Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Measurement Levels (Details)

v3.19.2
Fair Value Measurements - Measurement Levels (Details) - Fair value, measurements, recurring - USD ($)
$ in Thousands
Jun. 30, 2019
Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability $ 4,523 $ 2,798
Quoted Prices in Active Markets (Level 1)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 0 0
Significant Other Observable Inputs (Level 2)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 0 0
Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 4,523 2,798
Derivative warrant liability - ESW warrant    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 3,391 2,015
Derivative warrant liability - ESW warrant | Quoted Prices in Active Markets (Level 1)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 0 0
Derivative warrant liability - ESW warrant | Significant Other Observable Inputs (Level 2)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 0 0
Derivative warrant liability - ESW warrant | Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 3,391 2,015
Derivative warrant liability - Hale warrant    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 936 750
Derivative warrant liability - Hale warrant | Quoted Prices in Active Markets (Level 1)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 0 0
Derivative warrant liability - Hale warrant | Significant Other Observable Inputs (Level 2)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 0 0
Derivative warrant liability - Hale warrant | Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 936 750
Derivative warrant liability - iStudy    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 196 33
Derivative warrant liability - iStudy | Quoted Prices in Active Markets (Level 1)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 0 0
Derivative warrant liability - iStudy | Significant Other Observable Inputs (Level 2)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 0 0
Derivative warrant liability - iStudy | Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability $ 196 $ 33