Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Narrative (Details)

v3.22.2.2
Summary of Significant Accounting Policies - Narrative (Details) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 6 Months Ended
Jul. 22, 2022
Mar. 22, 2022
Mar. 22, 2022
Sep. 13, 2021
Feb. 11, 2021
Jun. 30, 2022
Mar. 31, 2022
Jun. 30, 2021
Mar. 31, 2021
Jun. 30, 2022
Jun. 30, 2021
Dec. 31, 2021
Class of Stock [Line Items]                        
Working capital surplus           $ 65,200       $ 65,200    
Cash and cash equivalents           65,755       65,755   $ 52,480
Net (loss) income           $ (20,330) $ (11,557) $ 14,506 $ (12,539) (31,887) $ 1,967  
Net cash provided by (used in) operating activities                   $ (19,544) (14,163)  
Preferred stock, shares authorized (in shares)           5,000,000       5,000,000   5,000,000
Number of shares sold under offering (in shares)         3,000,000              
Net proceeds from issuance of preferred stock and warrants       $ 50,600           $ 46,906 0  
Debt securities, available-for-sale, unrealized loss           $ 40   60   120 60  
Unrealized (gain)/loss on equity securities           (247)   28,965   $ 1,256 28,965  
Stated term                   1 year    
Renewal option term                   1 year    
Term for students                   2 years    
Deferred revenue           3,600       $ 3,600   $ 4,800
Stock based compensation           $ 700   $ 2,100   $ 2,274 $ 7,149  
Subsequent Event | Equity Distribution Agreement                        
Class of Stock [Line Items]                        
Sale of stock, maximum potential offering $ 25,000                      
Initial Principal Amount | Subsequent Event | Promissory Note | Streeterville Capital, LLC                        
Class of Stock [Line Items]                        
Debt, initial aggregate principal amount 6,500                      
Payment for note purchase agreement $ 5,000                      
Series 7 Convertible Preferred Stock                        
Class of Stock [Line Items]                        
Series 7 Preferred redeemed for cash     $ 49,300       $ 49,300          
Net proceeds from issuance of preferred stock and warrants       $ 50,600                
Series 8 Convertible Preferred Stock                        
Class of Stock [Line Items]                        
Preferred stock, shares authorized (in shares)   53,197.7234 53,197.7234                  
Number of shares sold under offering (in shares)   112,778,720                    
Subscription price (in usd per share)   $ 940 $ 940                  
Original issuance discount percentage   6.00% 6.00%                  
Aggregate subscription value   $ 50,000 $ 50,000                  
Net proceeds from issuance of preferred stock and warrants   $ 46,900