foreign exchange contract. Alcoa had a forward contract to purchase $231 (R$543) to mitigate the foreign currency risk associated with a potential future transaction denominated in Brazilian reais. This contract expired on March 31, 2014 and a loss of $4 was recognized in Other expenses, net on the accompanying Statement of Consolidated Operations in the 2014 first quarter.

For the aluminum contracts classified as Level 1, the total fair value of derivatives recorded as assets and liabilities was $6 and $54 and $2 and $31 at September 30, 2015 and December 31, 2014, respectively. These contracts were entered into to either hedge forecasted sales or purchases of aluminum in order to manage the associated aluminum price risk. Certain of these contracts are designated as hedging instruments, either fair value or cash flow, and the remaining are not designated as such. Combined, Alcoa recognized a net loss of $7 and a net gain of $34 in the 2015 third quarter and nine-month period, respectively, and a net loss of $2 and $15 in the 2014 third quarter and nine-month period, respectively, in Sales on the accompanying Statement of Consolidated Operations related to these aluminum contracts.

In addition to the Level 1 and 2 derivative instruments described above, Alcoa has nine derivative instruments classified as Level 3 under the fair value hierarchy. These instruments are composed of seven embedded aluminum derivatives, an energy contract, and an embedded credit derivative, all of which relate to energy supply contracts associated with eight smelters and three refineries. Five of the embedded aluminum derivatives and the energy contract were designated as cash flow hedging instruments and two of the embedded aluminum derivatives and the embedded credit derivative were not designated as hedging instruments.

The following section describes the valuation methodologies used by Alcoa to measure its Level 3 derivative instruments at fair value. Derivative instruments classified as Level 3 in the fair value hierarchy represent those in which management has used at least one significant unobservable input in the valuation model. Alcoa uses a discounted cash flow model to fair value all Level 3 derivative instruments. Where appropriate, the description below includes the key inputs to those models and any significant assumptions. These valuation models are reviewed and tested at least on an annual basis.

Inputs in the valuation models for Level 3 derivative instruments are composed of the following: (i) quoted market prices (e.g., aluminum prices on the 10-year London Metal Exchange (LME) forward curve and energy prices), (ii) significant other observable inputs (e.g., information concerning time premiums and volatilities for certain option type embedded derivatives and regional premiums for aluminum contracts), and (iii) unobservable inputs (e.g., aluminum and energy prices beyond those quoted in the market). For periods beyond the term of quoted market prices for aluminum, Alcoa estimates the price of aluminum by extrapolating the 10-year LME forward curve. Additionally, for periods beyond the term of quoted market prices for energy, management has developed a forward curve based on independent consultant market research. Where appropriate, valuations are adjusted for various factors such as liquidity, bid/offer spreads, and credit considerations. Such adjustments are generally based on available market evidence (Level 2). In the absence of such evidence, management’s best estimate is used (Level 3). If a significant input that is unobservable in one period becomes observable in a subsequent period, the related asset or liability would be transferred to the appropriate classification (Level 1 or 2) in the period of such change (there were no such transfers in the periods presented).

Alcoa has embedded derivatives in two power contracts that index the price of power to the LME price of aluminum. Additionally, in late 2014, Alcoa renewed three power contracts, each of which contain an embedded derivative that indexes the price of power to the LME price of aluminum plus the Midwest premium. The embedded derivatives in these five power contracts are primarily valued using observable market prices; however, due to the length of the contracts, the valuation models also require management to estimate the long-term price of aluminum based upon an extrapolation of the 10-year LME forward curve and/or 5-year Midwest premium curve. Significant increases or decreases in the actual LME price beyond 10 years and/or the Midwest premium beyond 5 years would result in a higher or lower fair value measurement. An increase in actual LME price and/or the Midwest premium over the inputs used in the valuation models will result in a higher cost of power and a corresponding decrease to the derivative asset or increase to the derivative liability. The embedded derivatives have been designated as cash flow hedges of forward sales of aluminum. Unrealized gains and losses were included in Other comprehensive loss on the accompanying Consolidated Balance Sheet while realized gains and losses were included in Sales on the accompanying Statement of Consolidated Operations.

Also, Alcoa has a power contract separate from above that contains an LME-linked embedded derivative. The embedded derivative is valued using the probability and interrelationship of future LME prices, Australian dollar to U.S. dollar exchange rates, and the U.S. consumer price index. Significant increases or decreases in the LME price would result in a higher or lower fair value measurement. An increase in actual LME price over the inputs used in the valuation model will result in a higher cost of power and a corresponding decrease to the derivative asset. This embedded derivative did not qualify for hedge accounting treatment. Unrealized gains and losses from the embedded derivative were included in Other (income) expenses, net on the accompanying Statement of Consolidated Operations while realized gains and losses were included in Cost of goods sold on the accompanying Statement of Consolidated Operations as electricity purchases were made under the contract. At the time this derivative asset was recognized, an equivalent amount was recognized as a deferred credit in Other noncurrent liabilities and deferred credits on the accompanying Consolidated Balance Sheet. This deferred credit is recognized in Other (income) expenses, net on the accompanying Statement of Consolidated Operations as power is received over the life of the contract. Alcoa had a similar power contract and related embedded derivative associated with another smelter and rolling mill combined; however, the contract and related derivative instrument matured in July 2014.

Additionally, Alcoa has a natural gas supply contract, which has an LME-linked ceiling. This embedded derivative is valued using probabilities of future LME aluminum prices and the price of Brent crude oil (priced on Platts), including the interrelationships between the two commodities subject to the ceiling. Any change in the interrelationship would result in a higher or lower fair value measurement. An LME ceiling was embedded into the contract price to protect against an increase in the price of oil without a corresponding increase in the price of LME. An increase in oil prices with no similar increase in the LME price would limit the increase of the price paid for natural gas. This embedded derivative did not qualify for hedge accounting treatment. Unrealized gains and losses from the embedded derivative were included in Other (income) expenses, net on the accompanying Statement of Consolidated Operations while realized gains and losses were included in Cost of goods sold on the accompanying Statement of Consolidated Operations as gas purchases were made under the contract.

Furthermore, Alcoa has an embedded derivative in a power contract that indexes the difference between the long-term debt ratings of Alcoa and the counterparty from any of the three major credit rating agencies. Management uses market prices, historical relationships, and forecast services to determine fair value. Significant increases or decreases in any of these inputs would result in a lower or higher fair value measurement. A wider credit spread between Alcoa and the counterparty would result in a higher cost of power and a corresponding increase in the derivative liability. This embedded derivative did not qualify for hedge accounting treatment. Unrealized gains and losses were included in Other (income) expenses, net on the accompanying Statement of Consolidated Operations while realized gains and losses were included in Cost of goods sold on the accompanying Statement of Consolidated Operations as electricity purchases were made under the contract.

Finally, Alcoa has a derivative contract that will hedge the anticipated power requirements at one of its smelters once the existing power contract expires in 2016. Beyond the term where market information is available, management has developed a forward curve, for valuation purposes, based on independent consultant market research. Significant increases or decreases in the power market may result in a higher or lower fair value measurement. Lower prices in the power market would cause a decrease in the derivative asset. The derivative contract has been designated as a cash flow hedge of future purchases of electricity. Unrealized gains and losses on this contract were recorded in Other comprehensive loss on the accompanying Consolidated Balance Sheet. Once the designated hedge period begins in 2016, realized gains and losses will be recorded in Cost of goods sold as electricity purchases are made under the power contract.

The following table presents quantitative information related to the significant unobservable inputs described above for Level 3 derivative contracts:


	Fair value at September 30, 2015		Unobservable input	Range ($ in full amounts)
Assets:
Embedded aluminum derivatives	$	784	Price of aluminum beyond forward curve	Aluminum: $2,160 per metric ton in 2026 to $2,347 per metric ton in 2029 (two contracts) and $2,643 per metric ton in 2036 (one contract) Midwest premium: $0.0795 per pound in 2021 to $0.0795 per pound in 2029 (two contracts) and 2036 (one contract)
Embedded aluminum derivative		87	Interrelationship of future aluminum prices, foreign currency exchange rates, and the U.S. consumer price index (CPI)	Aluminum: $1,562 per metric ton in 2015 to $1,615 per metric ton in 2016 Foreign currency: A$1 = $0.70 in 2015 to $0.70 in 2016 CPI: 1982 base year of 100 and 235 in 2015 to 239 in 2016
Embedded aluminum derivative		4	Interrelationship of LME price to overall energy price	Aluminum: $1,560 per metric ton in 2015 to $1,817 per metric ton in 2019
Embedded aluminum derivative		—	Interrelationship of future aluminum and oil prices	Aluminum: $1,562 per metric ton in 2015 to $1,762 per metric ton in 2018 Oil: $47 per barrel in 2015 to $60 per barrel in 2018
Liabilities:
Embedded aluminum derivative		223	Price of aluminum beyond forward curve	Aluminum: $2,160 per metric ton in 2026 to $2,239 per metric ton in 2027
Embedded credit derivative		32	Credit spread between Alcoa and counterparty	3.04% to 3.50% (3.27% median)
Energy contract		5	Price of electricity beyond forward curve	Electricity: $45 per megawatt hour in 2018 to $121 per megawatt hour in 2036

The fair values of Level 3 derivative instruments recorded as assets and liabilities in the accompanying Consolidated Balance Sheet were as follows:


	September 30, 2015		December 31, 2014
Asset Derivatives
Derivatives designated as hedging instruments:
Prepaid expenses and other current assets:
Embedded aluminum derivatives	$	70	$	24
Other noncurrent assets:
Embedded aluminum derivative		718		73
Energy contract		—		2

Total derivatives designated as hedging instruments	$	788	$	99


Derivatives not designated as hedging instruments:
Prepaid expenses and other current assets:
Embedded aluminum derivatives	$	87	$	98
Other noncurrent assets:
Embedded aluminum derivatives		—		71

Total derivatives not designated as hedging instruments	$	87	$	169


Total Asset Derivatives	$	875	$	268


Liability Derivatives
Derivatives designated as hedging instruments:
Other current liabilities:
Embedded aluminum derivative	$	11	$	24
Other noncurrent liabilities and deferred credits:
Embedded aluminum derivatives		213		352
Energy contract		4		—

Total derivatives designated as hedging instruments	$	228	$	376


Derivatives not designated as hedging instruments:
Other current liabilities:
Embedded credit derivative	$	4	$	2
Other noncurrent liabilities and deferred credits:
Embedded credit derivative		28		16

Total derivatives not designated as hedging instruments	$	32	$	18


Total Liability Derivatives	$	260	$	394

The following tables present a reconciliation of activity for Level 3 derivative contracts:


	Assets					Liabilities
Third quarter ended September 30, 2015	Embedded aluminum derivatives			Energy contract		Embedded aluminum derivatives			Embedded credit derivative		Energy contract
Opening balance – July 1, 2015	$	680		$	—	$	298		$	19	$	9
Total gains or losses (realized and unrealized) included in:
Sales		(2	)		—		(3	)		—		—
Cost of goods sold		(25	)		—		—			—		—
Other income, net		(4	)		—		—			13		—
Other comprehensive loss		229			—		(72	)		—		(5	)
Purchases, sales, issuances, and settlements*		—			—		—			—		—
Transfers into and/or out of Level 3*		—			—		—			—		—
Foreign currency translation		(3	)		—		—			—		1

Closing balance – September 30, 2015	$	875		$	—	$	223		$	32	$	5


Change in unrealized gains or losses included in earnings for derivative contracts held at September 30, 2015:
Sales	$	—		$	—	$	—		$	—	$	—
Cost of goods sold		—			—		—			—		—
Other income, net		(4	)		—		—			13		—

*	There were no purchases, sales, issuances or settlements of Level 3 derivative instruments. Additionally, there were no transfers of derivative instruments into or out of Level 3.


	Assets						Liabilities
Nine months ended September 30, 2015	Embedded aluminum derivatives			Energy contract			Embedded aluminum derivatives			Embedded credit derivative		Energy contract
Opening balance – January 1, 2015	$	266		$	2		$	376		$	18	$	—
Total gains or losses (realized and unrealized) included in:
Sales		11			—			(14	)		—		—
Cost of goods sold		(70	)		—			—			—		—
Other income, net		(5	)		—			—			14		—
Other comprehensive loss		680			(2	)		(139	)		—		4
Purchases, sales, issuances, and settlements*		—			—			—			—		—
Transfers into and/or out of Level 3*		—			—			—			—		—
Foreign currency translation		(7	)		—			—			—		1

Closing balance – September 30, 2015	$	875		$	—		$	223		$	32	$	5


Change in unrealized gains or losses included in earnings for derivative contracts held at September 30, 2015:
Sales	$	—		$	—		$	—		$	—	$	—
Cost of goods sold		—			—			—			—		—
Other income, net		(5	)		—			—			14		—

*	There were no purchases, sales, issuances or settlements of Level 3 derivative instruments. Additionally, there were no transfers of derivative instruments into or out of Level 3.

Derivatives Designated As Hedging Instruments – Cash Flow Hedges

For derivative instruments that are designated and qualify as cash flow hedges, the effective portion of unrealized gains or losses on the derivative is reported as a component of other comprehensive income (OCI). Realized gains or losses on the derivative are reclassified from OCI into earnings in the same period or periods during which the hedged transaction impacts earnings. Gains and losses on the derivative representing either hedge ineffectiveness or hedge components excluded from the assessment of effectiveness are recognized directly in earnings immediately.

