Income Taxes - Tax Effects of Temporary Differences (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Accrued liabilities not currently deductible	$ 1,248	$ 1,929
Intangible assets-excess of tax basis over financial statement basis	15,464	17,729
Federal impact of deferred state taxes	6	3
Net operating losses	61,706	52,751
Stock-based compensation	1,670	1,761
Other	433	410
Total deferred tax assets	80,527	74,583
Deferred tax liabilities:
Intangible assets-excess of financial statement basis over tax basis	(143)	(206)
Property and equipment	(1,158)	(986)
Total deferred tax liabilities	(1,301)	(1,192)
Valuation allowance	(79,289)	(73,477)
Net deferred tax liabilities	(63)	(86)
Non-current	(63)	(86)
Total current and non-current deferred tax liabilities	$ (63)	$ (86)