Employee Benefit Plans Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 688	$ 579	$ 367
Interest cost	3,520	3,405	3,413
Expected return on assets	(2,318)	(3,009)	(3,240)
Net amortization and deferral	2,420	3,127	974
Net periodic benefit cost	4,310	4,102	1,514
Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	15
Interest cost	85	206	206
Net amortization and deferral	(551)	(258)	(347)
Net periodic benefit cost	$ (466)	$ (52)	$ (126)