Alcoa has five Level 3 embedded aluminum derivatives and one Level 3 energy contract that have been designated as cash flow hedges as follows.

Embedded aluminum derivatives. Alcoa has entered into energy supply contracts that contain pricing provisions related to the LME aluminum price. The LME-linked pricing features are considered embedded derivatives. Five of these embedded derivatives have been designated as cash flow hedges of forward sales of aluminum, three of which were new derivatives contained in three power contracts that were renewed in late 2014. At September 30, 2015 and December 31, 2014, these embedded aluminum derivatives hedge forecasted aluminum sales of 3,369 kmt and 3,610 kmt, respectively.

In the 2015 third quarter and nine-month period and the 2014 third quarter and nine-month period, Alcoa recognized an unrealized gain of $301 and $819 and an unrealized loss of $4 and $28, respectively, in Other comprehensive loss related to these five derivative instruments. Additionally, Alcoa reclassified a realized loss of $1 and $25 and $8 and $19 from Accumulated other comprehensive loss to Sales in the 2015 third quarter and nine-month period and the 2014 third quarter and nine-month period, respectively. Assuming market rates remain constant with the rates at September 30, 2015, a realized gain of $41 is expected to be recognized in Sales over the next 12 months.

In the 2015 third quarter and nine-month period and the 2014 third quarter and nine-month period, Alcoa also recognized a gain of less than $1 and $2 and a loss of less than $1 and $1, respectively, in Other (income) expenses, net related to the amount excluded from the assessment of hedge effectiveness. There was no ineffectiveness related to these five derivative instruments in the 2015 third quarter and nine-month period and the 2014 third quarter and nine-month period.

Energy contract. Alcoa has a derivative contract that will hedge the anticipated power requirements at one of its smelters once the existing power contract expires in 2016. At September 30, 2015 and December 31, 2014, this energy contract hedges forecasted electricity purchases of 59,409,328 megawatt hours. In the 2015 third quarter and nine-month period and the 2014 third quarter and nine-month period, Alcoa recognized an unrealized gain of $3 and an unrealized loss of $8 and an unrealized loss of $28 and $10, respectively, in Other comprehensive loss. There was no ineffectiveness related to the energy contract in the 2015 third quarter and nine-month period and the 2014 third quarter and nine-month period.

Derivatives Not Designated As Hedging Instruments

Alcoa has two Level 3 embedded aluminum derivatives and one Level 3 embedded credit derivative that do not qualify for hedge accounting treatment. As such, gains and losses related to the changes in fair value of these instruments are recorded directly in earnings. In the third quarter of 2015 and 2014, Alcoa recognized a loss of $17 and $21, respectively, in Other (income) expenses, net, of which a loss of $4 and $11, respectively, related to the two embedded aluminum derivatives and a loss of $13 and $10, respectively, related to the embedded credit derivative. In the nine-month period of 2015 and 2014, Alcoa recognized a loss of $19 and $15, respectively, in Other (income) expenses, net, of which a loss of $5 and $12, respectively, related to the two embedded aluminum derivatives and a loss of $14 and $3, respectively, related to the embedded credit derivative.

Material Limitations

The disclosures with respect to commodity prices, interest rates, and foreign currency exchange risk do not take into account the underlying commitments or anticipated transactions. If the underlying items were included in the analysis, the gains or losses on the futures contracts may be offset. Actual results will be determined by a number of factors that are not under Alcoa’s control and could vary significantly from those factors disclosed.

Alcoa is exposed to credit loss in the event of nonperformance by counterparties on the above instruments, as well as credit or performance risk with respect to its hedged customers’ commitments. Although nonperformance is possible, Alcoa does not anticipate nonperformance by any of these parties. Contracts are with creditworthy counterparties and are further supported by cash, treasury bills, or irrevocable letters of credit issued by carefully chosen banks. In addition, various master netting arrangements are in place with counterparties to facilitate settlement of gains and losses on these contracts.

Other Financial Instruments

The carrying values and fair values of Alcoa’s other financial instruments were as follows:


	September 30, 2015				December 31, 2014
	Carrying value		Fair value		Carrying value		Fair value
Cash and cash equivalents	$	1,739	$	1,739	$	1,877	$	1,877
Restricted cash		24		24		20		20
Noncurrent receivables		17		17		17		17
Available-for-sale securities		177		177		153		153
Short-term borrowings		50		50		54		54
Commercial paper		—		—		—		—
Long-term debt due within one year		136		136		29		29
Long-term debt, less amount due within one year		9,091		9,062		8,769		9,445

The following methods were used to estimate the fair values of other financial instruments:

Cash and cash equivalents, Restricted cash, Short-term borrowings, and Commercial paper. The carrying amounts approximate fair value because of the short maturity of the instruments. The fair value amounts for Cash and cash equivalents, Restricted cash, and Commercial paper were classified in Level 1, and Short-term borrowings were classified in Level 2.

Noncurrent receivables. The fair value of noncurrent receivables was based on anticipated cash flows, which approximates carrying value, and was classified in Level 2 of the fair value hierarchy.

Available-for-sale securities. The fair value of such securities was based on quoted market prices. These financial instruments consist of exchange-traded fixed income and equity securities, which are carried at fair value and were classified in Level 1 of the fair value hierarchy.

Long-term debt due within one year and Long-term debt, less amount due within one year. The fair value was based on quoted market prices for public debt and on interest rates that are currently available to Alcoa for issuance of debt with similar terms and maturities for non-public debt. The fair value amounts for all Long-term debt were classified in Level 2 of the fair value hierarchy.

- Definition

The entire disclosure for derivative instruments and hedging activities including, but not limited to, risk management strategies, non-hedging derivative instruments, assets, liabilities, revenue and expenses, and methodologies and assumptions used in determining the amounts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
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Reference 14: http://www.xbrl.org/2003/role/presentationRef
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Reference 15: http://www.xbrl.org/2003/role/presentationRef
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Reference 19: http://www.xbrl.org/2003/role/presentationRef
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+ Details

Proposed Separation Transaction	9 Months Ended
Proposed Separation Transaction	Sep. 30, 2015
Text Block [Abstract]
Proposed Separation Transaction	O. Proposed Separation Transaction – On September 28, 2015, Alcoa announced that its Board of Directors approved a plan to separate into two independent, publicly-traded companies. One company will comprise the Alumina and Primary Metals segments and the other company will comprise the Global Rolled Products, Engineered Products and Solutions, and Transportation and Construction Solutions segments. Alcoa is targeting to complete the separation in the second half of 2016. The transaction is subject to a number of conditions, including, but not limited to, final approval by Alcoa’s Board of Directors, receipt of a favorable opinion of legal counsel with respect to the tax-free nature of the transaction for U.S. federal income tax purposes, and the effectiveness of a Form 10 registration statement to be filed with the U.S. Securities and Exchange Commission. Upon completion of the separation, Alcoa shareholders will own all of the outstanding shares of both companies. Alcoa may, at any time and for any reason until the proposed transaction is complete, abandon the separation plan or modify or change its terms.

Subsequent Events	9 Months Ended
Subsequent Events	Sep. 30, 2015
Subsequent Events [Abstract]
Subsequent Events	P. Subsequent Events – Management evaluated all activity of Alcoa and concluded that no subsequent events have occurred that would require recognition in the Consolidated Financial Statements or disclosure in the Notes to the Consolidated Financial Statements.

Accumulated Other Comprehensive Loss (Tables)

9 Months Ended

Sep. 30, 2015

Equity [Abstract]

Summary of Changes in Accumulated Other Comprehensive Loss by Component

The following table details the activity of the four components that comprise Accumulated other comprehensive loss for both Alcoa’s shareholders and noncontrolling interests:


	Alcoa						Noncontrolling Interests
	Third quarter ended September 30,						Third quarter ended September 30,
	2015			2014			2015			2014
Pension and other postretirement benefits (M)
Balance at beginning of period	$	(3,500	)	$	(3,441	)	$	(59	)	$	(50	)
Other comprehensive income (loss):
Unrecognized net actuarial loss and prior service cost/benefit		46			96			10			(9	)
Tax (expense) benefit		(10	)		(33	)		(1	)		3

Total Other comprehensive income (loss) before reclassifications, net of tax		36			63			9			(6	)

Amortization of net actuarial loss and prior service cost/benefit⁽¹⁾		116			97			—			3
Tax expense⁽²⁾		(41	)		(34	)		—			(1	)

Total amount reclassified from Accumulated other comprehensive loss, net of tax⁽⁸⁾		75			63			—			2

Total Other comprehensive income (loss)		111			126			9			(4	)

Balance at end of period	$	(3,389	)	$	(3,315	)	$	(50	)	$	(54	)


Foreign currency translation
Balance at beginning of period	$	(1,606	)	$	569		$	(569	)	$	36
Other comprehensive loss⁽³⁾		(889	)		(774	)		(299	)		(226	)

Balance at end of period	$	(2,495	)	$	(205	)	$	(868	)	$	(190	)


Available-for-sale securities
Balance at beginning of period	$	—		$	3		$	—		$	—
Other comprehensive (loss) income⁽⁴⁾		(2	)		(1	)		—			—

Balance at end of period	$	(2	)	$	2		$	—		$	—


Cash flow hedges (N)
Balance at beginning of period	$	140		$	(299	)	$	(6	)	$	(8	)
Other comprehensive income (loss):
Net change from periodic revaluations		288			(35	)		1			7
Tax (expense) benefit		(79	)		11			—			(2	)

Total Other comprehensive income (loss) before reclassifications, net of tax		209			(24	)		1			5

Net amount reclassified to earnings:
Aluminum contracts⁽⁵⁾		3			7			—			—
Foreign exchange contracts⁽⁵⁾		2			(1	)		—			—
Nickel contracts⁽⁶⁾		1			—			—			—

Sub-total		6			6			—			—
Tax expense⁽²⁾		(1	)		(1	)		—			—

Total amount reclassified from Accumulated other comprehensive income (loss), net of tax⁽⁸⁾		5			5			—			—

Total Other comprehensive income (loss)		214			(19	)		1			5

Balance at end of period	$	354		$	(318	)	$	(5	)	$	(3	)


	Alcoa						Noncontrolling Interests
	Nine months ended September 30,						Nine months ended September 30,
	2015			2014			2015			2014
Pension and other postretirement benefits (M)
Balance at beginning of period	$	(3,601	)	$	(3,532	)	$	(64	)	$	(51	)
Other comprehensive income (loss):
Unrecognized net actuarial loss and prior service cost/benefit		(30	)		33			13			(9	)
Tax benefit (expense)		18			(8	)		(1	)		3

Total Other comprehensive (loss) income before reclassifications, net of tax		(12	)		25			12			(6	)

Amortization of net actuarial loss and prior service cost/benefit⁽¹⁾		345			296			4			5
Tax expense⁽²⁾		(121	)		(104	)		(2	)		(2	)

Total amount reclassified from Accumulated other comprehensive loss, net of tax⁽⁸⁾		224			192			2			3

Total Other comprehensive income (loss)		212			217			14			(3	)

Balance at end of period	$	(3,389	)	$	(3,315	)	$	(50	)	$	(54	)


Foreign currency translation
Balance at beginning of period	$	(846	)	$	179		$	(351	)	$	(110	)
Other comprehensive loss⁽³⁾		(1,649	)		(384	)		(517	)		(80	)

Balance at end of period	$	(2,495	)	$	(205	)	$	(868	)	$	(190	)


Available-for-sale securities
Balance at beginning of period	$	—		$	2		$	—		$	—
Other comprehensive loss⁽⁴⁾		(2	)		—			—			—

Balance at end of period	$	(2	)	$	2		$	—		$	—


Cash flow hedges (N)
Balance at beginning of period	$	(230	)	$	(308	)	$	(2	)	$	(2	)
Other comprehensive income (loss):
Net change from periodic revaluations		792			(31	)		(4	)		(2	)
Tax (expense) benefit		(235	)		7			1			1

Total Other comprehensive income (loss) before reclassifications, net of tax		557			(24	)		(3	)		(1	)

Net amount reclassified to earnings:
Aluminum contracts⁽⁵⁾		26			18			—			—
Energy contracts⁽⁶⁾		4			—			—			—
Foreign exchange contracts⁽⁵⁾		3			(2	)		—			—
Interest rate contracts⁽⁷⁾		1			1			—			—
Nickel contracts⁽⁶⁾		1			—			—			—

Sub-total		35			17			—			—
Tax expense⁽²⁾		(8	)		(3	)		—			—

Total amount reclassified from Accumulated other comprehensive loss, net of tax⁽⁸⁾		27			14			—			—

Total Other comprehensive income (loss)		584			(10	)		(3	)		(1	)

Balance at end of period	$	354		$	(318	)	$	(5	)	$	(3	)

⁽¹⁾	These amounts were included in the computation of net periodic benefit cost for pension and other postretirement benefits (see Note M).

⁽²⁾	These amounts were included in Provision for income taxes on the accompanying Statement of Consolidated Operations.

⁽³⁾	In all periods presented, there were no tax impacts related to rate changes and no amounts were reclassified to earnings.

⁽⁴⁾	In all periods presented, unrealized and realized gains and losses related to these securities were immaterial. Realized gains and losses were included in Other (income) expenses, net on the accompanying Statement of Consolidated Operations.

