Offsetting of Assets and Liabilities (Offsetting of Derivative Assets and Securities Purchased Under Agreements to Resell) (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED ASSETS	$ 2,141.5	$ 3,151.2
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	1,245.9	2,810.7
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	895.6	340.5
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	3.9	5.0
NET AMOUNT	891.7	335.5
Total Derivatives Not Subject to a Master Netting Arrangement
GROSS RECOGNIZED ASSETS	436.5	581.2
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	0.0	0.0
NET AMOUNT	436.5	581.2
Total Derivatives
GROSS RECOGNIZED ASSETS	2,578.0	3,732.4
Derivative Assets	1,332.1	921.7
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	3.9	5.0
NET AMOUNT	1,328.2	916.7
Securities Purchased under Agreements to Resell
GROSS RECOGNIZED ASSETS	35,761.2	12,494.2
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	34,532.3	11,423.9
Securities Purchased under Agreements to Resell	1,228.9	1,070.3
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	1,228.9	1,070.3
Other assets excluding derivatives and non financial instruments	9,800.0	8,900.0
Foreign Exchange Contracts | Over the Counter Derivative
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED ASSETS	1,827.6	2,928.9
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	1,001.1	2,666.4
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	826.5	262.5
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	3.9	5.0
NET AMOUNT	822.6	257.5
Interest Rate Swap Contracts | Over the Counter Derivative
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED ASSETS	313.9	217.6
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	244.8	144.3
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	69.1	73.3
NET AMOUNT	69.1	73.3
Interest Rate Swap Contracts | Interest Rate Swaps Exchange Cleared
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED ASSETS	0.0	4.4
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	0.0	0.0
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	0.0	4.4
NET AMOUNT	0.0	4.4
Other Financial Derivatives
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED ASSETS	0.0	0.3
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	0.0	0.0
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	0.0	0.3
NET AMOUNT	$ 0.0	$ 0.3