Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Pension and Supplemental Executive Retirement Plans
Components of Net Periodic Benefit Cost [Abstract]
Service cost	$ 1,757	$ 1,664
Interest cost	2,877	2,810
Expected return on plan assets	(4,952)	(5,202)
Amortization of net actuarial losses (gains)	1,183	1,550
Amortization of prior service cost (credit)	(53)	(60)
Net periodic benefit cost (benefit)	812	762
Future company contributions to pension and supplemental executive retirements plans	6,500
Other Postretirement Benefit Plans
Components of Net Periodic Benefit Cost [Abstract]
Service cost	348	364
Interest cost	177	164
Expected return on plan assets	(2,625)	(2,215)
Amortization of net actuarial losses (gains)	(754)	(439)
Amortization of prior service cost (credit)	122	53
Net periodic benefit cost (benefit)	$ (2,732)	$ (2,073)