Share-Based Compensation - Summary of Outstanding and Exercisable Options and SARs (Detail) - SARs - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Summary of SARs outstanding
Aggregate intrinsic value, outstanding	$ 149
Aggregate intrinsic value, exercisable	$ 91
Weighted-average remaining contractual term, outstanding	4 years 10 months 24 days
Weighted-average remaining contractual term, exercisable	4 years 6 months
Intrinsic value of SARs exercised	$ 58	$ 59	$ 14
Fair value of SARs vested	$ 9	$ 12	$ 8

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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-Publisher FASB
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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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