Stock-Based Compensation Stock-Based Compensation (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock option expense	$ 22	$ 20	$ 48	$ 51
Restricted stock expense	$ 10	$ 8	$ 18	$ 13
Stock options granted			8
Stock options fair value	$ 12.45
Stock options, weighted average exercise price	$ 54.54
Stock options outstanding at end of period	40		40
Stock option weighted average exercise price at end of period	$ 40.63		$ 40.63
Stock options, weighted average contractual term at end of period			4 years 8 months 5 days

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

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

+ References

No definition available.

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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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- Definition

The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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- Definition

Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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- Definition

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.

+ References

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

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No definition available.

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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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