XML 60 R43.htm IDEA: XBRL DOCUMENT v3.19.1
Stockholders' Equity (Schedule of Assumptions Used to Value Stock Options) (Details) - Stock Incentive Plan and Stock Option Grants to Employees and Directors [Member]
9 Months Ended
Jan. 31, 2019
Jan. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected life (years) 3 years 6 months  
Expected volatility 51.00%  
Expected volatility, minimum   40.00%
Expected volatility, maximum   43.00%
Risk-free interest rate 2.70% 0.38%
Dividend yield 0.00% 0.00%
Expected forfeiture rate
Minimum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected life (years)   4 years
Maximum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected life (years)   6 years 6 months