Stock-Based Employee Compensation Plans (Details Textual) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2011 Y	Dec. 31, 2010	Dec. 31, 2009
Stock-Based Employee Compensation Plans (Textual) [Abstract]
Compensation cost related to stock-based compensation plan	$ 82	$ 81	$ 80
Total income tax benefit related to stock-based compensation plan	29	28	28
Unrecognized compensation cost related to nonvested awards	84
Weighted average period of years over which unrecognized compensation cost will be reflected in operating results	1.7
Maximum number of shares in respect to which stock-based awards may be granted under the plan most recently approved by shareholders	8,650,000
Shares available for grant	8,036,130
Performance period in which performance unit awards are based	3 years
Percentage of number of shares that may be earned related to performance units, Minimum	0.00%
Percentage of number of shares that may be earned related to performance units, Maximum	200.00%
Percentage of performance units earned as it relates to vested shares	87.40%
Number of performance units earned as it relates to vested shares	674,626
Weighted average fair value per stock option granted	$ 11.55	$ 9.46	$ 6.34
Stock option expiration period	10 years
Total intrinsic value of stock options exercised	35	37	12
Cash received from the exercise of stock options	53	58	26
Tax benefit realized with respect to the exercise of stock options	11	11	4
Restricted Stock Units [Member]
Stock-Based Employee Compensation Plans (Textual) [Abstract]
Weighted average fair value per share of the restricted stock units and performance units granted	$ 60.58	$ 51.04	$ 40.38
Total fair value of the restricted stock units and performance units vested	59	46	41
Performance Units [Member]
Stock-Based Employee Compensation Plans (Textual) [Abstract]
Weighted average fair value per share of the restricted stock units and performance units granted	$ 64.34	$ 60.06	$ 45.60
Total fair value of the restricted stock units and performance units vested	$ 47	$ 53	$ 41

The number of the vested performance units earned during the reporting period.

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Maximum percentage of number of shares that may be earned in terms of performance units awarded.

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Minimum percentage of number of shares that may be earned in terms of performance units awarded.

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The percentage of the vested performance units earned during the reporting period.

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Performance period in which performance unit awards are based.

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The expiration period of stock options.

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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.

+ References

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

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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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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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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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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 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 maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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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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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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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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