Other Gains (Losses), Net - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
Component Of Other Expense Income Nonoperating [Line Items]
Other gains (losses), net	$ (5,757)	$ 15,005	$ (50)
Gains (losses) in trading securities	(5,920)	13,611
Net realized and unrealized foreign currency exchange gain (losses)	(600)	1,800	500
Gain on disposal of assets			$ 475
Non Cash
Component Of Other Expense Income Nonoperating [Line Items]
Gains (losses) in trading securities	(12,300)	12,800
Gain on purchase of Notes	800
Cash
Component Of Other Expense Income Nonoperating [Line Items]
Gains (losses) in trading securities	$ 6,400	$ 800