Offsetting of Assets and Liabilities - Offsetting of Derivative Assets and Securities Purchased Under Agreements to Resell (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED ASSETS	$ 3,151.2	$ 1,902.7
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	2,810.7	1,533.8
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	340.5	368.9
Gross amounts not offset in the balance sheet	5.0	2.8
Net Amount	335.5	366.1
Total Derivatives Not Subject to a Master Netting Arrangement
Total Derivatives Not Subject to a Master Netting Arrangement	581.2	444.7
Gross amounts not offset in the balance sheet	0.0	0.0
Net Amount	581.2	444.7
Total Derivatives
GROSS RECOGNIZED ASSETS	3,732.4	2,347.4
Derivative Assets	921.7	813.6
Gross amounts not offset in the balance sheet	5.0	2.8
Net Amount	916.7	810.8
Securities Purchased under Agreements to Resell
GROSS RECOGNIZED ASSETS	12,494.2	2,078.9
Gross amounts offset in the balance sheet	11,423.9	1,392.5
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	1,070.3	686.4
Gross amounts not offset in the balance sheet	1,070.3	686.4
Other assets (excluding derivative assets)	8,900.0	7,800.0
Foreign Exchange Contracts | Over the Counter Derivative
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED ASSETS	2,928.9	1,762.7
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	2,666.4	1,530.7
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	262.5	232.0
Gross amounts not offset in the balance sheet	5.0	2.8
Net Amount	257.5	229.2
Interest Rate Swaps | Over the Counter Derivative
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED ASSETS	217.6	140.0
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	144.3	3.1
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	73.3	136.9
Net Amount	73.3	$ 136.9
Interest Rate Swaps | Interest Rate Swaps Exchange Cleared
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED ASSETS	4.4
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	0.0
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	4.4
Net Amount	4.4
Other Financial Derivatives | Other Financial Derivatives
Total Derivatives Subject to a Master Netting Arrangement
GROSS RECOGNIZED ASSETS	0.3
GROSS AMOUNTS OFFSET IN THE BALANCE SHEET	0.0
NET AMOUNTS PRESENTED IN THE BALANCE SHEET	0.3
Net Amount	$ 0.3