Recent Authoritative Accounting Guidance (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent	$ 1,986.6	$ 1,959.8	$ 2,013.9	$ 1,693.9
Financing Receivable, Allowance for Credit Loss	122.3	144.3
Off-Balance Sheet, Credit Loss, Liability	3.8	3.7	0.0
Retained Earnings [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent	$ 1,052.6	$ 962.1	$ 953.6	$ 851.8