Annual Activity Of RSUs (Parenthetical) (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate unrecognized compensation expense related to awards	$ 61	50
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs outstanding, intrinsic value	69
Aggregate unrecognized compensation expense related to awards	$ 25
Weighted average life	1 year 7 months 6 days
Time-based restricted stock units outstanding	1,439,000	1,281,000	1,393,000
Number of performance-based and market-based stock units outstanding	2,058,000	1,717,000	1,666,000
Restricted Stock Units (RSUs) \| Time Based Vesting Schedule
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted at fair market value (in number of RSUs)	835,000	652,000	989,000
Share based compensation, RSUs eligible to vest	687,000
Restricted Stock Units (RSUs) \| Performance Based Vesting Schedule
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted at fair market value (in number of RSUs)	486,000
Vested (in number of RSUs)	615,000	0	0
Restricted Stock Units (RSUs) \| Market Based Vesting Schedule
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation, RSUs eligible to vest	440,000

Number of performance based and market based stock units outstanding

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- Definition

Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Aggregate Intrinsic Value

+ References

No definition available.

+ Details

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- Definition

Share Based Compensation Arrangement by Share Based Payment Award, Equity Instruments Other than Options, Eligible to Vest in Next Year

+ References

No definition available.

+ Details

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- Definition

Time based restricted stock units outstanding

+ References

No definition available.

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- Definition

Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements. Represents currently earned compensation under compensation arrangements that is not actually paid until a later date.

+ References

No definition available.

+ Details

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- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ 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 (c)(2)(iii)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(c)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

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

+ 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 (c)(2)(iii)(2)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(d)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

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

+ Details

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