Loans, Allowance for Loan Losses, and Credit Quality Commercial Loans by Credit Quality Indicator (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Commercial loans by credit quality indicator
Commercial and industrial	$ 4,752,838	$ 4,502,021
Commercial real estate - owner occupied	1,174,866	1,219,747
Lease financing	55,084	64,196
Commercial and business lending	5,982,788	5,785,964
Commercial real estate - investor	3,010,992	2,906,759
Real estate construction	800,569	655,381
Commercial real estate lending	3,811,561	3,562,140
Total commercial	9,794,349	9,348,104
Pass [Member]
Commercial loans by credit quality indicator
Commercial and industrial	4,459,010	4,208,478
Commercial real estate - owner occupied	997,132	1,030,632
Lease financing	54,222	58,099
Commercial and business lending	5,510,364	5,297,209
Commercial real estate - investor	2,773,560	2,634,035
Real estate construction	761,487	603,481
Commercial real estate lending	3,535,047	3,237,516
Total commercial	9,045,411	8,534,725
Special Mention [Member]
Commercial loans by credit quality indicator
Commercial and industrial	105,174	97,787
Commercial real estate - owner occupied	64,321	51,417
Lease financing	511	2,802
Commercial and business lending	170,006	152,006
Commercial real estate - investor	50,011	65,309
Real estate construction	3,114	6,976
Commercial real estate lending	53,125	72,285
Total commercial	223,131	224,291
Potential Problem [Member]
Commercial loans by credit quality indicator
Commercial and industrial	127,382	128,434
Commercial real estate - owner occupied	75,074	99,592
Lease financing	279	264
Commercial and business lending	202,735	228,290
Commercial real estate - investor	89,342	107,068
Real estate construction	9,184	13,092
Commercial real estate lending	98,526	120,160
Total commercial	301,261	348,450
Impaired [Member]
Commercial loans by credit quality indicator
Commercial and industrial	61,272	67,322
Commercial real estate - owner occupied	38,339	38,106
Lease financing	72	3,031
Commercial and business lending	99,683	108,459
Commercial real estate - investor	98,079	100,347
Real estate construction	26,784	31,832
Commercial real estate lending	124,863	132,179
Total commercial	$ 224,546	$ 240,638

Amount before allowance of commercial leases and leveraged lease transactions where the entity is long-term creditor. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes leases covered under loss sharing agreements.

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

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-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

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-Glossary Leveraged Lease

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-Publisher SEC

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-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)

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-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

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+ Details

- Definition

Amount before allowance of commercial loans and leases receivable includes, but not limited to, commercial and industrial loans, agricultural loans, mortgage loans, promissory notes, interbank and other loans to financial institutions, draws against credit facilities, trade financing, lease financings. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References+ Details

- Definition

Amount before allowance of loans issued to commercial and industrial institutions. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes real estate loans and loans covered under loss sharing agreements.

+ References+ Details

- Definition

Amount before allowance of commercial construction loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans covered under loss sharing agreements.

+ References+ Details

- Definition

Amount before allowance of commercial loans issued to businesses to acquire, develop, construct, improve, or refinance land or building. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans covered under loss sharing agreements.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

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-URI http://asc.fasb.org/extlink&oid=7512638&loc=d3e5066-111524

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

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 01-6

-Paragraph 13

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-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 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 SEC

-Name Regulation S-X (SX)

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-Name Accounting Standards Codification

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+ Details