Pension and Other Postretirement Benefits - Participation in Multi-Employer Pension Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Retirement Benefits [Abstract]
EIN	236648508
PN	499
Pension protection act zone status		Green	Green
Subject to financial improvement/rehabilitation plan	No
Contributions of century aluminum company	$ 1.6	$ 1.7	$ 1.4
Withdrawal from Plan Probable	No
Surcharge Imposed	No
Expiration date of collective bargaining agreement	Mar. 31, 2026