Other Operating Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Other Income and Other Expense [Line Items]
Business Promotion	$ 65.5	$ 59.2	$ 104.2
Staff Related	33.9	29.4	42.8
FDIC Insurance Premiums	14.6	11.8	9.9
Amortization of intangible assets	14.8	16.9	16.6
Other Expenses	170.3	229.4	156.3
Total Other Operating Expense	299.1	346.7	329.8
Noninterest expense	4,535.9	$ 4,348.2	$ 4,143.5
Lower Charges Associated with Account Servicing Activities And A Decline In Other Miscellaneous Expenses
Other Income and Other Expense [Line Items]
Noninterest expense	$ 43.4