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Regulatory Matters (Details Textual) (USD $) | 3 Months Ended | 6 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Jun. 30, 2012 | Jun. 30, 2012 | Jul. 03, 2012 | Dec. 31, 2011 | Dec. 31, 2009 | May 15, 2009
Regulatory matters (Additional Textual) [Abstract] |  |  |  |  |  |
Total consolidated assets |  |  |  |  | $ 15,000,000,000 |
Outstanding balance of trust preferred securities | 32,000,000 | 32,000,000 |  | 32,000,000 |  |
Aggregate amount of restricted core elements allowed in Tier 1 capital |  | 25.00% |  |  |  |
Issued Non Voting Preferred Stock to Treasury's Capital Purchase Program, Shares |  |  |  |  |  | 616,438
Issued Non Voting Preferred Stock to Treasury's Capital Purchase Program, Per Share |  |  |  |  |  | $ 5.11
Repurchase price of warrant |  |  | 7,500,000 |  |  |
Cash dividend paid by bank to parent company to fund the repurchase of the warrant | 7,800,000 |  |  |  |  |
Reduction in retained earnings for accelerated discount on preferred stock | $ 7,500,000 | $ 7,500,000 |  |  |  |
Dividend payable date |  | Jul. 02, 2012 |  |  |  |
Maximum [Member] |  |  |  |  |  |
Regulatory Matters (Textual) [Abstract] |  |  |  |  |  |
Decline in consolidated and bank's regulatory capital ratios, pro-forma basis | 0.65% | 0.65% |  |  |  |
Minimum [Member] |  |  |  |  |  |
Regulatory Matters (Textual) [Abstract] |  |  |  |  |  |
Decline in consolidated and bank's regulatory capital ratios, pro-forma basis | 0.55% | 0.55% |  |  |  |

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