Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Net operating losses and tax credits	$ 29,514	$ 29,322
Stock-based compensation expense	4,028	4,118
Deferred rent	0	1,049
Depreciation and amortization expense	275	1,585
Accrued expenses	831	583
ROU liability	7,656	0
Transaction costs	467	0
Allowance for doubtful accounts	339	283
Unrealized gains and losses	165	51
Total deferred tax assets before valuation allowance	43,275	36,991
Less: valuation allowance	(36,877)	(36,692)
Total deferred tax assets, net of valuation allowance	6,398	299
Deferred tax liabilities:
Intangible assets	(993)	(1,243)
Unrealized gains and losses	(135)	(16)
Depreciation Expense	(90)
ROU asset	(6,126)	0
Total deferred tax liabilities	(7,344)	(1,259)
Total deferred tax liabilities, net	$ (946)	$ (960)