Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Total revenue	$ 222,789	$ 176,619	$ 191,359
Point in time
Disaggregation of Revenue [Line Items]
Total revenue	185,215	168,699	185,989
Over time
Disaggregation of Revenue [Line Items]
Total revenue	37,574	7,920	5,370
North America
Disaggregation of Revenue [Line Items]
Total revenue	107,624	67,511	70,694
China
Disaggregation of Revenue [Line Items]
Total revenue	70,882	64,134	70,196
Rest of World
Disaggregation of Revenue [Line Items]
Total revenue	44,283	44,974	50,469
Industrial
Disaggregation of Revenue [Line Items]
Total revenue	84,478	76,668	82,763
Microfabrication
Disaggregation of Revenue [Line Items]
Total revenue	51,649	57,153	74,108
Aerospace and Defense
Disaggregation of Revenue [Line Items]
Total revenue	$ 86,662	$ 42,798	$ 34,488