Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements (Measurement Levels) (Details)

v3.21.2
Fair Value Measurements (Measurement Levels) (Details) - Fair value, measurements, recurring - USD ($)
$ in Thousands
Sep. 30, 2021
Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability $ 881 $ 2,947
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 881 2,947
Warrants    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 881 2,910
Warrants | Quoted Prices in Active Markets (Level 1)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 0 0
Warrants | Significant Other Observable Inputs (Level 2)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 0 0
Warrants | Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 881 2,910
Warrants | Warrant liability - Hale    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 729 2,245
Warrants | Warrant liability - Hale | Quoted Prices in Active Markets (Level 1)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 0 0
Warrants | Warrant liability - Hale | Significant Other Observable Inputs (Level 2)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 0 0
Warrants | Warrant liability - Hale | Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 729 2,245
Warrants | Warrant liability - iStudy    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 152 665
Warrants | Warrant liability - iStudy | Quoted Prices in Active Markets (Level 1)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 0 0
Warrants | Warrant liability - iStudy | Significant Other Observable Inputs (Level 2)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 0 0
Warrants | Warrant liability - iStudy | Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 152 665
Derivative    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 0 37
Derivative | Quoted Prices in Active Markets (Level 1)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 0 0
Derivative | Significant Other Observable Inputs (Level 2)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability 0 0
Derivative | Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative liability $ 0 $ 37