Securities with Unrealized Losses, Aggregated by Category and Period of Continuous Unrealized Loss (Parenthetical) (Detail)	Jun. 30, 2011 Investment	Dec. 31, 2010 Investment
Securities available for sale
Gain (Loss) on Investments [Line Items]
Number of investment positions with Unrealized Losses	165	178
Securities held to maturity
Gain (Loss) on Investments [Line Items]
Number of investment positions with unrealized losses	17	37

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