Statement of Consolidated Operations (unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Abstract]
Sales (E)	$ 2,833	$ 2,148	$ 5,703	$ 4,529
Cost of goods sold (exclusive of expenses below)	2,156	1,932	4,448	3,957
Selling, general administrative, and other expenses	54	44	106	104
Research and development expenses	6	5	13	12
Provision for depreciation, depletion, and amortization	161	152	343	322
Restructuring and other charges, net (D)	33	37	40	39
Interest expense	67	32	109	62
Other (income) expenses, net (Q)	(105)	51	(129)	(81)
Total costs and expenses	2,372	2,253	4,930	4,415
Income (loss) before income taxes	461	(105)	773	114
Provision for income taxes	111	45	204	125
Net income (loss)	350	(150)	569	(11)
Less: Net income attributable to noncontrolling interest	41	47	85	106
NET INCOME (LOSS) ATTRIBUTABLE TO ALCOA CORPORATION	$ 309	$ (197)	$ 484	$ (117)
EARNINGS PER SHARE ATTRIBUTABLE TO ALCOA CORPORATION COMMON SHAREHOLDERS (F):
Basic	$ 1.66	$ (1.06)	$ 2.60	$ (0.63)
Diluted	$ 1.63	$ (1.06)	$ 2.56	$ (0.63)