Statement of Consolidated Operations (unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Sales (C & E)	$ 3,579	$ 2,859	$ 6,669	$ 5,514
Cost of goods sold (exclusive of expenses below)	2,632	2,289	5,013	4,312
Selling, general administrative, and other expenses	64	70	131	141
Research and development expenses	9	8	17	15
Provision for depreciation, depletion, and amortization	192	190	386	369
Restructuring and other charges (D)	231	12	212	22
Interest expense	32	25	58	51
Other expenses (income), net (O)	9	28	30	(51)
Total costs and expenses	3,169	2,622	5,847	4,859
Income before income taxes	410	237	822	655
Provision for income taxes	180	99	318	209
Net income	230	138	504	446
Less: Net income attributable to noncontrolling interest	155	63	279	146
Consolidated net income attributable to Alcoa Corporation	$ 75	$ 75	$ 225	$ 300
EARNINGS PER SHARE ATTRIBUTABLE TO ALCOA CORPORATION COMMON SHAREHOLDERS (F):
Basic	$ 0.40	$ 0.41	$ 1.21	$ 1.63
Diluted	$ 0.39	$ 0.40	$ 1.19	$ 1.61