Other Gains (Losses), Net - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2013	Jan. 31, 2012
Gain (Loss) on Investments [Line Items]
Foreign exchange gains (losses)	$ 1.0	$ 0.8	$ 2.1	$ 2.0
Europe | Gain Loss On Foreign Currency Transactions
Gain (Loss) on Investments [Line Items]
Realized and unrealized gains and losses from foreign currency exposures and settled transactions	1.0	0.8	2.3	1.6
Asia | Gain Loss On Foreign Currency Transactions
Gain (Loss) on Investments [Line Items]
Realized and unrealized gains and losses from foreign currency exposures and settled transactions	0.6	0.4	1.1	0.7
Americas | Gain Loss On Foreign Currency Transactions
Gain (Loss) on Investments [Line Items]
Realized and unrealized gains and losses from foreign currency exposures and settled transactions	$ 0.6	$ 0.4	$ 1.3	$ 0.3