Statement of Consolidated Comprehensive Income (Loss) (unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net income (loss)	$ 322	$ 11
Other comprehensive income (loss), net of tax (C):
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	31	33
Foreign currency translation adjustments	67	410
Net change in unrealized gains/losses on available-for-sale securities	(33)	1
Net change in unrecognized gains/losses on cash flow hedges	5	(82)
Total Other comprehensive income, net of tax	70	362
Comprehensive income	392	373
Arconic [Member]
Net income (loss)	322	16
Other comprehensive income (loss), net of tax (C):
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	31	32
Foreign currency translation adjustments	67	303
Net change in unrealized gains/losses on available-for-sale securities	(33)	1
Net change in unrecognized gains/losses on cash flow hedges	5	(80)
Total Other comprehensive income, net of tax	70	256
Comprehensive income	$ 392	272
Noncontrolling Interests [Member]
Net income (loss)		(5)
Other comprehensive income (loss), net of tax (C):
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits		1
Foreign currency translation adjustments		107
Net change in unrecognized gains/losses on cash flow hedges		(2)
Total Other comprehensive income, net of tax		106
Comprehensive income		$ 101