Income Taxes - Summary of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Stock compensation expense	$ 1,882	$ 1,867
Goodwill	1,490	1,927
Royalty accruals	560	484
Bad debt allowance	466	345
Net operating loss carryforwards	9,146	6,654
Credit carry-forwards	814	685
Inventory reserve	243	277
Depreciation	502	515
Other	340	539
Total deferred tax assets	15,443	13,293
Deferred tax liabilities:
Intangible assets	(220)	(283)
Other	0	(137)
Total deferred tax liabilities	(220)	(420)
Net deferred tax asset before valuation allowance	15,223	12,873
Valuation allowances for deferred tax assets	(15,394)	(13,044)	$ (12,234)	$ (13,179)
Net deferred tax liability	$ (171)	$ (171)