Other Operating Income - (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Components of Other Operating Income [Line Items]
Other operating income	$ 41.1	$ 54.9
Loan Service Fees
Components of Other Operating Income [Line Items]
Other operating income	16.7	15.4
Banking Service Fees
Components of Other Operating Income [Line Items]
Other operating income	12.7	12.7
Other Income
Components of Other Operating Income [Line Items]
Other operating income	$ 11.7	$ 26.8