Other Operating Income - (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Components of Other Operating Income [Line Items]
Total Other Operating Income	$ 54.9	$ 34.4
Loan Service Fees
Components of Other Operating Income [Line Items]
Total Other Operating Income	15.4	11.9
Banking Service Fees
Components of Other Operating Income [Line Items]
Total Other Operating Income	12.7	11.4
Other Income
Components of Other Operating Income [Line Items]
Total Other Operating Income	$ 26.8	$ 11.1