Business Combinations - Additional Information (Detail) (USD $)	3 Months Ended				0 Months Ended	3 Months Ended				1 Months Ended			0 Months Ended	3 Months Ended
	Oct. 31, 2014	Oct. 31, 2013	Jul. 31, 2014	Oct. 31, 2014 Maximum	Sep. 20, 2013 PocketSonics	Oct. 31, 2013 PocketSonics	Sep. 20, 2013 PocketSonics	Apr. 30, 2010 PocketSonics	Sep. 20, 2013 PocketSonics Maximum	May 30, 2014 PocketSonics In-process research and development	Sep. 20, 2013 PocketSonics In-process research and development	Apr. 30, 2010 PocketSonics In-process research and development	Oct. 28, 2014 Pathfinder Therapeutics Inc	Oct. 31, 2014 Pathfinder Therapeutics Inc
Business Acquisition [Line Items]
Total purchase price	$ 1,600,000	$ 10,561,000											$ 1,600,000
Weighted average amortization period for intangible assets														10 years
Business Acquisition, Goodwill Expected Tax Deductible Period														15 years
Acquisition related charges						100,000								100,000
Ownership interests				50.00%				10.00%
Amount of equity investment												1,900,000
Amount merger consideration paid					11,100,000
Contingent consideration							1,900,000		3,000,000
Intangible assets											11,500,000			1,000,000
Amortization period										10 years
Business acquisition, goodwill	57,589,000		56,955,000				6,900,000							600,000
Loss from pre-acquisition equity interest						$ 500,000