Components of Other Gains (Losses), Net (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2018	Jan. 31, 2017
Component Of Other Expense Income Nonoperating [Line Items]
Foreign currency exchange gains (losses)	$ (1,436)	$ 29	$ (2,071)	$ 426
Gains on Trading Securities		1,011	1,876	94
Other, net	(280)	(21)	(99)	11
Other gains (losses), net	$ (1,716)	$ 1,019	$ (294)	$ 531