Stockholders' Equity - Schedule of Weighted-Average Assumptions Used to Estimate Grant Date Fair Value of Options Granted (Detail) - Stock Options [Member] |
3 Months Ended | |
|---|---|---|
Apr. 30, 2018 |
Apr. 30, 2017 |
|
| Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | ||
| Volatility | 41.00% | 44.00% |
| Expected term (in years) | 6 years 4 months 6 days | 6 years 4 months 6 days |
| Risk-free interest rate | 2.73% | |
| Risk-free interest rate, Minimum | 1.95% | |
| Risk-free interest rate, Maximum | 2.17% | |
| Dividend yield | 0.00% | 0.00% |