Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Defined Benefits Plan Estimated Future Employer Contributions In Next Fiscal Year			$ 3,700
Post-Retirement Health Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefits Plan Estimated Future Employer Contributions In Next Fiscal Year			$ 251
Service cost	$ 10	$ 9
Interest cost	31	36
Expected return on plan assets	0	0
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	0	0
Net amortization of net (gain) loss	0	(4)
Net Periodic Benefit Cost	41	41
Defined Benefit Plan, Plan Assets, Contributions by Employer	60
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	325	304
Interest cost	779	866
Expected return on plan assets	(1,050)	(896)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	0	0
Net amortization of net (gain) loss	492	389
Net Periodic Benefit Cost	546	$ 663
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 435