Summary of Significant Accounting Policies (Narrative) (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) segment	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of reportable segments | segment			1
Uninsured cash and cash equivalents	$ 2.8		$ 2.8		$ 7.1
Total provision for credit losses	184.6	$ 180.3	572.5	$ 351.1
Restricted Cash and Cash Equivalents [Member]
Summary Of Significant Accounting Policies [Line Items]
Uninsured cash and cash equivalents	431.2		431.2		$ 406.5
New Consumer Loan Assignments [Member]
Summary Of Significant Accounting Policies [Line Items]
Total provision for credit losses	78.3	83.4	253.1	283.5
Loans Receivable [Member]
Summary Of Significant Accounting Policies [Line Items]
Total provision for credit losses	$ 0.0	$ 0.0	$ 0.0	$ 0.0