⁽⁵⁾	These amounts were included in Sales on the accompanying Statement of Consolidated Operations.

⁽⁶⁾	These amounts were included in Cost of goods sold on the accompanying Statement of Consolidated Operations.

⁽⁷⁾	These amounts were included in Interest expense on the accompanying Statement of Consolidated Operations.

⁽⁸⁾	A positive amount indicates a corresponding charge to earnings and a negative amount indicates a corresponding benefit to earnings. These amounts were reflected on the accompanying Statement of Consolidated Operations in the line items indicated in footnotes 1 through 7.

Restructuring and Other Charges (Tables)

9 Months Ended

Sep. 30, 2015

Restructuring and Related Activities [Abstract]

Schedule of Restructuring and Other Charges by Reportable Segments, Pretax

The pretax impact of allocating such charges to segment results would have been as follows:


	Third quarter ended September 30,					Nine months ended September 30,
	2015			2014		2015		2014
Alumina	$	38		$	1	$	55	$	8
Primary Metals		11			193		209		608
Global Rolled Products		(17	)		13		119		126
Engineered Products and Solutions		22			—		33		1
Transportation and Construction Solutions		3			—		6		3

Segment total		57			207		422		746
Corporate		9			2		38		34

Total restructuring and other charges	$	66		$	209	$	460	$	780

Activity and Reserve Balances for Restructuring Charges

Activity and reserve balances for restructuring charges were as follows:


	Layoff costs			Other exit costs			Total
Reserve balances at December 31, 2013	$	96		$	42		$	138

2014:
Cash payments		(191	)		(22	)		(213	)
Restructuring charges		259			194			453
Other*		(66	)		(180	)		(246	)

Reserve balances at December 31, 2014		98			34			132

2015:
Cash payments		(100	)		(9	)		(109	)
Restructuring charges		111			89			200
Other*		(52	)		(90	)		(142	)

Reserve balances at September 30, 2015	$	57		$	24		$	81

Acquisitions and Divestitures (Tables)

9 Months Ended

Sep. 30, 2015

Business Combinations [Abstract]

Summary of Preliminary Allocation of Purchase Price by Major Asset Acquired and Liability Assumed and Amount of Goodwill Recognized

The following table represents the preliminary allocation of the purchase price by major asset acquired and liability assumed, as well as the amount of goodwill recognized:


Assets:
Cash and cash equivalents	$	302
Receivables from customers		103
Inventories		538
Other current assets		68
Properties, plants, and equipment, net		436
Goodwill		209
Other noncurrent assets		91

Total assets	$	1,747


Liabilities:
Accounts payable	$	90
Long-term debt due within one year		115
Other current liabilities		93
Long-term debt		440
Other noncurrent liabilities		139

Total liabilities	$	877

Inventories (Tables)

9 Months Ended

Sep. 30, 2015

Inventory Disclosure [Abstract]

Schedule of Inventory Components


	September 30, 2015		December 31, 2014
Finished goods	$	850	$	768
Work-in-process		1,233		1,035
Bauxite and alumina		493		578
Purchased raw materials		790		508
Operating supplies		193		193

	$	3,559	$	3,082

Other (Income) Expenses, Net (Tables)

9 Months Ended

Sep. 30, 2015

Other Income and Expenses [Abstract]

Schedule of Other (Income) Expenses, Net


	Third quarter ended September 30,						Nine months ended September 30,
	2015			2014			2015			2014
Equity loss	$	24		$	16		$	68		$	84
Interest income		(4	)		(3	)		(11	)		(13	)
Foreign currency gains, net		(17	)		(5	)		(27	)		—
Net gain from asset sales		(41	)		(15	)		(69	)		(44	)
Net loss on mark-to-market derivative contracts (N)		16			20			19			17
Other, net		7			10			(7	)		9

	$	(15	)	$	23		$	(27	)	$	53

Segment Information (Tables)

9 Months Ended

Sep. 30, 2015

Segment Reporting [Abstract]

Schedule of Operating Results of Alcoa's Reportable Segments

The operating results of Alcoa’s reportable segments were as follows (differences between segment totals and consolidated totals are in Corporate):


	Alumina			Primary Metals			Global Rolled Products			Engineered Products and Solutions		Transportation and Construction Solutions		Total
Third quarter ended September 30, 2015
Sales:
Third-party sales	$	912		$	1,249		$	1,527		$	1,397	$	475	$	5,560
Intersegment sales		391			479			29			—		—		899

Total sales	$	1,303		$	1,728		$	1,556		$	1,397	$	475	$	6,459

Profit and loss:
Equity loss	$	(9	)	$	(7	)	$	(8	)	$	—	$	—	$	(24	)
Depreciation, depletion, and amortization		71			106			56			61		11		305
Income taxes		85			(49	)		28			71		18		153
After-tax operating income (ATOI)		212			(59	)		62			151		44		410
Third quarter ended September 30, 2014
Sales:
Third-party sales	$	886		$	1,865		$	1,926		$	1,034	$	523	$	6,234
Intersegment sales		482			730			52			—		—		1,264

Total sales	$	1,368		$	2,595		$	1,978		$	1,034	$	523	$	7,498

Profit and loss:
Equity loss	$	(7	)	$	—		$	(8	)	$	—	$	—	$	(15	)
Depreciation, depletion, and amortization		100			124			62			32		10		328
Income taxes		26			95			26			78		20		245
ATOI		62			245			69			155		50		581


	Alumina			Primary Metals			Global Rolled Products			Engineered Products and Solutions		Transportation and Construction Solutions		Total
Nine months ended September 30, 2015
Sales:
Third-party sales	$	2,723		$	4,355		$	4,816		$	3,933	$	1,438	$	17,265
Intersegment sales		1,323			1,733			99			—		—		3,155

Total sales	$	4,046		$	6,088		$	4,915		$	3,933	$	1,438	$	20,420

Profit and loss:
Equity loss	$	(27	)	$	(15	)	$	(24	)	$	—	$	—	$	(66	)
Depreciation, depletion, and amortization		228			324			168			166		32		918
Income taxes		264			14			89			228		49		644
ATOI		648			195			192			472		126		1,633
Nine months ended September 30, 2014
Sales:
Third-party sales	$	2,492		$	4,948		$	5,463		$	3,103	$	1,521	$	17,527
Intersegment sales		1,472			2,182			139			—		—		3,793

Total sales	$	3,964		$	7,130		$	5,602		$	3,103	$	1,521	$	21,320

Profit and loss:
Equity loss	$	(19	)	$	(45	)	$	(19	)	$	—	$	—	$	(83	)
Depreciation, depletion, and amortization		297			377			178			95		31		978
Income taxes		78			114			73			234		55		554
ATOI		192			327			193			455		142		1,309

Schedule of Segment ATOI to Consolidated Net Income Attributable to Alcoa

The following table reconciles total segment ATOI to consolidated net income attributable to Alcoa:


	Third quarter ended September 30,						Nine months ended September 30,
	2015			2014			2015			2014
Total segment ATOI	$	410		$	581		$	1,633		$	1,309
Unallocated amounts (net of tax):
Impact of LIFO		50			(18	)		93			(33	)
Metal price lag		(48	)		38			(110	)		56
Interest expense		(80	)		(81	)		(240	)		(228	)
Noncontrolling interests		(62	)		18			(189	)		46
Corporate expense		(72	)		(72	)		(199	)		(204	)
Restructuring and other charges		(48	)		(189	)		(368	)		(587	)
Other		(106	)		(128	)		(241	)		(250	)

Consolidated net income attributable to Alcoa	$	44		$	149		$	379		$	109

Earnings Per Share (Tables)

9 Months Ended

Sep. 30, 2015

Earnings Per Share [Abstract]

Reconciliation of Information Used to Compute Basic and Diluted EPS

The information used to compute basic and diluted EPS attributable to Alcoa common shareholders was as follows (shares in millions):


	Third quarter ended September 30,				Nine months ended September 30,
	2015		2014		2015		2014
Net income attributable to Alcoa	$	44	$	149	$	379	$	109
Less: preferred stock dividends declared		18		—		52		1

Net income available to Alcoa common shareholders – basic		26		149		327		108
Add: dividends related to mandatory convertible preferred stock		—		—		—		—
Add: interest expense related to convertible notes		—		—		—		—

Net income available to Alcoa common shareholders – diluted	$	26	$	149	$	327	$	108

Average shares outstanding – basic		1,281		1,177		1,241		1,150
Effect of dilutive securities:
Stock options		1		8		4		6
Stock and performance awards		12		12		12		11
Mandatory convertible preferred stock		—		8		—		3
Convertible notes		—		—		—		—

Average shares outstanding – diluted		1,294		1,205		1,257		1,170

Pension and Other Postretirement Benefits (Tables)

9 Months Ended

Sep. 30, 2015

Compensation and Retirement Disclosure [Abstract]

Components of Net Periodic Benefit Cost

The components of net periodic benefit cost were as follows:


	Third quarter ended September 30,						Nine months ended September 30,
Pension benefits	2015			2014			2015			2014
Service cost	$	44		$	42		$	132		$	125
Interest cost		144			157			433			476
Expected return on plan assets		(189	)		(198	)		(566	)		(586	)
Recognized net actuarial loss		117			97			352			292
Amortization of prior service cost		4			5			12			14
Settlements*		13			18			14			18
Curtailments*		9			—			9			—
Special termination benefits*		—			—			12			—

Net periodic benefit cost	$	142		$	121		$	398		$	339

*	Except for Settlements of $2 in both the third quarter and nine months ended September 30, 2015, these amounts were recorded in Restructuring and other charges on the accompanying Statement of Consolidated Operations (see Note D).


	Third quarter ended September 30,						Nine months ended September 30,
Other postretirement benefits	2015			2014			2015			2014
Service cost	$	4		$	4		$	11		$	12
Interest cost		23			28			69			86
Recognized net actuarial loss		4			4			13			10
Amortization of prior service benefit		(9	)		(6	)		(28	)		(15	)
Curtailments*		(5	)		—			(6	)		—
Special termination benefits*		—			—			1			—

Net periodic benefit cost	$	17		$	30		$	60		$	93

*	These amounts were recorded in Restructuring and other charges on the accompanying Statement of Consolidated Operations (see Note D).

Derivatives and Other Financial Instruments (Tables)

9 Months Ended

Sep. 30, 2015

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Quantitative Information for Level 3 Derivative Contracts

The following table presents quantitative information related to the significant unobservable inputs described above for Level 3 derivative contracts:


	Fair value at September 30, 2015		Unobservable input	Range ($ in full amounts)
Assets:
Embedded aluminum derivatives	$	784	Price of aluminum beyond forward curve	Aluminum: $2,160 per metric ton in 2026 to $2,347 per metric ton in 2029 (two contracts) and $2,643 per metric ton in 2036 (one contract) Midwest premium: $0.0795 per pound in 2021 to $0.0795 per pound in 2029 (two contracts) and 2036 (one contract)
Embedded aluminum derivative		87	Interrelationship of future aluminum prices, foreign currency exchange rates, and the U.S. consumer price index (CPI)	Aluminum: $1,562 per metric ton in 2015 to $1,615 per metric ton in 2016 Foreign currency: A$1 = $0.70 in 2015 to $0.70 in 2016 CPI: 1982 base year of 100 and 235 in 2015 to 239 in 2016
Embedded aluminum derivative		4	Interrelationship of LME price to overall energy price	Aluminum: $1,560 per metric ton in 2015 to $1,817 per metric ton in 2019
Embedded aluminum derivative		—	Interrelationship of future aluminum and oil prices	Aluminum: $1,562 per metric ton in 2015 to $1,762 per metric ton in 2018 Oil: $47 per barrel in 2015 to $60 per barrel in 2018
Liabilities:
Embedded aluminum derivative		223	Price of aluminum beyond forward curve	Aluminum: $2,160 per metric ton in 2026 to $2,239 per metric ton in 2027
Embedded credit derivative		32	Credit spread between Alcoa and counterparty	3.04% to 3.50% (3.27% median)
Energy contract		5	Price of electricity beyond forward curve	Electricity: $45 per megawatt hour in 2018 to $121 per megawatt hour in 2036

Schedule of Fair Values of Level 3 Derivative Instruments Recorded as Assets and Liabilities

The fair values of Level 3 derivative instruments recorded as assets and liabilities in the accompanying Consolidated Balance Sheet were as follows:


	September 30, 2015		December 31, 2014
Asset Derivatives
Derivatives designated as hedging instruments:
Prepaid expenses and other current assets:
Embedded aluminum derivatives	$	70	$	24
Other noncurrent assets:
Embedded aluminum derivative		718		73
Energy contract		—		2

Total derivatives designated as hedging instruments	$	788	$	99


Derivatives not designated as hedging instruments:
Prepaid expenses and other current assets:
Embedded aluminum derivatives	$	87	$	98
Other noncurrent assets:
Embedded aluminum derivatives		—		71

Total derivatives not designated as hedging instruments	$	87	$	169


Total Asset Derivatives	$	875	$	268


Liability Derivatives
Derivatives designated as hedging instruments:
Other current liabilities:
Embedded aluminum derivative	$	11	$	24
Other noncurrent liabilities and deferred credits:
Embedded aluminum derivatives		213		352
Energy contract		4		—

Total derivatives designated as hedging instruments	$	228	$	376


Derivatives not designated as hedging instruments:
Other current liabilities:
Embedded credit derivative	$	4	$	2
Other noncurrent liabilities and deferred credits:
Embedded credit derivative		28		16

Total derivatives not designated as hedging instruments	$	32	$	18


Total Liability Derivatives	$	260	$	394

Schedule of Reconciliation of Activity for Derivative Contracts

The following tables present a reconciliation of activity for Level 3 derivative contracts:


	Assets					Liabilities
Third quarter ended September 30, 2015	Embedded aluminum derivatives			Energy contract		Embedded aluminum derivatives			Embedded credit derivative		Energy contract
Opening balance – July 1, 2015	$	680		$	—	$	298		$	19	$	9
Total gains or losses (realized and unrealized) included in:
Sales		(2	)		—		(3	)		—		—
Cost of goods sold		(25	)		—		—			—		—
Other income, net		(4	)		—		—			13		—
Other comprehensive loss		229			—		(72	)		—		(5	)
Purchases, sales, issuances, and settlements*		—			—		—			—		—
Transfers into and/or out of Level 3*		—			—		—			—		—
Foreign currency translation		(3	)		—		—			—		1

Closing balance – September 30, 2015	$	875		$	—	$	223		$	32	$	5


Change in unrealized gains or losses included in earnings for derivative contracts held at September 30, 2015:
Sales	$	—		$	—	$	—		$	—	$	—
Cost of goods sold		—			—		—			—		—
Other income, net		(4	)		—		—			13		—

*	There were no purchases, sales, issuances or settlements of Level 3 derivative instruments. Additionally, there were no transfers of derivative instruments into or out of Level 3.


