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Loans Receivable (Summary of Provision for Credit Losses) (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Provision for credit losses | $ 8.4 | $ 556.9 | $ 76.4
Dealer Loans [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Provision for credit losses | (28.2) | 239.7 | 65.9
Purchased Loans [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Provision for credit losses | 36.6 | 317.2 | 10.5
New Consumer Loan assignments |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Provision for credit losses | 365.1 | 518.6 | 0.0
New Consumer Loan assignments | Dealer Loans [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Provision for credit losses | 153.1 | 209.7 | 0.0
New Consumer Loan assignments | Purchased Loans [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Provision for credit losses | 212.0 | 308.9 | $ 0.0
Forecast Changes [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Provision for credit losses | (356.7) | 38.3 |
Forecast Changes [Member] | Dealer Loans [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Provision for credit losses | (181.3) | 30.0 |
Forecast Changes [Member] | Purchased Loans [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Provision for credit losses | $ (175.4) | $ 8.3 |

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- Definition Amount of expense related to estimated loss from loan and lease transactions. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.11) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953423-111524 + Details
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