Pension and Retirement Plans - Components of Net Periodic Benefit Cost (Credit) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Pension Plan
Net periodic benefit cost (credit)
Interest cost	$ 345	$ 303	$ 655	$ 606
Expected return on assets	(1,002)	(891)	(1,938)	(1,783)
Amortization of prior service credit				(1)
Net periodic benefit cost (credit)	(657)	(588)	(1,283)	(1,178)
Supplemental Retirement Plan
Net periodic benefit cost (credit)
Service cost	98	106	199	212
Interest cost	71	56	130	113
Amortization of net actuarial loss		11		22
Net periodic benefit cost (credit)	169	173	329	347
Postretirement Healthcare Plan
Net periodic benefit cost (credit)
Service cost	6	8	14	17
Interest cost	5	5	10	9
Net periodic benefit cost (credit)	$ 11	$ 13	$ 24	$ 26