Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		$ 859,947
Other comprehensive income before reclassifications		(567)	$ 23,856
Amounts reclassified from OCI		(149)	8
Ending balance		877,724
Accumulated Other Comprehensive (Loss) Income [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		(165,555)	(149,334)
Ending balance		(166,271)	(125,470)
Cash Flow Hedges [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	[1]	147	(669)
Other comprehensive income before reclassifications	[1]	597	670
Amounts reclassified from OCI	[1]	(112)	38
Ending balance	[1]	632	39
Pension Items [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	[1]	549	(309)
Other comprehensive income before reclassifications	[1]	0	0
Amounts reclassified from OCI	[1]	(37)	(30)
Ending balance	[1]	512	(339)
Foreign Currency Items [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		(166,251)	(148,356)
Other comprehensive income before reclassifications		(1,164)	23,186
Amounts reclassified from OCI		0	0
Ending balance		$ (167,415)	$ (125,170)

[1] Cash Flow Hedges and Pension Items are net of tax.