XML 105 R132.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Guarantee of Registered Securities - Condensed Consolidating Statement of Cash Flows (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
CASH FLOWS FROM OPERATING ACTIVITIES |  |  |
CASH PROVIDED BY (USED FOR) OPERATING ACTIVITIES | $ 1,642 us-gaap_NetCashProvidedByUsedInOperatingActivities | $ 1,633 us-gaap_NetCashProvidedByUsedInOperatingActivities | $ 1,419 us-gaap_NetCashProvidedByUsedInOperatingActivities
CASH FLOWS FROM INVESTING ACTIVITIES |  |  |
Proceeds from sale of long-term investments | 52 us-gaap_ProceedsFromSaleAndMaturityOfOtherInvestments | 93 us-gaap_ProceedsFromSaleAndMaturityOfOtherInvestments | 178 us-gaap_ProceedsFromSaleAndMaturityOfOtherInvestments
Purchases of long-term investments | (20)us-gaap_PaymentsToAcquireOtherInvestments | (15)us-gaap_PaymentsToAcquireOtherInvestments | (12)us-gaap_PaymentsToAcquireOtherInvestments
Net (purchases) sales of short-term investments - non-fiduciary | 110 aon_PaymentsForProceedsFromMarketableSecurities | (174)aon_PaymentsForProceedsFromMarketableSecurities | 440 aon_PaymentsForProceedsFromMarketableSecurities
Acquisition of businesses, net of cash acquired | (479)us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired | (54)us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired | (162)us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired
Proceeds from sale of businesses | 48 us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested | 40 us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested | 2 us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested
Capital expenditures | (256)us-gaap_PaymentsToAcquirePropertyPlantAndEquipment | (229)us-gaap_PaymentsToAcquirePropertyPlantAndEquipment | (269)us-gaap_PaymentsToAcquirePropertyPlantAndEquipment
CASH (USED FOR) PROVIDED BY INVESTING ACTIVITIES | (545)us-gaap_NetCashProvidedByUsedInInvestingActivities | (339)us-gaap_NetCashProvidedByUsedInInvestingActivities | 177 us-gaap_NetCashProvidedByUsedInInvestingActivities
CASH FLOWS FROM FINANCING ACTIVITIES |  |  |
Share repurchase | (2,250)us-gaap_PaymentsForRepurchaseOfCommonStock | (1,102)us-gaap_PaymentsForRepurchaseOfCommonStock | (1,125)us-gaap_PaymentsForRepurchaseOfCommonStock
Advances from (to) affiliates | 0 us-gaap_IncreaseDecreaseInDueToAffiliates | 0 us-gaap_IncreaseDecreaseInDueToAffiliates | 0 us-gaap_IncreaseDecreaseInDueToAffiliates
Issuance of shares for employee benefit plans | 65 us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions | 98 us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions | 118 us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions
Issuance of debt | 5,239 us-gaap_ProceedsFromIssuanceOfLongTermDebt | 4,906 us-gaap_ProceedsFromIssuanceOfLongTermDebt | 733 us-gaap_ProceedsFromIssuanceOfLongTermDebt
Repayment of debt | (3,918)us-gaap_RepaymentsOfLongTermDebt | (4,679)us-gaap_RepaymentsOfLongTermDebt | (1,077)us-gaap_RepaymentsOfLongTermDebt
Cash dividends to shareholders | (273)us-gaap_PaymentsOfDividendsCommonStock | (212)us-gaap_PaymentsOfDividendsCommonStock | (204)us-gaap_PaymentsOfDividendsCommonStock
Sales (purchases) of shares to (from) noncontrolling interests | 3 us-gaap_ProceedsFromPaymentsToMinorityShareholders | (8)us-gaap_ProceedsFromPaymentsToMinorityShareholders | (4)us-gaap_ProceedsFromPaymentsToMinorityShareholders
Dividends paid to noncontrolling interests | (24)us-gaap_PaymentsOfDividendsMinorityInterest | (19)us-gaap_PaymentsOfDividendsMinorityInterest | (27)us-gaap_PaymentsOfDividendsMinorityInterest
Proceeds from sale-leaseback | 25 us-gaap_SaleLeasebackTransactionNetProceeds | 0 us-gaap_SaleLeasebackTransactionNetProceeds | 0 us-gaap_SaleLeasebackTransactionNetProceeds
CASH USED FOR FINANCING ACTIVITIES | (1,133)us-gaap_NetCashProvidedByUsedInFinancingActivities | (1,016)us-gaap_NetCashProvidedByUsedInFinancingActivities | (1,586)us-gaap_NetCashProvidedByUsedInFinancingActivities
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS | (67)us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents | (92)us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents | 9 us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS | (103)us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease | 186 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease | 19 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR | 477 us-gaap_CashAndCashEquivalentsAtCarryingValue | 291 us-gaap_CashAndCashEquivalentsAtCarryingValue | 272 us-gaap_CashAndCashEquivalentsAtCarryingValue
CASH AND CASH EQUIVALENTS AT END OF YEAR | 374 us-gaap_CashAndCashEquivalentsAtCarryingValue | 477 us-gaap_CashAndCashEquivalentsAtCarryingValue | 291 us-gaap_CashAndCashEquivalentsAtCarryingValue
Aon plc [Member] |  |  |
CASH FLOWS FROM OPERATING ACTIVITIES |  |  |
CASH PROVIDED BY (USED FOR) OPERATING ACTIVITIES | 599 us-gaap_NetCashProvidedByUsedInOperatingActivities / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | (50)us-gaap_NetCashProvidedByUsedInOperatingActivities / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | (87)us-gaap_NetCashProvidedByUsedInOperatingActivities / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
CASH FLOWS FROM INVESTING ACTIVITIES |  |  |
