Investment Securities (Available For Sale Securities Unrealized Gains And Losses, By Security Type) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Investment [Line Items]
Amortized Cost	$ 9,732,856	$ 9,386,302
Gross unreailzed gain in accumulated other comprehensive income at period end	204,113	172,642
Gross unreailzed losses in accumulated other comprehensive income at period end	(19,727)	(35,384)
Fair Value	9,917,242us-gaap_AvailableForSaleSecurities	9,523,560us-gaap_AvailableForSaleSecurities
U.S. Government And Federal Agency Obligations [Member]
Investment [Line Items]
Amortized Cost	422,890	497,336
Gross unreailzed gain in accumulated other comprehensive income at period end	16,427	9,095
Gross unreailzed losses in accumulated other comprehensive income at period end	(2,925)	(5,024)
Fair Value	436,392	501,407
Government-Sponsored Enterprise Obligations [Member]
Investment [Line Items]
Amortized Cost	1,064,644	968,574
Gross unreailzed gain in accumulated other comprehensive income at period end	7,224	2,593
Gross unreailzed losses in accumulated other comprehensive income at period end	(3,101)	(8,040)
Fair Value	1,068,767	963,127
State And Municipal Obligations [Member]
Investment [Line Items]
Amortized Cost	1,781,285	1,789,215
Gross unreailzed gain in accumulated other comprehensive income at period end	36,872	32,340
Gross unreailzed losses in accumulated other comprehensive income at period end	(6,612)	(8,354)
Fair Value	1,811,545	1,813,201
Agency Mortgage-Backed Securities [Member]
Investment [Line Items]
Amortized Cost	2,626,920	2,523,377
Gross unreailzed gain in accumulated other comprehensive income at period end	86,710	75,923
Gross unreailzed losses in accumulated other comprehensive income at period end	(3,716)	(5,592)
Fair Value	2,709,914	2,593,708
Non-Agency Mortgage-Backed Securities [Member]
Investment [Line Items]
Amortized Cost	478,285	372,911
Gross unreailzed gain in accumulated other comprehensive income at period end	12,226	11,061
Gross unreailzed losses in accumulated other comprehensive income at period end	(278)	(1,228)
Fair Value	490,233	382,744
Asset-Backed Securities [Member]
Investment [Line Items]
Amortized Cost	3,156,146	3,090,174
Gross unreailzed gain in accumulated other comprehensive income at period end	9,287	6,922
Gross unreailzed losses in accumulated other comprehensive income at period end	(2,609)	(5,103)
Fair Value	3,162,824	3,091,993
Total Mortgage And Asset-Backed Securities [Member]
Investment [Line Items]
Amortized Cost	6,261,351	5,986,462
Gross unreailzed gain in accumulated other comprehensive income at period end	108,223	93,906
Gross unreailzed losses in accumulated other comprehensive income at period end	(6,603)	(11,923)
Fair Value	6,362,971	6,068,445
Other Debt Securities [Member]
Investment [Line Items]
Amortized Cost	197,008	140,784
Gross unreailzed gain in accumulated other comprehensive income at period end	1,496	420
Gross unreailzed losses in accumulated other comprehensive income at period end	(486)	(2,043)
Fair Value	198,018	139,161
Equity Securities [Member]
Investment [Line Items]
Amortized Cost	5,678	3,931
Gross unreailzed gain in accumulated other comprehensive income at period end	33,871	34,288
Gross unreailzed losses in accumulated other comprehensive income at period end	0	0
Fair Value	$ 39,549	$ 38,219

This item represents the gross unrealized gains for securities which are categorized as neither held-to-maturity nor trading securities. Such gross unrealized gains are the excess of the fair value of the Available-for-sale Securities over their carrying value as of the reporting date. Such gross unrealized gains are included in other comprehensive income in the statement of shareholders' equity. This concept represents the balance in unrealized gains at period-end.

No definition available.

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- Definition

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. This concept represents the balance in unrealized loss at period end.

+ References

No definition available.

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- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=28360136&loc=d3e22054-111558

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 5

-Subparagraph (aa)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562

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- 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

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.2)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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