Statement of Consolidated Comprehensive Income (unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Statement of Comprehensive Income [Abstract]
NET INCOME (LOSS) ATTRIBUTABLE TO ALCOA CORPORATION	$ 20	$ (102)	$ (232)	$ (333)
Net income (loss), Noncontrolling interest	11	(19)	(44)	(20)
Net income (loss)	31	(121)	(276)	(353)
Change in unrecognized net actuarial gain/loss and prior service cost/benefit related to pension and other postretirement benefits, Alcoa Corporation	13	10	22	14
Change in unrecognized net actuarial gain/loss and prior service cost/benefit related to pension and other postretirement benefits, Noncontrolling interest	5	(2)	6	(2)
Change in unrecognized net actuarial gain/loss and prior service cost/benefit related to pension and other postretirement benefits	18	8	28	12
Foreign currency translation adjustments, Alcoa Corporation	(60)	25	(182)	27
Foreign currency translation adjustments, Noncontrolling interest	(16)	11	(70)	26
Foreign currency translation adjustments	(76)	36	(252)	53
Net change in unrecognized gains/losses on cash flow hedges, Alcoa Corporation	(62)	226	68	104
Net change in unrecognized gains/losses on cash flow hedges, Noncontrolling interest	(1)	0	(1)	0
Net change in unrecognized gains/losses on cash flow hedges	(63)	226	67	104
Total Other comprehensive (loss) income, net of tax, Alcoa Corporation	(109)	261	(92)	145
Total Other comprehensive (loss) income, net of tax, Noncontrolling interest	(12)	9	(65)	24
Total Other comprehensive (loss) income, net of tax	(121)	270	(157)	169
Comprehensive (loss) income , Alcoa Corporation	(89)	159	(324)	(188)
Comprehensive (loss) income , Noncontrolling interest	(1)	(10)	(109)	4
Comprehensive (loss) income	$ (90)	$ 149	$ (433)	$ (184)