Loans Receivable Loans Receivable (Summary of Provision for Credit Losses) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for Credit Losses	$ 172.6	$ 320.6	$ 334.5	$ 506.6
Dealer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for Credit Losses	102.0	212.3	206.7	334.0
Purchased Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for Credit Losses	70.6	108.3	127.8	172.6
New Consumer Loan Assignments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for Credit Losses	71.3	82.8	156.9	181.6
New Consumer Loan Assignments [Member] \| Dealer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for Credit Losses	36.8	48.6	88.9	106.0
New Consumer Loan Assignments [Member] \| Purchased Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for Credit Losses	34.5	34.2	68.0	75.6
Forecast Changes [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for Credit Losses	101.3	237.8	177.6	325.0
Forecast Changes [Member] \| Dealer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for Credit Losses	65.2	163.7	117.8	228.0
Forecast Changes [Member] \| Purchased Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for Credit Losses	$ 36.1	$ 74.1	$ 59.8	$ 97.0