Employee Benefit Plans - Additional Information (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2012 Y	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee retirement and savings plan cost	$ 138	$ 126	$ 113
Closing stock price as of December 31, 2012	$ 68.63
Percentage of retirement and savings plan's assets invested in our company common stock	11.00%
Shares of retirement and savings plans invested in company's common stock	3.4
Percentage of the retirement and savings plan's assets invested in our common stock as compared to company's outstanding shares at year-end	2.00%
Number of shares of our common stock reserved for issuance under our defined contribution retirement savings plans	5.2
Combination of age and years necessary for retirement provision as related to our equity award program	65
Minimum age required for retirement eligibility as related to our equity award program	55
Minimum number of years of service for retirement eligibility as related to our equity award program	5
Employee service share based compensation tax benefit realized from exercise of stock options and restricted stock vesting	43	44	15
Common stock shares reserved for stock award plans	26.6
Outstanding intrinsic value of stock options	25
Weighted-average remaining contractual term, years	3 years 8 months 12 days
Exercisable stock options intrinsic value	15
Exercisable stock options weighted-average remaining contractual term, years	2 years 4 months 24 days
Total intrinsic value of stock options exercised	45	88	11
Cash received from stock options exercises	60	134	17
Weighted-average grant date fair value of restricted stock awards	$ 85.29	$ 67.70	$ 49.29
Fair value of shares vested	75	36	30
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation expense not yet recognized related to nonvested restricted stock	70
Compensation expense over a weighted-average period, years	1 year 10 months 24 days
Award vesting period	3 years
2003 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares available for future grants if all grants are options	0.5
Common stock shares available for future grants if all grants are restricted shares	0.3
2011 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares available for future grants if all grants are options	16.7
Common stock shares available for future grants if all grants are restricted shares	7.3
Employee Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation expense not yet recognized related to nonvested restricted stock	$ 9
Compensation expense over a weighted-average period, years	1 year 9 months 18 days
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of year for stock options to vest	1
Number of years for stock options to expire	7
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of year for stock options to vest	3
Number of years for stock options to expire	10

Closing stock price for the company per the New York Stock Exchange

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Combination of age and years necessary for retirement provision as related to our equity award program

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Disclosure of the aggregate tax benefit realized from the exercise of stock options and vesting of restricted stock

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Minimum age required for retirement eligibility as related to our equity award program

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Minimum number of years of service for retirement eligibility as related to our equity award program

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- Definition

Number of shares of our common stock reserved for issuance under our defined contribution retirement savings plans

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Number of year for stock options to vest

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Number of years for stock options to expire

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Percentage of the retirement and savings plan's assets invested in our common stock as compared to company's outstanding shares at year-end

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Percentage of retirement and savings plan's assets invested in our company common stock

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Number of common shares available for grant assuming all options

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Number of common shares available for grant assuming all restricted stock

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Shares Of Retirement And Savings Plans Invested In Our Companys Common Stock

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- Definition

The amount of the cost recognized during the period for defined contribution plans.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 70

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6414718&loc=d3e28014-114942

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Aggregate proceeds received by the entity during the annual period from exercises of stock or unit options and conversion of similar instruments granted under equity-based payment arrangements.

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As of the balance sheet date, the aggregate unrecognized cost of equity-based awards made to employees under equity-based compensation awards that have yet to vest.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The weighted average fair value at grant date for nonvested equity-based awards issued 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).

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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

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The total fair value of equity-based awards for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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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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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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The total accumulated difference between fair values of underlying shares on dates of exercise and exercise price on options which were exercised (or share units converted) into shares during the reporting period under the plan.

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

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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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