Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets
Net operating loss carryforwards	$ 43,610	$ 30,285
Operating lease liability	6,175	4,915
Other	1,834	1,522
Total deferred tax assets	51,619	36,722
Deferred tax liabilities
Depreciation and amortization	(3,264)	(3,598)
Deferred commissions and bonus	(4,161)	(2,652)
Operating lease right-of-use asset	(2,426)	(1,345)
Other	(1,056)	(847)
Total deferred tax liabilities	(10,907)	(8,442)
Less: Valuation allowance	(40,712)	(28,280)
Net deferred tax asset (liability)	$ 0	$ 0