Statement of Consolidated Operations (unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Sales (C)	$ 3,541	$ 3,445
Cost of goods sold (exclusive of expenses below)	2,818	2,768
Selling, general administrative, and other expenses	178	172
Research and development expenses	22	23
Provision for depreciation and amortization	137	142
Restructuring and other charges (D)	12	7
Operating income	374	333
Interest expense	85	114
Other expense, net (E)	32	20
Income before income taxes	257	199
Provision for income taxes (G)	70	56
Net income	187	143
Amounts Attributable to Arconic Common Shareholders (I):
Net income	$ 186	$ 142
Earnings per share - basic (in usd per share)	$ 0.40	$ 0.30
Earnings per share - diluted (in usd per share)	$ 0.39	$ 0.29
Average Shares Outstanding (I):
Average shares outstanding - basic (in shares)	471	482
Average shares outstanding - diluted (in shares)	489	503