Net Carrying Values of Debt Securities by Contractual Maturity (Detail) (USD $) In Thousands, unless otherwise specified	Feb. 29, 2012
Available-for-Sale Securities, amortized cost
Less than one year, amortized cost	$ 2,679
One year through five years, amortized cost	11,591
Six years through ten years, amortized cost	5,031
After ten years, amortized cost	2,424
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Total	21,725
Available-for-Sale Securities, fair value
Less than one year, fair value	2,632
One year through five years, fair value	11,861
Six years through ten years, fair value	5,175
After ten years, fair value	2,816
Available-for-sale Securities, Debt Securities, Total	$ 22,484

This item represents debt securities, at cost, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments, as defined), and fair value hedge accounting adjustments, if any, which are expected to mature after five years and through ten years from the balance sheet date and which are categorized neither as held-to-maturity nor trading securities.

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This item represents debt securities, at cost, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments, as defined), and fair value hedge accounting adjustments, if any, which are expected to mature within one year of the balance sheet date and which are categorized neither as held-to-maturity nor trading securities.

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