Investments (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Schedule of Investments [Line Items]
Available-for-sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	$ 87	$ 108
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	12,147	13,864
Held-to-maturity securities	109,040	109,449	109,449
Held-to-maturity gross unrealized losses	231	122
U.S. Treasury [Member]
Schedule of Investments [Line Items]
Available-for-sale, securities in unrealized loss positions, qualitative disclosure, nature	U.S. Government Treasuries – Available for Sale – There were no securities issued by the U.S. Treasury in the Available for Sale portfolio as of March 31, 2015 in a loss position.
Available-for-sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	0	11
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	0	0
US government agencies [Member]
Schedule of Investments [Line Items]
Available-for-sale, securities in unrealized loss positions, qualitative disclosure, nature	U.S. Government Agencies – Available for Sale – There were no U.S. government agencies in an unrealized loss position for less than 12 months as of March 31, 2015. There was one U.S. government agency 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 its amortized cost basis, which may be at maturity. Accordingly, management does not consider this investment to be other-than-temporarily impaired at March 31, 2015.
Available-for-sale, securities in unrealized loss positions, qualitative disclosure, number of positions, greater than or equal to one year	1
Available-for-sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	0	0
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	75	253
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Nature	U.S. Government Agencies – Held to Maturity – There were no securities issued by government agencies in the Held to Maturity portfolio as of March 31, 2015 in a loss position.
Held-to-maturity securities	24,566	24,520
Held-to-maturity gross unrealized losses	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 – Available for Sale - There were no residential mortgage-backed agencies in an unrealized loss position for less than 12 months as of March 31, 2015. There was one residential mortgage-backed agency security 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 the security 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 March 31, 2015
Available-for-sale, securities in unrealized loss positions, qualitative disclosure, number of positions, less than one year	0
Available-for-sale, securities in unrealized loss positions, qualitative disclosure, number of positions, greater than or equal to one year	1
Available-for-sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	0	0
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	244	412
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Nature	Residential Mortgage-Backed Agencies – Held to Maturity - Three residential mortgage-backed agencies have been in an unrealized loss position for less than 12 months as of March 31, 2015. The Corporation has the intent and ability to hold the investments to maturity. Accordingly, management does not consider these investments to be other-than-temporarily impaired at March 31, 2015. There were no residential mortgage-backed agencies in an unrealized loss position for 12 months or more.
Held-to-maturity securities	58,427	58,400
Held-to-maturity gross unrealized losses	34	5
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 – Available for Sale – There were two commercial mortgage-backed agencies in an unrealized loss position for less than 12 months as of March 31, 2015. There were no commercial 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 them before recovery of their amortized cost basis, which may be at maturity. Accordingly, management does not consider these investments to be other-than-temporarily impaired at March 31, 2015.
Available-for-sale, securities in unrealized loss positions, qualitative disclosure, number of positions, less than one year	2
Available-for-sale, securities in unrealized loss positions, qualitative disclosure, number of positions, greater than or equal to one year	0
Available-for-sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	29	97
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	0	6
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Nature	Commercial Mortgage-Backed Agencies – Held to Maturity - There were no commercial mortgage-backed agencies in the Held to Maturity portfolio as of March 31, 2015 in a loss position.
Held-to-maturity, securities in unrealized loss positions, qualitative disclosure, number of positions	0
Held-to-maturity securities	16,331	16,425
Held-to-maturity gross unrealized losses	0	0
Collateralized mortgage obligations [Member]
Schedule of Investments [Line Items]
Available-for-sale, securities in unrealized loss positions, qualitative disclosure, nature	Collateralized Mortgage-Obligations – Available for Sale – There were no collateralized mortgage obligations in the Available for Sale portfolio as of March 31, 2015 in a loss position.
Available-for-sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	0	0
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	0	0
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Nature	Collateralized Mortgage-Obligations – Held to Maturity – There were no collateralized mortgage obligations in the Held to Maturity portfolio as of March 31, 2015 in a loss position.
Held-to-maturity securities	6,991	7,379
Held-to-maturity gross unrealized losses	0	0
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 – Available for Sale – There were four obligations of state and political subdivisions securities that have been in an unrealized loss position for less than 12 months at March 31, 2015. There was one security that had been in an unrealized loss position for 12 months or more. These investments are of investment grade as determined by the major rating agencies and management reviews the ratings of the underlying issuers and performs an in-depth credit analysis on the securities. 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 these investments and it is not more likely than not that the Corporation will be required to sell the investments before recovery of their amortized cost basis, which may be at maturity. Accordingly, management does not consider these investments to be other-than-temporarily impaired at March 31, 2015.
Available-for-sale, securities in unrealized loss positions, qualitative disclosure, number of positions, less than one year	4
Available-for-sale, securities in unrealized loss positions, qualitative disclosure, number of positions, greater than or equal to one year	1
Available-for-sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	58	0
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	157	260
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Nature	Obligations of State and Political Subdivisions – Held to Maturity – No obligations of state and political subdivisions securities have been in an unrealized loss position for less than 12 months at March 31, 2015. There was one obligation of state and political subdivisions security that has been in an unrealized loss position for 12 months or more. This bond is a Tax Increment Fund (TIF) bond. Management performs an in-depth credit analysis on this security. The Corporation has the intent and ability to hold the investment to maturity. Accordingly, management does not consider this investment to be other-than-temporarily impaired at March 31, 2015.
Held-to-maturity securities	2,725	2,725
Held-to-maturity gross unrealized losses	197	117
Collateralized debt obligations [Member]
Schedule of Investments [Line Items]
Available-for-sale, securities in unrealized loss positions, qualitative disclosure, nature	Collateralized Debt Obligations – Available for Sale - The $11.7 million in unrealized losses greater than 12 months at March 31, 2015 relates to 14 pooled trust preferred securities that are included in the CDO portfolio. See Note 9 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 three months of 2015. 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, greater than or equal to one year	14
Available-for-sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	0	0
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	$ 11,671	$ 12,933
Less Than 12 Months [Member] | Residential mortgage-backed agencies [Member]
Schedule of Investments [Line Items]
Held-to-maturity, securities in unrealized loss positions, qualitative disclosure, number of positions	3
Less Than 12 Months [Member] | Obligations of states and political subdivisions [Member]
Schedule of Investments [Line Items]
Held-to-maturity, 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]
Held-to-maturity, 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]
Held-to-maturity, securities in unrealized loss positions, qualitative disclosure, number of positions	1