Derivatives and Hedging Activities - Additional Information (Detail) £ in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 31, 2016 USD ($)	Jan. 31, 2015 USD ($)	Jan. 31, 2016 USD ($)	Jan. 31, 2015 USD ($)	Jan. 31, 2016 GBP (£)	Jul. 31, 2015 USD ($)	May. 13, 2010 GBP (£)
Derivatives, Fair Value [Line Items]
Derivative Maturities			18 months
Derivative, Notional Amount	$ 104,759		$ 104,759			$ 139,300
Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months	(608)	$ (1,724)	(608)	$ (1,724)
Cash Flow Hedge Gain (Loss) Reclassified to Earnings	(115)	116	342	95
Total Outstanding Forward Foreign Exchange Contracts	16,616		16,616
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	$ (100)	$ (1,173)	$ (513)	$ (2,050)
GBP-denominated interco debt [Member]
Derivatives, Fair Value [Line Items]
Derivative, Amount of Hedged Item | £					£ 25,036
Senior Unsecured Notes [Member]
Derivatives, Fair Value [Line Items]
Derivative, Amount of Hedged Item | £							£ 75,000