Schedule of Fair Value, Assets Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Jul. 31, 2017	Jul. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation plan assets	$ 28,095	$ 15,529
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	176,663	143,282
Deferred compensation plan assets	$ 28,095	$ 15,529