Income Tax - Major components of deferred tax assets and liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carryforward	$ 29,831	$ 20,095
Stock based compensation	1,167	319
Other	491	34
Total deferred tax assets	31,489	20,448
Deferred tax liabilities:
Intangible asset	(2,189)	(2,057)
Other	(71)	0
Total deferred tax liabilities	(2,260)	(2,057)
Net deferred tax assets before valuation allowance	29,229	18,391
Valuation allowance	(29,229)	(18,391)
Deferred tax, net	$ 0	$ 0