Stockholders' Equity Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax	[1]	$ (14,959)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax		17,392
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		(179)
Other Comprehensive Income (Loss), Net of Tax		17,213	$ 2,029
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent		(2)
Accumulated Other Comprehensive Income (Loss), Net of Tax		2,254
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax		(14,578)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax		15,397
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		0
Other Comprehensive Income (Loss), Net of Tax		15,397
Accumulated Other Comprehensive Income (Loss), Net of Tax		819
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax		(365)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax		1,993
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax		(179)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax, Portion Attributable to Parent		1,814
Accumulated Other Comprehensive Income (Loss), Net of Tax		1,449
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax		(16)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax		2
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax		0
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent		2
Accumulated Other Comprehensive Income (Loss), Net of Tax		$ (14)

[1] December 31, 2017 balances were derived from audited consolidated financial statements.