Impact of Recently Issued Accounting Pronouncements - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	$ 98,244	$ 82,682	$ 191,078	$ 164,244
United States
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	40,278	32,143	77,580	63,913
EMEA
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	29,601	24,320	59,281	49,280
APAC
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	24,944	22,882	47,533	44,142
Other Americas
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	3,421	3,337	6,684	6,909
Product sales
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	75,720	62,533	146,301	124,913
Product sales | Product transferred to customers at a point in time
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	75,720	62,533	146,301	124,913
Product sales | Product transferred to customers over time
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	0	0	0	0
Service sales
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	22,524	20,149	44,777	39,331
Service sales | Product transferred to customers at a point in time
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	9,907	8,530	19,359	17,172
Service sales | Product transferred to customers over time
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Sales	$ 12,617	$ 11,619	$ 25,418	$ 22,159