v2.4.0.6

Restructuring (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended | 1 Months Ended | 12 Months Ended
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Dec. 31, 2011 Aon Hewitt Restructuring Plan | Dec. 31, 2010 Aon Hewitt Restructuring Plan | Dec. 31, 2011 Aon Hewitt Restructuring Plan Risk Solutions | Dec. 31, 2011 Aon Hewitt Restructuring Plan HR Solutions | Dec. 31, 2010 Aon Hewitt Restructuring Plan HR Solutions | Dec. 31, 2011 Aon Hewitt Restructuring Plan Workforce reduction job | Dec. 31, 2010 Aon Hewitt Restructuring Plan Workforce reduction | Oct. 31, 2010 Aon Hewitt Restructuring Plan Workforce reduction Minimum job | Oct. 31, 2010 Aon Hewitt Restructuring Plan Workforce reduction Maximum job | Dec. 31, 2011 Aon Hewitt Restructuring Plan Lease consolidation | Dec. 31, 2010 Aon Hewitt Restructuring Plan Lease consolidation | Dec. 31, 2011 Aon Hewitt Restructuring Plan Asset impairments | Dec. 31, 2011 Aon Hewitt Restructuring Plan Other costs associated with restructuring | Dec. 31, 2011 Aon Hewitt Restructuring Plan Real estate lease realization | Dec. 31, 2011 Aon Benfield Restructuring Plan | Dec. 31, 2010 Aon Benfield Restructuring Plan | Dec. 31, 2009 Aon Benfield Restructuring Plan | Dec. 31, 2008 Aon Benfield Restructuring Plan Original Estimate Y | Dec. 31, 2009 Aon Benfield Restructuring Plan Adjustment | Dec. 31, 2011 Aon Benfield Restructuring Plan Current Estimate | Dec. 31, 2011 Aon Benfield Restructuring Plan Workforce reduction job | Dec. 31, 2010 Aon Benfield Restructuring Plan Workforce reduction | Dec. 31, 2009 Aon Benfield Restructuring Plan Workforce reduction | Dec. 31, 2008 Aon Benfield Restructuring Plan Workforce reduction job | Dec. 31, 2011 Aon Benfield Restructuring Plan Lease consolidation | Dec. 31, 2010 Aon Benfield Restructuring Plan Lease consolidation | Dec. 31, 2009 Aon Benfield Restructuring Plan Lease consolidation | Dec. 31, 2011 Aon Benfield Restructuring Plan Asset impairments | Dec. 31, 2010 Aon Benfield Restructuring Plan Asset impairments | Dec. 31, 2009 Aon Benfield Restructuring Plan Asset impairments | Dec. 31, 2011 Aon Benfield Restructuring Plan Other costs associated with restructuring | Dec. 31, 2010 Aon Benfield Restructuring Plan Other costs associated with restructuring | Dec. 31, 2009 Aon Benfield Restructuring Plan Other costs associated with restructuring | Dec. 31, 2011 2007 Restructuring Plan | Dec. 31, 2010 2007 Restructuring Plan | Dec. 31, 2009 2007 Restructuring Plan | Dec. 31, 2008 2007 Restructuring Plan | Dec. 31, 2007 2007 Restructuring Plan | Dec. 31, 2011 2007 Restructuring Plan Risk Solutions | Dec. 31, 2010 2007 Restructuring Plan Risk Solutions | Dec. 31, 2009 2007 Restructuring Plan Risk Solutions | Dec. 31, 2008 2007 Restructuring Plan Risk Solutions | Dec. 31, 2007 2007 Restructuring Plan Risk Solutions | Dec. 31, 2011 2007 Restructuring Plan HR Solutions | Dec. 31, 2010 2007 Restructuring Plan HR Solutions | Dec. 31, 2009 2007 Restructuring Plan HR Solutions | Dec. 31, 2008 2007 Restructuring Plan HR Solutions | Dec. 31, 2007 2007 Restructuring Plan HR Solutions | Dec. 31, 2011 2007 Restructuring Plan Workforce reduction job | Dec. 31, 2010 2007 Restructuring Plan Workforce reduction | Dec. 31, 2009 2007 Restructuring Plan Workforce reduction | Dec. 31, 2008 2007 Restructuring Plan Workforce reduction | Dec. 31, 2007 2007 Restructuring Plan Workforce reduction | Dec. 31, 2011 2007 Restructuring Plan Lease consolidation | Dec. 31, 2010 2007 Restructuring Plan Lease consolidation | Dec. 31, 2009 2007 Restructuring Plan Lease consolidation | Dec. 31, 2008 2007 Restructuring Plan Lease consolidation | Dec. 31, 2007 2007 Restructuring Plan Lease consolidation | Dec. 31, 2011 2007 Restructuring Plan