Securitization Activities - Additional Information (Detail) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | 12 Months Ended | ||
|---|---|---|---|---|---|
Sep. 30, 2021 |
Sep. 30, 2020 |
Sep. 30, 2021 |
Sep. 30, 2020 |
Dec. 31, 2020 |
|
| Assets securitized in a non-cash exchange for loans and investments | $ 266 | $ 132 | $ 679 | $ 435 | |
| Net Asset related to Other Continuing Involvement | 55 | 55 | $ 52 | ||
| Notional amount related to Other Continuing Involvement | 2,160 | 2,160 | 1,430 | ||
| Fair Value of Retained Interests | 3,640 | 3,640 | 3,190 | ||
| Other Retained Interests [Member] | |||||
| Fair Value of Retained Interests | 352 | $ 352 | $ 192 | ||
| Weighted average life (years) | 3 years 4 months 24 days | 3 years 10 months 24 days | |||
| Maximum Exposure to Adverse Changes in the value of Other retained interests | $ 352 | $ 352 | $ 192 | ||