Summary of Significant Accounting Policies (Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2024 USD ($) segment	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of reportable segments | segment	1
Uninsured cash and cash equivalents	$ 8.1		$ 12.8
Total provision for credit losses	186.0	$ 137.4
Restricted Cash and Cash Equivalents [Member]
Summary Of Significant Accounting Policies [Line Items]
Uninsured cash and cash equivalents	554.7		$ 453.7
New Consumer Loan Assignments [Member]
Summary Of Significant Accounting Policies [Line Items]
Total provision for credit losses	98.8	93.1
Loans Receivable [Member]
Summary Of Significant Accounting Policies [Line Items]
Total provision for credit losses	$ 0.0	$ 0.0