Loans Held for Investment - Narrative (Details) - USD ($) $ in Millions |
6 Months Ended | 12 Months Ended | ||||
|---|---|---|---|---|---|---|
Jun. 30, 2024 |
Jun. 30, 2023 |
Dec. 31, 2023 |
Jul. 01, 2006 |
Jun. 30, 2006 |
Sep. 30, 1993 |
|
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||||||
| Percent of private loans indexed to LIBOR | 28.00% | 33.00% | ||||
| Tier 1 of government guarantee (at least) | 97.00% | 97.00% | ||||
| Tier 2 of government guarantee | 98.00% | |||||
| Tier 3 of government guarantee | 100.00% | |||||
| Estimated weighted average life of student loans | 5 years 3 months 18 days | 5 years | ||||
| Private Education Loans | ||||||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||||||
| Gain on sales of loans, net | $ 255 | $ 128 | ||||
| Proceeds from sale of loans receivable | 3,690 | 2,100 | ||||
| Net proceeds from sales of loans held for investment, principal | 3,420 | 1,960 | ||||
| Net proceeds from sales of loans held for investment, capitalized interest | $ 274 | $ 144 | ||||