Other Operating Income - (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Components of Other Operating Income [Line Items]
Other Operating Income	$ 1,157.4	$ 228.7	$ 191.3
Pre-tax gain on sale of equity investment	68.1
Loan Service Fees
Components of Other Operating Income [Line Items]
Other Operating Income	55.0	83.1	71.5
Banking Service Fees
Components of Other Operating Income [Line Items]
Other Operating Income	55.0	53.0	49.8
Bank Owned Life Insurance
Components of Other Operating Income [Line Items]
Other Operating Income	79.1	69.5	61.0
Other Income
Components of Other Operating Income [Line Items]
Other Operating Income	$ 968.3	$ 23.1	$ 9.0