Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets (liabilities):
Accrued expenses	$ 88	$ 141
Deferred revenue	287	417
Stock-based compensation	449	396
Fixed assets	287	329
Goodwill	102	167
Inventory	197	47
Intangible amortization	(1,777)	(2,285)
R&D credit	2,154	2,154
Texas margin tax temporary credit	139	159
Other	62	285
Total deferred tax asset, net	35,220	30,542
Valuation allowance	(35,220)	(30,542)
Net deferred tax liability	0	0
Federal
Deferred tax assets (liabilities):
Tax benefit of operating loss carry forward	26,902	23,184
State
Deferred tax assets (liabilities):
Tax benefit of operating loss carry forward	$ 6,225	$ 5,548