Description of Business, Basis of Presentation, and Summary of Significant Accounting Policies (Details) - USD ($)
$ in Millions |
6 Months Ended |
12 Months Ended |
Jun. 30, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
| Schedule of Trading and Available-for-sale Securities [Line Items] |
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| Loans receivable, minimum number of days past due to be placed on non-accrual status |
|
90 days
|
|
|
| Advertising expense |
|
$ 9
|
$ 10
|
$ 9
|
| Cash flow estimates, projection period (years) |
|
3 years
|
|
|
| DOJ Agreement |
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|
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| Schedule of Trading and Available-for-sale Securities [Line Items] |
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|
|
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| Litigation settlement payment amount |
$ 118
|
$ 118
|
|
|
| Litigation settlement liability |
$ 84
|
$ 84
|
$ 82
|
|
| Consumer Loan Secured by Real Estate |
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|
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| Schedule of Trading and Available-for-sale Securities [Line Items] |
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| Loans receivable, excluding real estate loans, minimum number of days past due for charge-off |
|
180 days
|
|
|
| Consumer Loan Not Secured by Real Estate |
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|
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| Schedule of Trading and Available-for-sale Securities [Line Items] |
|
|
|
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| Loans receivable, excluding real estate loans, minimum number of days past due for charge-off |
|
120 days
|
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