Property, Plant and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 459,369	$ 436,491
Accumulated depreciation	(316,834)	(295,173)
Property, plant and equipment, net	142,535	141,318
Depreciation expense	49,513	37,299	$ 38,185
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	2,471	2,404
Buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	90,683	88,201
Machinery and other equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	226,320	221,325
Computer equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	77,508	70,110
Software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 62,387	$ 54,451