Investments (Narrative) (Details) (USD $)
9 Months Ended
Sep. 30, 2012
Dec. 31, 2011
Schedule of Investments [Line Items]    
Unrealized Loss $ 99,000 $ 286,000
Unrealized Loss 26,681,000 27,070,000
US government agencies [Member]
   
Schedule of Investments [Line Items]    
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Nature U.S. Government Agencies - One U.S. government agency has been in a slight unrealized loss position for less than 12 months as of September 30, 2012. There were no U.S. government agencies in an unrealized loss position for 12 months or more. The security is of the highest investment grade and the Corporation does not intend to sell it, and it is not more likely than not that the Corporation will be required to sell it before recovery of their amortized cost basis, which may be at maturity. Therefore, no OTTI exists at September 30, 2012.  
Unrealized Loss 3,000 17,000
Unrealized Loss 0 0
Residential mortgage-backed agencies [Member]
   
Schedule of Investments [Line Items]    
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Nature Residential Mortgage-Backed Agencies - Three residential mortgage-backed agencies have been in a slight unrealized loss position for less than 12 months as of September 30, 2012. There were two residential mortgage-backed agency securities in an unrealized loss position for 12 months or more. The securities are of the highest investment grade and the Corporation does not intend to sell them, and it is not more likely than not that the Corporation will be required to sell the securities before recovery of their amortized cost basis, which may be at maturity. Therefore, no OTTI exists at September 30, 2012.  
Unrealized Loss 95,000 134,000
Unrealized Loss 41,000 1,000
Commercial mortgage-backed agencies [Member]
   
Schedule of Investments [Line Items]    
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Nature Commercial Mortgage-Backed Agencies - No commercial mortgage-backed agencies were in an unrealized loss position for less than 12 months or more than 12 months as of September 30, 2012. Therefore, no OTTI exists at September 30, 2012  
Unrealized Loss   135,000
Unrealized Loss   0
Collateralized mortgage obligations [Member]
   
Schedule of Investments [Line Items]    
Unrealized Loss   0
Unrealized Loss   123,000
Obligations of states and political subdivisions [Member]
   
Schedule of Investments [Line Items]    
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Nature Obligations of State and Political Subdivisions – The unrealized losses on the Corporation's investments in state and political subdivisions were $1,055 at September 30, 2012. One security has been in an unrealized loss position for less than 12 months. There are no securities that have been in an unrealized loss position for 12 months or more. This investment is of investment grade as determined by the major rating agencies and management reviews the ratings of the underlying issuers. Management believes that this portfolio is well-diversified throughout the United States, and all bonds continue to perform according to their contractual terms. The Corporation does not intend to sell this investment and it is not more likely than not that the Corporation will be required to sell the investment before recovery of its amortized cost basis, which may be at maturity. Accordingly, management does not consider this investment to be other-than-temporarily impaired at September 30, 2012.  
Unrealized Loss 1,000 0
Unrealized Loss 0 8,000
Collateralized debt obligations [Member]
   
Schedule of Investments [Line Items]    
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Nature Collateralized Debt Obligations - The $26.6 million in unrealized losses greater than 12 months at September 30, 2012 relates to 18 pooled trust preferred securities that comprise the CDO portfolio. See Note 8 for a discussion of the methodology used by management to determine the fair values of these securities. Based upon a review of credit quality and the cash flow tests performed by the independent third party, management determined that there were no securities that had credit-related non-cash OTTI charges during the first nine months of 2012. The unrealized losses on the remaining securities in the portfolio are primarily attributable to continued depression in market interest rates, marketability, liquidity and the current economic environment.  
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions 18  
Unrealized Loss 0 0
Unrealized Loss 26,640,000 26,938,000
Less Than 12 Months [Member] | US government agencies [Member]
   
Schedule of Investments [Line Items]    
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions 1  
Less Than 12 Months [Member] | Residential mortgage-backed agencies [Member]
   
Schedule of Investments [Line Items]    
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions 3  
Less Than 12 Months [Member] | Commercial mortgage-backed agencies [Member]
   
Schedule of Investments [Line Items]    
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions 0  
Less Than 12 Months [Member] | Obligations of states and political subdivisions [Member]
   
Schedule of Investments [Line Items]    
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions 1  
Unrealized Loss $ 1,055  
12 Months or More [Member] | US government agencies [Member]
   
Schedule of Investments [Line Items]    
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions 0  
12 Months or More [Member] | Residential mortgage-backed agencies [Member]
   
Schedule of Investments [Line Items]    
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions 2  
12 Months or More [Member] | Commercial mortgage-backed agencies [Member]
   
Schedule of Investments [Line Items]    
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions 0  
12 Months or More [Member] | Obligations of states and political subdivisions [Member]
   
Schedule of Investments [Line Items]    
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions 0  
12 Months or More [Member] | Collateralized debt obligations [Member]
   
Schedule of Investments [Line Items]    
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions 18