Investment Securities (Amortized Cost, Unrealized Gains And Losses, And Fair Value Of Investment Securities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Available-for-sale Securities, Amortized Cost	$ 3,111,797	$ 2,876,765
Available-for-sale Securities, Unrealized Gains	60,762	63,780
Available-for-sale Securities, Unrealized Losses	(3,981)	(21,365)
Available-for-sale Securities, Fair Value	3,168,578	2,919,180
Held-to-maturity Securities, Amortized Cost	4,714	4,762
Held-to-maturity Securities, Unrealized Gains	122	221
Held-to-maturity Securities, Unrealized Losses	(77)	(209)
Held-to-maturity Securities, Fair Value	4,759	4,774
U.S. Treasury And Agencies [Member]
Available-for-sale Securities, Amortized Cost	117,232	117,551
Available-for-sale Securities, Unrealized Gains	1,234	1,239
Available-for-sale Securities, Unrealized Losses	(1)	(1)
Available-for-sale Securities, Fair Value	118,465	118,789
Obligations Of States And Political Subdivisions [Member]
Available-for-sale Securities, Amortized Cost	237,302	213,129
Available-for-sale Securities, Unrealized Gains	16,264	4,985
Available-for-sale Securities, Unrealized Losses	(13)	(1,388)
Available-for-sale Securities, Fair Value	253,553	216,726
Held-to-maturity Securities, Amortized Cost	1,335	2,370
Held-to-maturity Securities, Unrealized Gains	2	5
Held-to-maturity Securities, Unrealized Losses
Held-to-maturity Securities, Fair Value	1,337	2,375
Residential Mortgage-Backed Securities And Collateralized Mortgage Obligations [Member]
Available-for-sale Securities, Amortized Cost	2,755,153	2,543,974
Available-for-sale Securities, Unrealized Gains	43,152	57,506
Available-for-sale Securities, Unrealized Losses	(3,950)	(19,976)
Available-for-sale Securities, Fair Value	2,794,355	2,581,504
Held-to-maturity Securities, Amortized Cost	3,379	2,392
Held-to-maturity Securities, Unrealized Gains	120	216
Held-to-maturity Securities, Unrealized Losses	(77)	(209)
Held-to-maturity Securities, Fair Value	3,422	2,399
Other Debt Securities [Member]
Available-for-sale Securities, Amortized Cost	151	152
Available-for-sale Securities, Unrealized Gains
Available-for-sale Securities, Unrealized Losses	(17)
Available-for-sale Securities, Fair Value	134	152
Investments In Mutual Funds And Other Equity Securities [Member]
Available-for-sale Securities, Amortized Cost	1,959	1,959
Available-for-sale Securities, Unrealized Gains	112	50
Available-for-sale Securities, Fair Value	$ 2,071	$ 2,009

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

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-Name Statement of Financial Accounting Standard (FAS)

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

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Reference 8: http://www.xbrl.org/2003/role/presentationRef

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-Name Statement of Financial Accounting Standard (FAS)

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Reference 9: http://www.xbrl.org/2003/role/presentationRef

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-Name Statement of Financial Accounting Standard (FAS)

-Number 115

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Reference 10: http://www.xbrl.org/2003/role/presentationRef

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-URI http://asc.fasb.org/extlink&oid=6379932&loc=d3e22054-111558

+ 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)

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

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-Number 115

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

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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

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Reference 7: http://www.xbrl.org/2003/role/presentationRef

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-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

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-Number 115

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Reference 10: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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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

- Definition

As of the balance sheet date, the excess of carrying value (amortized cost) over fair value 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 loss.

+ References+ Details