Employee Benefit Plans Summary of Pension Plan and Postretirement Plan Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 813	$ 763	$ 2,443	$ 2,290
Expected return on plan assets	(688)	(512)	(2,066)	(1,536)
Net amortization and deferral	496	607	1,486	1,822
Net periodic benefit	621	858	1,863	2,576
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	15	13	45	42
Net accretion and deferral	(139)	(139)	(417)	(419)
Net periodic benefit	$ (124)	$ (126)	$ (372)	$ (377)