Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue
Product warranty period	1 year
Extended warranty period	1 year
Change in contract liabilities	$ 4,400
Contract liabilities	22,584	$ 18,145
Deferred revenue	19,513	16,181
Long-term deferred revenue	3,071	$ 1,964
ASC 606 Adjustments
Disaggregation of Revenue
Contract liabilities	2,623
ASC 606 Adjustments | ASU 2014-09
Disaggregation of Revenue
Reclassification gross decrease in customer contract liabilities	$ 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%
Payment upon delivery of parts, period	90 days
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	$ 1,000
Aftermarket | Minimum
Disaggregation of Revenue
Extended warranty period	1 year
Aftermarket | Maximum
Disaggregation of Revenue
Extended warranty period	3 years