Deferred Revenue and Performance Obligations - Additional Information (Detail) - USD ($) $ in Millions |
3 Months Ended | |
|---|---|---|
Apr. 30, 2018 |
Apr. 30, 2017 |
|
| Deferred Revenue Arrangement [Line Items] | ||
| Revenue, remaining performance obligation, recognition period | 12 months | |
| Subscription Services [Member] | ||
| Deferred Revenue Arrangement [Line Items] | ||
| Recognition of deferred revenue | $ 116.0 | $ 92.1 |
| Revenue expected to be recognized from remaining performance obligations | 488.6 | |
| Revenue expected to recognize from remaining performance obligations over the next 12 months | $ 395.2 | |