Statement of Consolidated Comprehensive Loss - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net (loss) income	$ (878)	$ (197)	$ 177
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	(482)	(2)	(82)
Foreign currency translation adjustments	450	(1,995)	(1,266)
Net change in unrealized gains on available-for-sale securities	137	(5)	(2)
Net change in unrecognized losses on cash flow hedges	(612)	826	78
Total Other comprehensive (loss) income, net of tax	(507)	(1,176)	(1,272)
Comprehensive (loss) income	(1,385)	(1,373)	(1,095)
Arconic [Member]
Net (loss) income	(941)	(322)	268
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	(479)	(10)	(69)
Foreign currency translation adjustments	268	(1,566)	(1,025)
Net change in unrealized gains on available-for-sale securities	137	(5)	(2)
Net change in unrecognized losses on cash flow hedges	(617)	827	78
Total Other comprehensive (loss) income, net of tax	(691)	(754)	(1,018)
Comprehensive (loss) income	(1,632)	(1,076)	(750)
Noncontrolling Interests [Member]
Net (loss) income	63	125	(91)
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	(3)	8	(13)
Foreign currency translation adjustments	182	(429)	(241)
Net change in unrecognized losses on cash flow hedges	5	(1)
Total Other comprehensive (loss) income, net of tax	184	(422)	(254)
Comprehensive (loss) income	$ 247	$ (297)	$ (345)