Employee Benefit Plans Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost (1)	$ 0	$ 0	$ 688
Interest cost	3,053	3,320	3,520
Expected return on assets	(2,047)	(1,804)	(2,318)
Net amortization and deferral	2,429	2,652	2,420
Net periodic benefit cost	3,435	4,168	4,310
Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Interest cost	57	68	85
Net amortization and deferral	(559)	(565)	(551)
Net periodic benefit cost	$ (502)	$ (497)	$ (466)