Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Summary of Financial Instruments Measured on a Recurring Basis (Details)

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Fair Value Measurements - Summary of Financial Instruments Measured on a Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($)
$ in Thousands
Sep. 30, 2020
Dec. 31, 2019
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Fair value of financial assets $ 29,767 $ 42,193
Fair value of financial liabilities 4,888 21,588
Warrant liability    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Fair value of financial liabilities 2,282 18,396
Derivative liabilities    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Fair value of financial liabilities 2,606 3,192
Cash    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Fair value of financial assets 805 23
Restricted cash    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Fair value of financial assets 273 273
Money market funds    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Fair value of financial assets 28,689 41,897
Quoted Prices in Active Markets for Identical Assets (Level 1)    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Fair value of financial assets 29,767 42,193
Fair value of financial liabilities 0 0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Warrant liability    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Fair value of financial liabilities 0 0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Derivative liabilities    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Fair value of financial liabilities 0 0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Cash    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Fair value of financial assets 805 23
Quoted Prices in Active Markets for Identical Assets (Level 1) | Restricted cash    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Fair value of financial assets 273 273
Quoted Prices in Active Markets for Identical Assets (Level 1) | Money market funds    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Fair value of financial assets 28,689 41,897
Significant Other Observable Inputs (Level 2)    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Fair value of financial assets 0 0
Fair value of financial liabilities 0 0
Significant Other Observable Inputs (Level 2) | Warrant liability    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Fair value of financial liabilities 0 0
Significant Other Observable Inputs (Level 2) | Derivative liabilities    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Fair value of financial liabilities 0 0
Significant Other Observable Inputs (Level 2) | Cash    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Fair value of financial assets 0 0
Significant Other Observable Inputs (Level 2) | Restricted cash    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Fair value of financial assets 0 0
Significant Other Observable Inputs (Level 2) | Money market funds    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Fair value of financial assets 0 0
Significant Unobservable Inputs (Level 3)    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Fair value of financial assets 0 0
Fair value of financial liabilities 4,888 21,588
Significant Unobservable Inputs (Level 3) | Warrant liability    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Fair value of financial liabilities 2,282 18,396
Significant Unobservable Inputs (Level 3) | Derivative liabilities    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Fair value of financial liabilities 2,606 3,192
Significant Unobservable Inputs (Level 3) | Cash    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Fair value of financial assets 0 0
Significant Unobservable Inputs (Level 3) | Restricted cash    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Fair value of financial assets 0 0
Significant Unobservable Inputs (Level 3) | Money market funds    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Fair value of financial assets $ 0 $ 0