Statement of Consolidated Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net income (loss)	$ 642	$ (74)	$ (878)
Other comprehensive income (loss), net of tax (K):
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	255	(220)	(482)
Foreign currency translation adjustments	(146)	254	450
Net change in unrealized gains on available-for-sale securities	(1)	(134)	137
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax	(23)	26	(612)
Total Other comprehensive income (loss), net of tax	85	(74)	(507)
Comprehensive income (loss)	727	(148)	(1,385)
Arconic
Net income (loss)	642	(74)	(941)
Other comprehensive income (loss), net of tax (K):
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	255	(220)	(479)
Foreign currency translation adjustments	(146)	252	268
Net change in unrealized gains on available-for-sale securities	(1)	(134)	137
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax	(23)	26	(617)
Total Other comprehensive income (loss), net of tax	85	(76)	(691)
Comprehensive income (loss)	727	(150)	(1,632)
Noncontrolling Interests
Net income (loss)	0	0	63
Other comprehensive income (loss), net of tax (K):
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	0	0	(3)
Foreign currency translation adjustments	0	2	182
Net change in unrealized gains on available-for-sale securities	0	0	0
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax	0	0	5
Total Other comprehensive income (loss), net of tax	0	2	184
Comprehensive income (loss)	$ 0	$ 2	$ 247