Employee Benefit Plans - Pension plans with accumulated benefit obligation in excess of assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined benefit plans
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 448,993	$ 450,022
Projected benefit obligation	448,993	450,022	$ 603,309
Fair value of plan assets	387,429	383,725	517,148
SERPs
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	13,437	13,393
Projected benefit obligation	13,437	13,393	18,023
Fair value of plan assets	$ 0	$ 0	$ 0