Assets and Liabilities Carried at Fair Value Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 118,697	$ 123,800	$ 114,540	$ 113,033
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	118,700	123,800
Plan assets for deferred compensation	5,900	4,300
Total assets at fair value	124,600	128,100
Contingent consideration	12,200	2,000
Foreign currency forward contracts	300	500
Total liabilities at fair value	12,500	2,500
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	118,700	123,800
Plan assets for deferred compensation	5,900	4,300
Total assets at fair value	124,600	128,100
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency forward contracts	300	500
Total liabilities at fair value	300	500
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	12,200	2,000
Total liabilities at fair value	$ 12,200	$ 2,000