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Loans Receivable Loans Receivable (Summary of Provision for Credit Losses) (Details) - USD ($) $ in Millions | 3 Months Ended
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Mar. 31, 2020 | Mar. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Provision for credit losses | $ 354.7 | $ 14.5
Dealer Loans [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Provision for credit losses | 168.1 | 11.6
Purchased Loans [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Provision for credit losses | 186.6 | $ 2.9
New Consumer Loan Assignments [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Provision for credit losses | 157.9 |
New Consumer Loan Assignments [Member] | Dealer Loans [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Provision for credit losses | 64.8 |
New Consumer Loan Assignments [Member] | Purchased Loans [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Provision for credit losses | 93.1 |
Forecast Changes [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Provision for credit losses | 196.8 |
Forecast Changes [Member] | Dealer Loans [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Provision for credit losses | 103.3 |
Forecast Changes [Member] | Purchased Loans [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Provision for credit losses | $ 93.5 |

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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=121586364&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=121611835&loc=SL6953423-111524 + Details
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