Net Carrying Value of the Notes (Detail) (USD $) In Thousands, unless otherwise specified	Apr. 30, 2015	Jul. 31, 2014
Debt Instrument [Line Items]
Carrying amount of equity component (net of allocated debt issuance costs)	$ 27,177	$ 27,177
Principal amount of Notes	100,000us-gaap_DebtInstrumentFaceAmount	100,000us-gaap_DebtInstrumentFaceAmount
Unamortized debt discount	(23,304)	(26,609)
Net carrying amount	$ 76,696us-gaap_LongTermNotesPayable	$ 73,391us-gaap_LongTermNotesPayable

The carrying amount of the equity component of convertible debt which may be settled in cash upon conversion.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (a)

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- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

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- Definition

The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 1A

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- Definition

Carrying value as of the balance sheet date of notes payable (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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