Segment and Geographic Information - Geographic Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Product sales	$ 685,651	$ 722,666	$ 709,438
Service sales	244,481	233,614	218,016
Total sales	930,132	956,280	927,454
U.S. and Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Product sales	192,440	207,623	167,876
Service sales	105,255	97,966	92,759
Total sales	297,695	305,589	260,635
Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Product sales	182,720	200,995	205,857
Service sales	64,196	66,799	64,803
Total sales	246,916	267,794	270,660
Asia Pacific Region and Rest of World [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Product sales	310,491	314,048	335,705
Service sales	75,030	68,849	60,454
Total sales	$ 385,521	$ 382,897	$ 396,159