Goodwill and Other Intangible Assets - Additional Information (Detail) (USD $)	12 Months Ended					0 Months Ended	1 Months Ended		12 Months Ended			12 Months Ended				12 Months Ended
	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2014 Minimum	Jul. 31, 2014 Maximum	Dec. 31, 2013 In-process research and development	May 31, 2014 In-process research and development	Jul. 31, 2013 In-process research and development	Jul. 31, 2014 Developed technologies	May 31, 2014 Developed technologies	Jul. 31, 2013 Developed technologies	Jul. 31, 2014 Copley Controls	Jul. 31, 2014 Ultrasonix and PocketSonics	Jul. 31, 2014 PocketSonics	Sep. 20, 2013 PocketSonics	Jul. 31, 2014 PocketSonics In-process research and development
Goodwill and Intangible Assets Disclosure [Line Items]
Goodwill	$ 56,955,000	$ 50,073,000												$ 2,800,000	$ 6,900,000
Acquisition of goodwill	6,900,000											1,900,000	55,100,000
Business acquisition, additional increase in goodwill																4,100,000
Goodwill expected to be deductible for tax purposes	3,700,000	3,700,000
Intangible assets, estimated useful lives				1 year	14 years				10 years
Indefinite lived intangible assets	7,600,000	9,500,000
Amortization expense related to acquired intangible assets	7,800,000	4,100,000	3,100,000
Impairment of intangible assets						0	0
Intangible assets, carrying amount	$ 82,000,000	$ 72,400,000						$ 1,900,000	$ 29,600,000	$ 11,500,000	$ 18,100,000