Loans, Allowance for Loan Losses, and Credit Quality (Details 4) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Commercial loans by credit quality indicator
Commercial and industrial	$ 3,719,016	$ 3,724,736
Commercial real estate - owner occupied	1,074,755	1,086,829
Lease financing	61,208	58,194
Commercial and business lending	4,854,979	4,869,759
Commercial real estate - investor	2,664,251	2,563,767
Real estate construction	565,953	584,046
Commercial real estate lending	3,230,204	3,147,813
Total commercial	8,085,183	8,017,572
Pass [Member]
Commercial loans by credit quality indicator
Commercial and industrial	3,316,048	3,283,090
Commercial real estate - owner occupied	877,924	853,517
Lease financing	50,837	46,570
Commercial and business lending	4,244,809	4,183,177
Commercial real estate - investor	2,247,172	2,055,124
Real estate construction	479,848	494,839
Commercial real estate lending	2,727,020	2,549,963
Total commercial	6,971,829	6,733,140
Special Mention [Member]
Commercial loans by credit quality indicator
Commercial and industrial	168,927	209,713
Commercial real estate - owner occupied	45,344	53,090
Lease financing	844	822
Commercial and business lending	215,115	263,625
Commercial real estate - investor	114,865	135,668
Real estate construction	10,210	8,775
Commercial real estate lending	125,075	144,443
Total commercial	340,190	408,068
Potential Problem [Member]
Commercial loans by credit quality indicator
Commercial and industrial	157,778	153,306
Commercial real estate - owner occupied	112,673	136,366
Lease financing	487	158
Commercial and business lending	270,938	289,830
Commercial real estate - investor	167,339	230,206
Real estate construction	27,654	27,649
Commercial real estate lending	194,993	257,855
Total commercial	465,931	547,685
Impaired [Member]
Commercial loans by credit quality indicator
Commercial and industrial	76,263	78,627
Commercial real estate - owner occupied	38,814	43,856
Lease financing	9,040	10,644
Commercial and business lending	124,117	133,127
Commercial real estate - investor	134,875	142,769
Real estate construction	48,241	52,783
Commercial real estate lending	183,116	195,552
Total commercial	$ 307,233	$ 328,679

The total gross amount of commercial loans (money lent to commercial entities rather than consumers) made in the form of direct financing leases where the reporting entity (lessor) only recognizes interest revenue from the lease. It also includes the amount of lease financing arising from involvement with leveraged lease transactions where the Entity is in the position of long-term creditor.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(a)(5))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 9

-Section 03

-Paragraph 7

-Subparagraph a, b

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

-Publisher AICPA

-Name Audit and Accounting Guide (AAG)

-Number AAG-DEP

-Chapter 8

-Paragraph 47

-IssueDate 2006-05-01

-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 AICPA

-Name Statement of Position (SOP)

-Number 01-6

-Paragraph 13

-Subparagraph e

-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 Accounting Standards Codification

-Glossary Leveraged Lease

-URI http://asc.fasb.org/extlink&oid=6516780

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 13

-Paragraph 6

-Subparagraph b(iii)

-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 13

-Paragraph 42

-Subparagraph b, c

-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 Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6375948&loc=d3e4428-111522

+ Details

- Definition

Reflects the sum of the gross carrying amounts of the various categories of unpaid commercial loans and leases receivable, primarily issued to businesses. Includes: (1) commercial and industrial loans, consisting of general purpose loans to entities involved in producing, transporting, or merchandising products sold in the course of commerce; (2) agricultural loans consisting of borrowings used to finance major equipment and machinery purchases and expenses, livestock or crop production (including fisheries), and to supplement working capital needs of an entity engaged in farming operations; (3) mortgage loans secured by a [legal] security interest in real property [commercial building or business real property]; (4) obligation in the form of [promissory] notes, used for the funding of construction projects; (5) interbank and other loans to financial institutions for the purpose of liquidity management on the part of the borrower; (6) draws against credit facilities provided to companies involved in mortgage banking activities (warehousing); (7) amounts lent to businesses engaged in international activities (trade financing); (8) lease financings; and (9) loans to governmental entities.

+ References+ Details

- Definition

Reflects the gross carrying amount of unpaid loans issued to nonfinancial and nonagricultural businesses for uses other than for real property.

+ References+ Details

- Definition

Reflects the gross carrying amount of unpaid loans that had been issued to businesses to construct a facility. Acquisition, development and construction (ADC) loans are generally issued sequentially and the net proceeds of the latest debt is used by the borrower to pay off the preceding loan. A construction loan ( in the form of a promissory note) is generally expected to be paid off with the net proceeds from permanent financing.

+ References+ Details

- Definition

Reflects the sum of the gross carrying amounts of unpaid loans issued to businesses to acquire, develop, construct, improve, or refinance land or a building. Includes [but is not limited to] commercial mortgage loans, which are secured by a [legal] security interest in real property [commercial building or business real property] which thereby serves as collateral securing repayment of the loan; and construction financing, which is an obligation generally in the form of a [promissory] note, used for the funding of construction projects.

+ References

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

-Publisher AICPA

-Name Audit and Accounting Guide (AAG)

-Number AAG-DEP

-Chapter 8

-Paragraph 51, 52, 53

-IssueDate 2006-05-01

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6965416&loc=d3e5066-111524

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 60

-Paragraph 47

-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 Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(a))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 01-6

-Paragraph 13

-Subparagraph e

-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 SEC

-Name Regulation S-X (SX)

-Number 210

-Article 9

-Section 03

-Paragraph 7

-Subparagraph a

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.1(c))

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details