Pension and Retirement Plans - Components of Net Periodic Benefit Cost (Credit) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Pension Plan
Net periodic benefit cost (credit)
Interest cost	$ 451	$ 328	$ 1,354	$ 982
Expected return on assets	(801)	(968)	(2,403)	(2,907)
Net periodic benefit cost (credit)	(350)	(640)	(1,049)	(1,925)
Supplemental Retirement Plan
Net periodic benefit cost (credit)
Service cost	68	100	204	299
Interest cost	100	65	300	195
Amortization of net actuarial (gain) loss		7		21
Net periodic benefit cost (credit)	168	172	504	515
Postretirement Healthcare Plan
Net periodic benefit cost (credit)
Service cost	5	6	13	20
Interest cost	7	4	18	14
Amortization of net actuarial (gain) loss	(5)		(16)
Net periodic benefit cost (credit)	$ 7	$ 10	$ 15	$ 34