Statement of Consolidated Comprehensive Income (unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Statement of Comprehensive Income [Abstract]
NET (LOSS) INCOME ATTRIBUTABLE TO ALCOA CORPORATION	$ (168)	$ (746)	$ (501)	$ 272
Net income, Noncontrolling interest	(25)	(23)	(45)	186
Net (loss) income	(193)	(769)	(546)	458
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits, Alcoa Corporation	5	656	19	730
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits, Noncontrolling interest	(1)	6	(3)	7
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	4	662	16	737
Foreign currency translation adjustments, Alcoa Corporation	(67)	(173)	(40)	(217)
Foreign currency translation adjustments, Noncontrolling interest	(47)	(81)	(21)	(115)
Foreign currency translation adjustments	(114)	(254)	(61)	(332)
Net change in unrecognized gains/losses on cash flow hedges, Alcoa Corporation	(91)	128	13	435
Net change in unrecognized gains/losses on cash flow hedges, Noncontrolling interest				2
Net change in unrecognized gains/losses on cash flow hedges	(91)	128	13	437
Total Other comprehensive (loss) income, net of tax, Alcoa Corporation	(153)	611	(8)	948
Total Other comprehensive (loss) income, net of tax, Noncontrolling interest	(48)	(75)	(24)	(106)
Total Other comprehensive (loss) income, net of tax	(201)	536	(32)	842
Comprehensive (loss) income , Alcoa Corporation	(321)	(135)	(509)	1,220
Comprehensive (loss) income , Noncontrolling interest	(73)	(98)	(69)	80
Comprehensive (loss) income	$ (394)	$ (233)	$ (578)	$ 1,300