Stockholders' Equity Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 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				(5,980)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax				(522)
Other Comprehensive (loss) income, net of Tax		$ (4,231)	$ 5,609	(6,502)	$ 17,494
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent				(11)
Accumulated Other Comprehensive Income (Loss), Net of Tax		(21,461)		(21,461)
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				(7,705)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax				0
Other Comprehensive (loss) income, net of Tax				(7,705)
Accumulated Other Comprehensive Income (Loss), Net of Tax		(22,283)		(22,283)
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				1,714
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax				(522)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax, Portion Attributable to Parent				1,192
Accumulated Other Comprehensive Income (Loss), Net of Tax		827		827
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				11
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				11
Accumulated Other Comprehensive Income (Loss), Net of Tax		$ (5)		$ (5)

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