Pension Plans and Postretirement Benefit Plan (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Pension Benefits
Net periodic benefit cost for pension plans and the postretirement benefit plan
Service Cost	$ 0	$ 0
Interest Cost	900	1,094
Expected Return on Plan Assets	(1,258)	(1,249)
Amortization of Prior Service Credit	0	0
Amortization of Net Actuarial Losses (Gains)	570	484
Net Periodic Benefit Cost	212	329
Employer Contributions	100
Estimated Future Employer Contributions in Current Fiscal Year	400
Postretirement Benefits
Net periodic benefit cost for pension plans and the postretirement benefit plan
Service Cost	151	118
Interest Cost	231	258
Expected Return on Plan Assets	0	0
Amortization of Prior Service Credit	(61)	(72)
Amortization of Net Actuarial Losses (Gains)	0	(78)
Net Periodic Benefit Cost	321	$ 226
Employer Contributions	300
Estimated Future Employer Contributions in Current Fiscal Year	$ 1,000