Segment Information - Schedule of Combined Segment Adjusted EBITDA to Consolidated Net Income (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Combined segment adjusted EBITDA	$ 549	$ 524
Depreciation and amortization	(126)	(126)
Interest expense	(115)	(121)
Other income, net	354	12
Discontinued operations		(94)
Metal price lag	22
Net income attributable to Arconic	322	16
Other [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization	(133)	(133)
Interest expense	(115)	(121)
Restructuring and other charges	(73)	(16)
Other income, net	354	12
Discontinued operations		(94)
Income taxes	(162)	(51)
Impact of LIFO	(19)	(12)
Corporate expense	(91)	(76)
Other	$ (10)	$ (17)