Fair Value Disclosures [Line Items]

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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- Definition

Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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- Definition

Balance held at close of period in number of contracts.

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- Definition

Amount of investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading.

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Fair Value Measurements (Narrative) (Details) shares in Millions, $ in Millions	Sep. 30, 2015 USD ($) Securities shares	Dec. 31, 2014 USD ($) Securities	Sep. 30, 2014 USD ($)
Fair Value Disclosures [Line Items]
Available for sale securities portfolio, value	$ 31,091.7	$ 29,558.5
Trading account securities	$ 0.5	$ 4.7
Level 2
Fair Value Disclosures [Line Items]
Number of available for sale securities portfolio \| Securities	987	881
Available for sale securities portfolio, value	$ 26,000.0	$ 25,000.0
Fair Value, Measurements, Nonrecurring \| Level 3 \| Loans
Fair Value Disclosures [Line Items]
Fair Value	10.9		$ 26.6
Fair Value, Measurements, Nonrecurring \| Level 3 \| OREO
Fair Value Disclosures [Line Items]
Fair Value	$ 0.3		$ 1.5
External Pricing \| Level 2
Fair Value Disclosures [Line Items]
Number of available for sale securities portfolio \| Securities	987	881
Trading account securities	$ 0.5	$ 4.7
Visa Class B
Fair Value Disclosures [Line Items]
Number of common stock shares sold \| shares	1.0