Amount of (Income) Expense on Cash Flow and Fair Value Hedges Recognized in Interest and Other Borrowing Costs on Statements of Income (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	$ (15.5)	$ 8.9
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest and other borrowing costs	Interest and other borrowing costs
Hedged items	$ 22.6	$ (8.1)
Reclassified from AOCI into income	(4.6)	27.9	$ 12.4
Total (income) and expense	$ 2.5	$ 28.7