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Loans Receivable Loans Receivable (Summary of Provision for Credit Losses) (Details) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2024 | Mar. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Provision for credit losses | $ 186.0 | $ 137.4
Dealer Loans [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Provision for credit losses | 121.7 | 74.7
Purchased Loans [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Provision for credit losses | 64.3 | 62.7
New Consumer Loan Assignments [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Provision for credit losses | 98.8 | 93.1
New Consumer Loan Assignments [Member] | Dealer Loans [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Provision for credit losses | 57.4 | 37.7
New Consumer Loan Assignments [Member] | Purchased Loans [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Provision for credit losses | 41.4 | 55.4
Forecast Changes [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Provision for credit losses | 87.2 | 44.3
Forecast Changes [Member] | Dealer Loans [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Provision for credit losses | 64.3 | 37.0
Forecast Changes [Member] | Purchased Loans [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Provision for credit losses | $ 22.9 | $ 7.3

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