Stock-based Compensation (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2012	Mar. 31, 2011
Stock Based Compensation Tables Details [Abstract]
RSUs and PSUs	$ 30	$ 25
Stock options and equivalents	12	9
Stock-based compensation expense, before income taxes	42	34
Related tax benefit	(16)	(13)
Stock-based compensation expense, net of tax	26	21
Employee Stock Option [Member]
Stock-based compensation by award type [Line Items]
Number of stock options granted during the period	3
Weighted average per unit exercise price - options	$ 29.44
Unrecognized future expense of stock-based compensation awards	87
Weighted average period to expense unrecognized stock-based compensation expense (years)	2.8
Stock option term until expiration	8Y
Employee Stock Option [Member] \| Maximum [Member]
Stock-based compensation by award type [Line Items]
Service period over which grants vest	4Y
Employee Stock Option [Member] \| Minimum [Member]
Stock-based compensation by award type [Line Items]
Service period over which grants vest	3Y
Restricted Stock Units (RSUs) [Member]
Stock-based compensation by award type [Line Items]
Number of RSUs granted during the period	4
Weighted average per unit exercise price - options	$ 29.28
Unrecognized future expense of stock-based compensation awards	$ 230
Weighted average period to expense unrecognized stock-based compensation expense (years)	2.7
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	4Y
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	1Y

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

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

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No definition available.

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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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- Definition

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.

+ References

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The weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, using a decimal to express in number of years.

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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.

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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.

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Description of the period of time over 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, which may be expressed in a variety of ways (for example, in years, month and year).

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

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The weighted average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on stock options awarded under the plan during the reporting period.

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

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