Statement of Consolidated Comprehensive (Loss) Income (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Net income (loss)	$ 255us-gaap_ProfitLoss	$ (197)us-gaap_ProfitLoss
Other comprehensive (loss) income, net of tax (C):
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	107	77
Foreign currency translation adjustments	(1,207)	336
Net change in unrealized gains on available-for-sale securities	2
Net change in unrecognized losses on cash flow hedges	(64)	34
Total Other comprehensive (loss) income, net of tax	(1,162)	447
Comprehensive (loss) income	(907)us-gaap_ComprehensiveIncomeNetOfTax	250us-gaap_ComprehensiveIncomeNetOfTax
Alcoa [Member]
Net income (loss)	195	(178)
Other comprehensive (loss) income, net of tax (C):
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	105	77
Foreign currency translation adjustments	(957)	249
Net change in unrealized gains on available-for-sale securities	2
Net change in unrecognized losses on cash flow hedges	(64)	32
Total Other comprehensive (loss) income, net of tax	(914)	358
Comprehensive (loss) income	(719)	180
Noncontrolling Interests [Member]
Net income (loss)	60	(19)
Other comprehensive (loss) income, net of tax (C):
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	2
Foreign currency translation adjustments	(250)	87
Net change in unrecognized losses on cash flow hedges		2
Total Other comprehensive (loss) income, net of tax	(248)	89
Comprehensive (loss) income	$ (188)	$ 70

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 (increase) decrease in accumulated other comprehensive (income) loss related to pension and other postretirement defined benefit plans.

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