Net Carrying Values of Debt Securities by Contractual Maturity (Detail) (USD $) In Thousands, unless otherwise specified	May 31, 2012
Available-for-Sale Securities, amortized cost
Less than one year, amortized cost	$ 25,098
One year through five years, amortized cost	11,787
Six years through ten years, amortized cost	5,378
After ten years, amortized cost	2,369
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Total	44,632
Available-for-Sale Securities, fair value
Less than one year, fair value	25,104
One year through five years, fair value	12,070
Six years through ten years, fair value	5,628
After ten years, fair value	2,796
Available-for-sale Securities, Debt Securities, Total	$ 45,598

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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