Employee Compensation and Benefit Plans - Schedule of Stock-based Compensation Expense and Related Income Tax Benefits (Details) - USD ($) $ / shares in Units, $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2020 |
Jun. 30, 2019 |
Jun. 30, 2020 |
Jun. 30, 2019 |
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||
| Stock-based compensation expense | $ 259 | $ 130 | $ 397 | $ 240 |
| Income tax benefit related to stock-based compensation | $ 49 | $ 25 | $ 71 | $ 45 |
| Restricted Stock Units and Performance Stock Units | ||||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||
| Weighted average fair value per stock award granted (in USD per share) | $ 99.80 | $ 74.35 | $ 96.93 | $ 73.08 |
| Unrecognized compensation expense | $ 824 | $ 744 | $ 824 | $ 744 |
| Weighted average period to be recognized (years) | 2 years | 2 years | 2 years | 2 years |
| Fair value of stock awards vested | $ 367 | $ 24 | $ 815 | $ 342 |