Investments (Narrative) (Details) (USD $)
In Thousands, unless otherwise specified
6 Months Ended
Jun. 30, 2012
Dec. 31, 2011
Schedule of Investments [Line Items]    
Unrealized Loss $ 251 $ 286
Unrealized Loss 27,335 27,070
US government agencies [Member]
   
Schedule of Investments [Line Items]    
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Nature

 U.S. Government AgenciesThree U.S. government agencies have been in a slight unrealized loss position for less than 12 months as of June 30, 2012.  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 them before recovery of their amortized cost basis, which may be at maturity. Therefore, no OTTI exists at June 30, 2012.

 

 
Unrealized Loss 87 17
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 AgenciesFive residential mortgage-backed agencies have been in a slight unrealized loss position for less than 12 months as of June 30, 2012. There were no 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 June 30, 2012.

 

 
Unrealized Loss 154 134
Unrealized Loss 0 1
Commercial mortgage-backed agencies [Member]
   
Schedule of Investments [Line Items]    
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Nature  
Unrealized Loss 0 135
Unrealized Loss 51 0
Collateralized mortgage obligations [Member]
   
Schedule of Investments [Line Items]    
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Nature
  

Collateralized Mortgage Obligations – The collateralized mortgage obligation portfolio consisted of one security at June 30, 2012 that has been in an unrealized loss position for 12 months or more. The security with an unrealized loss of greater than 12 months is a private label residential mortgage-backed security and is reviewed for factors such as loan to value ratio, credit support levels, borrower FICO scores, geographic concentration, prepayment speeds, delinquencies, coverage ratios and credit ratings. Management believes that this security continues to demonstrate collateral coverage ratios that are adequate to support the Corporation's investment. At the time of purchase, this security was of the highest investment grade and was purchased at a discount relative to its face amount. As of June 30, 2012, this security remains at investment grade and continues to perform as expected at the time of purchase. The Corporation does not intend to sell this security 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 June 30, 2012.

               

 
Unrealized Loss 0 0
Unrealized Loss 42 123
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 $9,759 at June 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 June 30, 2012.

 

 
Unrealized Loss 10 0
Unrealized Loss 0 8
Collateralized debt obligations [Member]
   
Schedule of Investments [Line Items]    
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Nature Collateralized Debt Obligations - The $27.2 million in unrealized losses greater than 12 months at June 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 half 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.  
Unrealized Loss 0 0
Unrealized Loss $ 27,242 $ 26,938
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 3  
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 5  
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  
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 1  
12 Months or More [Member] | Collateralized mortgage obligations [Member]
   
Schedule of Investments [Line Items]    
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions 1  
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