Segment Information - Schedule of Segment Adjusted EBITDA to Consolidated Net (Loss) Income Attributable to Alcoa Corporation (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Segment Reporting Information [Line Items]
Total Segment Adjusted EBITDA	$ 143	$ 954	$ 430	$ 1,969
Transformation	(17)	(11)	(25)	(25)
Intersegment eliminations	(31)	(10)	23	(110)
Corporate expenses	(24)	(35)	(54)	(64)
Provision for depreciation, depletion, and amortization	(153)	(161)	(306)	(321)
Restructuring and other charges, net (D)	(24)	75	(173)	(50)
Interest expense	(27)	(30)	(53)	(55)
Other (expenses) income, net (R)	(6)	206	(60)	220
Income before income taxes	(99)	908	(279)	1,671
Provision for income taxes	(22)	(234)	(74)	(444)
Net loss (income) attributable to noncontrolling interest	19	(125)	20	(209)
NET (LOSS) INCOME ATTRIBUTABLE TO ALCOA CORPORATION	(102)	549	(333)	1,018
Other [Member]
Segment Reporting Information [Line Items]
Restructuring and other charges, net (D)	(24)	75	(173)	(50)
Other	$ (22)	$ (100)	$ (61)	$ (113)