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Loans Receivable Loans Receivable (Summary of Provision for Credit Losses) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2020 | Sep. 30, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |
Provision for credit losses | $ (29.8) | $ 19.3 | $ 464.3 | $ 49.2
Dealer Loans [Member] |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |
Provision for credit losses | (26.4) | 17.9 | 202.8 | 44.0
Purchased Loans [Member] |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |
Provision for credit losses | (3.4) | 1.4 | 261.5 | 5.2
New Consumer Loan Assignments [Member] |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |
Provision for credit losses | 114.1 | 0.0 | 426.2 | 0.0
New Consumer Loan Assignments [Member] | Dealer Loans [Member] |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |
Provision for credit losses | 45.6 | 0.0 | 171.3 | 0.0
New Consumer Loan Assignments [Member] | Purchased Loans [Member] |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |
Provision for credit losses | 68.5 | $ 0.0 | 254.9 | $ 0.0
Forecast Changes [Member] |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |
Provision for credit losses | (143.9) |  | 38.1 |
Forecast Changes [Member] | Dealer Loans [Member] |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |
Provision for credit losses | (72.0) |  | 31.5 |
Forecast Changes [Member] | Purchased Loans [Member] |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |
Provision for credit losses | $ (71.9) |  | $ 6.6 |

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