Basis and Summary of Significant Accounting Policies - Credit Quality Indicators (Details) |
Jun. 30, 2019 |
Dec. 31, 2018 |
|---|---|---|
| FICO Score, 600 or Less | ||
| Financing Receivable, Credit Quality Indicator [Line Items] | ||
| Financing receivable, percentage of loan portfolio per FICO Score | 4.50% | 3.70% |
| FICO Score, Between 600 and 700 | ||
| Financing Receivable, Credit Quality Indicator [Line Items] | ||
| Financing receivable, percentage of loan portfolio per FICO Score | 79.60% | 77.90% |
| FICO Score, 700 or Greater | ||
| Financing Receivable, Credit Quality Indicator [Line Items] | ||
| Financing receivable, percentage of loan portfolio per FICO Score | 15.90% | 18.40% |