Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity - Narrative (Details)

v3.20.4
Stockholders' Equity - Narrative (Details)
3 Months Ended 9 Months Ended
Feb. 26, 2021
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Oct. 16, 2020
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Sep. 14, 2020
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Sep. 02, 2020
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Aug. 31, 2020
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Jun. 18, 2020
Jun. 08, 2020
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Jun. 05, 2020
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Feb. 04, 2020
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Jan. 22, 2020
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Mar. 06, 2019
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Jan. 31, 2021
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Oct. 31, 2020
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Jul. 31, 2020
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Jan. 31, 2020
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Jan. 31, 2021
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Jan. 31, 2020
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Dec. 21, 2020
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Dec. 20, 2020
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Apr. 30, 2020
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Dec. 30, 2019
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Dec. 13, 2018
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Nov. 05, 2018
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Mar. 13, 2012
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Stockholders Equity [Line Items]                                                
Preferred stock, shares authorized (in shares)                       1,000,000       1,000,000       1,000,000        
Preferred stock issued (in shares)                       0       0       0        
Preferred stock outstanding (in shares)                       0       0       0        
Common stock, shares authorized (in shares)                       40,000,000       40,000,000       40,000,000        
Cashless exercise of stock options (in shares)                         36,111                      
Common stock issued for stock options exercised for cash | $                       $ 363,385     $ 530,668 $ 2,578,700 $ 768,381              
Number of shares of common stock surrendered (in shares)                               155,486                
Common stock issued for vested restricted stock units (in shares)                         132,109                      
Common stock issued for services | $                               $ 19,900 97,748              
Common stock issued for stock options exercised for cash (in shares)                         502,412                      
Common stock issued for stock options exercised for cash | $                         $ 945,332 $ 1,269,982                    
Common stock issued for cashless stock options exercised (in shares)                         22,339                      
Common stock issued for warrants exercised for cash (in shares)                           192,049                    
Common stock issued for warrants exercised for cash | $                           $ 1,081,792   1,081,792                
Share price (in dollars per share) | $ / shares       $ 9.49                                        
Proceeds from warrants exercised | $                               1,081,792 $ 0              
Modification charge for warrants exercised | $                           $ 26,000   25,966                
Compensation expense | $                       $ 721,067       $ 3,039,729                
Treasury stock (in shares)                       155,486       155,486       16,667        
Treasury stock, value | $                       $ 1,817,414       $ 1,817,414       $ 70,000        
Treasury shares cancelled (in shares)   16,667                                            
Retirement of treasury stock | $   $ 70,000                           $ 0                
Equity Distribution Agreement                                                
Stockholders Equity [Line Items]                                                
Common stock, capital shares reserved for future issuance, value | $         $ 12,309,750                                      
Number of shares sold (in shares)                               449,632                
Sale of stock, gross proceeds (as a percent)         3.00%                                      
Reimbursement expenses | $         $ 50,000                                      
Total expenses for offering | $         $ 50,000                                      
Loan Agreements                                                
Stockholders Equity [Line Items]                                                
Warrants granted, exercise price (in dollars per share) | $ / shares                     $ 6.00                          
Convertible Notes | Convertible Notes Payable                                                
Stockholders Equity [Line Items]                                                
Average closing price of common stock (in dollars per share) | $ / shares     $ 10.725             $ 10.725                            
Consecutive trading day period | day     20             20                            
Debt instrument, face amount of loan | $     $ 10,000,000             $ 5,000,000                            
Conversion price (in dollars per share) | $ / shares     $ 7.15             $ 7.15                            
Amortization expense | $                         $ 1,400,000                      
Convertible Notes | Convertible Notes Payable | Common Stock                                                
Stockholders Equity [Line Items]                                                
Debt conversion, converted instrument, shares issued (in shares)     1,398,602                                          
Revolving Credit Facility | Credit Facility Agreement                                                
Stockholders Equity [Line Items]                                                
Exercise price of warrants (in dollars per share) | $ / shares                                             $ 5.85  
Number of securities called by warrants or rights (in shares)                                             92,049  
Cooperman Warrants                                                
Stockholders Equity [Line Items]                                                
Decrease in exercise price of common stock purchase warrants               5.00%                                
Proceeds from warrants exercised | $             $ 1,081,792                                  
Number of securities called by warrants or rights (in shares)             192,049                                  
Cooperman Warrants | Loan Agreements                                                
Stockholders Equity [Line Items]                                                
Warrants granted, exercise price (in dollars per share) | $ / shares               $ 5.70     $ 6.00                          
Cooperman Warrants | Revolving Credit Facility | Credit Facility Agreement                                                
Stockholders Equity [Line Items]                                                
Exercise price of warrants (in dollars per share) | $ / shares               $ 5.56                             $ 5.85  
2018 Equity Incentive Plan                                                
Stockholders Equity [Line Items]                                                
Common stock, shares authorized (in shares)                                   1,600,000 1,100,000          
Number of shares authorized (in shares)                                         1,100,000 500,000    
Equity Incentive Plan                                                
Stockholders Equity [Line Items]                                                
