Goodwill and Intangible Assets - Additional Information (Detail) - USD ($)		1 Months Ended	12 Months Ended
	Dec. 31, 2013	May. 31, 2014	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2013	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Line Items]
Goodwill			$ 57,450,000	$ 56,955,000
Acquisition of goodwill			500,000
Goodwill expected to be deductible for tax purposes			4,000,000	3,700,000
Indefinite lived intangible assets			7,600,000	7,600,000
Amortization expense related to acquired intangible assets			$ 8,900,000	$ 7,800,000	$ 4,100,000
In-process research and development
Goodwill and Intangible Assets Disclosure [Line Items]
Impairment of intangible assets	$ 0	$ 0
Developed technologies
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible assets, estimated useful lives			10 years
Intangible assets, carrying amount		$ 11,500,000
Minimum
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible assets, estimated useful lives			1 year
Maximum
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible assets, estimated useful lives			14 years
Copley Controls
Goodwill and Intangible Assets Disclosure [Line Items]
Acquisition of goodwill			$ 1,900,000
Ultrasonix, PocketSonics and Pathfinder
Goodwill and Intangible Assets Disclosure [Line Items]
Acquisition of goodwill			55,100,000
Pathfinder Therapeutics Inc
Goodwill and Intangible Assets Disclosure [Line Items]
Goodwill			$ 400,000			$ 400,000
Pathfinder Therapeutics Inc | Developed technologies
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible assets, estimated useful lives			10 years