Summary of Significant Accounting Policies - Summary of Weighted Average Fair Value Assumptions on Common and Preferred Stock Warrant Liabilities (Detail) - Fair Value, Inputs, Level 3 [Member]	Jun. 30, 2020	Dec. 31, 2019
Minimum [Member] | Measurement Input, Risk Free Interest Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Common and preferred stock warrant liabilities, Fair value inputs	0.0015	0.0159
Minimum [Member] | Measurement Input, Maturity [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Common and preferred stock warrant liabilities, Fair value inputs	2 months 12 days	8 months 12 days
Minimum [Member] | Measurement Input, Price Volatility [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Common and preferred stock warrant liabilities, Fair value inputs	0.67	0.6
Maximum [Member] | Measurement Input, Risk Free Interest Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Common and preferred stock warrant liabilities, Fair value inputs	0.0018	0.016
Maximum [Member] | Measurement Input, Maturity [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Common and preferred stock warrant liabilities, Fair value inputs	6 months	1 year
Maximum [Member] | Measurement Input, Price Volatility [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Common and preferred stock warrant liabilities, Fair value inputs	1.23	1.105