Employee Benefit Plans Employee Benefit Plans and Components of Net Periodic Postretirement Benefit Cost (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Estimated Cost Reduction of Net Periodic Pension and Post Retirement Benefit Costs	$ 1,206
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements	0	$ 3,915	$ 0
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments	0	2,923	0
Pension Plans, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	377	549	453
Interest cost	5,182	6,938	6,885
Expected return on assets	(8,139)	(9,395)	(8,381)
Amortization of prior service cost	200	244	282
Amortization of actuarial loss (gain)	1,832	4,018	1,717
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements	0	3,915	0
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments	0	2,923	0
Net periodic pension plans (benefit) cost	(548)	9,192	956
Other Postretirement Benefit Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	71	83	56
Interest cost	65	79	76
Amortization of actuarial loss (gain)	(209)	(197)	(336)
Net periodic pension plans (benefit) cost	$ (73)	$ (35)	$ (204)