Investment Securities (Summary Of Available For Sale Investment Securities By Maturity Groupings) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Investment [Line Items]
Amortized Cost	$ 9,320,409	$ 9,258,525
Fair Value	9,572,751	9,522,248
U.S. Government And Federal Agency Obligations [Member]
Investment [Line Items]
Amortized Cost	397,689	399,971
Fair Value	437,308	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	245,326
Fair Value	274,127
U.S. Government And Federal Agency Obligations [Member] \| Available For Sale Securities Maturity After5 But Within10 Years [Member]
Investment [Line Items]
Amortized Cost	79,911
Fair Value	93,321
U.S. Government And Federal Agency Obligations [Member] \| Available For Sale Maturity After10 Years [Member]
Investment [Line Items]
Amortized Cost	72,452
Fair Value	69,860
Government-Sponsored Enterprise Obligations [Member]
Investment [Line Items]
Amortized Cost	451,110	467,063
Fair Value	453,702	471,574
Government-Sponsored Enterprise Obligations [Member] \| Available For Sale Securities Maturity Within1 Year [Member]
Investment [Line Items]
Amortized Cost	12,637
Fair Value	12,734
Government-Sponsored Enterprise Obligations [Member] \| Available For Sale Securities Maturity After1 But Within5 Years [Member]
Investment [Line Items]
Amortized Cost	97,483
Fair Value	100,759
Government-Sponsored Enterprise Obligations [Member] \| Available For Sale Securities Maturity After5 But Within10 Years [Member]
Investment [Line Items]
Amortized Cost	169,711
Fair Value	168,919
Government-Sponsored Enterprise Obligations [Member] \| Available For Sale Maturity After10 Years [Member]
Investment [Line Items]
Amortized Cost	171,279
Fair Value	171,290
State And Municipal Obligations [Member]
Investment [Line Items]
Amortized Cost	1,628,614	1,585,926
Fair Value	1,659,168	1,615,707
State And Municipal Obligations [Member] \| Available For Sale Securities Maturity Within1 Year [Member]
Investment [Line Items]
Amortized Cost	105,160
Fair Value	105,961
State And Municipal Obligations [Member] \| Available For Sale Securities Maturity After1 But Within5 Years [Member]
Investment [Line Items]
Amortized Cost	683,255
Fair Value	710,447
State And Municipal Obligations [Member] \| Available For Sale Securities Maturity After5 But Within10 Years [Member]
Investment [Line Items]
Amortized Cost	559,371
Fair Value	570,030
State And Municipal Obligations [Member] \| Available For Sale Maturity After10 Years [Member]
Investment [Line Items]
Amortized Cost	280,828
Fair Value	272,730
Agency Mortgage-Backed Securities [Member]
Investment [Line Items]
Amortized Cost	3,152,708	3,248,007
Fair Value	3,268,377	3,380,955
Non-Agency Mortgage-Backed Securities [Member]
Investment [Line Items]
Amortized Cost	229,520	224,223
Fair Value	243,907	237,011
Asset-Backed Securities [Member]
Investment [Line Items]
Amortized Cost	3,271,145	3,152,913
Fair Value	3,285,310	3,167,394
Total Mortgage And Asset-Backed Securities [Member]
Investment [Line Items]
Amortized Cost	6,653,373	6,625,143
Fair Value	6,797,594	6,785,360
Other Debt Securities [Member]
Investment [Line Items]
Amortized Cost	170,368	174,727
Fair Value	172,019	177,752
Other Debt Securities [Member] \| Available For Sale Securities Maturity Within1 Year [Member]
Investment [Line Items]
Amortized Cost	38,213
Fair Value	39,484
Other Debt Securities [Member] \| Available For Sale Securities Maturity After1 But Within5 Years [Member]
Investment [Line Items]
Amortized Cost	45,774
Fair Value	46,724
Other Debt Securities [Member] \| Available For Sale Securities Maturity After5 But Within10 Years [Member]
Investment [Line Items]
Amortized Cost	86,381
Fair Value	85,811
Equity Securities [Member]
Investment [Line Items]
Amortized Cost	19,255	5,695
Fair Value	$ 52,960	$ 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 FASB Staff Position (FSP)

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 12

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

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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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Reference 5: http://www.xbrl.org/2003/role/presentationRef

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-Name FASB Staff Position (FSP)

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

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

-Publisher FASB

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-Publisher FASB

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-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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-Name Statement of Financial Accounting Standard (FAS)

-Number 133

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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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