	Assets						Liabilities
Nine months ended September 30, 2015	Embedded aluminum derivatives			Energy contract			Embedded aluminum derivatives			Embedded credit derivative		Energy contract
Opening balance – January 1, 2015	$	266		$	2		$	376		$	18	$	—
Total gains or losses (realized and unrealized) included in:
Sales		11			—			(14	)		—		—
Cost of goods sold		(70	)		—			—			—		—
Other income, net		(5	)		—			—			14		—
Other comprehensive loss		680			(2	)		(139	)		—		4
Purchases, sales, issuances, and settlements*		—			—			—			—		—
Transfers into and/or out of Level 3*		—			—			—			—		—
Foreign currency translation		(7	)		—			—			—		1

Closing balance – September 30, 2015	$	875		$	—		$	223		$	32	$	5


Change in unrealized gains or losses included in earnings for derivative contracts held at September 30, 2015:
Sales	$	—		$	—		$	—		$	—	$	—
Cost of goods sold		—			—			—			—		—
Other income, net		(5	)		—			—			14		—

*	There were no purchases, sales, issuances or settlements of Level 3 derivative instruments. Additionally, there were no transfers of derivative instruments into or out of Level 3.

Schedule of Carrying Values and Fair Values of Other Financial Instruments

The carrying values and fair values of Alcoa’s other financial instruments were as follows:


	September 30, 2015				December 31, 2014
	Carrying value		Fair value		Carrying value		Fair value
Cash and cash equivalents	$	1,739	$	1,739	$	1,877	$	1,877
Restricted cash		24		24		20		20
Noncurrent receivables		17		17		17		17
Available-for-sale securities		177		177		153		153
Short-term borrowings		50		50		54		54
Commercial paper		—		—		—		—
Long-term debt due within one year		136		136		29		29
Long-term debt, less amount due within one year		9,091		9,062		8,769		9,445

Recently Adopted and Recently Issued Accounting Guidance - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	Aug. 31, 2015	Sep. 30, 2015	Sep. 30, 2014
Accounting Changes and Error Corrections [Abstract]
Decrease in other noncurrent assets	$ (60)	$ 348	$ (5)
Decrease in long term debt non current	$ (60)

Accumulated Other Comprehensive Loss - Summary of Changes in Accumulated Other Comprehensive Loss by Component (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Pension and other postretirement benefits
Total Other comprehensive income (loss)	$ 120	$ 122	$ 226	$ 214
Foreign currency translation
Other comprehensive loss	(1,188)	(1,000)	(2,166)	(464)
Available-for-sale securities
Other comprehensive (loss) income	(2)	(1)	(2)
Cash flow hedges
Total Other comprehensive income (loss)	215	(14)	581	(11)
Energy Contracts [Member]
Cash flow hedges
Total Other comprehensive income (loss) before reclassifications, net of tax	3	(28)	(8)	(10)
Alcoa [Member]
Pension and other postretirement benefits
Balance at beginning of period	(3,500)	(3,441)	(3,601)	(3,532)
Unrecognized net actuarial loss and prior service cost/benefit	46	96	(30)	33
Tax (expense) benefit	(10)	(33)	18	(8)
Total Other comprehensive (loss) income before reclassifications, net of tax	36	63	(12)	25
Amortization of net actuarial loss and prior service cost/benefit	116	97	345	296
Tax expense	(41)	(34)	(121)	(104)
Total amount reclassified from Accumulated other comprehensive loss, net of tax	75	63	224	192
Total Other comprehensive income (loss)	111	126	212	217
Balance at end of period	(3,389)	(3,315)	(3,389)	(3,315)
Foreign currency translation
Balance at beginning of period	(1,606)	569	(846)	179
Other comprehensive loss	(889)	(774)	(1,649)	(384)
Balance at end of period	(2,495)	(205)	(2,495)	(205)
Available-for-sale securities
Balance at beginning of period		3		2
Other comprehensive (loss) income	(2)	(1)	(2)
Balance at end of period	(2)	2	(2)	2
Cash flow hedges
Balance at beginning of period	140	(299)	(230)	(308)
Net change from periodic revaluations	288	(35)	792	(31)
Tax (expense) benefit	(79)	11	(235)	7
Total Other comprehensive income (loss) before reclassifications, net of tax	209	(24)	557	(24)
Net amount reclassified to earnings	6	6	35	17
Tax expense	(1)	(1)	(8)	(3)
Total amount reclassified from Accumulated other comprehensive income (loss), net of tax	5	5	27	14
Total Other comprehensive income (loss)	214	(19)	584	(10)
Balance at end of period	354	(318)	354	(318)
Alcoa [Member] \| Aluminum Contracts [Member]
Cash flow hedges
Net amount reclassified to earnings	3	7	26	18
Alcoa [Member] \| Energy Contracts [Member]
Cash flow hedges
Net amount reclassified to earnings			4
Alcoa [Member] \| Foreign Exchange Contracts [Member]
Cash flow hedges
Net amount reclassified to earnings	2	(1)	3	(2)
Alcoa [Member] \| Interest Rate Contracts [Member]
Cash flow hedges
Net amount reclassified to earnings			1	1
Alcoa [Member] \| Nickel Contracts [Member]
Cash flow hedges
Net amount reclassified to earnings	1		1
Noncontrolling Interests [Member]
Pension and other postretirement benefits
Balance at beginning of period	(59)	(50)	(64)	(51)
Unrecognized net actuarial loss and prior service cost/benefit	10	(9)	13	(9)
Tax (expense) benefit	(1)	3	(1)	3
Total Other comprehensive (loss) income before reclassifications, net of tax	9	(6)	12	(6)
Amortization of net actuarial loss and prior service cost/benefit		3	4	5
Tax expense		(1)	(2)	(2)
Total amount reclassified from Accumulated other comprehensive loss, net of tax		2	2	3
Total Other comprehensive income (loss)	9	(4)	14	(3)
Balance at end of period	(50)	(54)	(50)	(54)
Foreign currency translation
Balance at beginning of period	(569)	36	(351)	(110)
Other comprehensive loss	(299)	(226)	(517)	(80)
Balance at end of period	(868)	(190)	(868)	(190)
Cash flow hedges
Balance at beginning of period	(6)	(8)	(2)	(2)
Net change from periodic revaluations	1	7	(4)	(2)
Tax (expense) benefit		(2)	1	1
Total Other comprehensive income (loss) before reclassifications, net of tax	1	5	(3)	(1)
Total Other comprehensive income (loss)	1	5	(3)	(1)
Balance at end of period	$ (5)	$ (3)	$ (5)	$ (3)

Restructuring and Other Charges - Additional Information (Detail)		1 Months Ended				3 Months Ended				9 Months Ended		12 Months Ended
	Sep. 30, 2015 Employees	Aug. 31, 2014	Jun. 30, 2014 t	May 31, 2014 t	May 31, 2013 t	Sep. 30, 2015 USD ($) Employees t	Jun. 30, 2015 t	Sep. 30, 2014 USD ($) Employees Plant Facilities t	Mar. 31, 2014 t	Sep. 30, 2015 USD ($) Employees t	Sep. 30, 2014 USD ($) Employees Plant Facilities	Dec. 31, 2014 Employees
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges						$ 66,000,000		$ 209,000,000		$ 460,000,000	$ 780,000,000
Restructuring and other charges, after-tax and noncontrolling interest						$ 30,000,000		175,000,000		$ 329,000,000	$ 503,000,000
Capacity of lines under review \| t					460,000
Number of employees associated with layoff costs \| Employees						370				970
Number of employees associated with layoff costs \| Employees											245
Capacity of lines under review period					15 months
Minimum amount of cash payments expected to be paid beyond the end of the current annual period										$ 50,000,000
Maximum amount of cash payments expected to be paid beyond the end of the current annual period										55,000,000
Corporate [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges						$ 9,000,000		$ 2,000,000		$ 38,000,000	$ 34,000,000
Number of employees associated with layoff costs \| Employees										50
Number of employees associated with layoff costs \| Employees											90
Smelter [Member]
Restructuring Cost and Reserve [Line Items]
Number of plants permanently shut down and demolished \| Plant								2			3
Number of plants temporarily curtailed \| Plant											2
Rolling Mill [Member]
Restructuring Cost and Reserve [Line Items]
Number of plants permanently shut down and demolished \| Plant								2			2
Primary Metals [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges										$ 80,000,000
Restructuring and other charges, after-tax and noncontrolling interest										$ 43,000,000
Number of employees associated with layoff costs \| Employees										165
Global Rolled Products [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs \| Employees										70
Number of employees associated with layoff costs \| Employees											30
Alumina [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs \| Employees											10
Transportation and Construction Solutions [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs \| Employees						355				410
Number of employees associated with layoff costs \| Employees											50
Corporate and Three Other Segments [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs \| Employees						15
Engineered Products and Solutions [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs \| Employees										275
Number of employees associated with layoff costs \| Employees											65
Pocos De Caldas Refinery [Member]
Restructuring Cost and Reserve [Line Items]
Capacity of lines under review \| t			200,000	62,000
Reduction in production - result of market conditions, in mt per year \| t							96,000
Sao Luis Smelter [Member]
Restructuring Cost and Reserve [Line Items]
Capacity of lines under review \| t				85,000						74,000
Sao Luis Smelter [Member] \| Primary Metals [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs \| Employees										680
Suriname [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges						$ 42,000,000
Restructuring and other charges, after-tax and noncontrolling interest						$ 20,000,000
Capacity of lines under review \| t						887,000				1,330,000
Suriname [Member] \| Alumina [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs \| Employees										120
Sao Luis Smelter and Suriname [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs \| Employees										800
Point Henry Smelter [Member]
Restructuring Cost and Reserve [Line Items]
Power supplied as percentage of plant total power requirement		40.00%
Reduction in production - result of market conditions, in mt per year \| t									190,000
Massena East Smelter [Member]
Restructuring Cost and Reserve [Line Items]
Reduction in production - result of market conditions, in mt per year \| t									84,000
Massena East Ny And Point Henry And Yennora [Member]
Restructuring Cost and Reserve [Line Items]
Reduction in production - result of market conditions, in mt per year \| t									200,000
Portovesme [Member]
Restructuring Cost and Reserve [Line Items]
Capacity of lines under review \| t								150,000
Shutdown And Curtailment Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges								$ 60,000,000			$ 197,000,000
Number of employees associated with layoff costs \| Employees								1,780			1,780
Asset impairment charges								$ 74,000,000			$ 165,000,000
Inventory write-down - permanent shutdown and planned demolition of idled structures								33,000,000			67,000,000
Inventory write-down, after-tax and non-controlling interests								27,000,000			47,000,000
Accelerated depreciation								40,000,000			190,000,000
Amount of book value of asset write off								$ 45,000,000			$ 178,000,000
Shutdown And Curtailment Actions [Member] \| Corporate [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs \| Employees								30			30
Shutdown And Curtailment Actions [Member] \| Primary Metals [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs \| Employees								1,200			1,200
Shutdown And Curtailment Actions [Member] \| Global Rolled Products [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs \| Employees								470			470
Shutdown And Curtailment Actions [Member] \| Alumina [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs \| Employees								80			80
Shutdown And Curtailment Actions [Member] \| Australia [Member]
Restructuring Cost and Reserve [Line Items]
Number of facilities accelerated depreciation write off \| Facilities								3			3
Pension Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges								$ 18,000,000		$ 11,000,000	$ 18,000,000
Asset Retirement Obligations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges										45,000,000	95,000,000
Other exit costs								40,000,000		45,000,000	95,000,000
Environmental Remediation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges										29,000,000	47,000,000
Other exit costs								4,000,000		29,000,000	42,000,000
Supplier And Customer Contract [Member]
Restructuring Cost and Reserve [Line Items]
Other exit costs								1,000,000		8,000,000	41,000,000
Layoff Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges						$ 33,000,000				62,000,000	18,000,000
Restructuring and other charges, after-tax and noncontrolling interest						29,000,000				50,000,000	11,000,000
Gain on Sale of Discontinued Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges								5,000,000
Restructuring and other charges, after-tax and noncontrolling interest								4,000,000
Gain on Sale of Discontinued Operations [Member] \| Australia [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges						18,000,000				18,000,000
Restructuring and other charges, after-tax and noncontrolling interest						13,000,000				13,000,000
Other Exit Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges						11,000,000		220,000,000		190,000,000	663,000,000
Restructuring and other charges, after-tax and noncontrolling interest						5,000,000		186,000,000		120,000,000	426,000,000
Other Miscellaneous Items [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges						2,000,000		4,000,000		3,000,000	16,000,000
Restructuring and other charges, after-tax and noncontrolling interest						9,000,000		2,000,000		13,000,000	9,000,000
Small Layoff Reserves Related to Prior Periods [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges						4,000,000				12,000,000
Restructuring and other charges, after-tax and noncontrolling interest						2,000,000				9,000,000
Divested Businesses [Member] \| Russia [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges										161,000,000
Restructuring and other charges, after-tax and noncontrolling interest										151,000,000
Shutdown Costs [Member]
Restructuring Cost and Reserve [Line Items]
Asset impairment charges										86,000,000
Other exit costs										82,000,000
Inventory write-down - permanent shutdown and planned demolition of idled structures										4,000,000
Inventory write-down, after-tax and non-controlling interests										2,000,000
Shutdown Costs [Member] \| Primary Metals [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges						$ 11,000,000				$ 22,000,000
Number of employees associated with layoff costs \| Employees										90
Layoff Reserves Related to Prior Periods [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges								10,000,000			17,000,000
Restructuring and other charges, after-tax and noncontrolling interest								$ 9,000,000			13,000,000
Smelter Curtailments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges											67,000,000
Restructuring and other charges, after-tax and noncontrolling interest											$ 44,000,000
Smelter Curtailments [Member] \| Refinery [Member]
Restructuring Cost and Reserve [Line Items]
Number of plants temporarily curtailed \| Plant											1
Asset Impairment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges											$ 33,000,000
Restructuring and other charges, after-tax and noncontrolling interest											$ 26,000,000
Restructuring Programs Layoffs 2015 [Member]
Restructuring Cost and Reserve [Line Items]
Approximate number of employees already laid off \| Employees	1,240					1,240				1,240
Number of positions separated \| Employees	1,860
Cash payments made against the layoff reserves						$ 19,000,000				$ 34,000,000
Restructuring Programs Layoffs 2014 [Member]
Restructuring Cost and Reserve [Line Items]
Approximate number of employees already laid off \| Employees	2,500					2,500				2,500
Number of positions separated \| Employees	2,870											2,910
Cash payments made against the layoff reserves						$ 4,000,000				$ 60,000,000
Restructuring Programs Layoffs 2013 [Member]
Restructuring Cost and Reserve [Line Items]
Approximate number of employees already laid off \| Employees	1,480					1,480				1,480
Number of positions separated \| Employees	1,530
Cash payments made against the layoff reserves						$ 1,000,000				$ 6,000,000

