Fair Value Measurements - Schedule of Changes in Fair Value of Level 3 Financial Instruments (Details) - Fair Value Level 3 - Measure of Changes in Fair Value - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Redeemable Convertible Preferred Stock Tranche Liability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value, beginning balance		$ 3,113
Recognition of preferred stock warrant liabilities		0
Change in the fair value included in other income, net		(1,970)
Settlement		0
Termination		(1,143)
Fair value, ending balance		0
TRDF Liability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value, beginning balance		142
Recognition of preferred stock warrant liabilities		0
Change in the fair value included in other income, net		(54)
Settlement		(88)
Termination		0
Fair value, ending balance		0
Redeemable Convertible Preferred Stock Warrant Liability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value, beginning balance	$ 1,881	0
Recognition of preferred stock warrant liabilities	144	2,131
Change in the fair value included in other income, net	897	(62)
Settlement		0
Termination		0
Fair value, ending balance	0	$ 2,069
Conversion of convertible preferred stock warrant into common stock warrant in connection with Merger	$ (2,922)