Investments (Tables)

9 Months Ended

Sep. 30, 2021

Equity Method Investments And Joint Ventures [Abstract]

Summary of Unaudited Financial Information for Alcoa Corporation's Equity Investments

A summary of unaudited financial information for Alcoa Corporation’s equity investments is as follows (amounts represent 100% of investee financial information):

Third quarter ended September 30, 2021	Saudi Arabia Joint Venture			Mining			Energy		Other
Sales	$	776		$	198		$	73	$	100
Cost of goods sold		479			145			51		90
Net income (loss)		152			11			22		(12	)
Equity in net income (loss) of affiliated companies,    before reconciling adjustments		38			6			8		(5	)
Other		(3	)		(1	)		—		4
Alcoa Corporation’s equity in net income (loss) of    affiliated companies		35			5			8		(1	)
Third quarter ended September 30, 2020
Sales	$	552		$	195		$	51	$	72
Cost of goods sold		435			131			28		65
Net (loss) income		(38	)		16			28		(10	)
Equity in net (loss) income of affiliated companies,    before reconciling adjustments		(10	)		5			11		(4	)
Other		(1	)		—			1		3
Alcoa Corporation’s equity in net (loss) income of    affiliated companies		(11	)		5			12		(1	)
Nine months ended September 30, 2021
Sales	$	2,199		$	568		$	188	$	291
Cost of goods sold		1,490			414			108		261
Net income (loss)		299			31			74		(18	)
Equity in net income (loss) of affiliated companies,    before reconciling adjustments		75			16			29		(8	)
Other		(7	)		(2	)		—		15
Alcoa Corporation’s equity in net income of    affiliated companies		68			14			29		7
Nine months ended September 30, 2020
Sales	$	1,644		$	622		$	157	$	230
Cost of goods sold		1,343			409			78		207
Net (loss) income		(126	)		20			75		(25	)
Equity in net (loss) income of affiliated companies,    before reconciling adjustments		(32	)		14			29		(11	)
Other		(5	)		(1	)		—		13
Alcoa Corporation’s equity in net (loss) income of    affiliated companies		(37	)		13			29		2