Pension Plans and Postretirement Benefit Plan (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Pension Benefits
Net periodic benefit cost for pension plans and the postretirement benefit plan
Service Cost	$ 0	$ 0	$ 0	$ 0
Interest Cost	1,094	1,041	3,281	3,123
Expected Return on Plan Assets	(1,249)	(1,281)	(3,747)	(3,845)
Amortization of Prior Service Credit	0	0	0	0
Amortization of Net Actuarial Losses (Gains)	483	498	1,451	1,494
Net Periodic Benefit Cost	328	258	985	772
Employer Contributions	200		400
Estimated Future Employer Contributions in Current Fiscal Year	500		500
Postretirement Benefits
Net periodic benefit cost for pension plans and the postretirement benefit plan
Service Cost	118	114	353	344
Interest Cost	258	235	773	706
Expected Return on Plan Assets	0	0	0	0
Amortization of Prior Service Credit	(72)	(142)	(216)	(426)
Amortization of Net Actuarial Losses (Gains)	(77)	(61)	(233)	(185)
Net Periodic Benefit Cost	227	$ 146	677	$ 439
Employer Contributions	500		1,100
Estimated Future Employer Contributions in Current Fiscal Year	$ 1,500		$ 1,500