Summary of Estimated Fair Values of Separately Identifiable Assets Acquired and Liabilities Assumed (Detail) (USD $)	Apr. 30, 2015	Jul. 31, 2014
Business Acquisition [Line Items]
Goodwill	$ 57,358,000us-gaap_Goodwill	$ 56,955,000us-gaap_Goodwill
Pathfinder Therapeutics Inc
Business Acquisition [Line Items]
Inventory and receivables	200,000
Goodwill	400,000
Intangible assets	1,100,000
Total assets acquired	1,700,000
Accrued liabilities	(100,000)
Total liabilities assumed	(100,000)
Total purchase price	1,600,000
Pathfinder Therapeutics Inc \| Developed technologies
Business Acquisition [Line Items]
Intangible assets	700,000
Pathfinder Therapeutics Inc \| Customer relationships
Business Acquisition [Line Items]
Intangible assets	300,000
Pathfinder Therapeutics Inc \| Trade names
Business Acquisition [Line Items]
Intangible assets	$ 100,000

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Amount of assets acquired at the acquisition date.

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Amount of other assets expected to be realized or consumed before one year or the normal operating cycle, if longer, acquired at the acquisition date.

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Amount of liabilities incurred for goods and services received that are used in an entity's business and related party payables, assumed at the acquisition date.

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Amount of intangible assets, excluding goodwill, acquired at the acquisition date.

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Amount of liabilities assumed at the acquisition date.

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Amount recognized for assets, including goodwill, in excess of (less than) the aggregate liabilities assumed.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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