Other Operating Income - (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Components of Other Operating Income [Line Items]
Other operating income	$ 45.6	$ 54.4	$ 86.7	$ 109.3
Loan Service Fees
Components of Other Operating Income [Line Items]
Other operating income	18.1	17.8	34.8	33.2
Banking Service Fees
Components of Other Operating Income [Line Items]
Other operating income	12.9	12.5	25.6	25.2
Other Income
Components of Other Operating Income [Line Items]
Other operating income	$ 14.6	$ 24.1	$ 26.3	$ 50.9