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Acquisitions and Dispositions of Businesses - Acquisitions (Details) $ in Millions | 3 Months Ended |
--- | --- | ---
Mar. 31, 2016 USD ($) acquisition | Mar. 31, 2015 USD ($) acquisition | Dec. 31, 2015 USD ($)
Business Acquisition |  |  |
Number of business acquired under business combination | acquisition | 2 | 2 |
Intangible assets: |  |  |
Goodwill | $ 8,411 |  | $ 8,448
Business Acquisition 1 [Member] |  |  |
Business Acquisition |  |  |
Consideration | 21 | $ 21 |
Intangible assets: |  |  |
Goodwill | 7 | 16 |
Other intangible assets | 8 | 1 |
Total | $ 15 | $ 17 |
Risk Solutions [Member] |  |  |
Business Acquisition |  |  |
Number of business acquired under business combination | acquisition | 0 | 1 |
Intangible assets: |  |  |
Goodwill | $ 5,580 |  | 5,593
HR Solutions [Member] |  |  |
Business Acquisition |  |  |
Number of business acquired under business combination | acquisition | 2 | 1 |
Intangible assets: |  |  |
Goodwill | $ 2,831 |  | $ 2,855

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- Definition Amount of intangible assets, excluding goodwill, acquired at the acquisition date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=56956791&loc=d3e4845-128472 + Details
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- Definition Amount recognized as of the acquisition date for the identifiable assets acquired in excess of (less than) the aggregate liabilities assumed. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 55 -Paragraph 37 -URI http://asc.fasb.org/extlink&oid=35744172&loc=d3e2207-128464 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=56956791&loc=d3e4845-128472 + Details
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- Definition Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266 + Details
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