Proceeds from sale of long-term investments | 0 us-gaap_ProceedsFromSaleAndMaturityOfOtherInvestments / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_ProceedsFromSaleAndMaturityOfOtherInvestments / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_ProceedsFromSaleAndMaturityOfOtherInvestments / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Purchases of long-term investments | 0 us-gaap_PaymentsToAcquireOtherInvestments / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_PaymentsToAcquireOtherInvestments / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_PaymentsToAcquireOtherInvestments / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Net (purchases) sales of short-term investments - non-fiduciary | 0 aon_PaymentsForProceedsFromMarketableSecurities / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 aon_PaymentsForProceedsFromMarketableSecurities / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 aon_PaymentsForProceedsFromMarketableSecurities / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Acquisition of businesses, net of cash acquired | 0 us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | (50)us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Proceeds from sale of businesses | 0 us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Capital expenditures | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
CASH (USED FOR) PROVIDED BY INVESTING ACTIVITIES | 0 us-gaap_NetCashProvidedByUsedInInvestingActivities / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_NetCashProvidedByUsedInInvestingActivities / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | (50)us-gaap_NetCashProvidedByUsedInInvestingActivities / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
CASH FLOWS FROM FINANCING ACTIVITIES |  |  |
Share repurchase | (2,250)us-gaap_PaymentsForRepurchaseOfCommonStock / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | (1,102)us-gaap_PaymentsForRepurchaseOfCommonStock / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | (1,025)us-gaap_PaymentsForRepurchaseOfCommonStock / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Advances from (to) affiliates | 19 us-gaap_IncreaseDecreaseInDueToAffiliates / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 460 us-gaap_IncreaseDecreaseInDueToAffiliates / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 1,379 us-gaap_IncreaseDecreaseInDueToAffiliates / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Issuance of shares for employee benefit plans | 65 us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 98 us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 69 us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Issuance of debt | 2,908 us-gaap_ProceedsFromIssuanceOfLongTermDebt / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 1,730 us-gaap_ProceedsFromIssuanceOfLongTermDebt / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_ProceedsFromIssuanceOfLongTermDebt / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Repayment of debt | (1,068)us-gaap_RepaymentsOfLongTermDebt / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | (1,055)us-gaap_RepaymentsOfLongTermDebt / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_RepaymentsOfLongTermDebt / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Cash dividends to shareholders | (273)us-gaap_PaymentsOfDividendsCommonStock / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | (212)us-gaap_PaymentsOfDividendsCommonStock / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | (155)us-gaap_PaymentsOfDividendsCommonStock / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Sales (purchases) of shares to (from) noncontrolling interests | 0 us-gaap_ProceedsFromPaymentsToMinorityShareholders / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_ProceedsFromPaymentsToMinorityShareholders / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_ProceedsFromPaymentsToMinorityShareholders / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Dividends paid to noncontrolling interests | 0 us-gaap_PaymentsOfDividendsMinorityInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_PaymentsOfDividendsMinorityInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_PaymentsOfDividendsMinorityInterest / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Proceeds from sale-leaseback | 0 us-gaap_SaleLeasebackTransactionNetProceeds / dei_LegalEntityAxis = us-gaap_ParentCompanyMember |  |
CASH USED FOR FINANCING ACTIVITIES | (599)us-gaap_NetCashProvidedByUsedInFinancingActivities / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | (81)us-gaap_NetCashProvidedByUsedInFinancingActivities / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 268 us-gaap_NetCashProvidedByUsedInFinancingActivities / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS | 0 us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS | 0 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | (131)us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 131 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 131 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
CASH AND CASH EQUIVALENTS AT END OF YEAR | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember | 131 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ParentCompanyMember
Aon Corporation [Member] |  |  |
CASH FLOWS FROM OPERATING ACTIVITIES |  |  |
CASH PROVIDED BY (USED FOR) OPERATING ACTIVITIES | (927)us-gaap_NetCashProvidedByUsedInOperatingActivities / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | (441)us-gaap_NetCashProvidedByUsedInOperatingActivities / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | (105)us-gaap_NetCashProvidedByUsedInOperatingActivities / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember
CASH FLOWS FROM INVESTING ACTIVITIES |  |  |
