Defined Benefit Post-Retirement Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Defined Benefit Post-Retirement Plans [Abstract]
Employer contributions	$ 0	$ 0	$ 0	$ 0
Pension Benefits [Member]
Components of net periodic (benefit) cost [Abstract]
Service cost	517	446	1,486	1,338
Interest cost	679	809	2,034	2,427
Expected return on plan assets	(2,197)	(2,105)	(6,602)	(6,315)
Net amortization	331	368	957	1,104
Net periodic pension (benefit) cost	(670)	(482)	(2,125)	(1,446)
Other Benefits [Member]
Components of net periodic (benefit) cost [Abstract]
Service cost	2	2	6	6
Interest cost	45	55	135	165
Expected return on plan assets	0	0	0	0
Net amortization	13	13	39	39
Net periodic pension (benefit) cost	$ 60	$ 70	$ 180	$ 210