Stock-Based Compensation - Stock Option Exercises and Restricted Stock Vesting (Detail) - USD ($) shares in Thousands, $ in Millions	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Proceeds from stock option exercises	$ 3	$ 6
Aggregate intrinsic value	4	9
Tax benefit realized upon exercise	$ 1	$ 2
Number of shares exercised (shares)	20	100
Restricted Stock
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Fair value of shares vested	$ 166	$ 178
Tax benefit realized upon vesting	$ 39	$ 41
Number of shares vested (shares)	500	600
Performance Based Restricted Stock
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Fair value of shares vested	$ 50	$ 29
Tax benefit realized upon vesting	$ 12	$ 6
Number of shares vested (shares)	200	100

Amount of tax benefit from vesting of other than stock options granted under share-based compensation arrangement.

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Amount of tax benefit from exercise of option under share-based payment arrangement.

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Amount of cash inflow from exercise of option under share-based payment arrangement.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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Number of share options (or share units) exercised during the current period.

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