Statement of Consolidated Operations (unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Sales (I)	$ 3,236	$ 3,138	$ 9,689	$ 9,427
Cost of goods sold (exclusive of expenses below)	2,626	2,503	7,701	7,436
Selling, general administrative, and other expenses	155	229	580	673
Research and development expenses	25	30	83	93
Provision for depreciation and amortization	140	136	410	402
Restructuring and other charges (D & E)	19	3	118	33
Operating income	271	237	797	790
Interest expense (L)	100	126	398	371
Other income, net (G)	(1)	(11)	(526)	(40)
Income from continuing operations before income taxes	172	122	925	459
Provision for income taxes	53	56	272	230
Income from continuing operations after income taxes	119	66	653	229
Income from discontinued operations after income taxes (G)		120		146
Net income	119	186	653	375
Less: Income from discontinued operations attributable to noncontrolling interests (G)		20		58
Net income attributable to Arconic	119	166	653	317
Amounts Attributable to Arconic Common Shareholders (J):
Net income	$ 101	$ 148	$ 600	$ 265
Earnings per share - basic
Continuing operations	$ 0.23	$ 0.11	$ 1.36	$ 0.40
Discontinued operations		0.23		0.20
Net income per share - basic	0.23	0.34	1.36	0.60
Earnings per share - diluted
Continuing operations	0.22	0.11	1.31	0.40
Discontinued operations		0.22		0.20
Net income per share - diluted	0.22	0.33	1.31	0.60
Dividends paid per share	$ 0.06	$ 0.09	$ 0.18	$ 0.27
Weighted Average Shares Outstanding (J):
Average shares outstanding - basic	442	438	441	438
Average shares outstanding - diluted	462	453	501	443