Other Gains (Losses), Net - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Oct. 31, 2018	Oct. 31, 2017
Component Of Other Expense Income Nonoperating [Line Items]
Foreign currency exchange gains (losses)	$ 916	$ (635)
Gains (losses) on Trading Securities		1,876
Asia
Component Of Other Expense Income Nonoperating [Line Items]
Realized and unrealized gains (losses) from foreign currency exposures and settled transactions	400	(400)
Europe
Component Of Other Expense Income Nonoperating [Line Items]
Realized and unrealized gains (losses) from foreign currency exposures and settled transactions	(1,000)	$ (300)
Corporate
Component Of Other Expense Income Nonoperating [Line Items]
Realized and unrealized gains (losses) from foreign currency exposures and settled transactions	$ 1,700