Employee Benefit Plans Employee Benefit Plans and Components of Net Periodic Postretirement Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension curtailment			$ 0	$ (3,080)
Contributions paid	$ 0	$ 0	0	0
Anticipated cash contributions to pension plan in remaining fiscal year	0		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	224	474
Interest cost	1,312	1,795	2,624	3,590
Expected return on assets	(2,035)	(2,317)	(4,070)	(4,634)
Amortization of prior service cost	50	94	100	188
Amortization of actuarial loss	406	929	812	1,857
Pension curtailment	0	(3,080)	0	(3,080)
Net periodic pension and postretirement benefit cost	$ (155)	$ 3,818	$ (310)	$ 4,555