XML 99 R83.htm IDEA: XBRL DOCUMENT
v3.3.1.900

Employee Benefits - Schedule of changes in Level 3 fair value for U.K. Pension Plans (Details) - U.K. [Member] - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2015 | Dec. 31, 2014
Change in fair value of plan assets |  |
Balance at the beginning of the period | $ 6,224 | $ 5,398
Actual return on plan assets: |  |
Foreign exchange | (257) | (347)
Balance at the end of the period | 5,903 | 6,224
Global [Member] |  |
Change in fair value of plan assets |  |
Balance at the beginning of the period | 203 |
Actual return on plan assets: |  |
Balance at the end of the period | 360 | 203
Annuities [Member] |  |
Change in fair value of plan assets |  |
Balance at the beginning of the period | 836 |
Actual return on plan assets: |  |
Balance at the end of the period | 827 | 836
Alternative investments [Member] |  |
Change in fair value of plan assets |  |
Balance at the beginning of the period | 968 |
Actual return on plan assets: |  |
Balance at the end of the period | 717 | 968
Pooled funds - Fixed income securities [Member] |  |
Change in fair value of plan assets |  |
Balance at the beginning of the period | 279 |
Actual return on plan assets: |  |
Balance at the end of the period | 283 | 279
Significant Unobservable Inputs (Level 3) |  |
Change in fair value of plan assets |  |
Balance at the beginning of the period | 1,850 | 1,133
Actual return on plan assets: |  |
Relating to assets still held at the end of the year | (45) | 309
Relating to assets sold during the year | (9) | 6
Purchases, sales and settlements—net | 168 | 713
Transfer in/(out) of Level 3 | (242) | (206)
Foreign exchange | (73) | (105)
Balance at the end of the period | 1,649 | 1,850
Significant Unobservable Inputs (Level 3) | Global [Member] |  |
Change in fair value of plan assets |  |
Balance at the beginning of the period | 0 |
Actual return on plan assets: |  |
Balance at the end of the period | 0 | 0
Significant Unobservable Inputs (Level 3) | Annuities [Member] |  |
Change in fair value of plan assets |  |
Balance at the beginning of the period | 836 | 564
Actual return on plan assets: |  |
Relating to assets still held at the end of the year | (32) | (13)
Relating to assets sold during the year | 0 | 0
Purchases, sales and settlements—net | 58 | 333
Transfer in/(out) of Level 3 | 0 | 0
Foreign exchange | (35) | (48)
Balance at the end of the period | 827 | 836
Significant Unobservable Inputs (Level 3) | Pooled funds - Real estate [Member] |  |
Change in fair value of plan assets |  |
Balance at the beginning of the period | 46 | 23
Actual return on plan assets: |  |
Relating to assets still held at the end of the year | 11 | 3
Relating to assets sold during the year | (10) | 1
Purchases, sales and settlements—net | 41 | 21
Transfer in/(out) of Level 3 | 0 | 0
Foreign exchange | (3) | (2)
Balance at the end of the period | 85 | 46
Significant Unobservable Inputs (Level 3) | Alternative investments [Member] |  |
Change in fair value of plan assets |  |
Balance at the beginning of the period | 968 | 546
Actual return on plan assets: |  |
Relating to assets still held at the end of the year | (17) | 319
Relating to assets sold during the year | 2 | 5
Purchases, sales and settlements—net | 60 | 359
Transfer in/(out) of Level 3 | (266) | (206)
Foreign exchange | (34) | (55)
Balance at the end of the period | 713 | 968
Significant Unobservable Inputs (Level 3) | Pooled funds - Fixed income securities [Member] |  |
Change in fair value of plan assets |  |
Balance at the beginning of the period | 0 |
Actual return on plan assets: |  |
Relating to assets still held at the end of the year | (7) |
Relating to assets sold during the year | (1) |
Purchases, sales and settlements—net | 9 |
Transfer in/(out) of Level 3 | 24 |
Foreign exchange | (1) |
Balance at the end of the period | $ 24 | $ 0

X
- References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Actual return on plan assets, separately identifying the amount related to assets sold during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(02)(A) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (c)(iv)(02)(A) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e2446-114920 + Details
Name: | us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsSoldDuringPeriod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Actual return on plan assets, separately identifying the amount related to assets still held at the reporting date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(02)(A) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (c)(iv)(02)(A) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e2446-114920 + Details
Name: | us-gaap_DefinedBenefitPlanActualReturnOnPlanAssetsStillHeld
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 30 -Section 35 -Paragraph 50 -URI http://asc.fasb.org/extlink&oid=49178875&loc=d3e12355-114930 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The amount of increase or decrease in plan assets attributed to foreign currency changes. The effects of foreign currency exchange rate changes that are to be disclosed are those applicable to plans of a foreign operation whose functional currency is not the reporting currency. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(2) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesPlanAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of increase (decrease) in plan assets from purchases, sales and settlement of plan obligations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(02)(B) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (c)(iv)(02)(B) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e2446-114920 + Details
Name: | us-gaap_DefinedBenefitPlanPurchasesSalesAndSettlements
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Transfers in and out of Level 3. For example, transfers due to changes in the observability of significant inputs. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(02)(C) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (c)(iv)(02)(C) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e2446-114920 + Details
Name: | us-gaap_DefinedBenefitPlanTransfersBetweenMeasurementLevels
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=us-gaap_ForeignPensionPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=aon_GlobalMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=aon_AnnuitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=aon_AlternativeInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=aon_PooledFundsFixedIncomeSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_RealEstateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |