Organization, Use of Estimates and Basis of Presentation - Summary of Potentially Antidilutive Securities (Details) - shares |
3 Months Ended | |
---|---|---|
Jul. 31, 2017 |
Jul. 31, 2016 |
|
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | ||
Total common stock equivalents | 4,506,090 | 4,264,788 |
Stock options | ||
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | ||
Total common stock equivalents | 2,501,806 | 2,154,948 |
Warrants | ||
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | ||
Total common stock equivalents | 2,004,284 | 2,109,840 |