Business Segments - Segment Operating Results (Parenthetical) (Detail) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | ||||
|---|---|---|---|---|---|---|
Sep. 30, 2021 |
Sep. 30, 2020 |
Sep. 30, 2021 |
Sep. 30, 2020 |
Jan. 01, 2021 |
Dec. 31, 2020 |
|
| Product Liability Contingency [Line Items] | ||||||
| Operating expenses | $ 6,591 | $ 6,204 | $ 24,668 | $ 23,076 | ||
| Investment Banking and Global Markets [Member] | ||||||
| Product Liability Contingency [Line Items] | ||||||
| Operating expenses | $ 3,400 | |||||
| Standardized Capital Rules [Member] | ||||||
| Product Liability Contingency [Line Items] | ||||||
| Standardized risk based ratios stress capital buffer | 6.60% | 6.60% | 6.60% | 6.60% | ||