Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
CASH FLOWS FROM OPERATING ACTIVITIES
Net Income	$ 1,545.3	$ 1,209.3	$ 1,492.2
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities
Investment Security (Losses) Gains, net	0.3	0.4	1.4
Amortization and Accretion of Securities and Unearned Income, net	99.7	88.9	64.6
Provision for Credit Losses	(81.5)	125.0	(14.5)
Depreciation and Amortization	515.6	500.3	458.9
Change in Accrued Income Taxes	37.2	25.4	(70.7)
Pension Plan Contributions	(11.2)	(15.6)	(6.1)
Deferred Income Tax Provision	2.0	16.4	34.3
Change in Receivables	(460.9)	4.5	(50.3)
Change in Interest Payable	(7.8)	(23.6)	(23.6)
Change in Collateral With Derivative Counterparties, net	(466.5)	(17.8)	1,154.0
Other Operating Activities, net	183.8	(16.4)	(448.2)
Net Cash Provided by Operating Activities	1,356.0	1,896.8	2,592.0
CASH FLOWS FROM INVESTING ACTIVITIES
Change in Federal Funds Sold	0.0	5.0	129.0
Change in Securities Purchased under Agreements to Resell	897.7	(700.9)	357.3
Change in Interest-Bearing Deposits with Banks	2,344.5	712.6	(614.6)
Net Change in Federal Reserve and Other Central Bank Deposits	(9,970.4)	(19,845.2)	(3,683.2)
Purchases of Held to Maturity Debt Securities	(54,734.9)	(40,187.9)	(14,154.3)
Proceeds from Maturity and Redemption of Held to Maturity Debt Securities	54,902.6	35,658.6	16,290.9
Purchases of Available for Sale Debt Securities	(13,896.2)	(10,886.8)	(12,811.0)
Proceeds from Sale, Maturity and Redemption of Available for Sale Debt Securities	10,079.0	8,748.2	11,057.2
Change in Loans and Leases	(6,744.7)	(2,316.7)	1,087.9
Purchases of Buildings and Equipment	(95.5)	(135.8)	(158.0)
Purchases and Development of Computer Software	(419.6)	(424.6)	(441.8)
Change in Client Security Settlement Receivables	(801.4)	(226.8)	821.0
Acquisition of a Business, Net of Cash Received	0.0	0.0	(10.5)
Bank-Owned Life Insurance Policy Premiums	0.0	0.0	(1,500.0)
Other Investing Activities, net	(163.7)	(322.7)	225.1
Net Cash Used in Investing Activities	(18,602.6)	(29,923.0)	(3,405.0)
CASH FLOWS FROM FINANCING ACTIVITIES
Change in Deposits	17,885.5	32,137.9	4,263.6
Change in Federal Funds Purchased	(260.0)	(292.7)	(2,041.3)
Change in Securities Sold under Agreements to Repurchase	492.1	(450.0)	320.9
Change in Short-Term Other Borrowings	(426.5)	(2,698.3)	(1,184.5)
Redemption of Preferred Stock - Series C	0.0	(400.0)	0.0
Proceeds from Senior Notes	0.0	993.2	498.0
Repayments of Senior Notes	(500.0)	(508.6)	0.0
Repayment of Floating Rate Capital Debt	(278.8)	0.0	0.0
Proceeds from Issuance of Preferred Stock - Series E	0.0	0.0	392.5
Treasury Stock Purchased	(267.6)	(299.8)	(1,100.2)
Net Proceeds from Stock Options	53.8	19.5	44.0
Cash Dividends Paid on Common Stock	(583.3)	(584.6)	(529.7)
Cash Dividends Paid on Preferred Stock	(41.8)	(45.9)	(46.4)
Other Financing Activities, net	0.1	1.2	(1.0)
Net Cash Provided by Financing Activities	16,073.5	27,871.9	615.9
Effect of Foreign Currency Exchange Rates on Cash	(159.6)	84.6	74.7
Change in Cash and Due from Banks	(1,332.7)	(69.7)	(122.4)
Cash and Due from Banks at Beginning of Period	4,389.5	4,459.2	4,581.6
Cash and Due from Banks at End of Period	3,056.8	4,389.5	4,459.2
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Interest Paid	30.8	226.8	845.5
Income Taxes Paid	371.0	327.7	437.0
Transfers from Loans to OREO	12.9	0.2	3.5
Transfers from Available for Sale Debt Securities to Held to Maturity Debt Securities	6,864.1	301.5	160.8
Transfers to Leases Held For Sale from Leases	$ 0.0	$ 0.0	$ 53.6