Stock-Based Compensation - Summary of Stock Option Activity (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Jul. 31, 2012
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Beginning balance, Outstanding	469
Granted	263
Exercised
Cancelled / Forfeited	(28)
Ending balance, OUTSTANDING	704
Ending balance, EXERCISABLE	469
Beginning balance, Outstanding, Weighted-Average Exercise Price	$ 33.20
Granted, Outstanding, Weighted-Average Exercise Price	$ 13.42
Exercised, Outstanding, Weighted-Average Exercise Price
Cancelled / Forfeited, Outstanding, Weighted-Average Exercise Price	$ 20.84
Ending balance, OUTSTANDING, Outstanding, Weighted-Average Exercise Price	$ 16.63
Ending balance, EXERCISABLE, Outstanding, Weighted-Average Exercise Price	$ 18.62
Weighted- Average Remaining Contractual Term, OUTSTANDING	8 years 1 month 6 days
Weighted- Average Remaining Contractual Term, EXERCISABLE	6 years
Aggregate intrinsic value, OUTSTANDING
Aggregate intrinsic value, EXERCISABLE

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Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Prices

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Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Exercise Prices

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- Definition

Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

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Weighted average price of options that were either forfeited or expired.

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Net number of share options (or share units) granted during the period.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of options outstanding.

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- Definition

The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of share options (or share units) exercised during the current period.

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