Statement of Consolidated Operations - USD ($) shares in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Sales (B)	$ 14,192,000,000	$ 14,014,000,000	$ 12,960,000,000
Cost of goods sold (exclusive of expenses below)	11,227,000,000	11,397,000,000	10,221,000,000
Selling, general administrative, and other expenses	704,000,000	604,000,000	715,000,000
Research and development expenses	70,000,000	103,000,000	109,000,000
Provision for depreciation and amortization	536,000,000	576,000,000	551,000,000
Impairment of goodwill (A and N)	0	0	719,000,000
Restructuring and other charges (C)	620,000,000	9,000,000	165,000,000
Operating income	1,035,000,000	1,325,000,000	480,000,000
Interest expense (D)	338,000,000	378,000,000	496,000,000
Other expense (income), net (E)	122,000,000	79,000,000	(486,000,000)
Income before income taxes	575,000,000	868,000,000	470,000,000
Provision for income taxes (G)	105,000,000	226,000,000	544,000,000
Net income (loss)	470,000,000	642,000,000	(74,000,000)
Amounts Attributable to Arconic Common Shareholders (I):
Net income (loss)	$ 477,000,000	$ 651,000,000	$ (127,000,000)
Earnings (loss) per share - basic (in usd per share)	$ 1.05	$ 1.33	$ (0.28)
Earnings (loss) per share - diluted (in usd per share)	$ 1.03	$ 1.30
Average Shares Outstanding (I):
Average shares outstanding - basic (in shares)	446	483	451
Average shares outstanding - diluted (in shares)	463	503	451