Offsetting of Assets and Liabilities (Offsetting of Derivative Liabilities and Securities Sold Under Agreements to Repurchase) (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED LIABILITIES	$ 2,821.9	$ 1,566.5
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	2,430.4	1,283.5
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	391.5	283.0
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	0.0	0.0
Net Amount	391.5	283.0
Total Derivatives Not Subject to a Master Netting Arrangement
GROSS RECOGNIZED LIABILITIES	533.1	568.7
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	0.0
NET AMOUNT	533.1	568.7
Offsetting Derivative Liabilities [Abstract]
GROSS RECOGNIZED LIABILITIES	3,355.0	2,135.2
Derivative Liabilities	924.6	851.7
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	0.0	0.0
NET AMOUNT	924.6	851.7
Securities Sold under Agreements to Repurchase(2)
GROSS RECOGNIZED LIABILITIES	1,976.3	1,924.4
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	1,646.6	1,392.5
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	329.7	531.9
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	329.7	531.9
Other liabilities	3,300.0
Foreign Exchange Contracts | Over the Counter Derivative
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED LIABILITIES	2,586.0	1,430.1
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	2,381.2	1,234.5
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	204.8	195.6
GROSS AMOUNTS NOT OFFSET IN THE BALANCE SHEET	0.0	0.0
Net Amount	204.8	195.6
Interest Rate Swap Contracts | Over the Counter Derivative
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED LIABILITIES	199.3	98.7
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	15.4	48.1
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	183.9	50.6
Net Amount	183.9	50.6
Interest Rate Swap Contracts | Interest Rate Swaps Exchange Cleared
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED LIABILITIES	1.3	0.2
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	0.0	0.0
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	1.3	0.2
Net Amount	1.3	0.2
Other Financial Derivatives | Other Financial Derivatives
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED LIABILITIES	35.3	37.5
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	33.8	0.9
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	1.5	36.6
Net Amount	$ 1.5	$ 36.6