Restructuring and Other Charges - Schedule of Restructuring and Other Charges by Reportable Segments, Pretax (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	$ 66	$ 209	$ 460	$ 780
Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	57	207	422	746
Corporate [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	9	2	38	34
Alumina [Member] \| Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	38	1	55	8
Primary Metals [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			80
Primary Metals [Member] \| Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	11	193	209	608
Global Rolled Products [Member] \| Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	(17)	$ 13	119	126
Engineered Products and Solutions [Member] \| Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	22		33	1
Transportation and Construction Solutions [Member] \| Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	$ 3		$ 6	$ 3

Restructuring and Other Charges - Activity and Reserve Balances for Restructuring Charges (Detail) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Restructuring Cost and Reserve [Line Items]
Restructuring reserve beginning balance	$ 132	$ 138
Cash payments	(109)	(213)
Restructuring charges	200	453
Other	(142)	(246)
Restructuring reserve ending balance	81	132
Layoff Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve beginning balance	98	96
Cash payments	(100)	(191)
Restructuring charges	111	259
Other	(52)	(66)
Restructuring reserve ending balance	57	98
Other Exit Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve beginning balance	34	42
Cash payments	(9)	(22)
Restructuring charges	89	194
Other	(90)	(180)
Restructuring reserve ending balance	$ 24	$ 34

Restructuring and Other Charges - Activity and Reserve Balances for Restructuring Charges (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Restructuring Cost and Reserve [Line Items]
Other layoff cost including reclassification in pension cost			$ 142		$ 246
Restructuring and other charges	$ 66	$ 209	460	$ 780
Pension Costs [Member]
Restructuring Cost and Reserve [Line Items]
Other layoff cost including reclassification in pension cost				26
Restructuring and other charges		$ 18	11	18
Pension And Other Postretirement Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Other layoff cost including reclassification in pension cost			28
Asset Retirement Obligations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			45	95
Environmental Remediation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			$ 29	$ 47

Acquisitions and Divestitures - Additional Information (Detail) $ / shares in Units, € in Millions, $ in Millions		1 Months Ended			2 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Nov. 30, 2014 USD ($)	Jul. 31, 2015 shares	Mar. 31, 2015 EUR (€) Employees shares	Mar. 31, 2015 USD ($) Employees shares	Sep. 30, 2015 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) Tranche shares	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($) Employees	Mar. 31, 2015 USD ($) $ / shares	Mar. 06, 2015 $ / shares
Business Acquisition [Line Items]
Goodwill					$ 5,443	$ 5,443		$ 5,443		$ 5,247
After-tax operating income (ATOI)						410	$ 581	1,633	$ 1,309
Russia [Member]
Business Acquisition [Line Items]
Net cash received								30
Loss from divestitures before income tax								161
Net loss, after tax and noncontrolling interest								151
Stupino Titanium Company [Member]
Business Acquisition [Line Items]
Number of employees \| Employees			1,870	1,870
Generated sale,net				$ 130
Tital [Member]
Business Acquisition [Line Items]
Goodwill											$ 123
Number of employees \| Employees			650	650
Cash paid for business acquisition			€ 188	$ 204
Business acquisition transaction cost			€ 1								1
RTI [Member]
Business Acquisition [Line Items]
Total assets					1,747	1,747		1,747
Goodwill					209	209		209
Intangible assets					73	73		73
Total liabilities					877	877		877
Number of employees \| Employees										2,600
Common stock estimated value											$ 870
Business acquisition common stock issued, price per share \| $ / shares											$ 9.96	$ 14.48
Number of shares to be issued upon conversion \| $ / shares											$ 2.8315
Acquisition price per share \| $ / shares												$ 41
Number of common stock shares issued in a part of acquisition \| shares		87,000,000	87,397,414	87,397,414
Professional fees and costs				$ 25
Professional fees and costs , after tax				$ 19
Generated sale,net										$ 794
Third-party sales					127
After-tax operating income (ATOI)					(7)
Goodwill deductible for income tax purpose					0	0		$ 0
RTI [Member] \| Convertible Notes [Member]
Business Acquisition [Line Items]
Number of repayment tranches \| Tranche								2
Convertible debt, due date of first tranche								Dec. 01, 2015
Convertible debt, due date of second tranche								Dec. 31, 2019
Conversion of notes to common stock \| shares								37,009,898
Firth Rixson [Member]
Business Acquisition [Line Items]
Business acquisition purchase price	$ 2,995
Contingent consideration	130
Total assets	3,470
Goodwill	1,898
Intangible assets	398				$ 791	$ 791		$ 791
Total liabilities	$ 475
Properties, plants and equipment								166
Decrease in goodwill								393
Firth Rixson [Member] \| Goodwill [Member]
Business Acquisition [Line Items]
Decrease in goodwill								$ (94)

Acquisitions and Divestitures - Summary of Preliminary Allocation of Purchase Price by Major Asset Acquired and Liability Assumed and Amount of Goodwill Recognized (Detail) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Assets:
Goodwill	$ 5,443	$ 5,247
RTI [Member]
Assets:
Cash and cash equivalents	302
Receivables from customers	103
Inventories	538
Other current assets	68
Properties, plants, and equipment, net	436
Goodwill	209
Other noncurrent assets	91
Total assets	1,747
Liabilities:
Accounts payable	90
Long-term debt due within one year	115
Other current liabilities	93
Long-term debt	440
Other noncurrent liabilities	139
Total liabilities	$ 877

Inventories - Schedule of Inventory Components (Detail) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Inventory Disclosure [Abstract]
Finished goods	$ 850	$ 768
Work-in-process	1,233	1,035
Bauxite and alumina	493	578
Purchased raw materials	790	508
Operating supplies	193	193
Inventories, total	$ 3,559	$ 3,082

Inventories - Additional Information (Detail) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Inventory Disclosure [Abstract]
Inventories valued on a LIFO basis	$ 1,507	$ 1,514
Total inventories valued on an average-cost basis	$ 625	$ 767

Contingencies and Commitments - Additional Information (Detail)		1 Months Ended			9 Months Ended	15 Months Ended
	Nov. 19, 2009 EUR (€) Plant	Jul. 31, 2014 Plant	Jun. 30, 2012 EUR (€) Installment	Jun. 30, 2012 USD ($)	Sep. 30, 2015 EUR (€)	Dec. 31, 2013 EUR (€)	Dec. 31, 2013 USD ($)	Sep. 30, 2015 USD ($)	Jun. 05, 2015 USD ($)	Feb. 21, 2013 EUR (€)	Feb. 21, 2013 USD ($)	Dec. 31, 2012 t	Jun. 30, 2012 USD ($) Installment	Mar. 26, 2012 EUR (€)	Mar. 26, 2012 USD ($)	Sep. 30, 2010 t	Nov. 19, 2009 USD ($)
Loss Contingencies [Line Items]
Claimed obligation, minimum			€ 159,000,000										$ 178,000,000
Claimed obligation, maximum			303,000,000										340,000,000
Management estimate for maximum exposure from class action														€ 85,000,000	$ 110,000,000
Number of smelters \| Plant		2
Recovery amount			303,000,000	$ 375,000,000
Reduction in recovery amount			53,000,000										$ 65,000,000
Payments to Italian Government			€ 250,000,000	$ 310,000,000
Payments to Italian Government, installments amount						€ 50,000,000	$ 69,000,000
Number of installments, litigation payment \| Installment			5										5
Litigation reserve			€ 159,000,000										$ 178,000,000
Amount of curtailment, metric-tons-per-year \| t																44,000
Minimum [Member]
Loss Contingencies [Line Items]
Provision for contract losses											$ 0
Maximum [Member]
Loss Contingencies [Line Items]
Provision for contract losses										€ 76,000,000	97,000,000
Italy [Member]
Loss Contingencies [Line Items]
Number of years operating under a power supply structure					10 years
Charge related to European Commission announcement	€ 173,000,000																$ 250,000,000
Number of smelters \| Plant	2
Write-off of receivable	€ 14,000,000																20,000,000
Establishment reserve	€ 159,000,000																$ 230,000,000
Portovesme [Member]
Loss Contingencies [Line Items]
Amount of curtailment, metric-tons-per-year \| t												150,000
Alcoa [Member]
Loss Contingencies [Line Items]
Reduction in recovery amount					€ 53,000,000			$ 59,000,000
Noncurrent asset					€ 91,000,000			$ 103,000,000
Alcoa Trasformazioni [Member]
Loss Contingencies [Line Items]
Management estimate for maximum exposure from class action										€ 76,000,000	$ 97,000,000
Lockheed Martin [Member] \| Pending Litigation [Member]
Loss Contingencies [Line Items]
Claimed obligation, minimum									$ 0
Claimed obligation, maximum									$ 76,000,000

Contingencies and Commitments - Additional Information - 1 (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended	12 Months Ended
	Sep. 30, 2015	Jun. 30, 2015	Sep. 30, 2015	Dec. 31, 2014	Dec. 31, 2012	Dec. 31, 2009
Loss Contingencies [Line Items]
Number of cleanup locations			More than 100
Remediation reserve balance	$ 558		$ 558	$ 543
Remediation reserve balance, classified as a current liability	63		63	70
Increase in remediation reserve	1
Payments related to remediation expenses applied against the reserve	14		30
Increase (Decrease) in reserves due to effects of foreign currency translation	10		$ 16
Actual remediation fieldwork period			4 years
Guarantee debt service expiration year			2019
Firth Rixson [Member]
Loss Contingencies [Line Items]
Increase (Decrease) in reserves due to acquisition	5		$ 5
Minimum [Member]
Loss Contingencies [Line Items]
Majority of the project funding period			2016
Maximum [Member]
Loss Contingencies [Line Items]
Planning and design phase period			3 years
Majority of the project funding period			2020
Recurring Costs of Managing Hazardous Substances and Environmental Programs [Member]
Loss Contingencies [Line Items]
Percentage of cost of goods sold			2.00%
Grasse River [Member]
Loss Contingencies [Line Items]
Increase in remediation reserve	3		$ 56
Mosjoen [Member]
Loss Contingencies [Line Items]
Increase in remediation reserve	1	$ 11	12		$ 20
Other Sites [Member]
Loss Contingencies [Line Items]
Remediation reserve adjustment	2		8
Pocos De Caldas Smelter and the Anglesea Power Station [Member]
Loss Contingencies [Line Items]
Remediation reserve adjustment	29
Portovesme [Member]
Loss Contingencies [Line Items]
Increase in remediation reserve				3		$ 3
Remediation reserve adjustment			7
Massena West, NY [Member]
Loss Contingencies [Line Items]
Remediation reserve balance	235		235	239
Sherwin, TX site [Member]
Loss Contingencies [Line Items]
Remediation reserve balance	31		31	32
Expected portion of funding through 2019	16		16
East St. Louis, IL Site [Member]
Loss Contingencies [Line Items]
Remediation reserve balance	$ 11		$ 11	$ 15

