Basis of Presentation - Summary of Financial Instruments Measured at Fair Value on Recurring Basis (Details) - Fair Value Recurring - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Assets:
Total assets measured at fair value	$ 10,958	$ 39,983
Liabilities:
Preferred stock warrant liability		184
Commercial Paper
Assets:
Short-term investments	3,249	9,694
Corporate Debt Securities
Assets:
Short-term investments	4,707	24,781
Asset Backed Securities
Assets:
Short-term investments	3,002	5,508
Significant Other Observable Inputs (Level 2)
Assets:
Total assets measured at fair value	10,958	39,983
Significant Other Observable Inputs (Level 2) | Commercial Paper
Assets:
Short-term investments	3,249	9,694
Significant Other Observable Inputs (Level 2) | Corporate Debt Securities
Assets:
Short-term investments	4,707	24,781
Significant Other Observable Inputs (Level 2) | Asset Backed Securities
Assets:
Short-term investments	$ 3,002	5,508
Significant Observable Inputs (Level 3)
Liabilities:
Preferred stock warrant liability		$ 184