v2.3.0.15

Other Income (Expense) (Details) (USD $) In Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2011 | Sep. 30, 2010 | Sep. 30, 2011 | Sep. 30, 2010
Other Income (Expense) |  |  |  |
Equity earnings (losses) | $ 5 | $ (1) | $ 9 | $ 5
Realized gain on sale of investments | 1 |  | 10 | 1
Loss on disposal of businesses |  | (8) | (1) | (2)
Loss on extinguishment of debt |  |  | (19) |
Other | 1 |  | 2 | (1)
Other income | $ 7 | $ (9) | $ 1 | $ 3

X
- Details
Name: | aon_OtherIncomeDisclosureAbstract
Namespace Prefix: | aon
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The gain (loss) resulting from the sale of a disposal group that is not a discontinued operation. It is included in income from continuing operations before income taxes in the income statement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 144 -Paragraph 47 -Subparagraph b Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 144 -Paragraph 37, 45 + Details
Name: | us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal
Namespace Prefix: | us-gaap
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The net realized gain or loss on investments sold during the period, which, for cash flow reporting, is a component of proceeds from investing activities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 + Details
Name: | us-gaap_GainLossOnSaleOfInvestments
Namespace Prefix: | us-gaap
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount represents the difference between the fair value of the payments made and the carrying amount of the debt at the time of its extinguishment. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 26 -Paragraph 20, 21 + Details
Name: | us-gaap_GainsLossesOnExtinguishmentOfDebt
Namespace Prefix: | us-gaap
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. Such amount typically reflects adjustments similar to those made in preparing consolidated statements, including adjustments to eliminate intercompany gains and losses, and to amortize, if appropriate, any difference between cost and underlying equity in net assets of the investee at the date of investment. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 18 -Paragraph 19 -Subparagraph c Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 11 -Article 7 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 9 -Article 5 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 18 -Paragraph 6 -Subparagraph b + Details
Name: | us-gaap_IncomeLossFromEquityMethodInvestments
Namespace Prefix: | us-gaap
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Any other expense items resulting from secondary business-related activities, excluding those considered part of the normal operations of the business that have not been previously categorized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 9 -Article 5 + Details
Name: | us-gaap_OtherNonoperatingExpense
Namespace Prefix: | us-gaap
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The net amount of other nonoperating income and expense, which does not qualify for separate disclosure on the income statement under materiality guidelines. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 9 -Article 5 + Details
Name: | us-gaap_OtherNonoperatingIncomeExpense
Namespace Prefix: | us-gaap
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration