Statement of Consolidated Operations - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Sales (N)	$ 12,960	$ 12,394	$ 12,413
Cost of goods sold (exclusive of expenses below)	10,357	9,811	10,104
Selling, general administrative, and other expenses (C)	731	942	765
Research and development expenses	111	132	169
Provision for depreciation and amortization	551	535	508
Impairment of goodwill (A and E)	719	0	25
Restructuring and other charges (D)	165	155	214
Operating income	326	819	628
Interest expense (S)	496	499	473
Other income, net (L)	640	94	28
Income from continuing operations before income taxes	470	414	183
Provision for income taxes (Q)	544	1,476	339
Loss from continuing operations after income taxes	(74)	(1,062)	(156)
Income (loss) from discontinued operations after income taxes (C)	0	184	(41)
Net loss	(74)	(878)	(197)
Less: Net income from continuing operations attributable to noncontrolling interests	0	0	1
Less: Net income from discontinued operations attributable to noncontrolling interests (C)	0	63	124
Net loss attributable to Arconic	(74)	(941)	(322)
Amounts Attributable to Arconic Common Shareholders (P):
Net loss	$ (127)	$ (1,010)	$ (391)
(Loss) earnings per share—basic:
Continuing operations (in usd per share)	$ (0.28)	$ (2.58)	$ (0.54)
Discontinued operations (in usd per share)	0.00	0.27	(0.39)
Net loss per share-basic (in usd per share)	(0.28)	(2.31)	(0.93)
(Loss) earnings per share—diluted
Continuing operations (in usd per share)	(0.28)	(2.58)	(0.54)
Discontinued operations (in usd per share)	0.00	0.27	(0.39)
Net loss per share-diluted (in usd per share)	$ (0.28)	$ (2.31)	$ (0.93)