Securities Purchased Under Agreements to Resell and Securities Sold Under Agreements to Repurchase - Securities Sold under Agreements to Repurchase (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Securities Sold Under Agreements to Repurchase	$ 462.0	$ 784.7
Average Balance During the Year	$ 518.5	$ 401.5
Average Interest Rate Paid During the Year	632.65%	383.84%
Maximum Month-End Balance During the Year	$ 811.8	$ 988.1
Securities sold under agreements to repurchase, netting impact	$ 62,400.0	$ 29,100.0
Securities sold under agreements to repurchase, average rate paid excluding netting impact	5.21%	5.22%