Stockholders' Equity Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (21,272)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	6,862
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(549)
Other Comprehensive Income (Loss), Net of Tax	6,313	$ (514)	$ (11,204)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(14,959)	(21,272)
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(21,272)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	6,694
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0
Other Comprehensive Income (Loss), Net of Tax	6,694
Accumulated Other Comprehensive Income (Loss), Net of Tax	(14,578)	(21,272)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	0
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	184
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	(549)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax, Portion Attributable to Parent	(365)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(365)	0
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	0
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(16)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0
Other Comprehensive Income (Loss), Net of Tax	(16)
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (16)	$ 0