Asset impairments | Dec. 31, 2010 2007 Restructuring Plan Asset impairments | Dec. 31, 2009 2007 Restructuring Plan Asset impairments | Dec. 31, 2008 2007 Restructuring Plan Asset impairments | Dec. 31, 2007 2007 Restructuring Plan Asset impairments | Dec. 31, 2011 2007 Restructuring Plan Other costs associated with restructuring | Dec. 31, 2010 2007 Restructuring Plan Other costs associated with restructuring | Dec. 31, 2009 2007 Restructuring Plan Other costs associated with restructuring | Dec. 31, 2008 2007 Restructuring Plan Other costs associated with restructuring | Dec. 31, 2007 2007 Restructuring Plan Other costs associated with restructuring
Restructuring and Related Cost |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of jobs eliminated to date under the plan |  |  |  |  |  | 1,080 |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 785 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4,700 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of jobs expected to be eliminated under the plan |  |  |  |  |  |  |  | 1,500 | 1,800 |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 800 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated additional restructuring costs to be recorded in future earnings |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 7 |  |  | $ 81 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Restructuring charges paid total to date |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 129 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Purchase price allocation |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 53 |  |  | 104 | (49) | 53 | 32 |  |  |  | 20 |  |  |  |  |  | 1 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Restructuring and related charges | 105 | 52 | 15 | 90 | 52 | 64 | 49 |  |  | 32 | 3 | 7 | 2 |  | 19 | 26 | 55 |  |  |  | 33 | 15 | 38 |  | (15) | 7 | 14 |  | 2 | 2 | 1 | 2 | 1 | (11) | 94 | 357 | 251 | 46 | (10) | 84 | 322 | 234 | 41 | (1) | 10 | 35 | 17 | 5 | (2) | 72 | 251 | 166 | 17 | (9) | 15 | 78 | 38 | 22 |  | 2 | 15 | 18 | 4 |  | 5 | 13 | 29 | 3
Restructuring charges total to date |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 153 |  |  |  |  |  | 118 |  |  |  | 26 |  |  | 4 |  |  | 5 |  |  | 737 |  |  |  |  | 671 |  |  |  |  | 66 |  |  |  |  | 504 |  |  |  |  | 144 |  |  |  |  | 39 |  |  |  |  | 50 |  |  |  |
Estimated Total Cost for Restructuring Period | $ 325 |  | $ 28 | $ 297 |  | $ 180 |  |  |  | $ 95 |  | $ 47 | $ 3 | $ 145 | $ 160 |  |  | $ 185 |  | $ 160 | $ 125 |  |  |  | $ 26 |  |  | $ 4 |  |  | $ 5 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period over which the expected cost will be incurred (in years) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

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- Definition Represents the number of years over which the cumulative restructuring costs will be incurred. + References No definition available. + Details
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- Definition Amount of costs incurred to date for the specified type of restructuring cost. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 420 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 420 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SAB TOPIC 5.P.4(b)) -URI http://asc.fasb.org/extlink&oid=6394695&loc=d3e140904-122747 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 146 -Paragraph 20 -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. Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Emerging Issues Task Force (EITF) -Number 95-3 -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. Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 5 -Section P -Subsection 3, 4 + Details
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