Contingencies and Commitments - Additional Information - 2 (Detail) R$ in Millions, ر.س in Billions						1 Months Ended					3 Months Ended				9 Months Ended				12 Months Ended						36 Months Ended	93 Months Ended
	Apr. 08, 2015 USD ($) Installment Refinery	Feb. 27, 2014 EUR (€)	Feb. 27, 2014 USD ($)	Apr. 08, 2013 USD ($)	Apr. 08, 2013 BRL (R$)	Jan. 31, 2014	Oct. 31, 2013 USD ($)	Mar. 31, 2013 USD ($)	May 31, 2012 USD ($)	May 31, 2012 BRL (R$)	Sep. 30, 2015 USD ($)	Sep. 30, 2015 AUD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Sep. 30, 2015 USD ($) MWh Entity	Sep. 30, 2015 BRL (R$) MWh Entity	Sep. 30, 2015 AUD ($) MWh Entity	Sep. 30, 2015 SAR (ر.س) MWh Entity	Dec. 31, 2014 USD ($)	Dec. 31, 2014 AUD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2009 USD ($)	Dec. 31, 2004 USD ($)	Dec. 31, 2004 AUD ($)	Dec. 31, 2002 t	Sep. 30, 2011 USD ($)	Sep. 30, 2011 AUD ($)	Sep. 30, 2015 EUR (€)	Sep. 30, 2015 USD ($)	Sep. 30, 2015 BRL (R$)	Sep. 30, 2015 AUD ($)	Apr. 08, 2013 BRL (R$)	Mar. 31, 2013 BRL (R$)	Jun. 30, 2012 EUR (€) Installment	Jun. 30, 2012 USD ($) Installment
Loss Contingencies [Line Items]
Increase in remediation reserve											$ 1,000,000
Revised project cost submitted to reflect the removal of a larger volume of contaminated soil														$ 7,000,000
Total combined assessments																												€ 239,000,000	$ 268,000,000
Range of reasonable possible loss, maximum																																		€ 303,000,000	$ 340,000,000
Number of installments \| Installment																																		5	5
State and Local Jurisdiction [Member]
Loss Contingencies [Line Items]
Total combined assessments																													32,000,000	R$ 133
Maaden Alcoa Joint Venture Mine And Refinery Company [Member]
Loss Contingencies [Line Items]
Capital investment																													560,000,000
Percentage of amount required to be contributed in the event Alcoa would be required to make payments under the guarantees															40.00%	40.00%	40.00%	40.00%
Maaden Alcoa Joint Venture Mine And Refinery Company [Member] \| Other Noncurrent Liabilities and Deferred Credits [Member]
Loss Contingencies [Line Items]
Guarantee issued on behalf of smelting and rolling mill companies																			$ 4,000,000										$ 3,000,000
Maaden Alcoa Joint Venture Mine And Refinery Company [Member] \| Financial Guarantee [Member]
Loss Contingencies [Line Items]
Debt service requirements, principal															$ 120,000,000
Debt service requirements, interest maximum															$ 30,000,000
Maaden Alcoa Joint Venture [Member]
Loss Contingencies [Line Items]
Ownership interest issued as guarantee for Saudi Arabian Joint Venture																												25.10%	25.10%	25.10%	25.10%
Number of companies in Saudi Arabian joint venture \| Entity															1	1	1	1
Amount invested by Alcoa and Aluminum Financing Limited															$ 10,800,000,000			ر.س 40.5
Capital investment											6,000,000				15,000,000
Equity method investment, carrying value																			983,000,000										$ 935,000,000
Maaden Alcoa Joint Venture Smelter And Rolling Mill Companies [Member]
Loss Contingencies [Line Items]
Capital investment																													1,098,000,000
Maaden Alcoa Joint Venture Smelter And Rolling Mill Companies [Member] \| Other Noncurrent Liabilities and Deferred Credits [Member]
Loss Contingencies [Line Items]
Guarantee issued on behalf of smelting and rolling mill companies																			8,000,000										7,000,000
Maaden Alcoa Joint Venture Smelter And Rolling Mill Companies [Member] \| Financial Guarantee [Member]
Loss Contingencies [Line Items]
Debt service requirements, principal															176,000,000
Debt service requirements, interest maximum															50,000,000
Alcoa [Member] \| Maaden Alcoa Joint Venture Mine And Refinery Company [Member]
Loss Contingencies [Line Items]
Capital investment																													2,232,000,000
Alcoa [Member] \| Maaden Alcoa Joint Venture [Member]
Loss Contingencies [Line Items]
Amount invested by Alcoa and Aluminum Financing Limited															1,100,000,000
Capital investment															$ 967,000,000
Alcoa [Member] \| Maaden Alcoa Joint Venture Smelter And Rolling Mill Companies [Member]
Loss Contingencies [Line Items]
Capital investment																													$ 4,374,000,000
Alcoa World Alumina Brasil [Member]
Loss Contingencies [Line Items]
Disallowed tax credits								$ 110,000,000																									R$ 220
Percentage of penalty				50.00%	50.00%			50.00%
Value added tax receivable									$ 41,000,000	R$ 82
Estimated range of reasonably possible loss, minimum \| R$					R$ 103
Alcoa World Alumina Brasil [Member] \| Minimum [Member]
Loss Contingencies [Line Items]
Estimated range of reasonably possible loss, minimum				$ 0
Alcoa World Alumina Brasil [Member] \| Maximum [Member]
Loss Contingencies [Line Items]
Estimated range of reasonably possible loss, minimum				25,000,000
Alcoa World Alumina Brasil [Member] \| Fixed Assets [Member]
Loss Contingencies [Line Items]
Disallowed tax credits \| R$																																R$ 117
Alcoa World Alumina Brasil [Member] \| Fixed Assets [Member] \| Minimum [Member]
Loss Contingencies [Line Items]
Disallowed tax credits				0
Alcoa World Alumina Brasil [Member] \| Fixed Assets [Member] \| Maximum [Member]
Loss Contingencies [Line Items]
Disallowed tax credits				$ 28,000,000
Alcoa Aluminio [Member]
Loss Contingencies [Line Items]
Metal sold per month \| t																									2,000
Maaden Company [Member] \| Maaden Alcoa Joint Venture [Member]
Loss Contingencies [Line Items]
Percent of guarantee issued by co-venturing entity																												74.90%	74.90%	74.90%	74.90%
Estreito Project [Member]
Loss Contingencies [Line Items]
Investment percentage															25.49%	25.49%	25.49%	25.49%
Assured power from installed capacity \| MWh															150	150	150	150
Estimated project costs															$ 1,260,000,000	R$ 5,170
Aluminio's share of project															320,000,000	1,320
Commitment expended on the project															$ 310,000,000	R$ 1,270
Ligestra [Member]
Loss Contingencies [Line Items]
Costs and payments		€ 12,000,000	$ 17,000,000
Costs and payments related to damages		6,000,000	9,000,000
Payment period															10 years	10 years	10 years	10 years
Ligestra [Member] \| Minimum [Member]
Loss Contingencies [Line Items]
Percentage of payments and remediation costs						50.00%
Ligestra [Member] \| Maximum [Member]
Loss Contingencies [Line Items]
Percentage of payments and remediation costs						80.00%
Italian Ministry of Environment and Protection of Land and Sea[Member]
Loss Contingencies [Line Items]
Soil remediation project, estimated cost		24,000,000	33,000,000
Payments for emergency action and natural resource damages		€ 18,000,000	$ 25,000,000
Majority-Owned Subsidiary \| Alcoa Of Australia Limited [Member] \| Service Agreements [Member]
Loss Contingencies [Line Items]
Gas supply agreement period															12 years	12 years	12 years	12 years
Number of alumina refineries to be powered under supplied agreement \| Refinery	3
Number of installments \| Installment	2
Gas supply agreement prepayment amount	$ 500,000,000
Majority-Owned Subsidiary \| Alcoa Of Australia Limited [Member] \| Service Agreements [Member] \| First Installment [Member]
Loss Contingencies [Line Items]
Gas supply agreement prepayment amount	300,000,000
Majority-Owned Subsidiary \| Alcoa Of Australia Limited [Member] \| Service Agreements [Member] \| Second Installment [Member]
Loss Contingencies [Line Items]
Gas supply agreement prepayment amount	$ 200,000,000
Fusina [Member]
Loss Contingencies [Line Items]
Increase in remediation reserve							$ 0															$ 12,000,000
Portovesme [Member]
Loss Contingencies [Line Items]
Increase in remediation reserve																			3,000,000			$ 3,000,000
Baie Comeau [Member]
Loss Contingencies [Line Items]
Increase in remediation reserve																					$ 25,000,000
Mosjoen [Member]
Loss Contingencies [Line Items]
Increase in remediation reserve											1,000,000		$ 11,000,000		$ 12,000,000						$ 20,000,000
Dampier to Bunbury Natural Gas Pipeline [Member]
Loss Contingencies [Line Items]
Capital investment																							$ 17,000,000	$ 24,000,000		$ 141,000,000	$ 176,000,000
Investment percentage																							20.00%	20.00%
Dampier to Bunbury Natural Gas Pipeline [Member] \| Three-Year Equity Call Plan [Member]
Loss Contingencies [Line Items]
Amount invested by Alcoa and Aluminum Financing Limited																			$ 39,000,000	$ 40,000,000
Capital investment											$ 3,000,000	$ 4,000,000			11,000,000		$ 15,000,000
Prepayments made under the agreement for future gas transmission services																													$ 256,000,000		$ 366,000,000
Range of reasonable possible loss, maximum																													$ 370,000,000		$ 520,000,000
Dampier to Bunbury Natural Gas Pipeline [Member] \| New Equity Call Plan [Member]
Loss Contingencies [Line Items]
Amount invested by Alcoa and Aluminum Financing Limited															30,000,000		36,000,000
Capital investment															$ 12,000,000		$ 16,000,000

Other (Income) Expenses, Net - Schedule of Other (Income) Expenses, Net (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Other Income and Expenses [Abstract]
Equity loss	$ 24	$ 16	$ 68	$ 84
Interest income	(4)	(3)	(11)	(13)
Foreign currency gains, net	(17)	(5)	(27)
Net gain from asset sales	(41)	(15)	(69)	(44)
Net loss on mark-to-market derivative contracts (N)	16	20	19	17
Other, net	7	10	(7)	9
Other (income) expenses, net	$ (15)	$ 23	$ (27)	$ 53

Segment Information - Schedule of Operating Results of Alcoa's Reportable Segment (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting Information [Line Items]
Total sales	$ 5,573	$ 6,239	$ 17,289	$ 17,529
Equity loss	(24)	(15)	(66)	(83)
Depreciation, depletion, and amortization	305	328	918	978
Income taxes	153	245	644	554
After-tax operating income (ATOI)	410	581	1,633	1,309
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total sales	6,459	7,498	20,420	21,320
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment sales	899	1,264	3,155	3,793
Third-Party Sales [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales	5,560	6,234	17,265	17,527
Alumina [Member]
Segment Reporting Information [Line Items]
Equity loss	(9)	(7)	(27)	(19)
Depreciation, depletion, and amortization	71	100	228	297
Income taxes	85	26	264	78
After-tax operating income (ATOI)	212	62	648	192
Alumina [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total sales	1,303	1,368	4,046	3,964
Alumina [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment sales	391	482	1,323	1,472
Alumina [Member] \| Third-Party Sales [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales	912	886	2,723	2,492
Primary Metals [Member]
Segment Reporting Information [Line Items]
Equity loss	(7)		(15)	(45)
Depreciation, depletion, and amortization	106	124	324	377
Income taxes	(49)	95	14	114
After-tax operating income (ATOI)	(59)	245	195	327
Primary Metals [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total sales	1,728	2,595	6,088	7,130
Primary Metals [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment sales	479	730	1,733	2,182
Primary Metals [Member] \| Third-Party Sales [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales	1,249	1,865	4,355	4,948
Global Rolled Products [Member]
Segment Reporting Information [Line Items]
Equity loss	(8)	(8)	(24)	(19)
Depreciation, depletion, and amortization	56	62	168	178
Income taxes	28	26	89	73
After-tax operating income (ATOI)	62	69	192	193
Global Rolled Products [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total sales	1,556	1,978	4,915	5,602
Global Rolled Products [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment sales	29	52	99	139
Global Rolled Products [Member] \| Third-Party Sales [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales	1,527	1,926	4,816	5,463
Engineered Products and Solutions [Member]
Segment Reporting Information [Line Items]
Depreciation, depletion, and amortization	61	32	166	95
Income taxes	71	78	228	234
After-tax operating income (ATOI)	151	155	472	455
Engineered Products and Solutions [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total sales	1,397	1,034	3,933	3,103
Engineered Products and Solutions [Member] \| Third-Party Sales [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales	1,397	1,034	3,933	3,103
Transportation and Construction Solutions [Member]
Segment Reporting Information [Line Items]
Depreciation, depletion, and amortization	11	10	32	31
Income taxes	18	20	49	55
After-tax operating income (ATOI)	44	50	126	142
Transportation and Construction Solutions [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total sales	475	523	1,438	1,521
Transportation and Construction Solutions [Member] \| Third-Party Sales [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales	$ 475	$ 523	$ 1,438	$ 1,521

