Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue
Product warranty period	1 year
Extended warranty period	1 year
Contract liabilities	$ 29,251	$ 22,584	$ 18,145	$ 11,009
Short-term deferred revenue	24,601	19,513
Long-term deferred revenue	$ 4,650	$ 3,071
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