Stock-based Compensation (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Stock Based Compensation Tables Details [Abstract]
RSUs and PSUs	$ 32	$ 29
Stock options and equivalents	28	12
Stock-based compensation expense, before income taxes	60	41
Related tax benefit	(23)	(16)
Stock-based compensation expense, net of tax	37	25
Stock-based compensation details [Abstract]
Number of RSUs granted during the period	3
Weighted average grant date fair value - RSUs	$ 43.23
Number of stock options granted during the period	2
Weighted average per unit exercise price - options	$ 43.21
Unrecognized future expense of RSUs	250
Unrecognized future expense of stock options	$ 84
Term until expiration - options	8 years
Employee Stock Option [Member]
Stock-based compensation by award type [Line Items]
Service period over which grants vest	4 years
Weighted average period to expense unrecognized stock-based compensation expense	2 years 6 months
Restricted Stock Units (RSUs) [Member]
Stock-based compensation by award type [Line Items]
Weighted average period to expense unrecognized stock-based compensation expense	2 years 7 months
Restricted Stock Units (RSUs) [Member] \| Maximum [Member]
Stock-based compensation by award type [Line Items]
Payout on stock-based compensation award (percent)	120.00%
Service period over which grants vest	4 years
Restricted Stock Units (RSUs) [Member] \| Minimum [Member]
Stock-based compensation by award type [Line Items]
Payout on stock-based compensation award (percent)	0.00%
Service period over which grants vest	1 year

Payout on stock-based compensation award presented as a percentage of target award.

No definition available.

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- Definition

Reflects the timing, in number of years, as to when the share-based award expires as specified in the award agreement.

+ References

No definition available.

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- Definition

The amount of expense, net of income tax, 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.

+ References

No definition available.

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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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- Definition

Aggregate unrecognized cost of share-based awards, other than options, made to employees under an equity-based compensation plan, that have yet to vest.

+ References

No definition available.

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- Definition

Aggregate unrecognized cost of option awards made to employees under a stock option plan or plans, that have yet to vest.

+ References

No definition available.

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- Definition

The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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- Definition

The noncash expense that represents the cost of restricted stock or unit distributed to employees as compensation.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 28

-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 aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

+ References

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-Number 95

-Paragraph 28

-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

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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- 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

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- Definition

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).

+ References

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

-Publisher FASB

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-Topic 718

-SubTopic 10

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-Paragraph A240

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- Definition

Net number of share options (or share units) granted during the period.

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- Definition

Weighted average price at which grantees can acquire the shares reserved for issuance on stock options awarded.

+ References

No definition available.

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- Definition

The noncash expense that accounts for the value of stock or unit options distributed to employees as compensation.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

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