Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Components of net periodic benefit cost [Abstract]
Contribution made to pension and postretirement plans			$ 0
Pension Benefits [Member]
Components of net periodic benefit cost [Abstract]
Service (credit) cost	$ 0	$ 9	0	$ 28
Interest cost	214	269	642	807
Expected return on plan assets	(712)	(755)	(2,135)	(2,265)
Amortization of net loss (gain)	0	(5)	0	0
Amortization of prior service cost (credit)	0	0	0	0
Net periodic benefit	(498)	(482)	(1,493)	(1,430)
Other Postretirement Benefits [Member]
Components of net periodic benefit cost [Abstract]
Service (credit) cost	9	15	57	55
Interest cost	60	40	143	152
Expected return on plan assets	(274)	(296)	(891)	(887)
Amortization of net loss (gain)	(137)	(217)	(534)	(531)
Amortization of prior service cost (credit)	177	(49)	227	(147)
Net periodic benefit	$ (165)	$ (507)	$ (998)	$ (1,358)