Proceeds from sale of long-term investments | 39 us-gaap_ProceedsFromSaleAndMaturityOfOtherInvestments / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 8 us-gaap_ProceedsFromSaleAndMaturityOfOtherInvestments / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 79 us-gaap_ProceedsFromSaleAndMaturityOfOtherInvestments / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember
Purchases of long-term investments | (20)us-gaap_PaymentsToAcquireOtherInvestments / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | (15)us-gaap_PaymentsToAcquireOtherInvestments / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | (12)us-gaap_PaymentsToAcquireOtherInvestments / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember
Net (purchases) sales of short-term investments - non-fiduciary | (3)aon_PaymentsForProceedsFromMarketableSecurities / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | (74)aon_PaymentsForProceedsFromMarketableSecurities / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 232 aon_PaymentsForProceedsFromMarketableSecurities / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember
Acquisition of businesses, net of cash acquired | 0 us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 0 us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | (55)us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember
Proceeds from sale of businesses | 0 us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 7 us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 0 us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember
Capital expenditures | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember
CASH (USED FOR) PROVIDED BY INVESTING ACTIVITIES | 16 us-gaap_NetCashProvidedByUsedInInvestingActivities / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | (74)us-gaap_NetCashProvidedByUsedInInvestingActivities / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 244 us-gaap_NetCashProvidedByUsedInInvestingActivities / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember
CASH FLOWS FROM FINANCING ACTIVITIES |  |  |
Share repurchase | 0 us-gaap_PaymentsForRepurchaseOfCommonStock / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 0 us-gaap_PaymentsForRepurchaseOfCommonStock / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | (100)us-gaap_PaymentsForRepurchaseOfCommonStock / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember
Advances from (to) affiliates | 3,215 us-gaap_IncreaseDecreaseInDueToAffiliates / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 996 us-gaap_IncreaseDecreaseInDueToAffiliates / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 489 us-gaap_IncreaseDecreaseInDueToAffiliates / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember
Issuance of shares for employee benefit plans | 0 us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 0 us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 49 us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember
Issuance of debt | 2,326 us-gaap_ProceedsFromIssuanceOfLongTermDebt / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 2,944 us-gaap_ProceedsFromIssuanceOfLongTermDebt / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 732 us-gaap_ProceedsFromIssuanceOfLongTermDebt / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember
Repayment of debt | (2,150)us-gaap_RepaymentsOfLongTermDebt / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | (3,377)us-gaap_RepaymentsOfLongTermDebt / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | (1,061)us-gaap_RepaymentsOfLongTermDebt / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember
Cash dividends to shareholders | 0 us-gaap_PaymentsOfDividendsCommonStock / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 0 us-gaap_PaymentsOfDividendsCommonStock / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | (49)us-gaap_PaymentsOfDividendsCommonStock / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember
Sales (purchases) of shares to (from) noncontrolling interests | 0 us-gaap_ProceedsFromPaymentsToMinorityShareholders / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 0 us-gaap_ProceedsFromPaymentsToMinorityShareholders / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 0 us-gaap_ProceedsFromPaymentsToMinorityShareholders / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember
Dividends paid to noncontrolling interests | 0 us-gaap_PaymentsOfDividendsMinorityInterest / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 0 us-gaap_PaymentsOfDividendsMinorityInterest / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 0 us-gaap_PaymentsOfDividendsMinorityInterest / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember
Proceeds from sale-leaseback | 0 us-gaap_SaleLeasebackTransactionNetProceeds / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember |  |
CASH USED FOR FINANCING ACTIVITIES | 3,391 us-gaap_NetCashProvidedByUsedInFinancingActivities / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 563 us-gaap_NetCashProvidedByUsedInFinancingActivities / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 60 us-gaap_NetCashProvidedByUsedInFinancingActivities / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS | 0 us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 0 us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 0 us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS | 2,480 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 48 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 199 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR | 247 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 199 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember
