Stock-Based Compensation (Details 4) (Stock Options [Member], USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Stock Options [Member]
Stock Option Aggregate Disclosures [Abstract]
Intrinsic value of stock options exercised	$ 54	$ 41	$ 82	$ 103
Cash received from option exercises	17	24	31	45
Treasury shares repurchased for employee payroll taxes	(7)	(8)	(12)	(16)
Tax benefit realized from option exercises	21	15	32	39
Aggregate grant-date fair value of stock options vested	$ 0	$ 0	$ 16	$ 16

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.

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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph c(2)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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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