Employee Benefit Plans Summary of Pension Plan and Postretirement Plan Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 561	$ 681	$ 1,122	$ 1,362
Expected return on plan assets	(1,011)	(982)	(2,022)	(1,964)
Net amortization and deferral	504	465	1,008	930
Net periodic benefit	54	164	108	328
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	8	11	16	22
Net accretion and deferral	(134)	(137)	(268)	(274)
Net periodic benefit	$ (126)	$ (126)	$ (252)	$ (252)