Goodwill and Other Intangible Assets (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Intangible assets with indefinite lives
Tradenames	$ 1,019us-gaap_IndefiniteLivedTrademarks		$ 1,019us-gaap_IndefiniteLivedTrademarks
Intangible assets with finite lives
Intangible assets with finite lives, Gross Carrying Amount	4,461		4,542
Intangible assets with finite lives, Accumulated Amortization	2,051		2,022
Intangible assets, Net Carrying Amount	2,410		2,520
Amortization expense on intangible assets	80us-gaap_AmortizationOfIntangibleAssets	86us-gaap_AmortizationOfIntangibleAssets
Estimated amortization for intangible assets
Remainder of 2015	234
2016	271
2017	227
2018	169
2019	142
Thereafter	348
Total	1,391us-gaap_FiniteLivedIntangibleAssetsNet
Risk Solutions [Member]
Estimated amortization for intangible assets
Remainder of 2015	80
2016	99
2017	90
2018	78
2019	69
Thereafter	185
Total	601
HR Solutions [Member]
Estimated amortization for intangible assets
Remainder of 2015	154
2016	172
2017	137
2018	91
2019	73
Thereafter	163
Total	790
Customer related and contract based [Member]
Intangible assets with finite lives
Intangible assets with finite lives, Gross Carrying Amount	2,894		2,952
Intangible assets with finite lives, Accumulated Amortization	1,616		1,579
Intangible assets, Net Carrying Amount	1,278		1,373
Marketing, technology and other [Member]
Intangible assets with finite lives
Intangible assets with finite lives, Gross Carrying Amount	548		571
Intangible assets with finite lives, Accumulated Amortization	435		443
Intangible assets, Net Carrying Amount	$ 113		$ 128

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized in the remainder of the fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Carrying amount (original costs adjusted for previously recognized amortization and impairment) as of the balance sheet date for the rights acquired through registration of a trademark to gain or protect exclusive use of a business name, symbol or other device or style for a projected indefinite period of benefit.

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Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

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