Derivative Instruments - Additional Information (Detail) - Forward Contracts - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jan. 31, 2016	Jan. 31, 2016	Jul. 31, 2015
Derivative [Line Items]
Notional amount of cash flow hedge instruments	$ 4.8	$ 4.8
Unrealized loss on cash flow hedges	0.4	0.4
Designated as Hedging Instrument
Derivative [Line Items]
Derivative liability	0.5	0.5	$ 0.5
Cost of Revenue and Operating Expenses
Derivative [Line Items]
Realized gains (losses) on cash flow hedge instruments	$ 0.2	$ 0.5