Derivative Instruments - Additional Information (Detail) (Forward contracts) In Millions, unless otherwise specified		6 Months Ended	3 Months Ended		6 Months Ended
	Jan. 31, 2014 CAD	Jan. 31, 2014 Maximum USD ($)	Jan. 31, 2014 Cost of Revenue and Operating Expenses USD ($)	Jan. 31, 2013 Cost of Revenue and Operating Expenses USD ($)	Jan. 31, 2014 Cost of Revenue and Operating Expenses USD ($)	Jan. 31, 2013 Cost of Revenue and Operating Expenses USD ($)
Derivative [Line Items]
Notional amount of cash flow hedge instruments	5.0
Unrealized loss on cash flow hedges		(0.1)
Realized gains (losses) on cash flow hedge instruments			$ (0.2)	$ (0.3)	$ 0	$ 0.1