Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity (Preferred Stock, Common Stock, Treasury Stock and Warrants Narrative) (Details)

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Stockholders' Equity (Preferred Stock, Common Stock, Treasury Stock and Warrants Narrative) (Details) - USD ($)
 6 Months Ended
Sep. 06, 2018
Oct. 31, 2018
Oct. 31, 2017
Jul. 19, 2018
Apr. 30, 2018
Stockholders Equity [Line Items]          
Preferred stock, shares authorized   10,000,000     10,000,000
Preferred stock, shares issued   0     0
Preferred stock, shares outstanding   0     0
Share issued in exercise of stock options   26,807      
Proceeds from stock options exercised   $ 60,102 $ 53,045    
Per share price   $ 0.001     $ 0.001
Stock issuance costs paid by third parties   $ 30,000      
Compensation cost of unvested shares yet to be recognized, period of recognition   3 years      
Chief Financial Officer [Member]          
Stockholders Equity [Line Items]          
Compensation cost of unvested shares yet to be recognized, period of recognition 5 years        
Restricted Stock [Member] | Chief Financial Officer [Member]          
Stockholders Equity [Line Items]          
Restricted shares granted 25,000        
Award vesting period 36 months        
Compensation cost of unvested shares yet to be recognized $ 180,000        
Compensation cost of unvested shares yet to be recognized, period of recognition 36 months        
Market price of company stock $ 7.17        
Cashless Exercise of Stock Options [Member]          
Stockholders Equity [Line Items]          
Share issued in exercise of stock options   30,764      
Preferred Stock [Member]          
Stockholders Equity [Line Items]          
Preferred stock, shares authorized   10,000,000     10,000,000
Preferred stock, shares issued   0     0
Preferred stock, shares outstanding   0     0
Common Stock [Member]          
Stockholders Equity [Line Items]          
Share issued in exercise of stock options   26,807      
Proceeds from stock options exercised   $ 60,102      
Treasury stock repurchased       1,000,000  
Per share price       $ 7.40  
Sale of common stock per share price       $ 7.40  
Common Stock [Member] | Cashless Exercise of Stock Options [Member]          
Stockholders Equity [Line Items]          
Share issued in exercise of stock options   30,764