CASH AND CASH EQUIVALENTS AT END OF YEAR | 2,727 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 247 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember | 199 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_GuarantorSubsidiariesMember
Other Non-Guarantor Subsidiaries [Member] |  |  |
CASH FLOWS FROM OPERATING ACTIVITIES |  |  |
CASH PROVIDED BY (USED FOR) OPERATING ACTIVITIES | 1,970 us-gaap_NetCashProvidedByUsedInOperatingActivities / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 2,124 us-gaap_NetCashProvidedByUsedInOperatingActivities / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 1,611 us-gaap_NetCashProvidedByUsedInOperatingActivities / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember
CASH FLOWS FROM INVESTING ACTIVITIES |  |  |
Proceeds from sale of long-term investments | 13 us-gaap_ProceedsFromSaleAndMaturityOfOtherInvestments / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 85 us-gaap_ProceedsFromSaleAndMaturityOfOtherInvestments / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 99 us-gaap_ProceedsFromSaleAndMaturityOfOtherInvestments / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember
Purchases of long-term investments | 0 us-gaap_PaymentsToAcquireOtherInvestments / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 0 us-gaap_PaymentsToAcquireOtherInvestments / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 0 us-gaap_PaymentsToAcquireOtherInvestments / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember
Net (purchases) sales of short-term investments - non-fiduciary | 113 aon_PaymentsForProceedsFromMarketableSecurities / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | (100)aon_PaymentsForProceedsFromMarketableSecurities / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 208 aon_PaymentsForProceedsFromMarketableSecurities / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember
Acquisition of businesses, net of cash acquired | (479)us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | (54)us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | (57)us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember
Proceeds from sale of businesses | 48 us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 33 us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 2 us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember
Capital expenditures | (256)us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | (229)us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | (269)us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember
CASH (USED FOR) PROVIDED BY INVESTING ACTIVITIES | (561)us-gaap_NetCashProvidedByUsedInInvestingActivities / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | (265)us-gaap_NetCashProvidedByUsedInInvestingActivities / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | (17)us-gaap_NetCashProvidedByUsedInInvestingActivities / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember
CASH FLOWS FROM FINANCING ACTIVITIES |  |  |
Share repurchase | 0 us-gaap_PaymentsForRepurchaseOfCommonStock / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 0 us-gaap_PaymentsForRepurchaseOfCommonStock / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 0 us-gaap_PaymentsForRepurchaseOfCommonStock / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember
Advances from (to) affiliates | (536)us-gaap_IncreaseDecreaseInDueToAffiliates / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | (479)us-gaap_IncreaseDecreaseInDueToAffiliates / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | (1,850)us-gaap_IncreaseDecreaseInDueToAffiliates / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember
Issuance of shares for employee benefit plans | 0 us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 0 us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 0 us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember
Issuance of debt | 5 us-gaap_ProceedsFromIssuanceOfLongTermDebt / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 232 us-gaap_ProceedsFromIssuanceOfLongTermDebt / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 1 us-gaap_ProceedsFromIssuanceOfLongTermDebt / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember
Repayment of debt | (700)us-gaap_RepaymentsOfLongTermDebt / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | (247)us-gaap_RepaymentsOfLongTermDebt / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | (16)us-gaap_RepaymentsOfLongTermDebt / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember
Cash dividends to shareholders | 0 us-gaap_PaymentsOfDividendsCommonStock / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 0 us-gaap_PaymentsOfDividendsCommonStock / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 0 us-gaap_PaymentsOfDividendsCommonStock / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember
Sales (purchases) of shares to (from) noncontrolling interests | 3 us-gaap_ProceedsFromPaymentsToMinorityShareholders / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | (8)us-gaap_ProceedsFromPaymentsToMinorityShareholders / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | (4)us-gaap_ProceedsFromPaymentsToMinorityShareholders / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember
Dividends paid to noncontrolling interests | (24)us-gaap_PaymentsOfDividendsMinorityInterest / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | (19)us-gaap_PaymentsOfDividendsMinorityInterest / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | (27)us-gaap_PaymentsOfDividendsMinorityInterest / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember
