Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Net operating loss carryforward	$ 36,136	$ 28,496
Stock options and restricted stock	4,805	5,051
Interest expense	244	220
Inventory reserve	399	272
Allowance for doubtful accounts	17	50
Accrued expenses	1,073	1,190
Deferred revenue	880	5
Leasehold improvements and equipment	74	32
Intangibles	95	85
Operating leases	85	96
Deferred tax assets, gross	43,808	35,497
Less: Valuation allowance	(43,363)	(35,244)
Total deferred tax assets	445	253
Deferred tax liabilities:
Prepaid expenses	(445)	(253)
Total deferred tax liabilities	(445)	(253)
Net deferred tax assets (liabilities)	$ 0	$ 0