Other Operating Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Income and Other Expense [Line Items]
Business Promotion	$ 59.2	$ 104.2	$ 98.3
Staff Related	29.4	42.8	33.6
FDIC Insurance Premiums	11.8	9.9	27.4
Other Intangibles Amortization	16.9	16.6	17.4
Other Expenses	229.4	156.3	153.9
Total Other Operating Expense	346.7	$ 329.8	$ 330.6
Processing Error, Increase In Mutual Fund Fees and Lower Business Promotion Expense
Other Income and Other Expense [Line Items]
Total Other Operating Expense	$ 43.4