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Description of Business (Percentage of Consumer Loans Assigned Based on Unit Volumes) (Details) | 3 Months Ended
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Sep. 30, 2016 | Jun. 30, 2016 | Mar. 31, 2016 | Dec. 31, 2015 | Sep. 30, 2015 | Jun. 30, 2015 | Mar. 31, 2015
Portfolio Program [Member] |  |  |  |  |  |  |
Description Of Business [Line Items] |  |  |  |  |  |  |
Percentage of new consumer loans | 76.20% | 77.80% | 82.40% | 85.70% | 87.30% | 87.70% | 88.60%
Purchase Program [Member] |  |  |  |  |  |  |
Description Of Business [Line Items] |  |  |  |  |  |  |
Percentage of new consumer loans | 23.80% | 22.20% | 17.60% | 14.30% | 12.70% | 12.30% | 11.40%

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