Common Stock and Stockholders' Equity - PRSU's (Detail) - All Other Employees - Performance Based Restricted Stock Unit PRSU - USD ($) shares in Millions, $ in Millions |
3 Months Ended | 12 Months Ended |
|---|---|---|
Apr. 30, 2017 |
Jan. 31, 2017 |
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
| RSUs granted, number of Shares | 0.3 | |
| Compensation related cost | $ 6 |