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, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 194	$ 145	$ 344	$ 290
Interest cost	879	851	1,760	1,702
Expected return on plan assets	(433)	(752)	(1,159)	(1,504)
Net amortization and deferral	428	782	1,210	1,564
Net periodic benefit	1,068	1,026	2,155	2,052
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	5	52	43	104
Expected return on plan assets	(1)	0	(1)	0
Net accretion and deferral	(210)	(65)	(275)	(130)
Net periodic benefit	$ (206)	$ (13)	$ (233)	$ (26)