Net Interest Income (Net Interest Income) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Interest Income
Federal Reserve and Other Central Bank Deposits	$ 377.0	$ 17.6
Interest-Bearing Due from and Deposits with Banks	28.2	2.6
Federal Funds Sold	0.2	0.0
Securities Purchased under Agreements to Resell	125.9	0.9
Securities — Taxable	337.8	169.0
Securities - Non-Taxable	0.3	0.4
Loans and Leases	578.2	191.2
Other Interest-Earning Assets	7.8	1.8
Total Interest Income	1,455.4	383.5
Interest Expense
Deposits	564.6	(15.9)
Federal Funds Purchased	40.1	0.0
Securities Sold Under Agreements to Repurchase	116.1	0.3
Other Borrowings	135.0	3.1
Senior Notes	39.2	9.6
Long-Term Debt	29.2	5.4
Total Interest Expense	924.2	2.5
Net Interest Income	$ 531.2	$ 381.0