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, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Earnings Per Share [Abstract]
Net income	$ 534	$ 407	$ 1,114	$ 751
Less: preferred stock dividends declared	0	0	0	1
Net income available to Howmet Aerospace common shareholders - basic	534	407	1,114	750
Net income available to Howmet Aerospace common shareholders - diluted	$ 534	$ 407	$ 1,114	$ 750
Average shares outstanding - basic (in shares)	400	404	400	404
Effect of dilutive securities:
Stock and performance awards (in shares)	2	2	2	3
Average shares outstanding - diluted (in shares)	402	406	402	407