Statement of Consolidated Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other comprehensive income (loss), net of tax (J):
Net income (loss)	$ 470	$ 642	$ (74)
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	(388)	255	(220)
Foreign currency translation adjustments	(13)	(146)	254
Net change in unrealized gains on debt securities	3	(1)	(134)
Net change in unrecognized gains/losses on cash flow hedges	(3)	(23)	26
Total Other comprehensive (loss) income, net of tax	(401)	85	(74)
Comprehensive income (loss)	69	727	(148)
Arconic
Other comprehensive income (loss), net of tax (J):
Net income (loss)	470	642	(74)
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	(388)	255	(220)
Foreign currency translation adjustments	(13)	(146)	252
Net change in unrealized gains on debt securities	3	(1)	(134)
Net change in unrecognized gains/losses on cash flow hedges	(3)	(23)	26
Total Other comprehensive (loss) income, net of tax	(401)	85	(76)
Comprehensive income (loss)	69	727	(150)
Noncontrolling Interests
Other comprehensive income (loss), net of tax (J):
Net income (loss)	0	0	0
Foreign currency translation adjustments				$ 2
Total Other comprehensive (loss) income, net of tax			2
Comprehensive income (loss)	$ 0	$ 0	$ 2