Fair Value Measurements - Summary Fair Value of Outstanding Derivative Instruments (Detail) - Foreign currency derivative contracts [Member] - Derivatives not designated as hedging instruments [Member] - USD ($) $ in Thousands |
Apr. 30, 2018 |
Jan. 31, 2018 |
|---|---|---|
| Prepaid expenses and other current assets [Member] | ||
| Derivatives Fair Value [Line Items] | ||
| Derivative Assets | $ 18 | $ 127 |
| Accrued expenses [Member] | ||
| Derivatives Fair Value [Line Items] | ||
| Derivative Liabilities | $ 305 | $ 391 |