Summary of Significant Accounting Policies - Other Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Restricted assets	$ 1,591	$ 25,907
Prepaid pension costs	39,334	38,100
Other assets	37,709	31,310
Total other assets	$ 78,634	$ 95,317