Unsecured Borrowings - Unsecured Long-Term Borrowings (Detail) - USD ($) $ in Millions |
Jun. 30, 2021 |
Dec. 31, 2020 |
|---|---|---|
| Debt Instrument [Line Items] | ||
| Fixed-rate obligations | $ 158,419 | $ 139,317 |
| Floating-rate obligations | 80,511 | 74,164 |
| Total | 238,930 | 213,481 |
| U.S. Dollar [Member] | ||
| Debt Instrument [Line Items] | ||
| Fixed-rate obligations | 111,944 | 100,558 |
| Floating-rate obligations | 46,692 | 42,019 |
| Total | 158,636 | 142,577 |
| Non-U.S. Dollar [Member] | ||
| Debt Instrument [Line Items] | ||
| Fixed-rate obligations | 46,475 | 38,759 |
| Floating-rate obligations | 33,819 | 32,145 |
| Total | $ 80,294 | $ 70,904 |