Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Decrease in defined benefit plan obligation	$ 101,407	$ 101,445
Defined benefit pension plan
Defined Benefit Plan Disclosure [Line Items]
Revaluation discount rate	3.59%
Defined benefit pension plan | Change in assumptions for defined benefit plans
Defined Benefit Plan Disclosure [Line Items]
Decrease in defined benefit plan obligation	$ 3,600