Stock-Based Compensation - Additional Information (Detail) - USD ($) shares in Millions, $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Shares available for grant under Company's stock incentive plan (subject to adjustment for forfeitures)	32
Fair value of shares vested	$ 175	$ 182	$ 180
Stock-based compensation expense	178	174	163
Stock-based compensation expense on an after tax basis	133	$ 130	$ 101
Unrecognized compensation cost related to nonvested share-based arrangements granted under plans	$ 143
Unrecognized compensation cost recognized over a weighted-average period as compensation expense	1 year 8 months 12 days
Minimum [Member]
Date of grant exercisable period	10 years
Stock and unit awards vesting period	3 years
Maximum [Member]
Stock and unit awards vesting period	5 years

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Amount, after tax, of expense for award under share-based payment arrangement.

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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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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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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Date of grant exercisable period.

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