Other Operating Income - (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Components of Other Operating Income [Line Items]
Other operating income	$ 57.3	$ 62.3	$ 144.0	$ 171.6
Loan Service Fees
Components of Other Operating Income [Line Items]
Other operating income	17.8	16.1	52.6	49.3
Banking Service Fees
Components of Other Operating Income [Line Items]
Other operating income	12.2	12.6	37.8	37.8
Other Income
Components of Other Operating Income [Line Items]
Other operating income	$ 27.3	$ 33.6	$ 53.6	$ 84.5