Proceeds from sale-leaseback | 25 us-gaap_SaleLeasebackTransactionNetProceeds / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember |  |
CASH USED FOR FINANCING ACTIVITIES | (1,227)us-gaap_NetCashProvidedByUsedInFinancingActivities / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | (521)us-gaap_NetCashProvidedByUsedInFinancingActivities / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | (1,896)us-gaap_NetCashProvidedByUsedInFinancingActivities / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS | (67)us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | (92)us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 9 us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS | 115 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 1,246 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | (293)us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR | 1,246 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 293 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember
CASH AND CASH EQUIVALENTS AT END OF YEAR | 1,361 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 1,246 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_NonGuarantorSubsidiariesMember
Consolidating Adjustments [Member] |  |  |
CASH FLOWS FROM OPERATING ACTIVITIES |  |  |
CASH PROVIDED BY (USED FOR) OPERATING ACTIVITIES | 0 us-gaap_NetCashProvidedByUsedInOperatingActivities / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_NetCashProvidedByUsedInOperatingActivities / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_NetCashProvidedByUsedInOperatingActivities / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember
CASH FLOWS FROM INVESTING ACTIVITIES |  |  |
Proceeds from sale of long-term investments | 0 us-gaap_ProceedsFromSaleAndMaturityOfOtherInvestments / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_ProceedsFromSaleAndMaturityOfOtherInvestments / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_ProceedsFromSaleAndMaturityOfOtherInvestments / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember
Purchases of long-term investments | 0 us-gaap_PaymentsToAcquireOtherInvestments / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_PaymentsToAcquireOtherInvestments / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_PaymentsToAcquireOtherInvestments / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember
Net (purchases) sales of short-term investments - non-fiduciary | 0 aon_PaymentsForProceedsFromMarketableSecurities / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 aon_PaymentsForProceedsFromMarketableSecurities / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 aon_PaymentsForProceedsFromMarketableSecurities / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember
Acquisition of businesses, net of cash acquired | 0 us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember
Proceeds from sale of businesses | 0 us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember
Capital expenditures | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember
CASH (USED FOR) PROVIDED BY INVESTING ACTIVITIES | 0 us-gaap_NetCashProvidedByUsedInInvestingActivities / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_NetCashProvidedByUsedInInvestingActivities / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_NetCashProvidedByUsedInInvestingActivities / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember
CASH FLOWS FROM FINANCING ACTIVITIES |  |  |
Share repurchase | 0 us-gaap_PaymentsForRepurchaseOfCommonStock / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_PaymentsForRepurchaseOfCommonStock / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_PaymentsForRepurchaseOfCommonStock / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember
Advances from (to) affiliates | (2,698)us-gaap_IncreaseDecreaseInDueToAffiliates / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | (977)us-gaap_IncreaseDecreaseInDueToAffiliates / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | (18)us-gaap_IncreaseDecreaseInDueToAffiliates / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember
Issuance of shares for employee benefit plans | 0 us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember
Issuance of debt | 0 us-gaap_ProceedsFromIssuanceOfLongTermDebt / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_ProceedsFromIssuanceOfLongTermDebt / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_ProceedsFromIssuanceOfLongTermDebt / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember
Repayment of debt | 0 us-gaap_RepaymentsOfLongTermDebt / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_RepaymentsOfLongTermDebt / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_RepaymentsOfLongTermDebt / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember
Cash dividends to shareholders | 0 us-gaap_PaymentsOfDividendsCommonStock / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_PaymentsOfDividendsCommonStock / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_PaymentsOfDividendsCommonStock / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember
Sales (purchases) of shares to (from) noncontrolling interests | 0 us-gaap_ProceedsFromPaymentsToMinorityShareholders / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_ProceedsFromPaymentsToMinorityShareholders / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_ProceedsFromPaymentsToMinorityShareholders / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember
