Earnings Per Share - Reconciliation of Information Used to Compute Basic and Diluted EPS (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Earnings Per Share [Abstract]
Net income attributable to common shareholders	$ 131	$ 80
Less: preferred stock dividends declared	1	1
Net income available to Howmet Aerospace common shareholders - basic	130	79
Net income available to Howmet Aerospace common shareholders - diluted	$ 130	$ 79
Average shares outstanding - basic (in shares)	419	434
Effect of dilutive securities:
Stock options (in shares)	0	1
Stock and performance awards (in shares)	6	4
Average shares outstanding - diluted (in shares)	425	439