Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets
Net operating loss carryforward	$ 51,708	$ 36,093
Intangible assets	51	45
Accrued expense	598	605
Stock-based compensation	2,087	1,237
Other	299	126
Total deferred tax assets	70,346	49,553
Deferred tax liabilities
Depreciable assets	(203)	(72)
Total deferred tax liabilities	(203)	(72)
Less: Valuation allowance	(70,143)	(49,481)
Deferred tax assets, net	0	0
Federal
Deferred tax assets
Tax credits	14,764	10,859
State
Deferred tax assets
Tax credits	$ 839	$ 588