Other Operating Income - (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Components of Other Operating Income [Line Items]
Total Other Operating Income	$ 54.4	$ 56.5	$ 109.3	$ 90.9
Loan Service Fees
Components of Other Operating Income [Line Items]
Total Other Operating Income	17.8	11.8	33.2	23.7
Banking Service Fees
Components of Other Operating Income [Line Items]
Total Other Operating Income	12.5	10.9	25.2	22.3
Other Income
Components of Other Operating Income [Line Items]
Total Other Operating Income	$ 24.1	$ 33.8	$ 50.9	$ 44.9