Number of shares authorized (in shares)                                               3,500,000
Common stock, shares remaining for future issuance (in shares)                       515,491     286,398 515,491 286,398              
Common Stock                                                
Stockholders Equity [Line Items]                                                
Cashless exercise of stock options (in shares)                       447,134     121,407 1,364,721 234,233              
Common stock issued for stock options exercised for cash | $                       $ 447     $ 121 $ 1,365 $ 234              
Common stock issued for vested restricted stock units (in shares)                       74,000       206,109                
Common stock issued for services (in shares)                       2,000       2,000                
Common stock issued for stock options exercised for cash (in shares)                           415,175                    
Common stock issued for cashless stock options exercised (in shares)                             8,352 22,339 190,559              
Common stock issued for warrants exercised for cash (in shares)                               192,049                
Common stock issued for warrants exercised for cash | $                               $ 192                
Share price (in dollars per share) | $ / shares                 $ 9.49                              
Treasury shares cancelled (in shares)                               16,667                
Retirement of treasury stock | $                               $ 17                
Common Stock | Former Director                                                
Stockholders Equity [Line Items]                                                
Common stock issued for services (in shares)                       2,000                        
Grant date share price (in dollars per share) | $ / shares                       $ 9.95                        
Restricted Stock                                                
Stockholders Equity [Line Items]                                                
Unvested shares of restricted common stock outstanding (in shares)                       8,224     226,922 8,224 226,922              
Total unrecognized compensation expense | $                       $ 38,598     $ 1,285,524 $ 38,598 $ 1,285,524              
Weighted average recognition period                               1 year                
Compensation expense | $                       30,427       $ 51,480                
Unrecognized compensation costs | $                       $ 39,000       $ 39,000                
Restricted Stock Units (RSUs)                                                
Stockholders Equity [Line Items]                                                
Unvested shares of restricted common stock outstanding (in shares)                       669,337     0 669,337 0     643,175        
Total unrecognized compensation expense | $                       $ 4,600,000       $ 4,600,000                
Restricted shares granted (in shares)                 375,000             251,521                
Vested (in dollars per share) | $ / shares                               $ 12.46                
Stock based compensation expense | $                       175,754                        
Fair value of RSUs | $                 $ 3,400,000     2,100,000       $ 2,100,000                
Vesting period of award (in years)                               3 years                
Weighted average recognition period           4 years                   1 year 9 months 18 days                
Derived service period of award                 7 months 20 days                              
Amortization expense | $                       $ 1,200,000                        
Vested (in shares)                       131,250       206,109                
Forfeited (in shares)                               19,250                
Compensation expense | $                       $ 567,239       $ 2,553,717                
Unrecognized compensation costs | $                       $ 4,600,000       4,600,000                
Restricted Stock Units (RSUs) | Board of Directors                                                
Stockholders Equity [Line Items]                                                
Restricted shares granted (in shares)                       15,791                        
Vested (in dollars per share) | $ / shares                       $ 11.13                        
Restricted Stock Units (RSUs) | Former CFO | Subsequent Event                                                
Stockholders Equity [Line Items]                                                
Stock based compensation expense | $ $ 300,000                                              
Vested (in shares) 80,251                                              
Forfeited (in shares) 48,750                                              
Restricted Stock Units (RSUs) | Share-based Payment Arrangement, Tranche One                                                
Stockholders Equity [Line Items]                                                
Restricted shares granted (in shares)         37,500                                      
Minimum closing price of common stock (in dollars per share) | $ / shares         $ 9       $ 9                              
Consecutive trading days         20 days       20 days                              
Award vesting rights (as a percent)         10.00%       10.00%                              
Restricted Stock Units (RSUs) | Share-based Payment Arrangement, Tranche Two                                                
Stockholders Equity [Line Items]                                                
Restricted shares granted (in shares)       93,750                                        
Minimum closing price of common stock (in dollars per share) | $ / shares       $ 10         $ 10                              
Consecutive trading days       20 days         20 days                              
Award vesting rights (as a percent)       25.00%         25.00%                              
Restricted Stock Units (RSUs) | Share-based Payment Arrangement, Tranche Three                                                
Stockholders Equity [Line Items]                                                
Total unrecognized compensation expense | $                       $ 1,700,000       $ 1,700,000                
Restricted shares granted (in shares)                 243,750                              
Minimum closing price of common stock (in dollars per share) | $ / shares                 $ 12                              
Consecutive trading days                 20 days                              
Restricted Stock Units (RSUs) | Minimum                                                
Stockholders Equity [Line Items]                                                
Grant price of award (in dollars per share) | $ / shares                               $ 6.95                
Restricted Stock Units (RSUs) | Maximum                                                
Stockholders Equity [Line Items]                                                
Grant price of award (in dollars per share) | $ / shares                               $ 12.78                
Stock Incentive Plan and Stock Option Grants to Employees and Directors                                                
Stockholders Equity [Line Items]                                                
Cashless exercise of stock options (in shares)                               1,400,832                
Options granted (in shares)                       0       0                
Stock options                                                
Stockholders Equity [Line Items]                                                
Weighted average recognition period                               1 year 1 month 6 days                
Compensation expense | $                       $ 123,401       $ 434,532                
Unrecognized compensation costs | $                       $ 275,000       $ 275,000