Segment Information - Schedule of Segment Adjusted EBITDA to Consolidated Net Income (Loss) Attributable to Alcoa Corporation (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Segment Reporting Information [Line Items]
Total Segment Adjusted EBITDA	$ 419	$ 143	$ 608	$ 430
Transformation	(16)	(17)	(30)	(25)
Intersegment eliminations	(29)	31	(37)	23
Corporate expenses	(41)	(24)	(75)	(54)
Provision for depreciation, depletion, and amortization	(163)	(153)	(324)	(306)
Restructuring and other charges, net (D)	(18)	(24)	(220)	(173)
Interest expense	(40)	(27)	(67)	(53)
Other income (expenses), net (P)	22	(6)	(37)	(60)
Other	(42)	(22)	(51)	(61)
Consolidated income (loss) before income taxes	92	(99)	(233)	(279)
Provision for income taxes	(61)	(22)	(43)	(74)
Net (income) loss attributable to noncontrolling interest	(11)	19	44	20
NET INCOME (LOSS) ATTRIBUTABLE TO ALCOA CORPORATION	$ 20	$ (102)	$ (232)	$ (333)