Stock-Based Compensation - Components of Stock-Based Compensation Expense (Detail) - USD ($) $ 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] | |||
| Restricted stock and RSUs | $ 532 | $ 514 | $ 524 |
| Stock options | 35 | 36 | 3 |
| Total stock-based compensation | $ 567 | 564 | 542 |
| Long-Term Incentive Plans Funded by PNC [Member] | |||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Restricted stock and RSUs | $ 14 | $ 15 | |