Employee Benefit Plans Employee Benefit Plans and Components of Net Periodic Postretirement Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions paid	$ 0	$ 0
Anticipated cash contributions to pension plan in remaining fiscal year	0
Pension and Other Postretirement Plans, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	112	237
Interest cost	1,312	1,795
Expected return on assets	(2,035)	(2,317)
Amortization of prior service cost	50	94
Amortization of actuarial loss	406	928
Net periodic pension and postretirement benefit cost	$ (155)	$ 737