Retirement Plans, Components of Net Pension Cost for the Retirement Account Plan Tables (Details) - RAP - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Net period benefit cost for the pension and postretirement plans
Service cost	$ 3,670	$ 7,779	$ 8,244
Interest cost	7,152	6,570	8,185
Expected return on plan assets	(26,903)	(25,675)	(25,595)
Amortization of prior service cost	(250)	(73)	(73)
Amortization of actuarial loss	658	4,594	3,897
Recognized settlement loss	0	434	0
Total net periodic pension (income)	$ (15,673)	$ (6,370)	$ (5,342)