Statement of Consolidated Comprehensive Loss (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net income (loss)	$ 177us-gaap_ProfitLoss	$ (2,244)us-gaap_ProfitLoss	$ 162us-gaap_ProfitLoss
Other comprehensive loss, net of tax (B):
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	(82)	557	(507)
Foreign currency translation adjustments	(1,266)	(1,335)	(296)
Net change in unrealized gains on available-for-sale securities	(2)	(1)	2
Net change in unrecognized losses on cash flow hedges	78	184	(47)
Total Other comprehensive loss, net of tax	(1,272)	(595)	(848)
Comprehensive loss	(1,095)us-gaap_ComprehensiveIncomeNetOfTax	(2,839)us-gaap_ComprehensiveIncomeNetOfTax	(686)us-gaap_ComprehensiveIncomeNetOfTax
Alcoa [Member]
Net income (loss)	268	(2,285)	191
Other comprehensive loss, net of tax (B):
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	(69)	531	(529)
Foreign currency translation adjustments	(1,025)	(968)	(202)
Net change in unrealized gains on available-for-sale securities	(2)	(1)	2
Net change in unrecognized losses on cash flow hedges	78	181	(46)
Total Other comprehensive loss, net of tax	(1,018)	(257)	(775)
Comprehensive loss	(750)	(2,542)	(584)
Noncontrolling Interests [Member]
Net income (loss)	(91)	41	(29)
Other comprehensive loss, net of tax (B):
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	(13)	26	22
Foreign currency translation adjustments	(241)	(367)	(94)
Net change in unrecognized losses on cash flow hedges		3	(1)
Total Other comprehensive loss, net of tax	(254)	(338)	(73)
Comprehensive loss	$ (345)	$ (297)	$ (102)

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Amount after tax and reclassification adjustments, of (increase) decrease in accumulated other comprehensive (income) loss related to pension and other postretirement defined benefit plans.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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