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, 2021	$ 6,284	$ 2	$ 9,577	$ (315)	$ (4,592)	$ 1,612
Net (loss) income	553			469		84
Other comprehensive (loss) income (G)	(382)				(482)	100
Stock-based compensation	9		9
Net effect of tax withholding for compensation plans and exercise of stock options	2		2
Repurchase of common stock	(75)		(54)	(21)
Dividends paid on Alcoa common stock	(19)			(19)
Contributions	46					46
Distributions	(162)					(162)
Other	1		3			(2)
Balance at Mar. 31, 2022	6,257	2	9,537	114	(5,074)	1,678
Balance at Dec. 31, 2021	6,284	2	9,577	(315)	(4,592)	1,612
Net (loss) income	458
Other comprehensive (loss) income (G)	842
Balance at Sep. 30, 2022	6,892	2	9,171	(158)	(3,644)	1,521
Balance at Mar. 31, 2022	6,257	2	9,537	114	(5,074)	1,678
Net (loss) income	674			549		125
Other comprehensive (loss) income (G)	688				819	(131)
Stock-based compensation	11		11
Net effect of tax withholding for compensation plans and exercise of stock options	1		1
Repurchase of common stock	(275)		(236)	(39)
Dividends paid on Alcoa common stock	(18)			(18)
Contributions	37					37
Distributions	(83)					(83)
Balance at Jun. 30, 2022	7,292	2	9,313	606	(4,255)	1,626
Net (loss) income	(769)			(746)		(23)
Other comprehensive (loss) income (G)	536				611	(75)
Stock-based compensation	8		8
Repurchase of common stock	(150)		(150)
Dividends paid on Alcoa common stock	(18)			(18)
Contributions	67					67
Distributions	(74)					(74)
Balance at Sep. 30, 2022	6,892	2	9,171	(158)	(3,644)	1,521
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	(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, 2022	6,589	2	9,183	(570)	(3,539)	1,513
Net (loss) income	(546)
Other comprehensive (loss) income (G)	(32)
Balance at Sep. 30, 2023	6,092	2	9,179	(1,125)	(3,547)	1,583
Balance at Mar. 31, 2023	6,296	2	9,162	(819)	(3,655)	1,606
Net (loss) income	(121)			(102)		(19)
Other comprehensive (loss) income (G)	270				261	9
Stock-based compensation	11		11
Dividends paid on Alcoa common stock	(18)			(18)
Contributions	36					36
Distributions	(16)					(16)
Balance at Jun. 30, 2023	6,458	2	9,173	(939)	(3,394)	1,616
Net (loss) income	(193)			(168)		(25)
Other comprehensive (loss) income (G)	(201)				(153)	(48)
Stock-based compensation	6		6
Dividends paid on Alcoa common stock	(18)			(18)
Contributions	42					42
Distributions	(2)					(2)
Balance at Sep. 30, 2023	$ 6,092	$ 2	$ 9,179	$ (1,125)	$ (3,547)	$ 1,583