Assets and Liabilities Carried at Fair Value Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 123,800	$ 114,540	$ 113,033	$ 187,011
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	123,800	114,500
Plan assets for deferred compensation	4,300	3,600
Total assets at fair value	128,100	118,100
Contingent consideration	2,000	2,100
Foreign currency forward contracts	500
Total liabilities at fair value	2,500	2,100
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	123,800	114,500
Plan assets for deferred compensation	4,300	3,600
Total assets at fair value	128,100	118,100
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	500
Total liabilities at fair value	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	2,000	2,100
Total liabilities at fair value	$ 2,000	$ 2,100