Segment Information - Schedule of Segment ATOI to Consolidated Net Income Attributable to Alcoa (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting Information [Line Items]
Total segment ATOI	$ 410	$ 581	$ 1,633	$ 1,309
Interest expense	(123)	(126)	(369)	(351)
Noncontrolling interests	(62)	18	(189)	46
Consolidated net income attributable to Alcoa	44	149	379	109
Other [Member]
Segment Reporting Information [Line Items]
Impact of LIFO	50	(18)	93	(33)
Metal price lag	(48)	38	(110)	56
Interest expense	(80)	(81)	(240)	(228)
Noncontrolling interests	(62)	18	(189)	46
Corporate expense	(72)	(72)	(199)	(204)
Restructuring and other charges	(48)	(189)	(368)	(587)
Other	$ (106)	$ (128)	$ (241)	$ (250)

Earnings Per Share - Reconciliation of Information Used to Compute Basic and Diluted EPS (Detail) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Net income attributable to Alcoa	$ 44	$ 149	$ 379	$ 109
Less: preferred stock dividends declared	18		52	1
Net income available to Alcoa common shareholders - basic	26	149	327	108
Add: dividends related to mandatory convertible preferred stock	0	0	0	0
Add: interest expense related to convertible notes	0	0	0	0
Net income available to Alcoa common shareholders - diluted	$ 26	$ 149	$ 327	$ 108
Average shares outstanding - basic	1,281	1,177	1,241	1,150
Stock options	1	8	4	6
Stock and performance awards	12	12	12	11
Mandatory convertible preferred stock		8		3
Convertible notes	0	0	0	0
Average shares outstanding - diluted	1,294	1,205	1,257	1,170

Earnings Per Share - Additional Information (Detail) - $ / shares	1 Months Ended		3 Months Ended			9 Months Ended
	Jul. 31, 2015	Mar. 31, 2015	Sep. 30, 2015	Sep. 30, 2014	Mar. 31, 2014	Sep. 30, 2015	Sep. 30, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock outstanding			1,000,000	8,000,000		4,000,000	6,000,000
Number of weighted average outstanding diluted shares			1,294,000,000	1,205,000,000		1,257,000,000	1,170,000,000
Basic average number of share			58,000,000			20,000,000
Weighted average number of shares outstanding			1,281,000,000	1,177,000,000		1,241,000,000	1,150,000,000
RTI [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of common stock shares issued in a part of acquisition	87,000,000	87,397,414
Weighted average number of shares outstanding			87,000,000			87,000,000
Convertible Debt Securities [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of shares, option exercised					89,000,000
Common stock outstanding				89,000,000			89,000,000
Number of weighted average outstanding shares included in both basic and diluted shares							67,000,000
Common stock outstanding							89,000,000
Number of weighted average outstanding diluted shares							22,000,000
Equity Unit Purchase Agreements [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive securities						26,000,000	3,000,000
Stock options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average exercise price of options						$ 12.76	$ 16.24
Mandatory Convertible Notes [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive securities			77,000,000			77,000,000
Convertible Notes [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive securities			25,000,000			8,000,000

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended			6 Months Ended	9 Months Ended
	Sep. 30, 2015	Mar. 31, 2015	Sep. 30, 2014	Jun. 30, 2015	Sep. 30, 2015	Sep. 30, 2014
Income Tax Contingency [Line Items]
Effective tax rate	48.50%		60.30%		41.40%	76.00%
U.S federal statutory rate			35.00%			35.00%
Income tax benefit recognized	$ 100,000,000		$ 199,000,000		$ 401,000,000	$ 200,000,000
Discrete income tax charge						56,000,000
Operational losses in certain foreign jurisdictions			8,000,000			44,000,000
Discrete income tax benefit			9,000,000
Alcoa World Alumina and Chemicals [Member]
Income Tax Contingency [Line Items]
Discrete income tax charge		$ 83,000,000		$ 85,000,000
Alcoa World Alumina and Chemicals [Member] \| Alumina Limited [Member]
Income Tax Contingency [Line Items]
Percent of investment in AWAC joint venture by Alumina Limited		40.00%
Suriname [Member]
Income Tax Contingency [Line Items]
U.S federal statutory rate	35.00%
Income tax benefit recognized	$ 0
Net discrete income tax charge					$ 34,000,000
Brazil [Member]
Income Tax Contingency [Line Items]
Discrete income tax charge			56,000,000
Italy [Member]
Income Tax Contingency [Line Items]
Income tax benefit recognized			$ 0
Russia [Member]
Income Tax Contingency [Line Items]
U.S federal statutory rate					35.00%
Alcoa [Member] \| Alcoa World Alumina and Chemicals [Member]
Income Tax Contingency [Line Items]
Percent of investment in AWAC joint venture by Aloca		60.00%
Deferred tax liability		$ 50,000,000		$ 51,000,000
Deferred tax asset written off as valuation allowance		60.00%
Foreign Jurisdictions [Member]
Income Tax Contingency [Line Items]
Income tax benefit recognized						$ 0

Receivables - Additional Information (Detail)		9 Months Ended	12 Months Ended
Receivables - Additional Information (Detail)	Mar. 31, 2012 USD ($)	Sep. 30, 2015 USD ($) Agreement	Dec. 31, 2014 USD ($)
Schedule Of Financial Receivables [Line Items]
Number of arrangement with different financial institution to sell customer receivables \| Agreement		3
Deferred purchase price receivable	$ 254,000,000	$ 361,000,000	$ 356,000,000
Amount of cash draws under arrangement		0
Amount of cash repayments under arrangement		0
Accounts receivables		22,990,000,000
Cash collections of other receivables		22,379,000,000
Predecessor [Member]
Schedule Of Financial Receivables [Line Items]
Net cash funding received		250,000,000
Amount of cash draws under arrangement		1,308,000,000
Amount of cash repayments under arrangement		1,058,000,000
Minimum [Member]
Schedule Of Financial Receivables [Line Items]
Funding of customer receivables sold		200,000,000
Maximum [Member]
Schedule Of Financial Receivables [Line Items]
Funding of customer receivables sold		$ 500,000,000

Pension and Other Postretirement Benefits - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 44	$ 42	$ 132	$ 125
Interest cost	144	157	433	476
Expected return on plan assets	(189)	(198)	(566)	(586)
Recognized net actuarial loss	117	97	352	292
Amortization of prior service cost (benefit)	4	5	12	14
Settlements	13	18	14	18
Curtailments	9		9
Special termination benefits			12
Net periodic benefit cost	142	121	398	339
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	4	4	11	12
Interest cost	23	28	69	86
Recognized net actuarial loss	4	4	13	10
Amortization of prior service cost (benefit)	(9)	(6)	(28)	(15)
Curtailments	(5)		(6)
Special termination benefits			1
Net periodic benefit cost	$ 17	$ 30	$ 60	$ 93

Pension and Other Postretirement Benefits - Components of Net Periodic Benefit Cost (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015
Compensation and Retirement Disclosure [Abstract]
Settlements excluded from restructuring and other charges	$ 2	$ 2

Derivatives and Other Financial Instruments - Additional Information (Detail) t in Thousands, R$ in Millions	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Jul. 31, 2014 Plant Contract	Sep. 30, 2015 USD ($) Derivative	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) MWh Derivative Agency t	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($) MWh t	Sep. 30, 2015 BRL (R$) Derivative
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other derivative contracts estimated term of quoted market prices, in years				10 years
Number of contracts \| Contract	2
Number of smelters \| Plant	2
Number of credit rating agencies \| Agency				3
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of derivative instruments \| Derivative		9		9			9
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of derivatives recorded as assets		$ 6,000,000		$ 6,000,000		$ 2,000,000
Fair value of derivatives recorded as liabilities		54,000,000		54,000,000		$ 31,000,000
Net gain (loss) of derivative instruments		(7,000,000)	$ (15,000,000)	34,000,000	$ (2,000,000)
Derivatives Not Designated as Hedging Instruments [Member] \| Other (income) expenses, net
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net gain (loss) of derivative instruments		(17,000,000)	(21,000,000)	(19,000,000)	(15,000,000)
Foreign Exchange Contracts Two [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss recognized on forward contract				4,000,000
Foreign Exchange Contracts Two [Member] \| Forward Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Forward contract to purchase to mitigate the foreign currency risk related to a Canadian/Brazilian-denominated loan due in 2014		231,000,000		$ 231,000,000			R$ 543
Maturity date of forward contract				Mar. 31, 2014
Embedded Aluminum Derivative [Member] \| Cash Flow Hedging [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recognized an unrealized gain (loss)		301,000,000	(4,000,000)	$ 819,000,000	(28,000,000)
Realized gain (loss) on derivatives		$ (1,000,000)	(8,000,000)	$ (25,000,000)	(19,000,000)
Embedded Aluminum Derivative [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of derivative instruments \| Derivative		7		7			7
Embedded Aluminum Derivative [Member] \| Level 3 [Member] \| Cash Flow Hedging [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of derivative instruments \| Derivative		5		5			5
Embedded Aluminum Derivative [Member] \| Derivatives Not Designated as Hedging Instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net gain (loss) of derivative instruments		$ (4,000,000)	(11,000,000)	$ (5,000,000)	(12,000,000)
Embedded Aluminum Derivative [Member] \| Derivatives Not Designated as Hedging Instruments [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of derivative instruments \| Derivative		2		2			2
Embedded Aluminum Derivative [Member] \| Derivatives Designated as Hedging Instruments [Member] \| Cash Flow Hedging [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amount of loss expected to be recognized into earnings over the next 12 months				$ 41,000,000
Derivative instruments ineffectiveness		$ 0		0	0
Embedded Aluminum Derivative [Member] \| Derivatives Designated as Hedging Instruments [Member] \| Cash Flow Hedging [Member] \| Other (income) expenses, net
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other expenses (income), net				$ 2,000,000	(1,000,000)
Embedded Aluminum Derivative [Member] \| Derivatives Designated as Hedging Instruments [Member] \| Maximum [Member] \| Cash Flow Hedging [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments ineffectiveness			0
Embedded Aluminum Derivative [Member] \| Derivatives Designated as Hedging Instruments [Member] \| Maximum [Member] \| Cash Flow Hedging [Member] \| Other (income) expenses, net
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other expenses (income), net		1,000,000	(1,000,000)
Embedded Aluminum Derivative [Member] \| Derivatives Designated as Hedging Instruments [Member] \| Scenario, Forecast [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aluminum forecast sales \| t				3,369		3,610
Energy Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Recognized an unrealized gain (loss)		$ 3,000,000	(28,000,000)	$ (8,000,000)	(10,000,000)
Energy Contracts [Member] \| Level 3 [Member] \| Cash Flow Hedging [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of derivative instruments \| Derivative		1		1			1
Energy Contracts [Member] \| Derivatives Designated as Hedging Instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments ineffectiveness		$ 0	0	$ 0	0
Forecasted energy purchases in megawatt hours \| MWh				59,409,328		59,409,328
Embedded Credit Derivative [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of derivative instruments \| Derivative		1		1			1
Embedded Credit Derivative [Member] \| Derivatives Not Designated as Hedging Instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net gain (loss) of derivative instruments		$ (13,000,000)	$ (10,000,000)	$ (14,000,000)	$ (3,000,000)
Embedded Credit Derivative [Member] \| Derivatives Not Designated as Hedging Instruments [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of derivative instruments \| Derivative		0		0			0
Power Contract One [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Power contracts maturity date	Jun. 30, 2014
Power Contract Two [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Power contracts maturity date	Jun. 30, 2014

