Employee Benefit Plans Summary of Pension Plan and Postretirement Plan Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 681	$ 815
Expected return on plan assets	(982)	(689)
Net amortization and deferral	465	495
Net periodic benefit	164	621
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	11	15
Net accretion and deferral	(137)	(139)
Net periodic benefit	$ (126)	$ (124)