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Borrowings - Secured Financing (Details) - USD ($) |  |  |  |  | 1 Months Ended |  |
--- | --- | --- | --- | --- | --- | --- | ---
Feb. 28, 2017 | Oct. 31, 2016 | Jul. 31, 2016 | May 31, 2016 | Nov. 30, 2017 | Dec. 31, 2017 | Dec. 31, 2016
Debt Instrument [Line Items] |  |  |  |  |  |  |
Total Issued |  |  |  |  |  | $ 1,448,000,000 | $ 1,782,000,000
Total loans and accrued interest amount securitized at inception |  |  |  |  |  | $ 1,606,804,000 | $ 2,107,042,000
Issuance 2016-A |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Total Issued |  |  |  | $ 501,000,000 |  |  |
Weighted Average Life (in years) |  |  |  | 4 years 5 days |  |  |
Issuance 2016-B |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Total Issued |  |  | $ 607,000,000 |  |  |  |
Weighted Average Life (in years) |  |  | 4 years 5 days |  |  |  |
Issuance 2016-C |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Total Issued |  | $ 674,000,000 |  |  |  |  |
Weighted Average Life (in years) |  | 4 years 2 months 36 days |  |  |  |  |
Issuance 2017-A |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Total Issued | $ 772,000,000 |  |  |  |  |  |
Weighted Average Life (in years) | 4 years 2 months 36 days |  |  |  |  |  |
Derivative basis spread on variable rate | 0.93% |  |  |  |  |  |
Issuance 2017-B |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Total Issued |  |  |  |  | $ 676,000,000 |  |
Weighted Average Life (in years) |  |  |  |  | 4 years 25 days |  |
Derivative basis spread on variable rate |  |  |  |  | 0.80% |  |
London Interbank Offered Rate (LIBOR) | Issuance 2016-A |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Derivative basis spread on variable rate |  |  |  | 1.38% |  |  |
London Interbank Offered Rate (LIBOR) | Issuance 2016-B |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Derivative basis spread on variable rate |  |  | 1.36% |  |  |  |
London Interbank Offered Rate (LIBOR) | Issuance 2016-C |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Derivative basis spread on variable rate |  | 1.15% |  |  |  |  |

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- Definition Loan Amount Securitized + References No definition available. + Details
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- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399 + Details
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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. + Details
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