Summary of Significant Accounting Policies - Contractual Maturities Of The Company's Investment Securities (Detail) (USD $) In Thousands, unless otherwise specified	Jul. 31, 2012
Schedule Of Available-For-Sale Securities [Line Items]
Less than one year	$ 234,965
Due in one to three years	67,774
Total	302,739
Less than one year	234,937
Due in one to three years	67,758
Total	$ 302,695

Amount of available-for-sale debt securities at cost, net of adjustments, which include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

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Amount of available-for-sale debt securities at cost, net of adjustments, maturing in the next fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

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- Definition

Amount of debt securities categorized neither as held-to-maturity nor trading.

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