Statement of Consolidated Operations (unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Cost, Product and Service [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Sales (D)	$ 1,134	$ 1,794	$ 4,021	$ 5,364
Cost of goods sold (exclusive of expenses below)	900	1,317	3,006	3,945
Selling, general administrative, and other expenses	66	89	219	307
Research and development expenses	5	6	13	22
Provision for depreciation and amortization	68	70	212	224
Restructuring and other charges (E)	22	56	166	572
Operating income	73	256	405	294
Interest expense, net	77	85	305	256
Other expense, net (F)	8	8	0	26
Income (loss) before income taxes	(12)	163	100	12
Provision (benefit) for income taxes (H)	(48)	105	(5)	4
Income from continuing operations after income taxes	36	58	105	8
Income from discontinued operations after income taxes (B)	0	37	50	153
Net income (loss)	36	95	155	161
Amounts Attributable to Howmet Aerospace Common Shareholders (I):
Net income (loss)	$ 35	$ 94	$ 153	$ 159
Earnings per share - basic
Continuing operations (in usd per share)	$ 0.08	$ 0.13	$ 0.24	$ 0.01
Discontinued operations (in usd per share)	0	0.09	0.11	0.34
Earnings per share - diluted
Continuing operations (in usd per share)	0.08	0.13	0.23	0.01
Discontinued operations (in usd per share)	$ 0	$ 0.08	$ 0.11	$ 0.34
Average Shares Outstanding (I):
Average shares outstanding - basic (in shares)	436	436	436	451
Average shares outstanding - diluted (in shares)	439	457	440	455