| **LOANS AND ALLOWANCE FOR CREDIT LOSSES (Consumer Lending Asset Quality Indicators - Credit Score) (Details) - USD ($)**                                                                                                                                                                                                                                                                                                                                                                                    | Sep. 30, 2015 | Dec. 31, 2014    |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------|------------------|
| **Loans Receivable [Line Items]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |               |             |   |
| Financing receivable                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        | [1],[2]       | $ 78,709,721,000 | $ 76,032,562,000 |
| Consumer | Personal unsecured loans                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |               |             |   |
| **Loans Receivable [Line Items]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |               |             |   |
| Loans held-for-sale                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |               | 1,900,000,000    | 0 |
| Consumer | Retail installment contracts and auto loans                                                                                                                                                                                                                                                                                                                                                                                                                                                      |               |             |   |
| **Loans Receivable [Line Items]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |               |             |   |
| Loans held-for-sale                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |               | 825,800,000      | 45,400,000 |
| Retail installment contracts and auto loans                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |               |             |   |
| **Loans Receivable [Line Items]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |               |             |   |
| Financing receivable                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |               | $ 25,423,613,000 | $ 22,475,665,000 |
| Percentage of total loans, Retail installment contracts and auto loans                                                                                                                                                                                                                                                                                                                                                                                                                                      |               | 100.00%          | 100.00% |
| Retail installment contracts and auto loans | FICO Score Less than 600                                                                                                                                                                                                                                                                                                                                                                                                                                      |               |             |   |
| **Loans Receivable [Line Items]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |               |             |   |
| Financing receivable                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |               | $ 13,049,938,000 | $ 11,731,114,000 |
| Percentage of total loans, Retail installment contracts and auto loans                                                                                                                                                                                                                                                                                                                                                                                                                                      |               | 51.30%           | 52.20% |
| Retail installment contracts and auto loans | FICO Score of 600 to 639                                                                                                                                                                                                                                                                                                                                                                                                                                      |               |             |   |
| **Loans Receivable [Line Items]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |               |             |   |
| Financing receivable                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |               | $ 4,133,831,000  | $ 4,071,918,000 |
| Percentage of total loans, Retail installment contracts and auto loans                                                                                                                                                                                                                                                                                                                                                                                                                                      |               | 16.30%           | 18.10% |
| Retail installment contracts and auto loans | FICO Score of 640 to 679                                                                                                                                                                                                                                                                                                                                                                                                                                      |               |             |   |
| **Loans Receivable [Line Items]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |               |             |   |
| Financing receivable                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |               | $ 3,080,110,000  | $ 4,066,539,000 |
| Percentage of total loans, Retail installment contracts and auto loans                                                                                                                                                                                                                                                                                                                                                                                                                                      |               | 12.10%           | 18.10% |
| Retail installment contracts and auto loans | FICO score not applicable                                                                                                                                                                                                                                                                                                                                                                                                                                     |               |             |   |
| **Loans Receivable [Line Items]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |               |             |   |
| Financing receivable                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |               | $ 5,159,734,000  | $ 2,606,094,000 |
| Percentage of total loans, Retail installment contracts and auto loans                                                                                                                                                                                                                                                                                                                                                                                                                                      |               | 20.30%           | 11.60% |
| Personal unsecured loans                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |               |             |   |
| **Loans Receivable [Line Items]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |               |             |   |
| Financing receivable                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |               | $ 2,528,739,000  | $ 2,696,820,000 |
| Percentage of total loans, Personal unsecured loans balance                                                                                                                                                                                                                                                                                                                                                                                                                                                 |               | 100.00%          | 100.00% |
| Personal unsecured loans | FICO Score Less than 600                                                                                                                                                                                                                                                                                                                                                                                                                                                         |               |             |   |
| **Loans Receivable [Line Items]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |               |             |   |
| Financing receivable                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |               | $ 405,059,000    | $ 479,537,000 |
| Percentage of total loans, Personal unsecured loans balance                                                                                                                                                                                                                                                                                                                                                                                                                                                 |               | 16.00%           | 17.80% |
| Personal unsecured loans | FICO Score of 600 to 639                                                                                                                                                                                                                                                                                                                                                                                                                                                         |               |             |   |
| **Loans Receivable [Line Items]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |               |             |   |
| Financing receivable                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |               | $ 406,943,000    | $ 440,476,000 |
| Percentage of total loans, Personal unsecured loans balance                                                                                                                                                                                                                                                                                                                                                                                                                                                 |               | 16.10%           | 16.30% |
| Personal unsecured loans | FICO Score of 640 to 679                                                                                                                                                                                                                                                                                                                                                                                                                                                         |               |             |   |
| **Loans Receivable [Line Items]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |               |             |   |
| Financing receivable                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |               | $ 1,071,993,000  | $ 1,135,068,000 |
| Percentage of total loans, Personal unsecured loans balance                                                                                                                                                                                                                                                                                                                                                                                                                                                 |               | 42.40%           | 42.10% |
| Personal unsecured loans | FICO score not applicable                                                                                                                                                                                                                                                                                                                                                                                                                                                        |               |             |   |
| **Loans Receivable [Line Items]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |               |             |   |
| Financing receivable                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |               | $ 644,744,000    | $ 641,739,000 |
| Percentage of total loans, Personal unsecured loans balance                                                                                                                                                                                                                                                                                                                                                                                                                                                 |               | 25.50%           | 23.80% |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
| [1]Loans held for investment includes $374.2 million and $845.9 million of loans recorded at fair value at September 30, 2015 and December 31, 2014, respectively.[2]The Company has interests in certain securitization trusts ("Trusts") that are considered variable interest entities ("VIEs") for accounting purposes. The Company consolidates VIEs where it is deemed the primary beneficiary. See Note 7 to these Condensed Consolidated Financial Statements for additional information. |

| X                                                                                                                                                                                                                                                                             |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Percentage of Total Loans, Personal Unsecured Loans
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No definition available.
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| X                                                                                                                                                                                                                                                                                                                |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Percentage of Total Loans, Retail Installment Contracts and Auto Loans
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No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                |
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| - Definition
Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
+ References
No definition available.
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|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5074-111524
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| X                                                                                                                                                                                                                                                                                                                                               |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.
+ References
No definition available.
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| X                                                                                                                                               |
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