Quarterly report pursuant to Section 13 or 15(d)

Commitments and Contingent Liabilities (Details Textual)

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Commitments and Contingent Liabilities (Details Textual) (USD $)
 3 Months Ended
Mar. 31, 2013
Dec. 31, 2012
Additional Commitments and Contingent Liabilities (Textuals) [Abstract]    
Maturity period of majority of standby letters of credit within two years  
Carrying amount of deferred revenue associated with guarantees $ 1,400,000 $ 1,400,000
Maturity period of Commercial letters of credit no longer than 90 days  
Percentage of Outstanding standby letters of credit collateralized 81.00%  
Commitments and Contingent Liabilities (Textuals) [Abstract]    
Commitments to sell residential real estate loans 737,300,000 849,800,000
Maturity period of forward contracts relating mortgage banking business less than one year  
Gross unrecognized tax benefit 6,200,000  
Total interest accrued on the unrecognized tax benefits 400,000  
Aggregate range of reasonably possible losses current legal proceedings, Min 0  
Aggregate range of reasonably possible losses current legal proceedings, Max 130,000,000  
Recovery from the bank as a form of unjust enrichment 1,900,000  
Direct damage claimed by Plantiffs 32,000,000  
Additional consequential damages by plantiffs excess of $20.0 million  
Bankruptcy trustee alleging for the amount 70,000,000  
Preferential transfer alleged by bankruptcy trustee 1,200,000  
Fraudulent transfers alleged by Teleservices bankruptcy trustee 73,000,000  
Credit related to recoveries in preference actions filed 4,000,000  
Bankruptcy trustee unable to recover 900,000  
Bankruptcy Court recommended judgment amount in Cyberco case, principal 71,800,000  
Bankruptcy Court recommended judgment amount in Cyberco case, interest 8,800,000  
Standby Letters of Credit [Member]
    
Additional Commitments and Contingent Liabilities (Textuals) [Abstract]    
Outstanding standby letters of credit 478,801,000 514,705,000
Risk Level, Low [Member]
    
Additional Commitments and Contingent Liabilities (Textuals) [Abstract]    
Outstanding standby letters of credit 71,000,000  
Risk Level, Medium [Member]
    
Additional Commitments and Contingent Liabilities (Textuals) [Abstract]    
Outstanding standby letters of credit 383,000,000  
Risk Level, High [Member]
    
Additional Commitments and Contingent Liabilities (Textuals) [Abstract]    
Outstanding standby letters of credit $ 25,000,000