Employee Benefits - Schedule of changes in Level 3 fair value for U.K. Pension Plans (Details) (U.K. [Member], USD $) In Millions, unless otherwise specified
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12 Months Ended |
Dec. 31, 2014
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Dec. 31, 2013
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Change in fair value of plan assets |
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Balance at the beginning of the period |
$ 5,398us-gaap_DefinedBenefitPlanFairValueOfPlanAssets |
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$ 4,860us-gaap_DefinedBenefitPlanFairValueOfPlanAssets |
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Actual return on plan assets: |
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Foreign exchange |
(347)us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesPlanAssets |
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104us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesPlanAssets |
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Balance at the end of the period |
6,224us-gaap_DefinedBenefitPlanFairValueOfPlanAssets |
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5,398us-gaap_DefinedBenefitPlanFairValueOfPlanAssets |
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Global [Member]
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Actual return on plan assets: |
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Balance at the end of the period |
203us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_GlobalMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember |
[1] |
668us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_GlobalMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember |
[1] |
Annuities [Member]
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Actual return on plan assets: |
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Balance at the end of the period |
836us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AnnuitiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember |
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564us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AnnuitiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember |
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Alternative investments [Member]
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Actual return on plan assets: |
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Balance at the end of the period |
968us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AlternativeInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember |
[1],[2] |
546us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AlternativeInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember |
[1],[2] |
Significant Unobservable Inputs (Level 3) [Member]
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Change in fair value of plan assets |
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Balance at the beginning of the period |
1,133us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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1,084us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Actual return on plan assets: |
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Relating to assets still held at the end of the year |
309us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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20us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Relating to assets sold during the year |
6us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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8us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Purchases, sales and settlements—net |
713us-gaap_DefinedBenefitPlanPurchasesSalesAndSettlements / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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1us-gaap_DefinedBenefitPlanPurchasesSalesAndSettlements / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Transfer in/(out) of Level 3 |
(206)us-gaap_DefinedBenefitPlanTransfersBetweenMeasurementLevels / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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0us-gaap_DefinedBenefitPlanTransfersBetweenMeasurementLevels / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Foreign exchange |
(105)us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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20us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Balance at the end of the period |
1,850us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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1,133us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Significant Unobservable Inputs (Level 3) [Member] | Global [Member]
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Actual return on plan assets: |
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Balance at the end of the period |
0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_GlobalMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
[1] |
0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_GlobalMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
[1] |
Significant Unobservable Inputs (Level 3) [Member] | Annuities [Member]
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Change in fair value of plan assets |
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Balance at the beginning of the period |
564us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AnnuitiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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568us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AnnuitiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Actual return on plan assets: |
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Relating to assets still held at the end of the year |
(13)us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AnnuitiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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(13)us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AnnuitiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Relating to assets sold during the year |
0us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AnnuitiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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0us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AnnuitiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Purchases, sales and settlements—net |
333us-gaap_DefinedBenefitPlanPurchasesSalesAndSettlements / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AnnuitiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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0us-gaap_DefinedBenefitPlanPurchasesSalesAndSettlements / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AnnuitiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Transfer in/(out) of Level 3 |
0us-gaap_DefinedBenefitPlanTransfersBetweenMeasurementLevels / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AnnuitiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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0us-gaap_DefinedBenefitPlanTransfersBetweenMeasurementLevels / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AnnuitiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Foreign exchange |
(48)us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AnnuitiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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9us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AnnuitiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Balance at the end of the period |
836us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AnnuitiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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564us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AnnuitiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Significant Unobservable Inputs (Level 3) [Member] | Pooled funds - Real estate [Member]
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Change in fair value of plan assets |
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Balance at the beginning of the period |
23us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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70us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Actual return on plan assets: |
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Relating to assets still held at the end of the year |
3us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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1us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Relating to assets sold during the year |
1us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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3us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Purchases, sales and settlements—net |
21us-gaap_DefinedBenefitPlanPurchasesSalesAndSettlements / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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(50)us-gaap_DefinedBenefitPlanPurchasesSalesAndSettlements / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Transfer in/(out) of Level 3 |
0us-gaap_DefinedBenefitPlanTransfersBetweenMeasurementLevels / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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0us-gaap_DefinedBenefitPlanTransfersBetweenMeasurementLevels / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Foreign exchange |
(2)us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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(1)us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Balance at the end of the period |
46us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
|
23us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_RealEstateMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Significant Unobservable Inputs (Level 3) [Member] | Alternative investments [Member]
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Change in fair value of plan assets |
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Balance at the beginning of the period |
546us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AlternativeInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
[1],[2] |
446us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AlternativeInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Actual return on plan assets: |
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Relating to assets still held at the end of the year |
319us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AlternativeInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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32us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AlternativeInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Relating to assets sold during the year |
5us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AlternativeInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
|
5us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AlternativeInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Purchases, sales and settlements—net |
359us-gaap_DefinedBenefitPlanPurchasesSalesAndSettlements / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AlternativeInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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51us-gaap_DefinedBenefitPlanPurchasesSalesAndSettlements / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AlternativeInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Transfer in/(out) of Level 3 |
(206)us-gaap_DefinedBenefitPlanTransfersBetweenMeasurementLevels / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AlternativeInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
|
0us-gaap_DefinedBenefitPlanTransfersBetweenMeasurementLevels / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AlternativeInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Foreign exchange |
(55)us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AlternativeInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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12us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AlternativeInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Balance at the end of the period |
$ 968us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AlternativeInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
[1],[2] |
$ 546us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = aon_AlternativeInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
[1],[2] |
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