Offsetting of Assets and Liabilities (Offsetting of Derivative Liabilities and Securities Sold Under Agreements to Repurchase) (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED LIABILITIES	$ 3,148.1	$ 1,371.1
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	2,757.4	1,175.7
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	390.7	195.4
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	0.0	0.0
NET AMOUNT	390.7	195.4
Total Derivatives Not Subject to a Master Netting Arrangement
Total Derivatives Not Subject to a Master Netting Arrangement	645.4	1,038.5
Offsetting Derivative Liabilities [Abstract]
GROSS RECOGNIZED LIABILITIES	3,793.5	2,409.6
Derivative Liabilities	1,036.1	1,233.9
NET AMOUNT	1,036.1	1,233.9
Securities Sold under Agreements to Repurchase
GROSS RECOGNIZED LIABILITIES	97,513.7	90,307.8
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	97,183.2	90,015.6
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	330.5	292.2
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	330.5	292.2
NET AMOUNT	0.0	0.0
Foreign Exchange Contracts | Over the Counter Derivative
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED LIABILITIES	3,120.8	1,334.8
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	2,753.8	1,139.4
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	367.0	195.4
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	0.0	0.0
NET AMOUNT	367.0	195.4
Interest Rate Swap Contracts | Over the Counter Derivative
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED LIABILITIES	3.6	5.0
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	3.6	5.0
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	0.0	0.0
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	0.0	0.0
NET AMOUNT	0.0	0.0
Interest Rate Swap Contracts | Interest Rate Swaps Exchange Cleared
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED LIABILITIES		0.0
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET		0.0
NET AMOUNTS PRESENTED IN THE BALANCE SHEET		0.0
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET		0.0
NET AMOUNT		0.0
Other Financial Derivatives | Other Financial Derivatives
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED LIABILITIES	23.7	31.3
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	0.0	31.3
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	23.7	0.0
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	0.0	0.0
NET AMOUNT	$ 23.7	$ 0.0