Revenue From Contracts With Customers - Summary of Product and Service Revenue Disaggregated by Geographic Region (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation Of Revenue [Line Items]
Product and service revenue	$ 6,987	$ 6,072	$ 19,701	$ 15,579
United States
Disaggregation Of Revenue [Line Items]
Product and service revenue	3,521	3,119	10,901	7,559
South Korea
Disaggregation Of Revenue [Line Items]
Product and service revenue	1,165	642	3,353	2,048
Europe
Disaggregation Of Revenue [Line Items]
Product and service revenue	908	761	2,718	2,301
Asia (Excluding South Korea)
Disaggregation Of Revenue [Line Items]
Product and service revenue	1,278	1,463	2,453	3,447
Other
Disaggregation Of Revenue [Line Items]
Product and service revenue	$ 115	$ 87	$ 276	$ 224

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details