Earnings Per Share and Common Stock - 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, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Earnings Per Share [Abstract]
Net income	$ 266	$ 193	$ 509	$ 341
Less: preferred stock dividends declared	0	0	1	1
Net income available to Howmet Aerospace common shareholders - basic	266	193	508	340
Net income available to Howmet Aerospace common shareholders - diluted	$ 266	$ 193	$ 508	$ 340
Average shares outstanding - basic (in shares)	408	413	409	413
Effect of dilutive securities:
Stock and performance awards (in shares)	3	4	2	4
Average shares outstanding - diluted (in shares)	411	417	411	417