Certain Balance Sheet Items - Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property and equipment, gross	$ 19,891	$ 18,875
Accumulated depreciation and amortization	(13,100)	(11,582)
Property and equipment, net	6,791	7,293
Operating Lease, Right-of-Use Asset	2,003	3,300
Property, Plant, and Equipment and Operating Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization	$ 8,794	$ 10,593
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Property, Plant, and Equipment and Operating Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization	Property, Plant, and Equipment and Operating Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization
Research equipment
Property and equipment, gross	$ 7,174	$ 7,085
Manufacturing equipment
Property and equipment, gross	5,719	5,336
Computer and office equipment
Property and equipment, gross	5,370	4,826
Leasehold improvements
Property and equipment, gross	$ 1,628	$ 1,628