Other Gains (Losses), Net - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Apr. 30, 2015	Apr. 30, 2014	Apr. 30, 2015	Apr. 30, 2014
Component Of Other Expense Income Nonoperating [Line Items]
Foreign currency exchange gains (losses)	$ (84,000)	$ (537,000)	$ 2,346,000	$ (707,000)
Non-cash gains (losses) in trading securities	3,227,000		5,328,000
Foreign Exchange Contract
Component Of Other Expense Income Nonoperating [Line Items]
Foreign currency exchange gains (losses)	500,000		(600,000)
Americas | Gain Loss On Foreign Currency Transactions
Component Of Other Expense Income Nonoperating [Line Items]
Realized and unrealized gains (losses) from foreign currency exposures and settled transactions	100,000	200,000	500,000	100,000
Asia | Gain Loss On Foreign Currency Transactions
Component Of Other Expense Income Nonoperating [Line Items]
Realized and unrealized gains (losses) from foreign currency exposures and settled transactions	500,000	(200,000)	400,000	(500,000)
Europe | Gain Loss On Foreign Currency Transactions
Component Of Other Expense Income Nonoperating [Line Items]
Realized and unrealized gains (losses) from foreign currency exposures and settled transactions	(400,000)	(500,000)	1,600,000	(300,000)
All Other Countries | Gain Loss On Foreign Currency Transactions
Component Of Other Expense Income Nonoperating [Line Items]
Realized and unrealized gains (losses) from foreign currency exposures and settled transactions	$ (300,000)		$ (200,000)