Annual report pursuant to Section 13 and 15(d)

Fair Value Measurement - Schedule of Fair Value Hierarchies for Financial Assets and Liabilities on Recurring Basis (Details)

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Fair Value Measurement - Schedule of Fair Value Hierarchies for Financial Assets and Liabilities on Recurring Basis (Details) - USD ($)
$ in Thousands
Dec. 31, 2019
Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Warrant liabilities $ 4,307 $ 585
Contingent success fee liability 6  
Recurring    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Warrant liabilities 4,307 585
Contingent success fee liability 6 34
Level 1 | Recurring    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Warrant liabilities 0 0
Contingent success fee liability 0 0
Level 2 | Recurring    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Warrant liabilities 0 0
Contingent success fee liability 0 0
Level 3 | Recurring    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Warrant liabilities 4,307 585
Contingent success fee liability $ 6 $ 34