Derivative Instruments - Additional Information (Detail) - Forward Contracts - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | |||
|---|---|---|---|---|---|
Apr. 30, 2017 |
Apr. 30, 2016 |
Apr. 30, 2017 |
Apr. 30, 2016 |
Jul. 31, 2016 |
|
| Derivative [Line Items] | |||||
| Unrealized loss on cash flow hedges | $ 0.3 | $ 0.3 | $ 0.2 | ||
| Notional amount of cash flow hedge instruments | 11.6 | 11.6 | 18.6 | ||
| Cost of Revenue and Operating Expenses | |||||
| Derivative [Line Items] | |||||
| Realized gains (losses) on cash flow hedge instruments | (0.2) | $ (0.2) | (0.5) | $ (0.6) | |
| Designated as Hedging Instrument | |||||
| Derivative [Line Items] | |||||
| Derivative liability, current | $ 0.5 | $ 0.5 | $ 0.3 | ||