Assets and Liabilities Carried at Fair Value Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Jan. 31, 2016	Jul. 31, 2015	Jan. 31, 2015	Jul. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 120,067	$ 123,800	$ 116,163	$ 114,540
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	120,100	123,800
Plan assets for deferred compensation	4,900	4,300
Total assets at fair value	125,000	128,100
Contingent consideration	13,300	2,000
Foreign currency forward contracts	500	500
Total liabilities at fair value	13,800	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	120,100	123,800
Plan assets for deferred compensation	4,900	4,300
Total assets at fair value	125,000	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	500	500
Total liabilities at fair value	500	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	13,300	2,000
Total liabilities at fair value	$ 13,300	$ 2,000