Earnings Per Share - Reconciliation of Information Used to Compute Basic and Diluted EPS (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Earnings Per Share [Abstract]
Net income attributable to common shareholders	$ 147	$ 74	$ 278	$ 154
Less: preferred stock dividends declared	0	0	1	1
Net income available to Howmet Aerospace common shareholders - basic	147	74	277	153
Net income available to Howmet Aerospace common shareholders - diluted	$ 147	$ 74	$ 277	$ 153
Average shares outstanding - basic (in shares)	417	432	418	433
Effect of dilutive securities:
Stock options (in shares)	0	1	0	1
Stock and performance awards (in shares)	5	4	5	4
Average shares outstanding - diluted (in shares)	422	437	423	438