Other Operating Income - (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Components of Other Operating Income [Line Items]
Total Other Operating Income	$ 145.5	$ 127.5	$ 157.5
Loan Service Fees
Components of Other Operating Income [Line Items]
Total Other Operating Income	48.0	48.9	50.7
Banking Service Fees
Components of Other Operating Income [Line Items]
Total Other Operating Income	45.6	46.4	48.6
Other Income
Components of Other Operating Income [Line Items]
Total Other Operating Income	$ 51.9	$ 32.2	$ 58.2