Investment Securities (Summary Of Available For Sale Investment Securities By Maturity Groupings) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Investment [Line Items]
Amortized Cost	$ 8,850,269	$ 9,258,525
Fair Value	8,927,815	9,522,248
U.S. Government And Federal Agency Obligations [Member]
Investment [Line Items]
Amortized Cost	401,075	399,971
Fair Value	413,857	438,759
U.S. Government And Federal Agency Obligations [Member] \| Available For Sale Securities Maturity After1 But Within5 Years [Member]
Investment [Line Items]
Amortized Cost	247,531
Fair Value	265,394
U.S. Government And Federal Agency Obligations [Member] \| Available For Sale Securities Maturity After5 But Within10 Years [Member]
Investment [Line Items]
Amortized Cost	80,681
Fair Value	86,284
U.S. Government And Federal Agency Obligations [Member] \| Available For Sale Maturity After10 Years [Member]
Investment [Line Items]
Amortized Cost	72,863
Fair Value	62,179
Government-Sponsored Enterprise Obligations [Member]
Investment [Line Items]
Amortized Cost	426,556	467,063
Fair Value	414,818	471,574
Government-Sponsored Enterprise Obligations [Member] \| Available For Sale Securities Maturity Within1 Year [Member]
Investment [Line Items]
Amortized Cost	20,177
Fair Value	20,323
Government-Sponsored Enterprise Obligations [Member] \| Available For Sale Securities Maturity After1 But Within5 Years [Member]
Investment [Line Items]
Amortized Cost	89,693
Fair Value	92,140
Government-Sponsored Enterprise Obligations [Member] \| Available For Sale Securities Maturity After5 But Within10 Years [Member]
Investment [Line Items]
Amortized Cost	169,719
Fair Value	161,361
Government-Sponsored Enterprise Obligations [Member] \| Available For Sale Maturity After10 Years [Member]
Investment [Line Items]
Amortized Cost	146,967
Fair Value	140,994
State And Municipal Obligations [Member]
Investment [Line Items]
Amortized Cost	1,625,628	1,585,926
Fair Value	1,621,194	1,615,707
State And Municipal Obligations [Member] \| Available For Sale Securities Maturity Within1 Year [Member]
Investment [Line Items]
Amortized Cost	103,698
Fair Value	104,485
State And Municipal Obligations [Member] \| Available For Sale Securities Maturity After1 But Within5 Years [Member]
Investment [Line Items]
Amortized Cost	698,390
Fair Value	716,807
State And Municipal Obligations [Member] \| Available For Sale Securities Maturity After5 But Within10 Years [Member]
Investment [Line Items]
Amortized Cost	564,173
Fair Value	554,505
State And Municipal Obligations [Member] \| Available For Sale Maturity After10 Years [Member]
Investment [Line Items]
Amortized Cost	259,367
Fair Value	245,397
Agency Mortgage-Backed Securities [Member]
Investment [Line Items]
Amortized Cost	2,889,382	3,248,007
Fair Value	2,937,002	3,380,955
Non-Agency Mortgage-Backed Securities [Member]
Investment [Line Items]
Amortized Cost	230,729	224,223
Fair Value	242,432	237,011
Asset-Backed Securities [Member]
Investment [Line Items]
Amortized Cost	3,094,715	3,152,913
Fair Value	3,088,148	3,167,394
Total Mortgage And Asset-Backed Securities [Member]
Investment [Line Items]
Amortized Cost	6,214,826	6,625,143
Fair Value	6,267,582	6,785,360
Other Debt Securities [Member]
Investment [Line Items]
Amortized Cost	170,263	174,727
Fair Value	165,735	177,752
Other Debt Securities [Member] \| Available For Sale Securities Maturity Within1 Year [Member]
Investment [Line Items]
Amortized Cost	38,193
Fair Value	38,961
Other Debt Securities [Member] \| Available For Sale Securities Maturity After1 But Within5 Years [Member]
Investment [Line Items]
Amortized Cost	45,751
Fair Value	45,826
Other Debt Securities [Member] \| Available For Sale Securities Maturity After5 But Within10 Years [Member]
Investment [Line Items]
Amortized Cost	86,319
Fair Value	80,948
Equity Securities [Member]
Investment [Line Items]
Amortized Cost	11,921	5,695
Fair Value	$ 44,629	$ 33,096

Amount of investment in debt and equity securities 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

-SubTopic 10

-Section 45

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-URI http://asc.fasb.org/extlink&oid=7534914&loc=d3e22054-111558

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 12

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 16

-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 FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 14

-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)

-Number 115

-Paragraph 13

-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)

-Number 133

-Paragraph 22

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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 15D

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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 15E

-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 FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 15C

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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.

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