Derivative Liabilities - Summary of Weighted-average Assumptions Used on Derivative Liabilities (Details) |
12 Months Ended |
|---|---|
Apr. 30, 2019 | |
| Expected Dividend Yield [Member] | |
| Derivative liability, measurement input, percent | 0 |
| Minimum [Member] | |
| Expected term (in years) | 1 year |
| Minimum [Member] | Expected Average Volatility [Member] | |
| Derivative liability, measurement input, percent | 107 |
| Minimum [Member] | Risk-free Interest Rate [Member] | |
| Derivative liability, measurement input, percent | 1.65 |
| Maximum [Member] | |
| Expected term (in years) | 5 years |
| Maximum [Member] | Expected Average Volatility [Member] | |
| Derivative liability, measurement input, percent | 237 |
| Maximum [Member] | Risk-free Interest Rate [Member] | |
| Derivative liability, measurement input, percent | 2.96 |