Retirement Plans, Components of Net Pension Cost for the Retirement Account Plan Tables (Details) - RAP - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Net period benefit cost for the pension and postretirement plans
Service cost	$ 7,779	$ 8,244	$ 7,263
Interest cost	6,570	8,185	9,752
Expected return on plan assets	(25,675)	(25,595)	(24,332)
Amortization of prior service cost	(73)	(73)	(73)
Amortization of actuarial loss	4,594	3,897	480
Recognized settlement loss	434	0	0
Total net periodic pension (income)	$ (6,370)	$ (5,342)	$ (6,910)