Amortized Cost and Estimated Fair Values of Debt Securities by Contractual Maturity (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012
Available-for-sale, Amortized Cost
Due in one year or less	$ 4,810
Due after one year through five years	16,982
Due after five years through ten years	141,396
Due after ten years	495,487
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Total	658,675
Available-for-sale, Fair Value
Due in one year or less	4,881
Due after one year through five years	17,477
Due after five years through ten years	146,321
Due after ten years	508,583
Available-for-sale Securities, Debt Securities, Total	$ 677,262

Amount of available-for-sale debt securities at cost, net of adjustments, maturing in the sixth fiscal year through the tenth 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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