Securities (Schedule of Amortized Cost and Fair Value of Securities Available for Sale) (Details) (USD $) In Thousands	6 Months Ended	12 Months Ended
Jun. 30, 2011	Dec. 31, 2010
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	$ 822,860	$ 744,292
Available-for-sale Securities, Gross Unrealized Gains	11,713	9,856
Available-for-sale, Unrealized Loss	(13,726)	(16,023)
Available-for-sale Securities, Fair Value	820,847	738,125
U.S. Treasury and Other U.S. Government Agencies and Corporations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	332,046	299,861
Available-for-sale Securities, Gross Unrealized Gains	1,329	1,395
Available-for-sale, Unrealized Loss	(91)	(688)
Available-for-sale Securities, Fair Value	333,284	300,568
Agency Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	234,465	205,443
Available-for-sale Securities, Gross Unrealized Gains	6,683	6,064
Available-for-sale Securities, Fair Value	241,148	211,507
Agency Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	184,665	146,977
Available-for-sale Securities, Gross Unrealized Gains	2,320	1,081
Available-for-sale, Unrealized Loss		(192)
Available-for-sale Securities, Fair Value	186,985	147,866
Non-Agency Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	34	37
Available-for-sale Securities, Gross Unrealized Gains	1	1
Available-for-sale Securities, Fair Value	35	38
States Of The U.S. And Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	43,910	57,830
Available-for-sale Securities, Gross Unrealized Gains	1,048	934
Available-for-sale, Unrealized Loss	(1)	(26)
Available-for-sale Securities, Fair Value	44,957	58,738
Collateralized Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	19,288	19,288
Available-for-sale, Unrealized Loss	(12,683)	(13,314)
Available-for-sale Securities, Fair Value	6,605	5,974
Other Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	6,859	12,989
Available-for-sale, Unrealized Loss	(913)	(1,744)
Available-for-sale Securities, Fair Value	5,946	11,245
Total Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	821,267	742,425
Available-for-sale Securities, Gross Unrealized Gains	11,381	9,475
Available-for-sale, Unrealized Loss	(13,688)	(15,964)
Available-for-sale Securities, Fair Value	818,960	735,936
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost	1,593	1,867
Available-for-sale Securities, Gross Unrealized Gains	332	381
Available-for-sale, Unrealized Loss	(38)	(59)
Available-for-sale Securities, Fair Value	$ 1,887	$ 2,189

For an unclassified balance sheet, this item represents investments in debt and equity securities which are categorized neither as held-to-maturity nor trading. Such securities are reported at fair value, with unrealized gains and losses excluded from earnings and reported in a separate component of shareholders' equity (other comprehensive income), unless the Available-for-sale Security is designated as a hedge or is determined to have had an other than temporary decline in fair value below its amortized cost basis. All or a portion of the unrealized holding gain or loss of an Available-for-sale Security that is designated as being hedged in a fair value hedge shall be recognized in earnings during the period of the hedge, as should other than temporary declines in fair value below costs basis.

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This item represents the gross unrealized losses for securities which are categorized neither as held-to-maturity nor trading securities. Such gross unrealized losses are the excess of the carrying value of the Available-for-sale Securities over their fair value as of the reporting date. Such gross unrealized losses are included in other comprehensive income in the statement of shareholders' equity, unless the Available-for-sale Security is designated as a hedge or is determined to have had an other than temporary decline in fair value below its amortized cost basis. All or a portion of the unrealized holding loss of an Available-for-sale Security that is designated as being hedged in a fair value hedge shall be recognized in earnings during the period of the hedge, as should other than temporary declines in fair value below costs basis.

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