Statement of Consolidated Comprehensive Income (unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Net income	$ 212	$ 178	$ 534	$ 189
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	48	67	79	100
Foreign currency translation adjustments	99	77	166	487
Net change in unrealized gains/losses on available-for-sale securities	(101)	3	(134)	4
Net change in unrecognized gains/losses on cash flow hedges	(2)	(137)	3	(219)
Total Other comprehensive income (loss), net of tax	44	10	114	372
Comprehensive income	256	188	648	561
Arconic [Member]
Net income	212	135	534	151
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	48	65	79	97
Foreign currency translation adjustments	99	45	166	348
Net change in unrealized gains/losses on available-for-sale securities	(101)	3	(134)	4
Net change in unrecognized gains/losses on cash flow hedges	(2)	(153)	3	(233)
Total Other comprehensive income (loss), net of tax	44	(40)	114	216
Comprehensive income	$ 256	95	$ 648	367
Noncontrolling Interests [Member]
Net income		43		38
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		2		3
Foreign currency translation adjustments		32		139
Net change in unrecognized gains/losses on cash flow hedges		16		14
Total Other comprehensive income (loss), net of tax		50		156
Comprehensive income		$ 93		$ 194