Other Gains (Losses), Net - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2017	Jan. 31, 2016
Component Of Other Expense Income Nonoperating [Line Items]
Foreign currency exchange gains (losses)	$ 29	$ (179)	$ 426	$ (753)
Gains (losses) in trading securities	1,011	1,115	94	(8,348)
Foreign Exchange Contract
Component Of Other Expense Income Nonoperating [Line Items]
Foreign currency exchange gains (losses)		400		100
Asia
Component Of Other Expense Income Nonoperating [Line Items]
Realized and unrealized gains (losses) from foreign currency exposures and settled transactions	(500)	400	(400)	1,100
Europe
Component Of Other Expense Income Nonoperating [Line Items]
Realized and unrealized gains (losses) from foreign currency exposures and settled transactions	(100)	200	(400)	500
Corporate Segment
Component Of Other Expense Income Nonoperating [Line Items]
Realized and unrealized gains (losses) from foreign currency exposures and settled transactions	$ 600	$ 400	$ 1,300	$ 800