Statement of Consolidated Operations (unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Sales (E)	$ 3,109	$ 2,365	$ 8,812	$ 6,894
Cost of goods sold (exclusive of expenses below)	2,322	2,038	6,770	5,995
Selling, general administrative, and other expenses	53	47	159	151
Research and development expenses	8	6	21	18
Provision for depreciation, depletion, and amortization	156	161	499	483
Restructuring and other charges, net (D)	33	5	73	44
Interest expense	58	41	167	103
Other (income) expenses, net (Q)	(18)	45	(147)	(36)
Total costs and expenses	2,612	2,343	7,542	6,758
Income before income taxes	497	22	1,270	136
Provision for income taxes	127	42	331	167
Net income (loss)	370	(20)	939	(31)
Less: Net income attributable to noncontrolling interest	33	29	118	135
NET INCOME (LOSS) ATTRIBUTABLE TO ALCOA CORPORATION	$ 337	$ (49)	$ 821	$ (166)
EARNINGS PER SHARE ATTRIBUTABLE TO ALCOA CORPORATION COMMON SHAREHOLDERS (F):
Basic	$ 1.80	$ (0.26)	$ 4.40	$ (0.89)
Diluted	$ 1.76	$ (0.26)	$ 4.32	$ (0.89)