Revenue (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Disaggregation of Revenue
Product warranty period		1 year
Change in contract liabilities	$ (3,000)	$ (3,000)
Contract liabilities	15,175	15,175		$ 18,145
Deferred revenue	11,927	11,927		16,181
Long-term deferred revenue	3,248	3,248		$ 1,964
ASC 606 Adjustments
Disaggregation of Revenue
Contract liabilities	2,430	2,430
ASC 606 Adjustments | ASU 2014-09
Disaggregation of Revenue
Change in contract liabilities	(1,600)	$ (1,600)	$ (1,600)
ASC 606 Adjustments | Maximum
Disaggregation of Revenue
Unsatisfied extended warranty performance obligations, period		24 months
Systems
Disaggregation of Revenue
Payment upon shipment of tool, as a percent		90.00%
Payment upon installation, as a percent		10.00%
Systems | Minimum
Disaggregation of Revenue
Payment upon delivery of parts, period		30 days
Systems | Maximum
Disaggregation of Revenue
Payment upon delivery of parts, period		60 days
Systems | ASC 606 Adjustments
Disaggregation of Revenue
Increase in revenue	$ 800	$ 1,800
Aftermarket | Minimum
Disaggregation of Revenue
Extended warranty period		1 year
Aftermarket | Maximum
Disaggregation of Revenue
Extended warranty period		3 years