Fair Value Measurements - Summary of Outstanding Balance Sheet Hedges (Detail) - Foreign currency forward contracts [Member] - USD ($) |
Apr. 30, 2018 |
Jan. 31, 2018 |
|---|---|---|
| Derivatives Fair Value [Line Items] | ||
| Notional amount of foreign currency derivative contracts | $ 9,203,000 | $ 36,266,000 |
| Fair value of foreign currency derivative contracts | $ 9,491,000 | $ 36,531,000 |