Marketable Securities - Summary of Available-for-Sale Securities (Detail) (USD $) In Thousands, unless otherwise specified	Jul. 31, 2013
Investments Debt And Equity Securities [Abstract]
Within one year	$ 9,684
After one year through five years
After five years through ten years
After ten years
Fair Value	$ 9,684

Amount of available-for-sale debt securities at fair value maturing in the sixth fiscal year through the tenth fiscal year following the latest fiscal year.

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-Publisher FASB

-Name Accounting Standards Codification

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-Section 50

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Amount of available-for-sale debt securities at fair value maturing in the second fiscal year through the fifth fiscal year following the latest fiscal year.

+ References

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Amount of available-for-sale debt securities at fair value maturing after the tenth fiscal year following the latest fiscal year.

+ References

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Amount of available-for-sale debt securities at fair value maturing in the next fiscal year following the latest fiscal year.

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Amount of investments in debt and equity securities, including, but not limited to, held-to-maturity, trading and available-for-sale expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer.

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