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.

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- Definition

Sum of the carrying amounts as of the date of the latest financial statement presented of securities which are owned but transferred to another party to serve as collateral to partially or fully secure a debt obligation, repurchase agreement or other current or potential obligation, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

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Investment Securities (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended
Investment Securities (Narrative) (Details) (USD $)	Jun. 30, 2012 Banks Securities	Jun. 30, 2011	Jun. 30, 2012 Organizaion Banks Securities	Jun. 30, 2011	Dec. 31, 2011 Securities	Dec. 31, 2010
Investment [Line Items]
Number of HTM investment securities in an unrealized loss position	89		89		72
Number of AFS investment securities in an unrealized loss position	365		365		525
Number of banks in CDO pools current following deferral period	53		53
Number of banks in CDO pools remaining in deferral	215		215
Number of NRSRO Ratings			1
Nontaxable interest income on securities	$ 4,693,000	$ 5,365,000	$ 9,495,000	$ 11,209,000
Carrying value of pledged securities	$ 1,254,459,000		$ 1,254,459,000			$ 1,500,000,000
Small Business Administration Loan-Backed Securities [Member] \| Minimum [Member]
Investment [Line Items]
Investment term of maturity, in years			5
Small Business Administration Loan-Backed Securities [Member] \| Maximum [Member]
Investment [Line Items]
Investment term of maturity, in years			25
Municipal Securities [Member] \| Minimum [Member]
Investment [Line Items]
Investment term of maturity, in years			1
Municipal Securities [Member] \| Maximum [Member]
Investment [Line Items]
Investment term of maturity, in years			25