Derivatives and Other Financial Instruments - Schedule of Quantitative Information for Level 3 Derivative Contracts (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2015 USD ($) Index $ / Metric_Ton $ / MWh $ / Barrels $ / AUD $ / lb	Dec. 31, 2014 USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative Assets, Fair value \| $	$ 875	$ 268
Embedded Aluminum Derivative [Member] \| Interrelationship of Future Aluminum Prices, Foreign Currency Exchange Rates, and U.S. Consumer Price Index [Member] \| Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative Assets, Fair value \| $	$ 87
Embedded Aluminum Derivative [Member] \| Interrelationship of Future Aluminum Prices, Foreign Currency Exchange Rates, and U.S. Consumer Price Index [Member] \| Average Price [Member] \| Level 3 [Member] \| Minimum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Expected future aluminum prices	1,562
Maturity year of future aluminum price	2015
Expected future aluminum prices	1,562
Maturity year of future aluminum price	2015
Embedded Aluminum Derivative [Member] \| Interrelationship of Future Aluminum Prices, Foreign Currency Exchange Rates, and U.S. Consumer Price Index [Member] \| Average Price [Member] \| Level 3 [Member] \| Maximum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Expected future aluminum prices	1,615
Maturity year of future aluminum price	2016
Expected future aluminum prices	1,615
Maturity year of future aluminum price	2016
Embedded Aluminum Derivative [Member] \| Interrelationship of Future Aluminum Prices, Foreign Currency Exchange Rates, and U.S. Consumer Price Index [Member] \| Estimated Foreign Currency Exchange Rate [Member] \| Level 3 [Member] \| Minimum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Foreign currency exchange rate \| $ / AUD	0.70
Foreign currency exchange rate expected year	2015
Embedded Aluminum Derivative [Member] \| Interrelationship of Future Aluminum Prices, Foreign Currency Exchange Rates, and U.S. Consumer Price Index [Member] \| Estimated Foreign Currency Exchange Rate [Member] \| Level 3 [Member] \| Maximum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Foreign currency exchange rate \| $ / AUD	0.70
Foreign currency exchange rate expected year	2016
Embedded Aluminum Derivative [Member] \| Interrelationship of Future Aluminum Prices, Foreign Currency Exchange Rates, and U.S. Consumer Price Index [Member] \| Consumer Price Index [Member] \| Level 3 [Member] \| Minimum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Expected consumer price index \| Index	235
Expected consumer price index, Year	2015
Embedded Aluminum Derivative [Member] \| Interrelationship of Future Aluminum Prices, Foreign Currency Exchange Rates, and U.S. Consumer Price Index [Member] \| Consumer Price Index [Member] \| Level 3 [Member] \| Maximum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Consumer price index base year	1982
Consumer price index base \| Index	100
Expected consumer price index \| Index	239
Expected consumer price index, Year	2016
Embedded Aluminum Derivative [Member] \| Interrelationship of Future Aluminum and Oil Prices [Member] \| Average Price [Member] \| Level 3 [Member] \| Minimum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Expected future aluminum prices	1,562
Maturity year of future aluminum price	2015
Expected future oil prices \| $ / Barrels	47
Maturity year of future oil price	2015
Expected future aluminum prices	1,562
Maturity year of future aluminum price	2015
Embedded Aluminum Derivative [Member] \| Interrelationship of Future Aluminum and Oil Prices [Member] \| Average Price [Member] \| Level 3 [Member] \| Maximum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Expected future aluminum prices	1,762
Maturity year of future aluminum price	2018
Expected future oil prices \| $ / Barrels	60
Maturity year of future oil price	2018
Expected future aluminum prices	1,762
Maturity year of future aluminum price	2018
Embedded Aluminum Derivative [Member] \| Price of Aluminum beyond Forward Curve [Member] \| Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative Assets, Fair value \| $	$ 784
Derivative Liabilities, Fair value \| $	$ 223
Embedded Aluminum Derivative [Member] \| Price of Aluminum beyond Forward Curve [Member] \| Average Price [Member] \| Level 3 [Member] \| Minimum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Expected future aluminum prices	2,160
Maturity year of future aluminum price	2026
Expected future aluminum prices	2,160
Maturity year of future aluminum price	2026
Embedded Aluminum Derivative [Member] \| Price of Aluminum beyond Forward Curve [Member] \| Average Price [Member] \| Level 3 [Member] \| Maximum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Expected future aluminum prices	2,239
Maturity year of future aluminum price	2027
Expected future aluminum prices	2,239
Maturity year of future aluminum price	2027
Embedded Aluminum Derivative [Member] \| Interrelationship of LME Price to Overall Energy Price [Member] \| Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative Assets, Fair value \| $	$ 4
Embedded Aluminum Derivative [Member] \| Interrelationship of LME Price to Overall Energy Price [Member] \| Average Price [Member] \| Level 3 [Member] \| Minimum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Expected future aluminum prices	1,560
Maturity year of future aluminum price	2015
Expected future aluminum prices	1,560
Maturity year of future aluminum price	2015
Embedded Aluminum Derivative [Member] \| Interrelationship of LME Price to Overall Energy Price [Member] \| Average Price [Member] \| Level 3 [Member] \| Maximum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Expected future aluminum prices	1,817
Maturity year of future aluminum price	2019
Expected future aluminum prices	1,817
Maturity year of future aluminum price	2019
Embedded Aluminum Derivative [Member] \| Two Contracts [Member] \| Price of Aluminum beyond Forward Curve [Member] \| Average Price [Member] \| Level 3 [Member] \| Maximum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Expected future aluminum prices	2,347
Maturity year of future aluminum price	2029
Expected future aluminum prices	2,347
Maturity year of future aluminum price	2029
Embedded Aluminum Derivative [Member] \| Two Contracts [Member] \| Price of Aluminum beyond Forward Curve [Member] \| Midwest Premium \| Level 3 [Member] \| Maximum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Foreign currency exchange rate expected year	2029
Embedded Aluminum Derivative [Member] \| One Contract [Member] \| Price of Aluminum beyond Forward Curve [Member] \| Average Price [Member] \| Level 3 [Member] \| Maximum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Expected future aluminum prices	2,643
Maturity year of future aluminum price	2036
Expected future aluminum prices	2,643
Maturity year of future aluminum price	2036
Embedded Aluminum Derivative [Member] \| One Contract [Member] \| Price of Aluminum beyond Forward Curve [Member] \| Midwest Premium \| Level 3 [Member] \| Minimum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Midwest Premium \| $ / lb	0.0795
Foreign currency exchange rate expected year	2021
Embedded Aluminum Derivative [Member] \| One Contract [Member] \| Price of Aluminum beyond Forward Curve [Member] \| Midwest Premium \| Level 3 [Member] \| Maximum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Midwest Premium \| $ / lb	0.0795
Foreign currency exchange rate expected year	2036
Embedded Credit Derivative [Member] \| Credit Spread between Alcoa and Counterparty [Member] \| Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative Liabilities, Fair value \| $	$ 32
Embedded Credit Derivative [Member] \| Credit Spread between Alcoa and Counterparty [Member] \| Credit Spread [Member] \| Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Percentage of credit spread	3.27%
Embedded Credit Derivative [Member] \| Credit Spread between Alcoa and Counterparty [Member] \| Credit Spread [Member] \| Level 3 [Member] \| Minimum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Percentage of credit spread	3.04%
Embedded Credit Derivative [Member] \| Credit Spread between Alcoa and Counterparty [Member] \| Credit Spread [Member] \| Level 3 [Member] \| Maximum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Percentage of credit spread	3.50%
Energy Contracts [Member] \| Price of Electricity beyond Forward Curve [Member] \| Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative Liabilities, Fair value \| $	$ 5
Energy Contracts [Member] \| Price of Electricity beyond Forward Curve [Member] \| Average Price [Member] \| Level 3 [Member] \| Minimum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Price of electricity beyond forward curve \| $ / MWh	45
Maturity date of electricity beyond forward curve	2018
Energy Contracts [Member] \| Price of Electricity beyond Forward Curve [Member] \| Average Price [Member] \| Level 3 [Member] \| Maximum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Price of electricity beyond forward curve \| $ / MWh	121
Maturity date of electricity beyond forward curve	2036

Derivatives and Other Financial Instruments - Schedule of Fair Values of Level 3 Derivative Instruments Recorded as Assets and Liabilities (Detail) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Fair value asset derivatives	$ 875	$ 268
Fair value liability derivatives	260	394
Derivatives Designated as Hedging Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fair value asset derivatives	788	99
Fair value liability derivatives	228	376
Derivatives Designated as Hedging Instruments [Member] \| Prepaid Expenses and Other Current Assets [Member] \| Embedded Aluminum Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fair value asset derivatives	70	24
Derivatives Designated as Hedging Instruments [Member] \| Other Noncurrent Assets [Member] \| Embedded Aluminum Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fair value asset derivatives	718	73
Derivatives Designated as Hedging Instruments [Member] \| Other Noncurrent Assets [Member] \| Energy Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fair value asset derivatives		2
Derivatives Designated as Hedging Instruments [Member] \| Other Current Liabilities [Member] \| Embedded Aluminum Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fair value liability derivatives	11	24
Derivatives Designated as Hedging Instruments [Member] \| Other Noncurrent Liabilities and Deferred Credits [Member] \| Embedded Aluminum Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fair value liability derivatives	213	352
Derivatives Designated as Hedging Instruments [Member] \| Other Noncurrent Liabilities and Deferred Credits [Member] \| Energy Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fair value liability derivatives	4
Derivatives Not Designated as Hedging Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fair value asset derivatives	87	169
Fair value liability derivatives	32	18
Derivatives Not Designated as Hedging Instruments [Member] \| Prepaid Expenses and Other Current Assets [Member] \| Embedded Aluminum Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fair value asset derivatives	87	98
Derivatives Not Designated as Hedging Instruments [Member] \| Other Noncurrent Assets [Member] \| Embedded Aluminum Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fair value asset derivatives		71
Derivatives Not Designated as Hedging Instruments [Member] \| Other Current Liabilities [Member] \| Embedded Credit Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fair value liability derivatives	4	2
Derivatives Not Designated as Hedging Instruments [Member] \| Other Noncurrent Liabilities and Deferred Credits [Member] \| Embedded Credit Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fair value liability derivatives	$ 28	$ 16

Derivatives and Other Financial Instruments - Schedule of Reconciliation of Activity for Derivative Contracts (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015
Embedded Aluminum Derivative [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value measurement, Assets, Beginning balance	$ 680	$ 266
Fair value measurement, Assets, Sales	(2)	11
Fair value measurement, Assets, Cost of goods sold	(25)	(70)
Fair value measurement, Assets, Other income, net	(4)	(5)
Fair value measurement, Assets, Other comprehensive loss	229	680
Fair value measurement, Assets, Purchases, sales, issuances, and settlements	0	0
Fair value measurement, Assets, Transfers into and/or out of Level 3	0	0
Fair value measurement, Assets, Foreign currency translation	(3)	(7)
Fair value measurement, Assets, Ending balance	875	875
Fair value measurement, Assets, Sales	0	0
Fair value measurement, Assets, Cost of goods sold	0	0
Fair value measurement, Assets, Other income, net	(4)	(5)
Fair value measurement, Liabilities, Beginning balance	298	376
Fair value measurement, Liabilities, Sales	(3)	(14)
Fair value measurement, Liabilities, Cost of goods sold	0	0
Fair value measurement, Liabilities, Other comprehensive loss	(72)	(139)
Fair value measurement, Liabilities, Purchases, sales, issuances, and settlements	0	0
Fair value measurement, Liabilities, Transfers into and/or out of Level 3	0	0
Fair value measurement, Liabilities, Ending balance	223	223
Fair value measurement, Liabilities, Sales	0	0
Fair value measurement, Liabilities, Cost of goods sold	0	0
Embedded Credit Derivative [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value measurement, Liabilities, Beginning balance	19	18
Fair value measurement, Liabilities, Cost of goods sold	0	0
Fair value measurement, Liabilities, Other income, net	13	14
Fair value measurement, Liabilities, Purchases, sales, issuances, and settlements	0	0
Fair value measurement, Liabilities, Transfers into and/or out of Level 3	0	0
Fair value measurement, Liabilities, Ending balance	32	32
Fair value measurement, Liabilities, Sales	0	0
Fair value measurement, Liabilities, Cost of goods sold	0	0
Fair value measurement, Liabilities, Other income, net	13	14
Energy Contracts [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value measurement, Assets, Beginning balance		2
Fair value measurement, Assets, Other comprehensive loss		(2)
Fair value measurement, Assets, Purchases, sales, issuances, and settlements	0	0
Fair value measurement, Assets, Transfers into and/or out of Level 3	0	0
Fair value measurement, Assets, Sales	0	0
Fair value measurement, Assets, Cost of goods sold	0	0
Fair value measurement, Liabilities, Beginning balance	9
Fair value measurement, Liabilities, Cost of goods sold	0	0
Fair value measurement, Liabilities, Other comprehensive loss	(5)	4
Fair value measurement, Liabilities, Purchases, sales, issuances, and settlements	0	0
Fair value measurement, Liabilities, Transfers into and/or out of Level 3	0	0
Fair value measurement, Liabilities, Foreign currency translation	1	1
Fair value measurement, Liabilities, Ending balance	5	5
Fair value measurement, Liabilities, Sales	0	0
Fair value measurement, Liabilities, Cost of goods sold	$ 0	$ 0

Derivatives and Other Financial Instruments - Schedule of Carrying Values and Fair Values of Other Financial Instruments (Detail) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Carrying Value[Member]
Derivative [Line Items]
Cash and cash equivalents	$ 1,739	$ 1,877
Restricted cash	24	20
Noncurrent receivables	17	17
Available-for-sale securities	177	153
Short-term borrowings	50	54
Commercial paper	0	0
Long-term debt due within one year	136	29
Long-term debt, less amount due within one year	9,091	8,769
Fair Value [Member]
Derivative [Line Items]
Cash and cash equivalents	1,739	1,877
Restricted cash	24	20
Noncurrent receivables	17	17
Available-for-sale securities	177	153
Short-term borrowings	50	54
Commercial paper	0	0
Long-term debt due within one year	136	29
Long-term debt, less amount due within one year	$ 9,062	$ 9,445