Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity - Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions (Details)

v3.3.1.900
Stockholders' Equity - Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions (Details)
9 Months Ended
Jan. 31, 2016
$ / shares
Expected volatility, minimum 79.00%
Expected volatility, maximum 80.00%
Dividend yield 0.00%
Risk-free interest rate, minimum 0.90%
Risk-free interest rate, maximum 1.01%
Minimum  
Expected term (years) 2 years 6 months
Weighted average per share grant date fair value $ 0.78
Maximum  
Expected term (years) 3 years
Weighted average per share grant date fair value $ 1.03