Segment and Related Information - Schedule of Segment Adjusted EBITDA to Consolidated Net (Loss) Income Attributable to Alcoa Corporation (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Total Segment Adjusted EBITDA		$ 734	$ 2,280	$ 3,071
Transformation		(80)	(66)	(44)
Intersegment eliminations		7	138	(119)
Corporate expenses		(133)	(128)	(129)
Provision for depreciation, depletion, and amortization		(632)	(617)	(664)
Restructuring and other charges, net (D)		(184)	(696)	(1,128)
Interest expense (U)		(107)	(106)	(195)
Other (expenses) income, net (U)		(134)	118	445
(Loss) income before income taxes		(584)	702	1,199
Provision for income taxes (Q)	$ 36	(189)	(664)	(629)
Net loss (income) attributable to noncontrolling interest		122	(161)	(141)
Net (loss) income attributable to Alcoa Corporation		(651)	(123)	429
Other [Member]
Segment Reporting Information [Line Items]
Restructuring and other charges, net (D)		(184)	(696)	(1,128)
Other		$ (55)	$ (221)	$ (38)