Securities with Unrealized Losses, Aggregated by Category and Period of Continuous Unrealized Loss (Parenthetical) (Detail)	Jun. 30, 2012 Investment	Dec. 31, 2011 Investment
Investment [Line Items]
Number of available for sale securities in unrealized loss positions	170	296
Number of held to maturity securities in unrealized loss positions	3	3

Disclosure regarding factors used to determine that the impairment of securities not categorized as either held-to-maturity securities or trading securities (hence equal to available for sale securities) where cost exceeds fair value is not an other than temporary impairment (OTTI). This item contains disclosure of the number of investment positions in the available-for-sale investments determined to be temporarily impaired.

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Disclosure regarding factors used to determine that the impairment of securities categorized as held-to-maturity where cost exceeds fair value is not an other than temporary impairment (OTTI). This item contains disclosure of the number of investment positions in the held-to-maturity investments determined to be temporarily impaired.

+ References+ Details