Statement of Changes in Consolidated Equity (unaudited) - USD ($) $ in Millions	Total	Common Stock [Member]	Additional Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]	Non-controlling Interest [Member]
Balance at Dec. 31, 2022	$ 6,589	$ 2	$ 9,183	$ (570)	$ (3,539)	$ 1,513
Net (loss) income	(232)			(231)		(1)
Other comprehensive (loss) income (G)	(101)				(116)	15
Stock-based compensation	10		10
Net effect of tax withholding for compensation plans and exercise of stock options	(33)		(33)
Dividends paid on Alcoa common stock ($0.10 per share)	(18)			(18)
Contributions	86					86
Distributions	(6)					(6)
Other	1		2			(1)
Balance at Mar. 31, 2023	6,296	2	9,162	(819)	(3,655)	1,606
Balance at Dec. 31, 2023	5,845	2	9,187	(1,293)	(3,645)	1,594
Net (loss) income	(307)			(252)		(55)
Other comprehensive (loss) income (G)	(36)				17	(53)
Stock-based compensation	10		10
Net effect of tax withholding for compensation plans and exercise of stock options	(15)		(15)
Dividends paid on Alcoa common stock ($0.10 per share)	(19)			(19)
Contributions	61					61
Distributions	(6)					(6)
Other	1		2			(1)
Balance at Mar. 31, 2024	$ 5,534	$ 2	$ 9,184	$ (1,564)	$ (3,628)	$ 1,540