Contractual Maturities of Available-for-Sale Debt Securities (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Due within one year	$ 30,135
Due in 1-5 years	47,892
Due in 5-10 years	10,671
Due after 10 years	113,822
Total	$ 202,520	$ 155,644

Total of debt securities categorized neither as held-to-maturity nor trading which are intended be sold or mature within one year from the balance sheet date or the normal operating cycle, whichever is longer.

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

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+ Details