Qualified Employee Benefit Plans - Net (Benefit) Expense Under the Retirement Plan (Details) - Retirement Plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Interest cost on projected benefit obligations	$ 5,199	$ 3,958	$ 3,794
Expected return on plan assets	(4,776)	(6,591)	(6,351)
Amortization of prior service cost	24	24	24
Settlement loss recognized	0	1,678	2,024
Recognized actuarial loss	952	1,042	1,447
Net pension expense	$ 1,399	$ 111	$ 938