Statement of Consolidated Operations (unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Sales (D)	$ 2,567	$ 3,390	$ 7,997	$ 10,059
Cost of goods sold (exclusive of expenses below) (H)	2,120	2,485	6,489	7,540
Selling, general administrative, and other expenses	66	58	218	189
Research and development expenses	7	7	21	24
Provision for depreciation, depletion, and amortization	184	173	530	559
Restructuring and other charges, net (C)	185	177	668	389
Interest expense	30	33	90	91
Other expenses, net (N)	27	2	118	32
Total costs and expenses	2,619	2,935	8,134	8,824
(Loss) income before income taxes	(52)	455	(137)	1,235
Provision for income taxes	95	260	361	569
Net (loss) income	(147)	195	(498)	666
Less: Net income attributable to noncontrolling interest	74	201	324	467
NET (LOSS) INCOME ATTRIBUTABLE TO ALCOA CORPORATION	$ (221)	$ (6)	$ (822)	$ 199
EARNINGS PER SHARE ATTRIBUTABLE TO ALCOA CORPORATION COMMON SHAREHOLDERS (E):
Basic	$ (1.19)	$ (0.03)	$ (4.43)	$ 1.07
Diluted	$ (1.19)	$ (0.03)	$ (4.43)	$ 1.06