Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
CASH FLOWS FROM OPERATING ACTIVITIES
Net Income	$ 1,138.9	$ 968.4
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities
Investment Security (Losses) Gains, net	0.0	(0.1)
Amortization and Accretion of Securities and Unearned Income, net	75.3	63.3
Provision for Credit Losses	(70.0)	127.5
Depreciation and Amortization	382.8	372.5
Pension Plan Contributions	(6.7)	(10.6)
Change in Receivables	(139.3)	47.6
Change in Interest Payable	3.8	(5.0)
Change in Collateral With Derivative Counterparties, net	(2,101.2)	(937.2)
Other Operating Activities, net	30.5	(205.9)
Net Cash (Used in) Provided by Operating Activities	(685.9)	420.5
CASH FLOWS FROM INVESTING ACTIVITIES
Change in Federal Funds Sold	0.0	5.0
Change in Securities Purchased under Agreements to Resell	711.2	(722.9)
Change in Interest-Bearing Deposits with Banks	1,371.0	2,194.9
Net Change in Federal Reserve and Other Central Bank Deposits	4,689.0	(4,592.3)
Purchases of Held to Maturity Debt Securities	(40,859.6)	(28,474.0)
Proceeds from Maturity and Redemption of Held to Maturity Debt Securities	43,934.8	23,901.2
Purchases of Available for Sale Debt Securities	(9,811.6)	(8,558.6)
Proceeds from Sale, Maturity and Redemption of Available for Sale Debt Securities	6,229.6	5,761.9
Change in Loans and Leases	(5,721.5)	(1,339.6)
Purchases of Buildings and Equipment	(65.0)	(102.6)
Purchases and Development of Computer Software	(278.7)	(287.5)
Change in Client Security Settlement Receivables	(814.1)	(1,377.3)
Other Investing Activities, net	803.3	477.3
Net Cash Provided by (Used in) Investing Activities	188.4	(13,114.5)
CASH FLOWS FROM FINANCING ACTIVITIES
Change in Deposits	(271.9)	12,697.8
Change in Federal Funds Purchased	(260.0)	1,650.8
Change in Securities Sold under Agreements to Repurchase	533.8	(219.9)
Change in Short-Term Other Borrowings	1,609.1	(934.0)
Proceeds from Senior Notes	0.0	993.2
Repayments of Senior Notes	(500.0)	0.0
Redemption of Preferred Stock - Series C	0.0	(400.0)
Treasury Stock Purchased	(265.8)	(298.5)
Net Proceeds from Stock Options	48.8	10.7
Cash Dividends Paid on Common Stock	(437.8)	(438.8)
Cash Dividends Paid on Preferred Stock	(25.6)	(29.7)
Other Financing Activities, net	(0.6)	0.7
Net Cash Provided by Financing Activities	430.0	13,032.3
Effect of Foreign Currency Exchange Rates on Cash	(127.3)	(60.0)
Change in Cash and Due from Banks	(194.8)	278.3
Cash and Due from Banks at Beginning of Period	4,389.5	4,459.2
Cash and Due from Banks at End of Period	4,194.7	4,737.5
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Interest Paid	17.7	190.3
Income Taxes Paid	267.8	264.5
Transfers from Loans to OREO	10.1	0.2
Transfers from Available for Sale Debt Securities to Held to Maturity Debt Securities	$ 6,864.1	$ 301.5