Share-Based Compensation - Summary of Outstanding and Exercisable Options and SARs (Detail) $ in Millions	12 Months Ended
Dec. 31, 2015 USD ($)
Stock Option
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Aggregate intrinsic value, Outstanding	$ 11
Aggregate intrinsic value, Exercisable	$ 11
Weighted-average remaining contractual term, Outstanding	2 years 1 month 12 days
Weighted-average remaining contractual term, Exercisable	2 years 1 month 12 days
Stock Appreciation Rights (SARs)
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Aggregate intrinsic value, Outstanding	$ 52
Aggregate intrinsic value, Exercisable	$ 40
Weighted-average remaining contractual term, Outstanding	6 years 9 months 7 days
Weighted-average remaining contractual term, Exercisable	5 years 3 months 7 days

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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+ References

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- Definition

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.

+ References

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (e)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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