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, 2023	Dec. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Securities Sold Under Agreements to Repurchase	$ 784.7	$ 567.2
Average Balance During the Year	$ 401.5	$ 433.6
Average Interest Rate Paid During the Year	383.84%	20.94%
Maximum Month-End Balance During the Year	$ 988.1	$ 869.0
Securities sold under agreements to repurchase, netting impact	$ 29,100.0	$ 3,600.0