Share-Based Payments - Data Related to All Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Weighted-average grant-date fair value per stock option (in dollars per share) | $ 5.98 | $ 5.06 | $ 4.01 |
| Aggregate intrinsic value on exercise | $ 261 | $ 625 | $ 331 |
| Cash received upon exercise | 394 | 1,259 | 862 |
| Tax benefits realized related to exercise | 47 | 115 | 95 |
| Share-based Payment Arrangement, Option [Member] | |||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Total compensation cost related to nonvested stock options not yet recognized, pre-tax | $ 5 | $ 5 | $ 10 |
| Weighted-average period over which stock option compensation cost is expected to be recognized (years) | 1 year 7 months 6 days | 1 year 8 months 12 days | 9 months 18 days |