Pension and Other Postretirement Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Pension Plans
Components of net periodic benefit costs:
Service cost	$ 119	$ 107	$ 96
Interest cost	528	674	839
Expected return on plan assets	(1,425)	(1,261)	(1,086)
Amortization of net loss (gain)	539	580	660
Net periodic benefit cost	(239)	100	509
Other changes in plan assets and benefit obligations recognized in other comprehensive income:
Net loss (gain)	(2,645)	503	(872)
Amortization of net loss (gain)	(539)	(580)	(660)
Total recognized in other comprehensive income	(3,184)	(77)	(1,532)
Total recognized in net periodic benefit cost and other comprehensive income	(3,423)	23	(1,023)
Chairman and President Non-Qualified Defined Benefit Plans
Components of net periodic benefit costs:
Service cost	1,235	1,209	502
Interest cost	1,044	1,350	1,025
Amortization of prior service cost	59	59	59
Amortization of net loss (gain)	5,131	5,781	1,391
Net periodic benefit cost	7,469	8,399	2,977
Other changes in plan assets and benefit obligations recognized in other comprehensive income:
Net loss (gain)	(7,420)	21,736	7,438
Amortization of prior service cost	(59)	(59)	(59)
Amortization of net loss (gain)	(5,131)	(5,781)	(1,391)
Total recognized in other comprehensive income	(12,610)	15,896	5,988
Total recognized in net periodic benefit cost and other comprehensive income	(5,141)	24,295	8,965
Defined Benefit Postretirement Healthcare Plans
Components of net periodic benefit costs:
Interest cost	148	165	198
Amortization of prior service cost	0	0	52
Amortization of net loss (gain)	292	158	244
Net periodic benefit cost	440	323	494
Other changes in plan assets and benefit obligations recognized in other comprehensive income:
Net loss (gain)	(457)	522	1,354
Amortization of prior service cost	0	0	(52)
Amortization of net loss (gain)	(292)	(158)	(244)
Total recognized in other comprehensive income	(749)	364	1,058
Total recognized in net periodic benefit cost and other comprehensive income	$ (309)	$ 687	$ 1,552