Assets and Liabilities Carried at Fair Value and Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Jan. 31, 2017	Jul. 31, 2016	Jan. 31, 2016	Jul. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 152,990	$ 118,697	$ 120,067	$ 123,800
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	153,000	118,700
Plan assets for deferred compensation	6,500	5,900
Total assets at fair value	159,500	124,600
Contingent consideration	4,100	12,200
Foreign currency forward contracts		300
Total liabilities at fair value	4,100	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	153,000	118,700
Plan assets for deferred compensation	6,500	5,900
Total assets at fair value	159,500	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		300
Total liabilities at fair value		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	4,100	12,200
Total liabilities at fair value	$ 4,100	$ 12,200