Dividends paid to noncontrolling interests | 0 us-gaap_PaymentsOfDividendsMinorityInterest / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_PaymentsOfDividendsMinorityInterest / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_PaymentsOfDividendsMinorityInterest / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember
Proceeds from sale-leaseback | 0 us-gaap_SaleLeasebackTransactionNetProceeds / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember |  |
CASH USED FOR FINANCING ACTIVITIES | (2,698)us-gaap_NetCashProvidedByUsedInFinancingActivities / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | (977)us-gaap_NetCashProvidedByUsedInFinancingActivities / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | (18)us-gaap_NetCashProvidedByUsedInFinancingActivities / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS | 0 us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | 0 us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS | (2,698)us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | (977)us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | (18)us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR | (1,016)us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | (39)us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | (21)us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember
CASH AND CASH EQUIVALENTS AT END OF YEAR | $ (3,714)us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | $ (1,016)us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember | $ (39)us-gaap_CashAndCashEquivalentsAtCarryingValue / dei_LegalEntityAxis = us-gaap_ConsolidationEliminationsMember

X
- Definition The cash inflow or outflow from sales or purchases of marketable securities. + References No definition available. + Details
Name: | aon_PaymentsForProceedsFromMarketableSecurities
Namespace Prefix: | aon_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Cash -URI http://asc.fasb.org/extlink&oid=6506951 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Cash Equivalents -URI http://asc.fasb.org/extlink&oid=6507016 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 1 -Article 5 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.1) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6676-107765 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3044-108585 + Details
Name: | us-gaap_CashAndCashEquivalentsAtCarryingValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of increase (decrease) in cash and cash equivalents. Cash and cash equivalents are the amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Includes effect from exchange rate changes. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 24 -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3521-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 230 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6450594&loc=d3e33268-110906 + Details
Name: | us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of increase (decrease) from the effect of exchange rate changes on cash and cash equivalent balances held in foreign currencies. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 230 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6450594&loc=d3e33268-110906 + Details
Name: | us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The increase (decrease) in obligations owed to an entity that is controlling, under the control of, or within the same control group as the reporting entity by means of direct or indirect ownership. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585 + Details
Name: | us-gaap_IncreaseDecreaseInDueToAffiliates
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of cash inflow (outflow) from financing activities, including discontinued operations. Financing activity cash flows include obtaining resources from owners and providing them with a return on, and a return of, their investment; borrowing money and repaying amounts borrowed, or settling the obligation; and obtaining and paying for other resources obtained from creditors on long-term credit. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 24 -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3521-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 26 -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3574-108585 + Details
Name: | us-gaap_NetCashProvidedByUsedInFinancingActivities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of cash inflow (outflow) from investing activities, including discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 24 -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3521-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 26 -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3574-108585 + Details
Name: | us-gaap_NetCashProvidedByUsedInInvestingActivities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of cash inflow (outflow) from operating activities, including discontinued operations. Operating activity cash flows include transactions, adjustments, and changes in value not defined as investing or financing activities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 24 -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3521-108585 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 25 -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3536-108585 + Details
Name: | us-gaap_NetCashProvidedByUsedInOperatingActivities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The cash outflow to reacquire common stock during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Financing Activities -URI http://asc.fasb.org/extlink&oid=6513228 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3291-108585 + Details
