Offsetting of Assets and Liabilities (Offsetting of Derivative Liabilities and Securities Sold Under Agreements to Repurchase) (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED LIABILITIES	$ 1,618.1	$ 2,806.3
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	881.5	2,205.4
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	736.6	600.9
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	0.0	0.0
NET AMOUNT	736.6	600.9
Total Derivatives Not Subject to a Master Netting Arrangement
Total Derivatives Not Subject to a Master Netting Arrangement	263.7	843.5
Offsetting Derivative Liabilities [Abstract]
GROSS RECOGNIZED LIABILITIES	1,881.8	3,649.8
Derivative Liabilities	1,000.3	1,444.4
NET AMOUNT	1,000.3	1,444.4
Securities Sold under Agreements to Repurchase
GROSS RECOGNIZED LIABILITIES	70,839.9	62,860.2
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	70,210.7	62,075.5
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	629.2	784.7
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	629.2	784.7
NET AMOUNT	0.0	0.0
Other liabilities	3,500.0	4,000.0
Foreign Exchange Contracts | Over the Counter Derivative
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED LIABILITIES	1,114.8	2,411.7
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	850.0	2,175.7
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	264.8	236.0
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	0.0	0.0
NET AMOUNT	264.8	236.0
Interest Rate Swap Contracts | Over the Counter Derivative
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED LIABILITIES	468.6	368.3
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	2.3	6.0
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	466.3	362.3
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	0.0	0.0
NET AMOUNT	466.3	362.3
Interest Rate Swap Contracts | Interest Rate Swaps Exchange Cleared
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED LIABILITIES	4.1	0.9
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	0.0	0.0
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	4.1	0.9
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	0.0	0.0
NET AMOUNT	4.1	0.9
Other Financial Derivatives | Other Financial Derivatives
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED LIABILITIES	30.6	25.4
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	29.2	23.7
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	1.4	1.7
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	0.0	0.0
NET AMOUNT	$ 1.4	$ 1.7