Securities (Securities Available for Sale) (Details) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Amortized Cost	$ 954,415	$ 743,928
Gross Unrealized Gains	42,487	23,386
Gross Unrealized Losses	(1,048)	(3,448)
Fair Value	995,854	763,866
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member]
Amortized Cost	623,934	491,530
Gross Unrealized Gains	21,698	16,139
Gross Unrealized Losses	(906)	(1,027)
Fair Value	644,726	506,642
State and Municipal Securities [Member]
Amortized Cost	256,343	249,117
Gross Unrealized Gains	20,189	7,247
Gross Unrealized Losses	(115)	(2,383)
Fair Value	276,417	253,981
U.S. Government and Government-Sponsored Enterprise Securities [Member]
Amortized Cost	70,857
Gross Unrealized Gains	523
Gross Unrealized Losses	0
Fair Value	71,380
Other Securities [Member]
Amortized Cost	3,281	3,281
Gross Unrealized Gains	77	0
Gross Unrealized Losses	(27)	(38)
Fair Value	$ 3,331	$ 3,243

- Definition

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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