Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Product warranty period	1 year
Change in contract liabilities		$ 5,000
Deferred revenue	$ 15,507	16,181
Long-term deferred revenue	3,015	$ 1,964
ASC 606 Adjustments
Disaggregation of Revenue [Line Items]
Increase in revenue	$ (1,006)
ASC 606 Adjustments | Maximum
Disaggregation of Revenue [Line Items]
Unsatisfied extended warranty performance obligations, period	24 months
Systems
Disaggregation of Revenue [Line Items]
Payment upon shipment of tool, as a percent	90.00%
Payment upon installation, as a percent	10.00%
Systems | Minimum
Disaggregation of Revenue [Line Items]
Payment upon delivery of parts, period	30 days
Systems | Maximum
Disaggregation of Revenue [Line Items]
Payment upon delivery of parts, period	60 days
Systems | ASC 606 Adjustments
Disaggregation of Revenue [Line Items]
Increase in revenue	$ 1,000