Statement of Consolidated Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net (loss) income attributable to Alcoa Corporation	$ (651)	$ (123)	$ 429
Net (loss) income, Noncontrolling interest	(122)	161	141
Net (loss) income	(773)	38	570
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits, Alcoa Corporation	(62)	944	1,654
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits, Noncontrolling interest	(10)	8	54
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	(72)	952	1,708
Foreign currency translation adjustments, Alcoa Corporation	92	(71)	(229)
Foreign currency translation adjustments, Noncontrolling interest	57	(103)	(93)
Foreign currency translation adjustments	149	(174)	(322)
Net change in unrecognized gains/losses on cash flow hedges, Alcoa Corporation	(136)	180	(388)
Net change in unrecognized gains/losses on cash flow hedges, Noncontrolling interest	(1)	2
Net change in unrecognized gains/losses on cash flow hedges	(137)	182	(388)
Total Other comprehensive (loss) income, net of tax, Alcoa Corporation	(106)	1,053	1,037
Total Other comprehensive (loss) income, net of tax, Noncontrolling interest	46	(93)	(39)
Total Other comprehensive (loss) income, net of tax	(60)	960	998
Comprehensive (loss) income, Alcoa Corporation	(757)	930	1,466
Comprehensive (loss) income, Noncontrolling interest	(76)	68	102
Comprehensive (loss) income	$ (833)	$ 998	$ 1,568