Share-Based Payments - Data Related to All Restricted Stock Unit Activity (Detail) - Restricted Stock Units [Member] shares in Millions, $ in Millions |
12 Months Ended | ||
|---|---|---|---|
|
Dec. 31, 2019
USD ($)
|
Dec. 31, 2018
USD ($)
|
Dec. 31, 2017
USD ($)
Employee
shares
|
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Total fair value of shares vested | $ | $ 454 | $ 146 | $ 584 |
| Total compensation cost related to nonvested RSU awards not yet recognized, pre-tax | $ | $ 241 | $ 256 | $ 254 |
| Weighted-average period over which RSU cost is expected to be recognized (years) | 1 year 8 months 12 days | 1 year 8 months 12 days | 1 year 8 months 12 days |
| Number of shares modified to accelerate vesting | shares | 6.4 | ||
| Number of employees affected by accelerated vesting | Employee | 9,900 | ||
| Number of shares scheduled for near-term vesting | shares | 6.6 | ||