Stock-based Compensation (Schedule of Stock Option Exercises) (Details) (Stock Options [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Stock Options [Member]
Stock Option Aggregate Disclosures [Abstract]
Intrinsic value of stock options exercised	$ 32	$ 34
Cash received from option exercises	14	18
Treasury shares repurchased for employee payroll taxes	(7)	(7)
Tax benefit realized from option exercises	12	13
Aggregate grant-date fair value of stock options vested	$ 19	$ 17

Aggregate grant-date fair value of stock options vested.

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- Definition

Value of treasury shares repurchased during period for employee payroll taxes related to share-based compensation awards.

+ References

No definition available.

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- Definition

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.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (j)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

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

+ References

+ Details

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- Definition

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.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (d)(2)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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