Name: | us-gaap_PaymentsForRepurchaseOfCommonStock
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of cash outflow in the form of ordinary dividends to common shareholders of the parent entity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Financing Activities -URI http://asc.fasb.org/extlink&oid=6513228 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3291-108585 + Details
Name: | us-gaap_PaymentsOfDividendsCommonStock
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of cash outflow in the form of ordinary dividends provided by the non-wholly owned subsidiary to noncontrolling interests. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Financing Activities -URI http://asc.fasb.org/extlink&oid=6513228 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3291-108585 + Details
Name: | us-gaap_PaymentsOfDividendsMinorityInterest
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The cash outflow associated with the acquisition of a business, net of the cash acquired from the purchase. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Investing Activities -URI http://asc.fasb.org/extlink&oid=6516133 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3213-108585 + Details
Name: | us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The cash outflow associated with other investments held by the entity for investment purposes not otherwise defined in the taxonomy. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Investing Activities -URI http://asc.fasb.org/extlink&oid=6516133 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3213-108585 + Details
Name: | us-gaap_PaymentsToAcquireOtherInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The cash outflow associated with the acquisition of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale; includes cash outflows to pay for construction of self-constructed assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Investing Activities -URI http://asc.fasb.org/extlink&oid=6516133 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3213-108585 + Details
Name: | us-gaap_PaymentsToAcquirePropertyPlantAndEquipment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition This element represents the cash inflow during the period from the sale of a component of the entity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Investing Activities -URI http://asc.fasb.org/extlink&oid=6516133 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3179-108585 + Details
Name: | us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Financing Activities -URI http://asc.fasb.org/extlink&oid=6513228 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3255-108585 + Details
Name: | us-gaap_ProceedsFromIssuanceOfLongTermDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The total cash inflow associated with the amount received from holders to acquire the entity's shares under incentive and share awards, including stock option exercises. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Financing Activities -URI http://asc.fasb.org/extlink&oid=6513228 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3255-108585 + Details
Name: | us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of cash inflow (outflow) from (to) a noncontrolling interest. Excludes dividends paid to the noncontrolling interest. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3291-108585 + Details
Name: | us-gaap_ProceedsFromPaymentsToMinorityShareholders
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The cash inflow associated with the sale and maturity (principal being due) of other investments, prepayment and call (request of early payment) of other investments not otherwise defined in the taxonomy. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3179-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Investing Activities -URI http://asc.fasb.org/extlink&oid=6516133 + Details
Name: | us-gaap_ProceedsFromSaleAndMaturityOfOtherInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3291-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Financing Activities -URI http://asc.fasb.org/extlink&oid=6513228 + Details
Name: | us-gaap_RepaymentsOfLongTermDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The gross proceeds received from the asset(s) sold in connection with the transaction involving the sale of property to another party and the lease of the property back to the seller less the costs incurred in connection with the transaction, such as closing and deferred financing costs. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 40 -Section 55 -Paragraph 51 -URI http://asc.fasb.org/extlink&oid=28365400&loc=d3e51840-112757 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 40 -Section 55 -Paragraph 52 -URI http://asc.fasb.org/extlink&oid=28365400&loc=d3e51843-112757 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 40 -Section 55 -Paragraph 50 -URI http://asc.fasb.org/extlink&oid=28365400&loc=d3e51831-112757 + Details
Name: | us-gaap_SaleLeasebackTransactionNetProceeds
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=us-gaap_ConsolidationEliminationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=us-gaap_GuarantorSubsidiariesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=us-gaap_NonGuarantorSubsidiariesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=us-gaap_ParentCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |