Balance Sheet Accounts - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Inventory on consignment	$ 2,700		$ 2,700		$ 2,000
Depreciation and amortization expense	600	$ 600	1,200	$ 1,200
Finance Lease, ROU asset, before accumulated amortization	1,400		1,400		$ 1,400
Depreciation	$ 32	$ 21	$ 67	$ 42