Statement of Consolidated Comprehensive Income (unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Statement of Comprehensive Income [Abstract]
NET (LOSS) INCOME ATTRIBUTABLE TO ALCOA CORPORATION	$ (746)	$ 337	$ 272	$ 821
Net income, Noncontrolling interest	(23)	33	186	118
Net income	(769)	370	458	939
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits, Alcoa Corporation	656	72	730	456
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits, Noncontrolling interest	6	12	7	16
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	662	84	737	472
Foreign currency translation adjustments, Alcoa Corporation	(173)	(202)	(217)	(174)
Foreign currency translation adjustments, Noncontrolling interest	(81)	(78)	(115)	(87)
Foreign currency translation adjustments	(254)	(280)	(332)	(261)
Net change in unrecognized gains/losses on cash flow hedges, Alcoa Corporation	128	(111)	435	(581)
Net change in unrecognized gains/losses on cash flow hedges, Noncontrolling interest		(2)	2
Net change in unrecognized gains/losses on cash flow hedges	128	(113)	437	(581)
Total Other comprehensive income (loss), net of tax, Alcoa Corporation	611	(241)	948	(299)
Total Other comprehensive income (loss), net of tax, Noncontrolling interest	(75)	(68)	(106)	(71)
Total Other comprehensive income (loss), net of tax	536	(309)	842	(370)
Comprehensive income (loss), Alcoa Corporation	(135)	96	1,220	522
Comprehensive income (loss), Noncontrolling interest	(98)	(35)	80	47
Comprehensive income (loss)	$ (233)	$ 61	$ 1,300	$ 569