Pension and Other Postretirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Pension Benefits
Components of net periodic benefit cost
Service cost	$ 1,992	$ 1,992	$ 3,999	$ 4,127
Interest cost	2,217	2,194	4,451	4,145
Expected return on plan assets	(1,891)	(2,399)	(3,762)	(4,946)
Settlement expense	0	118	0	1,537
Amortization of net loss (gain)	1,042	695	1,977	2,116
Amortization of prior service cost (credit)	68	70	137	141
Net periodic benefit cost	3,428	2,670	6,802	7,120
Postretirement Benefits
Components of net periodic benefit cost
Service cost	121	173	281	335
Interest cost	92	76	176	151
Expected return on plan assets	0	0	0	0
Settlement expense	0	0	0	0
Amortization of net loss (gain)	(79)	(95)	(231)	(160)
Amortization of prior service cost (credit)	(34)	(34)	(68)	(68)
Net periodic benefit cost	$ 100	$ 120	$ 158	$ 258