Goodwill and Other Intangible Assets - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Oct. 31, 2012	Oct. 31, 2011	Jul. 31, 2012
Goodwill and Intangible Assets Disclosure [Line Items]
Goodwill	$ 1,849		$ 1,849
Amortization expense related to acquired intangible assets	$ 766	$ 766
Minimum
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible assets, estimated useful lives	6 months
Minimum | In Process Research And Development
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible assets, estimated useful lives	6 months
Maximum
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible assets, estimated useful lives	14 years
Maximum | In Process Research And Development
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible assets, estimated useful lives	18 months