Statement of Consolidated Comprehensive Loss - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net (loss) income	$ (197)	$ 177	$ (2,244)
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	(2)	(82)	557
Foreign currency translation adjustments	(1,995)	(1,266)	(1,335)
Net change in unrealized gains on available-for-sale securities	(5)	(2)	(1)
Net change in unrecognized losses on cash flow hedges	826	78	184
Total Other comprehensive loss, net of tax	(1,176)	(1,272)	(595)
Comprehensive loss	(1,373)	(1,095)	(2,839)
Alcoa [Member]
Net (loss) income	(322)	268	(2,285)
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	(10)	(69)	531
Foreign currency translation adjustments	(1,566)	(1,025)	(968)
Net change in unrealized gains on available-for-sale securities	(5)	(2)	(1)
Net change in unrecognized losses on cash flow hedges	827	78	181
Total Other comprehensive loss, net of tax	(754)	(1,018)	(257)
Comprehensive loss	(1,076)	(750)	(2,542)
Noncontrolling Interests [Member]
Net (loss) income	125	(91)	41
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	8	(13)	26
Foreign currency translation adjustments	(429)	(241)	(367)
Net change in unrecognized losses on cash flow hedges	(1)		3
Total Other comprehensive loss, net of tax	(422)	(254)	(338)
Comprehensive loss	$ (297)	$ (345)	$ (297)