Stock Incentive Plans - Components of Restricted Stock Units (Detail) $ in Millions	12 Months Ended
Dec. 31, 2019 USD ($) shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested restricted stock awards (in shares) \| shares	2,858,357
Unrecognized compensation expense	$ 14
Intrinsic value	$ 36
Weighted average remaining life (in years)	1 year 9 months 25 days
Service- Based Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested restricted stock awards (in shares) \| shares	1,922,120
Unrecognized compensation expense	$ 10
Intrinsic value	$ 24
Weighted average remaining life (in years)	1 year 9 months 29 days
Performance- Based Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested restricted stock awards (in shares) \| shares	936,237
Unrecognized compensation expense	$ 4
Intrinsic value	$ 12
Weighted average remaining life (in years)	1 year 9 months 21 days

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

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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Weighted average remaining contractual term for equity-based awards excluding options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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 by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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