Qualified Employee Benefit Plans - Net (Benefit) Expense Under the Retirement Plan (Details) - Retirement Plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Interest cost on projected benefit obligations	$ 3,794	$ 4,443	$ 4,944
Expected return on plan assets	(6,351)	(6,084)	(5,639)
Amortization of prior service cost	24	24	24
Settlement loss recognized	2,024	0	0
Recognized actuarial loss	1,447	1,386	1,146
Net pension expense	$ 938	$ (231)	$ 475