Pension and Other Postretirement Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Defined Benefit Plan Deferred Pension And Other Postretirement Benefit Plan Costs Recovered [Abstract]
Deferred (recognized) pension and OPEB costs	$ 400	$ (300)
Pension Benefits [Member]
Components of net periodic benefit cost:
Service cost	752	1,337
Interest cost	4,322	2,796
Expected return on assets	(6,322)	(7,851)
Amortization of:
Prior service credit	0	(5)
Actuarial (gain) loss	388	724
Net periodic benefit (credit) cost	(860)	(2,999)
Postretirement Benefits [Member]
Components of net periodic benefit cost:
Service cost	200	333
Interest cost	819	491
Expected return on assets	(651)	(843)
Amortization of:
Transition obligation	1	1
Prior service credit	(0)	(74)
Actuarial (gain) loss	(30)	48
Net periodic benefit (credit) cost	$ 339	$ (44)