Composition of Certain Consolidated Financial Statement Items - Property and Equipment, net (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 12,165	$ 13,062
Less: accumulated depreciation and amortization	(6,434)	(4,788)
Total property and equipment, net	5,731	8,274
Laboratory, manufacturing and computer equipment and furniture
Property, Plant and Equipment [Line Items]
Total property and equipment	2,911	2,645
Rental equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	821	1,247
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	4,941	4,941
Evaluation units
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 3,492	$ 4,229