Stock-Based Compensation - Components of Stock-Based Compensation Expense (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock and RSUs	$ 593	$ 532	$ 514
Stock options	29	35	36
Total stock-based compensation	$ 622	$ 567	564
Long-Term Incentive Plans Funded by PNC [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock and RSUs			$ 14

Amount of noncash expense for award of restricted stock or unit under share-based payment arrangement.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
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Amount of noncash expense for share-based payment arrangement.

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Amount of noncash expense for option under share-based payment arrangement.

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