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		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Earnings Per Share [Abstract]
Net income	$ 332	$ 188	$ 841	$ 529
Less: preferred stock dividends declared	1	1	2	2
Net income available to Howmet Aerospace common shareholders - basic	331	187	839	527
Net income available to Howmet Aerospace common shareholders - diluted	$ 331	$ 187	$ 839	$ 527
Average shares outstanding - basic (in shares)	408	412	408	412
Effect of dilutive securities:
Stock and performance awards (in shares)	2	3	3	5
Average shares outstanding - diluted (in shares)	410	415	411	417