Net Interest Income (Net Interest Income) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Interest Income
Federal Reserve and Other Central Bank Deposits and Other	$ 135.5	$ 4.2	$ 212.3	$ 5.6
Interest-Bearing Due from and Deposits with Banks	14.5	1.9	23.6	7.0
Securities Purchased under Agreements to Resell	30.5	0.8	38.4	2.7
Securities — Taxable	238.6	162.9	604.8	502.5
Securities - Non-Taxable	0.4	0.3	1.1	1.1
Loans and Leases	379.8	181.2	827.4	525.4
Total Interest Income	799.3	351.3	1,707.6	1,044.3
Interest Expense
Deposits	177.3	(16.3)	184.6	(44.5)
Federal Funds Purchased	9.9	0.0	12.7	(0.4)
Securities Sold Under Agreements to Repurchase	25.5	0.1	31.8	0.1
Other Borrowings	35.7	3.6	47.2	10.3
Senior Notes	28.6	11.7	57.1	39.2
Long-Term Debt	9.3	5.3	21.5	15.9
Floating Rate Capital Debt	0.0	0.5	0.0	1.6
Total Interest Expense	286.3	4.9	354.9	22.2
Net Interest Income	$ 513.0	$ 346.4	$ 1,352.7	$ 1,022.1

Interest expense incurred during the reporting period on senior notes.

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Interest Income, Federal Reserve Deposits and Other

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Represents the total of interest and dividend income, including any amortization and accretion (as applicable) of discounts and premiums, earned from (1) loans and leases whether held-for-sale or held-in-portfolio; (2) investment securities; (3) federal funds sold; (4) securities purchased under agreements to resell; (5) investments in banker's acceptances, commercial paper, or certificates of deposit; (6) dividend income; or (7) other investments not otherwise specified herein.

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The aggregate interest and fee income generated by: (1) loans the Entity has positive intent and ability to hold for the foreseeable future, or until maturity or payoff, including commercial and consumer loans, whether domestic or foreign, which may consist of: (a) industrial and agricultural; (b) real estate; and (c) real estate construction loans; (d) trade financing; (e) lease financing; (f) home equity lines-of-credit; (g) automobile and other vehicle loans; and (h) credit card and other revolving-type loans and (2) loans and leases held-for-sale which may include mortgage loans, direct financing, and sales-type leases.

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Amount of the cost of borrowed funds accounted for as interest expense.

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Aggregate amount of interest expense on all deposits.

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Gross expenses on the purchase of Federal funds at a specified price with a simultaneous agreement to sell the same to the same counterparty at a fixed or determinable price at a future date.

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Interest expense incurred during the reporting period on junior subordinated debentures. Includes amortization of expenses incurred in the issuance of subordinated notes and debentures.

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Amount of interest expense incurred on long-term debt classified as other, including, but not limited to, interest on long-term notes and amortization of issuance costs.

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Interest expense incurred during the reporting period on other short-term borrowings.

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Gross expenses on securities sold coupled with an agreement to repurchase the same from the same counterparty at a fixed or determinable price within a fixed or variable time period.

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Interest income derived from funds deposited with both domestic and foreign financial institutions including funds in money market and other accounts.

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The net amount of operating interest income (expense).

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Interest income derived from securities purchased under agreements to resell. The difference in the price at which the institution buys the securities and resells the securities represents interest for the use of the funds by the other party. Most repurchase and sale agreements involve obligations of the federal government or its agencies, but other financial instruments, such as commercial paper, banker's acceptances and negotiable certificates of deposits are sometimes used in such transactions.

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Amount of operating interest income, including amortization and accretion of premiums and discounts, on securities exempt from state, federal and other income tax.

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Amount of operating interest income, including amortization and accretion of premiums and discounts, on securities subject to state, federal and other income tax.

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