Stock-Based Compensation - RSUs and PSUs, Other Disclosures (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
|
| RSUs and PSUs | |||
| Stock-Based Compensation | |||
| Tax benefits realized in connection with vesting and release of awards | $ 139 | $ 131 | $ 117 |
| Restricted Stock Units | |||
| Stock-Based Compensation | |||
| Fair value of stock units granted | 1,220 | 674 | 583 |
| Fair value of stock units vested | $ 478 | 428 | 381 |
| Performance Share Units | |||
| Stock-Based Compensation | |||
| Vesting period | 3 years | ||
| Fair value of stock units granted | $ 186 | 164 | 118 |
| Fair value of stock units vested | $ 86 | $ 118 | $ 101 |