Assets and Liabilities Carried at Fair Value Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Oct. 31, 2016	Jul. 31, 2016	Oct. 31, 2015	Jul. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 141,952	$ 118,697	$ 130,506	$ 123,800
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	142,000	118,700
Plan assets for deferred compensation	6,300	5,900
Total assets at fair value	148,300	124,600
Contingent consideration	12,300	12,200
Foreign currency forward contracts	600	300
Total liabilities at fair value	12,900	12,500
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	142,000	118,700
Plan assets for deferred compensation	6,300	5,900
Total assets at fair value	148,300	124,600
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	600	300
Total liabilities at fair value	600	300
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	12,300	12,200
Total liabilities at fair value	$ 12,300	$ 12,200