Investment Securities (Details) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Investment securities available for sale:
Total investment securities available for sale, Amortized Cost	$ 5,571,851	$ 6,011,976
Total investment securities available for sale, Gross unrealized gains	173,680	135,189
Total investment securities available for sale, Gross unrealized losses	(3,497)	(45,824)
Total investment securities available for sale	5,742,034	6,101,341
US Treasury Securities [Member]
Investment securities available for sale:
Total investment securities available for sale, Amortized Cost	1,099	1,199
Total investment securities available for sale, Gross unrealized gains	7	9
Total investment securities available for sale, Gross unrealized losses	0	0
Total investment securities available for sale	1,106	1,208
Federal agency securities [Member]
Investment securities available for sale:
Total investment securities available for sale, Amortized Cost	27,156	29,791
Total investment securities available for sale, Gross unrealized gains	36	1
Total investment securities available for sale, Gross unrealized losses	0	(25)
Total investment securities available for sale	27,192	29,767
Obligations of state and political subdivisions (municipal securities) [Member]
Investment securities available for sale:
Total investment securities available for sale, Amortized Cost	787,768	829,058
Total investment securities available for sale, Gross unrealized gains	31,115	14,894
Total investment securities available for sale, Gross unrealized losses	(671)	(5,350)
Total investment securities available for sale	818,212	838,602
Residential mortgage-related securities [Member]
Investment securities available for sale:
Total investment securities available for sale, Amortized Cost	4,441,048	4,831,481
Total investment securities available for sale, Gross unrealized gains	138,350	117,530
Total investment securities available for sale, Gross unrealized losses	(1,011)	(38,514)
Total investment securities available for sale	4,578,387	4,910,497
Commercial mortgage-related securities [Member]
Investment securities available for sale:
Total investment securities available for sale, Amortized Cost	12,499	7,604
Total investment securities available for sale, Gross unrealized gains	551	149
Total investment securities available for sale, Gross unrealized losses	0	0
Total investment securities available for sale	13,050	7,753
Asset-backed securities [Member]
Investment securities available for sale:
Total investment securities available for sale, Amortized Cost	243,387	299,459
Total investment securities available for sale, Gross unrealized gains	193	3
Total investment securities available for sale, Gross unrealized losses	(465)	(621)
Total investment securities available for sale	243,115	298,841
Other securities (debt and equity) [Member]
Investment securities available for sale:
Total investment securities available for sale, Amortized Cost	58,894	13,384
Total investment securities available for sale, Gross unrealized gains	3,428	2,603
Total investment securities available for sale, Gross unrealized losses	(1,350)	(1,314)
Total investment securities available for sale	$ 60,972	$ 14,673

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