Income Taxes - Deferred Tax Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of income taxes computed using the federal statutory rate to the taxes reported in consolidated statements of operations
Loss before income taxes	$ (9,665)	$ (8,137)	$ (17,286)
Federal statutory rate	21.00%	21.00%	34.00%
Taxes computed at federal statutory rate	$ (2,030)	$ (1,709)	$ (5,877)
State taxes	(484)	(385)	(1,106)
Stock compensation	(1,329)	(605)	563
Federal and State Rate Change	(164)	839	11,749
Other	(49)	172	116
Change in valuation allowance	4,056	1,688	(5,445)
Reported income taxes	0	0	$ 0
Deferred tax assets
Net operating loss carryforwards	10,542	10,969
Employee benefits and stock compensation	4,329	2,798
Research and development costs	7,851	9,067
Fixed assets	0	418
Intangible assets	4,350	0
Operating lease liability	102	0
Inventory reserve	3,303	2,339
Other, net	119	345
Total deferred tax assets	30,596	25,936
Less: valuation allowance	(29,991)	(25,936)
Total net deferred tax assets	605	0
Deferred tax liabilities:
Fixed assets	(605)	0
Total net deferred tax liabilities	(605)	0
Net deferred tax assets and liabilities	$ 0	$ 0