Loans, Allowance for Loan Losses, and Credit Quality Loan Composition (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Loan composition
Commercial and industrial	$ 5,905,902	$ 4,822,680
Commercial real estate - owner occupied	1,007,937	1,114,715
Lease financing	51,529	55,483
Commercial and business lending	6,965,368	5,992,878
Commercial real estate - investor	3,056,485	2,939,456
Real estate construction	1,008,956	896,248
Commercial real estate lending	4,065,441	3,835,704
Total commercial	11,030,809	9,828,582
Home equity	1,636,058	1,825,014
Installment and Credit Cards	454,219	407,074
Residential mortgage	4,472,760	3,835,591
Total consumer	6,563,037	6,067,679
Total loans	$ 17,593,846	$ 15,896,261

Commercial and business lending subtotal

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Commercial Real Estate Investor loans receivable.

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Owner occupied commercial real estate.

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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.

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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.

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Amount before allowance of revolving, open-end loan, extended under a line of credit and secured by the borrower's residential property. 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.

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Amount before allowance of installment and revolving loans issued to individuals, including, but not limited to credit card, automobile, boat, student, durable home appliance loans. 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.

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Amount before allowance of consumer mortgage. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes subordinated loans such as home equity lines of credit and loans and leases covered under loss sharing agreements.

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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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.

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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.

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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.

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