Securities (Summary Of Available-For-Sale And Held-To-Maturity Securities) (Details) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010
Securities available-for-sale, Amortized Cost Basis	$ 1,573,909	$ 1,497,018
Securities available-for-sale, Gross Unrealized Holding Gains	67,117	47,901
Securities available-for-sale, Gross Unrealized Holding Losses	(1,034)	(7,741)
Securities available-for-sale, Estimated Fair Value	1,639,992	1,537,178	1,402,448
Securities held-to-maturity, Amortized Cost Basis	6,663	9,064	11,107
Securities held-to-maturity, Gross Unrealized Holding Gains	93	176
Securities held-to-maturity, Estimated Fair Value	6,756	9,240	11,403
U.S. Treasury Securities [Member]
Securities available-for-sale, Amortized Cost Basis	15,198	15,253
Securities available-for-sale, Gross Unrealized Holding Gains	271	263
Securities available-for-sale, Estimated Fair Value	15,469	15,516
Obligations Of U.S. Government Sponsored-Enterprises And Agencies [Member]
Securities available-for-sale, Amortized Cost Basis	251,648	270,706
Securities available-for-sale, Gross Unrealized Holding Gains	7,585	8,542
Securities available-for-sale, Estimated Fair Value	259,233	279,248
Obligations Of States And Political Subdivisions [Member]
Securities available-for-sale, Amortized Cost Basis	555,118	543,074
Securities available-for-sale, Gross Unrealized Holding Gains	28,944	12,695
Securities available-for-sale, Gross Unrealized Holding Losses	(489)	(5,861)
Securities available-for-sale, Estimated Fair Value	583,573	549,908
Securities held-to-maturity, Amortized Cost Basis	6,201	8,549
Securities held-to-maturity, Gross Unrealized Holding Gains	76	160
Securities held-to-maturity, Estimated Fair Value	6,277	8,709
Corporate Bonds And Other [Member]
Securities available-for-sale, Amortized Cost Basis	41,164	56,710
Securities available-for-sale, Gross Unrealized Holding Gains	4,058	4,118
Securities available-for-sale, Estimated Fair Value	45,222	60,828
Mortgage-Backed Securities [Member]
Securities available-for-sale, Amortized Cost Basis	710,781	611,275
Securities available-for-sale, Gross Unrealized Holding Gains	26,259	22,283
Securities available-for-sale, Gross Unrealized Holding Losses	(545)	(1,880)
Securities available-for-sale, Estimated Fair Value	736,495	631,678
Securities held-to-maturity, Amortized Cost Basis	462	515
Securities held-to-maturity, Gross Unrealized Holding Gains	17	16
Securities held-to-maturity, Estimated Fair Value	$ 479	$ 531

For an unclassified balance sheet, this item represents investments in debt and equity securities which are categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
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-Subparagraph b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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+ Details

- Definition

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.

+ References+ Details

- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

+ References+ Details

- Definition

For an unclassified balance sheet, this item represents investments in debt securities which are categorized as held-to-maturity. The held-to-maturity category is for those securities that the entity has the positive intent and ability to hold until maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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-Publisher FASB
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
-Section A
-Paragraph 4
-Chapter 3
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Number 115
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-URI http://asc.fasb.org/extlink&oid=6379932&loc=d3e22054-111558

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-Publisher FASB
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Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.6)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

- Definition

This item represents the aggregate fair value of investments in debt securities as of the balance sheet date and which are categorized as held-to-maturity.

+ References+ Details

- Definition

As of the balance sheet date, the excess of fair value over carrying value (amortized cost) of a debt security categorized as held-to-maturity, exclusive of dividend or interest income recognized but not yet received and exclusive of any write-downs for other-than-temporary impairment. Such item represents the gross unrecognized holding gain.

+ References+ Details