Segment Information - Schedule of Segment Adjusted EBITDA to Consolidated Net (Loss) Income Attributable to Alcoa Corporation (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Segment Reporting Information [Line Items]
Total Segment Adjusted EBITDA	$ 287	$ 1,015
Transformation	(8)	(14)
Intersegment eliminations	(8)	100
Corporate expenses	(30)	(29)
Provision for depreciation, depletion, and amortization	(153)	(160)
Restructuring and other charges, net (D)	(149)	(125)
Interest expense	(26)	(25)
Other (expenses) income, net (Q)	(54)	14
Income before income taxes	(180)	763
Provision for income taxes	(52)	(210)
Net loss (income) attributable to noncontrolling interest	1	(84)
NET (LOSS) INCOME ATTRIBUTABLE TO ALCOA CORPORATION	(231)	469
Other [Member]
Segment Reporting Information [Line Items]
Restructuring and other charges, net (D)		(125)
Other	$ (39)	$ (13)