Depreciation and Amortization by Type (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Depreciation And Amortization By Type [Line Items]
Depreciation And Amortization	$ 588us-gaap_DepreciationAndAmortization	$ 597us-gaap_DepreciationAndAmortization	$ 560us-gaap_DepreciationAndAmortization
Future Amortization Expense Year One	425
Future Amortization Expense Year Two	348
Future Amortization Expense Year Three	237
Future Amortization Expense Year Four	154
Future Amortization Expense Year Five	129
Internal-use software [Member]
Depreciation And Amortization By Type [Line Items]
Depreciation And Amortization	260	225	209
Other property and equipment [Member]
Depreciation And Amortization By Type [Line Items]
Depreciation And Amortization	153	160	144
Assets Recorded under Capital Leases [Member]
Depreciation And Amortization By Type [Line Items]
Depreciation And Amortization	20	16
Other Intangibles [Member]
Depreciation And Amortization By Type [Line Items]
Depreciation And Amortization	163	193	205
Value Of Business Acquired [Member]
Depreciation And Amortization By Type [Line Items]
Depreciation And Amortization	$ 12	$ 19	$ 2

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The current period expense charged against earnings on long-lived, physical assets not used in production, and which are not intended for resale, to allocate or recognize the cost of such assets over their useful lives; or to record the reduction in book value of an intangible asset over the benefit period of such asset; or to reflect consumption during the period of an asset that is not used in production.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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- Definition

Amount of amortization expense expected to be recognized during the next fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(3)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

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- Definition

Amount of amortization expense expected to be recognized during the fifth fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

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- Definition

Amount of amortization expense expected to be recognized during the fourth fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

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- Definition

Amount of amortization expense expected to be recognized during the third fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

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- Definition

Amount of amortization expense expected to be recognized during the second fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

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