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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Securities (Details Textual) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2011	Sep. 30, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Adjusted amortized cost of one structured pooled trust preferred security held by the corporation			$ 694,554	$ 618,911
Fair value of one structured pooled trust preferred security held by the corporation			719,284	638,107
Number of securities holdings			0
Securities (Textual) [Abstract]
Shareholders' equity percentage			10.00%
Securities			242,884	264,166
Additional credit loss for which other-than-temporary impairment was previously recognized	0	398
Number of structured pooled trust preferred securities deemed to be other-than-temporarily impaired			4	4
Amortized Cost			694,554	618,911
Pooled Trust Corporation [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted amortized cost of one structured pooled trust preferred security held by the corporation			800
Fair value of one structured pooled trust preferred security held by the corporation			360
Securities (Textual) [Abstract]
Amortized Cost			800
Pooled trust preferred [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted amortized cost of one structured pooled trust preferred security held by the corporation			800	800
Fair value of one structured pooled trust preferred security held by the corporation			360	340
Number of securities holdings			1
Securities (Textual) [Abstract]
Amortized Cost			800	800
Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted amortized cost of one structured pooled trust preferred security held by the corporation			0
Securities (Textual) [Abstract]
Amortized Cost			$ 0