Revenue From Contracts With Customers - Summary of Product and Service Revenue Disaggregated by Geographic Region (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disaggregation Of Revenue [Line Items]
Product and service revenue	$ 22,781	$ 26,347
United States
Disaggregation Of Revenue [Line Items]
Product and service revenue	11,604	10,918
South Korea
Disaggregation Of Revenue [Line Items]
Product and service revenue	3,077	7,876
Europe
Disaggregation Of Revenue [Line Items]
Product and service revenue	3,588	3,448
Asia (Excluding South Korea)
Disaggregation Of Revenue [Line Items]
Product and service revenue	4,193	3,664
Other
Disaggregation Of Revenue [Line Items]
Product and service revenue	$ 319	$ 441