Employee Benefit Plans (Pension Costs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Service costs	$ 0	$ 90	$ 161
Interest costs	1,879	2,587	1,205
Expected return on plan assets	(156)	(160)	0
Amortization of net (gain)/loss	(691)	979	(620)
Net periodic benefit cost	$ 1,032	$ 3,496	$ 746