Earnings Per Share - Reconciliation of Information Used to Compute Basic and Diluted EPS (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Earnings Per Share [Abstract]
Net income attributable to common shareholders	$ 1,155	$ 765	$ 469
Less: preferred stock dividends declared	2	2	2
Net income available to Howmet Aerospace common shareholders - basic	1,153	763	467
Net income available to Howmet Aerospace common shareholders - diluted	$ 1,153	$ 763	$ 467
Average shares outstanding - basic (in shares)	408	412	416
Effect of dilutive securities:
Stock and performance awards (in shares)	2	4	5
Average shares outstanding - diluted (in shares)	410	416	421