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Bonds and Notes Payable - Schedule of Asset-Backed Securitizations (Details) | 9 Months Ended
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Sep. 30, 2019 USD ($)
2019-1, Class A-1 Notes |
Debt Instrument [Line Items] |
Principal amount | $ 35,700,000
2019-1, Class A-1 Notes | Senior notes |
Debt Instrument [Line Items] |
Principal amount | 35,700,000
Bond discount | 0
Issue price | $ 35,700,000
2019-1, Class A-1 Notes | Senior notes | LIBOR |
Debt Instrument [Line Items] |
Cost of funds, spread on variable interest rate | 0.30%
2019-1, Class A-2 Notes |
Debt Instrument [Line Items] |
Principal amount | $ 448,000,000
2019-1, Class A-2 Notes | Senior notes |
Debt Instrument [Line Items] |
Principal amount | 448,000,000
Bond discount | 0
Issue price | $ 448,000,000
2019-1, Class A-2 Notes | Senior notes | LIBOR |
Debt Instrument [Line Items] |
Cost of funds, spread on variable interest rate | 0.75%
2019-1 |
Debt Instrument [Line Items] |
Principal amount | $ 496,800,000
2019-1, Class A Notes | Senior notes |
Debt Instrument [Line Items] |
Principal amount | 483,700,000
Bond discount | 0
Issue price | 483,700,000
2019-1, Class B Notes | Subordinated debt |
Debt Instrument [Line Items] |
Principal amount | 13,100,000
Bond discount | 0
Issue price | $ 13,100,000
2019-1, Class B Notes | Subordinated debt | LIBOR |
Debt Instrument [Line Items] |
Cost of funds, spread on variable interest rate | 1.40%
2019-2 |
Debt Instrument [Line Items] |
Principal amount | $ 416,100,000
2019-2, Class A Notes | Senior notes |
Debt Instrument [Line Items] |
Principal amount | 405,000,000
Bond discount | 0
Issue price | $ 405,000,000
2019-2, Class A Notes | Senior notes | LIBOR |
Debt Instrument [Line Items] |
Cost of funds, spread on variable interest rate | 0.90%
2019-2, Class B Notes | Subordinated debt |
Debt Instrument [Line Items] |
Principal amount | $ 11,100,000
Bond discount | 0
Issue price | $ 11,100,000
2019-2, Class B Notes | Subordinated debt | LIBOR |
Debt Instrument [Line Items] |
Cost of funds, spread on variable interest rate | 1.50%
Private education loan 2019-A |
Debt Instrument [Line Items] |
Principal amount | $ 47,159,000
Private education loan 2019-A | Senior notes |
Debt Instrument [Line Items] |
Principal amount | 47,159,000
Bond discount | 0
Issue price | $ 47,159,000
Private education loan 2019-A | Senior notes | Prime Rate |
Debt Instrument [Line Items] |
Cost of funds, spread on variable interest rate | 1.60%
2019-3 |
Debt Instrument [Line Items] |
Principal amount | $ 498,300,000
2019-3, Class A Notes | Senior notes |
Debt Instrument [Line Items] |
Principal amount | 485,800,000
Bond discount | 0
Issue price | $ 485,800,000
2019-3, Class A Notes | Senior notes | LIBOR |
Debt Instrument [Line Items] |
Cost of funds, spread on variable interest rate | 0.80%
2019-3, Class B Notes | Subordinated debt |
Debt Instrument [Line Items] |
Principal amount | $ 12,500,000
Bond discount | 0
Issue price | $ 12,500,000
2019-3, Class B Notes | Subordinated debt | LIBOR |
Debt Instrument [Line Items] |
Cost of funds, spread on variable interest rate | 1.55%
2019-4 |
Debt Instrument [Line Items] |
Principal amount | $ 418,600,000
2019-4, Class A Notes | Senior notes |
Debt Instrument [Line Items] |
Principal amount | 408,000,000
Bond discount | 0
Issue price | $ 408,000,000
2019-4, Class A Notes | Senior notes | LIBOR |
Debt Instrument [Line Items] |
Cost of funds, spread on variable interest rate | 0.87%
2019-4, Class B Notes | Subordinated debt |
Debt Instrument [Line Items] |
Principal amount | $ 10,600,000
Bond discount | 0
Issue price | $ 10,600,000
2019-4, Class B Notes | Subordinated debt | LIBOR |
Debt Instrument [Line Items] |
Cost of funds, spread on variable interest rate | 1.65%
2019-5 |
Debt Instrument [Line Items] |
Principal amount | $ 374,500,000
2019-5, Class A Notes | Senior notes |
Debt Instrument [Line Items] |
Principal amount | 364,500,000
Bond discount | (114,000)
Issue price | $ 364,386,000
Cost of funds | 2.53%
2019-5, Class B Notes | Subordinated debt |
Debt Instrument [Line Items] |
Principal amount | $ 10,000,000
Bond discount | (4,000)
Issue price | $ 9,996,000
Cost of funds | 3.45%
2019 Total |
Debt Instrument [Line Items] |
Principal amount | $ 2,251,459,000
2019 Class A | Senior notes |
Debt Instrument [Line Items] |
Principal amount | 2,194,159,000
Bond discount | (114,000)
Issue price | 2,194,045,000
2019 Class B | Subordinated debt |
Debt Instrument [Line Items] |
Principal amount | 57,300,000
Bond discount | (4,000)
Issue price | $ 57,296,000

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