Income Taxes - Schedule of Deferred Tax Assets and Deferred Tax Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Federal and state net operating loss carryforwards	$ 45,193	$ 31,508	$ 15,307
Research and development tax credits	7,771	3,794	2,127
Stock-based compensation	8,434	2,055	585
Accruals and reserves	1,270	1,009	405
Deferred revenue	4,127	2,487	1,286
Other	573	230	71
Gross deferred tax assets	67,368	41,083	19,781
Valuation allowance	(59,267)	(38,310)	(19,302)
Net deferred tax assets	8,101	2,773	479
Deferred tax liabilities:
Property and equipment	(2,450)	(1,313)	(436)
Acquired intangible assets	(4,119)	(1,460)	(43)
Prepaid insurance and deferred commissions	(1,532)	0	0
Net deferred tax liabilities	(8,101)	(2,773)	(479)
Net deferred tax assets	$ 0	$ 0	$ 0