Employee Benefit Plans Employee Benefit Plans (Schedule of Defined Benefit Plan Amounts Recognized in Other Comprehensive Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation [Abstract]
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	$ 838	$ 157	$ 935
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, Tax	(1,211)	(58)	(345)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax	(373)	99	$ 590
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax	6,560	7,399
Underfunded pension liability, deferred tax benefit	(1,527)	(2,739)
Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax	$ 5,033	$ 4,660