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Summary Of Significant Accounting Policies (Narrative) (Details) | 12 Months Ended
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Dec. 31, 2018 USD ($) portfolio_segment | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($)
Summary Of Significant Accounting Policies [Line Items] |  |  |
Number of Portfolio Segments | portfolio_segment | 2 |  |
Number of Reportable Segments | portfolio_segment | 1 |  |
Monthly fee charged Dealer in Portfolio Program | $ 599 |  |
Period after Consumer Loan assignment that Dealer Loans written off | 120 months |  |
Period after month of purchase that Purchased Loans written off | 120 months |  |
Threshold to determine likelihood of being sustained | 50.00% |  |
Employer matching contribution, match percentage | 100.00% |  |
Matching contribution | 2.00% |  |
Employer matching contribution, additional match percentage | 50.00% |  |
Additional matching contribution | 4.00% |  |
Maximum matching contribution | 4.00% |  |
Recognized compensation expense | $ 5,300,000 | $ 4,600,000 | $ 3,600,000
Advertising expense | 200,000 | 400,000 | $ 300,000
Cash and Cash Equivalents [Member] |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Uninsured cash and cash equivalents | 25,100,000 | 7,800,000 |
Restricted Cash And Cash Equivalents [Member] |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Uninsured cash and cash equivalents | $ 303,000,000 | $ 255,100,000 |
Building [Member] |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Estimated useful lives | P40Y |  |
Building Improvements [Member] |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Estimated useful lives | P10Y |  |
Data Processing Equipment [Member] |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Estimated useful lives | P3Y |  |
Software [Member] |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Estimated useful lives | P5Y |  |
Office Furniture And Equipment [Member] |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Estimated useful lives | P7Y |  |
Leasehold Improvements [Member] |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Estimated useful lives | P7Y |  |
Software Development [Member] |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Estimated useful lives | P5Y |  |

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