Defined Benefit Post-Retirement Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Defined Benefit Post-Retirement Plans [Abstract]
Employer contributions	$ 0	$ 0
Pension Benefits [Member]
Components of net periodic (benefit) cost [Abstract]
Service cost	446	435
Interest cost	809	981
Expected return on plan assets	(2,105)	(1,873)
Net amortization	368	639
Total net periodic (benefit) cost	(482)	182
Other Benefits [Member]
Components of net periodic (benefit) cost [Abstract]
Service cost	2	2
Interest cost	55	81
Expected return on plan assets	0	0
Net amortization	13	17
Total net periodic (benefit) cost	$ 70	$ 100