Summary of Fair Values of Separately Identifiable Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands	Jul. 31, 2015	Jul. 31, 2014	Sep. 20, 2013
Business Acquisition [Line Items]
Goodwill	$ 57,450	$ 56,955
PocketSonics
Business Acquisition [Line Items]
Cash			$ 500
Goodwill			6,900
IPR&D			11,500
Total assets acquired			18,900
Accounts payable and accrued expenses			(300)
Deferred taxes			(4,100)
Total liabilities assumed			(4,400)
Total purchase price			$ 14,500