Investment Securities (Available For Sale Securities Unrealized Gains And Losses, By Security Type) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Investment [Line Items]
Amortized Cost	$ 8,896,396	$ 9,012,095
Gross Unrealized Gains	253,007	238,507
Gross Unrealized Losses	(29,004)	(25,900)
Fair Value	9,120,399	9,224,702
U.S. Government And Federal Agency Obligations [Member]
Investment [Line Items]
Amortized Cost	328,781	328,530
Gross Unrealized Gains	39,881	36,135
Fair Value	368,662	364,665
Government-Sponsored Enterprise Obligations [Member]
Investment [Line Items]
Amortized Cost	275,112	311,529
Gross Unrealized Gains	3,580	4,169
Gross Unrealized Losses	(768)
Fair Value	277,924	315,698
State And Municipal Obligations [Member]
Investment [Line Items]
Amortized Cost	1,307,844	1,220,840
Gross Unrealized Gains	36,873	35,663
Gross Unrealized Losses	(17,850)	(11,219)
Fair Value	1,326,867	1,245,284
Agency Mortgage-Backed Securities [Member]
Investment [Line Items]
Amortized Cost	3,742,525	3,989,464
Gross Unrealized Gains	124,282	117,088
Gross Unrealized Losses	(351)	(493)
Fair Value	3,866,456	4,106,059
Non-Agency Mortgage-Backed Securities [Member]
Investment [Line Items]
Amortized Cost	287,375	315,752
Gross Unrealized Gains	10,288	8,962
Gross Unrealized Losses	(3,442)	(7,812)
Fair Value	294,221	316,902
Asset-Backed Securities [Member]
Investment [Line Items]
Amortized Cost	2,815,676	2,692,436
Gross Unrealized Gains	8,409	7,083
Gross Unrealized Losses	(6,593)	(6,376)
Fair Value	2,817,492	2,693,143
Other Debt Securities [Member]
Investment [Line Items]
Amortized Cost	117,831	135,190
Gross Unrealized Gains	5,524	6,070
Fair Value	123,355	141,260
Equity Securities [Member]
Investment [Line Items]
Amortized Cost	21,252	18,354
Gross Unrealized Gains	24,170	23,337
Fair Value	45,422	41,691
Total Mortgage And Asset-Backed Securities [Member]
Investment [Line Items]
Amortized Cost	6,845,576	6,997,652
Gross Unrealized Gains	142,979	133,133
Gross Unrealized Losses	(10,386)	(14,681)
Fair Value	$ 6,978,169	$ 7,116,104

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

-SubTopic 10

-Section 45

-Paragraph 1

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

Reference 2: 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 3: 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 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 22

-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 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 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 FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 15C

-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 8: 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 9: 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 10: 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=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