Summary of Significant Accounting Policies - Other Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Restricted assets	$ 26,178	$ 25,907
Prepaid pension costs	38,717	38,100
Other assets	31,656	31,310
Total other assets	$ 96,551	$ 95,317