Pension Plans and Postretirement Benefit Plan - Schedule of Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Pension Benefits
Net periodic benefit cost for pension plans and the postretirement benefit plan
Service Cost	$ 0	$ 0	$ 0	$ 0
Interest Cost	900	1,093	2,699	2,187
Expected Return on Plan Assets	(1,258)	(1,249)	(3,773)	(2,498)
Amortization of Prior Service Credit	0	0	0	0
Amortization of Net Actuarial Losses (Gains)	570	484	1,711	968
Net Periodic Benefit Cost	212	328	637	657
Postretirement Benefits
Net periodic benefit cost for pension plans and the postretirement benefit plan
Service Cost	152	117	454	235
Interest Cost	230	257	694	515
Expected Return on Plan Assets	0	0	0	0
Amortization of Prior Service Credit	(61)	(72)	(184)	(144)
Amortization of Net Actuarial Losses (Gains)	0	(78)	0	(156)
Net Periodic Benefit Cost	$ 321	$ 224	$ 964	$ 450