Common Stock - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock, authorized	1,000,000,000	1,000,000,000
Number of preferred stock, authorized	10,000,000
Common stock, par value	$ 0.01	$ 0.01
Preferred stock, par value	$ 0.01
Preferred stock, shares issued	0
Preferred stock, shares outstanding	0
Aggregated cash dividends paid	$ 389	$ 209	$ 191
Earlier authorized shares under stock based compensation	39,500,000
Duration of performance-based restricted stock awards, vested	Stock option plan generally vest over a three-year period starting one year from the date of grant and expire ten years from the date of grant
Remaining shares available for future grants under the Plan	14,500,000
Stock option, Minimum Range	$ 9.14
Stock option, Maximum Range	$ 84.58
Weighted-average fair value of options granted	$ 24.11	$ 30.01	$ 29.52
Total intrinsic value of options exercised	64	120
Total unrecognized compensation cost related to nonvested stock options	74
Weighted-average period recognition of unrecognized compensation cost related to nonvested RSA's	2 years
Total fair value of stock options vested	64	55	54
Cash received from option exercises	58	113	96
Tax benefit realized for the tax deductions from option exercises	39	42	43
Restricted stock granted	758,176	482,428	374,425
Restricted stock granted fair value	$ 69.07	$ 83.79	$ 79.53
Number of shares available except for special grant	16,352
Total stock-based compensation compensation arrangements under the Plan	86	74	68
Total number of restricted stock awards and restricted stock units granted	340,218	406,844	496,642
Restricted Stock and Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock granted	540,194
Restricted stock granted fair value	$ 69.33
TSR Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance based restricted stock awards granted in percent	50.00%
ROC Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance based restricted stock awards granted in percent	50.00%
Performance Based Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation compensation arrangements under the Plan	8
Restricted Stock Unit [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock granted	16,702
Restricted stock granted fair value	$ 69.17
Restricted Stock Unit [Member] \| Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Duration of performance-based restricted stock awards, vested	Restricted stock and restricted stock units were granted February 15, 2013 and vest on the third anniversary of the date of grant, except for a special grant of 16,352 restricted stock units which vest on the second anniversary of the date of grant (subject to the satisfaction of a performance condition). On May 22, 2013, the 16,702 restricted stock awards, with a fair value of $69.17 per share, were granted to the non-employee members of the board of directors. These restricted stock awards vest in equal thirds over three years on the anniversary of the grant date.
Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Duration of performance-based restricted stock awards, vested	Restricted stock awards vest in equal thirds over three years on the anniversary of the grant date
Total unrecognized compensation cost related to nonvested stock options	$ 54
Weighted-average period recognition of unrecognized compensation cost related to nonvested RSA's	2 years
Restricted stock granted fair value	$ 69.07	$ 83.79	$ 79.53
Performance based restricted stock awards vested, number of years	3 years
Total number of restricted stock awards and restricted stock units granted	340,218	406,844	496,642
Minimum [Member] \| Performance-base restricted stock [Member] \| Senior Management Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock granted	0
Maximum [Member] \| Performance-base restricted stock [Member] \| Senior Management Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock granted	368,860

Earlier authorized shares under stock based compensation.

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Performance based restricted stock awards granted in percent.

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Remaining shares available for future grants under the Plan.

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Share Based Compensation Arrangement By Share Based Payment Award Available Except For Special Grant

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Face amount or stated value per share of common stock.

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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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Amount of paid and unpaid common stock dividends declared with the form of settlement in cash.

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Unrecognized cost of unvested share-based compensation awards.

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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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Disclosure of the aggregate tax benefit realized from the exercise of stock options and the conversion of similar instruments during the annual period.

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Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.

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Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt.

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Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

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The cash inflow associated with the amount received from holders exercising their stock options. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately.

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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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Description of award terms as to how many shares or portion of an award are no longer contingent on satisfaction of either a service condition, market condition or a performance condition, thereby giving the employee the legal right to convert the award to shares, to sell the shares, and be entitled to the cash proceeds of such sale. For example, vesting may be expressed as being 25 percent of the shares under option on each anniversary of the grant date.

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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).

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

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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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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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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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The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

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The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

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