Business Combination - Additional Information (Detail) - USD ($)				3 Months Ended	12 Months Ended
	Oct. 28, 2014	May. 30, 2014	Sep. 20, 2013	Oct. 31, 2013	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2012	Dec. 31, 2014	Apr. 30, 2010
Business Acquisition [Line Items]
Acquisition of businesses, net of cash acquired					$ 1,600,000	$ 10,561,000	$ 79,273,000
Estimated (decreases) in contingent consideration					(62,000)	125,000	(25,000)
Business acquisition, goodwill					$ 57,450,000	56,955,000
Engineering Services
Business Acquisition [Line Items]
Engineering services expense							$ 900,000	$ 1,500,000
Maximum
Business Acquisition [Line Items]
Ownership interests					50.00%
Intangible assets, estimated useful lives					14 years
Pathfinder Therapeutics Inc
Business Acquisition [Line Items]
Acquisition of businesses, net of cash acquired	$ 1,600,000
Weighted average amortization period for intangible assets					7 years 7 months 6 days
Business Acquisition, Goodwill Expected Tax Deductible Period					15 years
Acquisition related charges					$ 100,000
Intangible assets					1,100,000
Business acquisition, goodwill					400,000				$ 400,000
PocketSonics
Business Acquisition [Line Items]
Acquisition related charges						100,000
Ownership interests										10.00%
Amount merger consideration paid			$ 11,100,000
Contingent consideration			1,900,000		2,000,000
Intangible assets			11,500,000
Estimated (decreases) in contingent consideration					$ (100,000)
Business acquisition, goodwill			6,900,000
Loss from pre-acquisition equity interest				$ 500,000		$ 500,000
PocketSonics | Maximum
Business Acquisition [Line Items]
Contingent consideration			3,000,000
PocketSonics | In-process research and development
Business Acquisition [Line Items]
Amount of equity investment										$ 1,900,000
Intangible assets			$ 11,500,000
Intangible assets, estimated useful lives		10 years