Securities (Details Textual) (USD $)	6 Months Ended
Jun. 30, 2013 Institutions Tranche	Jun. 30, 2012	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Carrying value of securities held to maturity	$ 4,292,000
Net gain recognized on sale of securities held to maturity	169,000
Securities classified as held to maturity		0
Investments in pooled trust preferred securities, cost basis	410,535,000		357,633,000
Investments in pooled trust preferred securities, fair value	398,190,000		356,311,000
Number of institutions issuing debt (institutions)	340
Number of securities representing interests in tranches of trusts (tranches)	4
Secure government, public and trust deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities pledged as collateral	398,924,000		308,362,000
Short-term borrowings [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities pledged as collateral	$ 14,229,000		$ 19,006,000

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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- Definition

This item represents the gain (loss) realized on the sale of held-to-maturity securities disposed of during the period. Additionally, this item may include, if not separately presented, any losses recognized for other than temporary impairments (OTTI) of the subject investments in debt securities which are being or have been recognized in earnings during the period.

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