XML 99 R85.htm IDEA: XBRL DOCUMENT
v3.19.2

Guarantee of Registered Securities - Narrative (Details) - subsidiary | Jun. 30, 2019 | May 02, 2019 | Dec. 31, 2018 | Dec. 03, 2018
--- | --- | --- | --- | ---
Condensed Financial Statements, Captions [Line Items] |  |  |  |
Number of subsidiaries |  |  | 2 |
Aon plc |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |
Parent company's percentage ownership of guarantors | 100.00% |  |  |
5.00% Senior notes due September 2020 |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |
Debt interest rate percentage (as a percent) | 5.00% |  |  |
8.205% Junior subordinated deferrable interest debentures due January 2027 |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |
Debt interest rate percentage (as a percent) | 8.205% |  |  |
6.25% Senior notes due September 2040 |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |
Debt interest rate percentage (as a percent) | 6.25% |  |  |
4.250% Senior notes due 2042 |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |
Debt interest rate percentage (as a percent) | 4.25% |  |  |
4.45% notes due 2043 |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |
Debt interest rate percentage (as a percent) | 4.45% |  |  |
4.00% notes due 2023 |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |
Debt interest rate percentage (as a percent) | 4.00% |  |  |
2.875% notes due 2026 |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |
Debt interest rate percentage (as a percent) | 2.875% |  |  |
3.50% Notes due June 2024 |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |
Debt interest rate percentage (as a percent) | 3.50% |  |  |
4.60% notes due May 2044 |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |
Debt interest rate percentage (as a percent) | 4.60% |  |  |
4.75% Notes Due May 2045 |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |
Debt interest rate percentage (as a percent) | 4.75% |  |  |
4.500% Senior Notes Due December 2028 | Senior Notes |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |
Debt interest rate percentage (as a percent) | 4.50% |  |  | 4.50%
3.75% Senior Notes Due May 2, 2029 | Senior Notes |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |
Debt interest rate percentage (as a percent) | 3.75% | 3.75% |  |
2.80% Senior Notes Due 2021 |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |
Debt interest rate percentage (as a percent) | 2.80% |  |  |
3.875% due in December 2025 |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |
Debt interest rate percentage (as a percent) | 3.875% |  |  |

X
- Definition Number Of Subsidiaries + References No definition available. + Details
Name: | aon_NumberOfSubsidiaries
Namespace Prefix: | aon_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition The parent's direct and indirect ownership percentage of the subsidiaries that are guarantors of the entity's debt. + References No definition available. + Details
Name: | aon_SubsidiaryGuarantorsPercentageOwned
Namespace Prefix: | aon_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | srt_CondensedFinancialStatementsCaptionsLineItems
Namespace Prefix: | srt_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | srt_ConsolidatedEntitiesAxis=srt_ParentCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=aon_SeniorNotes500PercentDue2020Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=aon_JuniorSubordinatedDeferrableInterestDebentures8Point205PercentDue2027Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=aon_SeniorNotes625PercentDue2040Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=aon_NotesDue2042At4250PercentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=aon_NotesDueat2043at4.45PercentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=aon_SeniorNotes4.00PercentDue2023Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=aon_A2.875notesdue2026Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=aon_A3.50NotesdueJune2024Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=aon_A4.60notesdueMay2044Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=aon_A4.75NotesDueMay2045Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=aon_A4.500SeniorNotesDueDecember2028Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=aon_A3.75SeniorNotesDueMay22029Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=aon_TwoPointEightZeroPercentSeniorNotesDueTwentyTwentyOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=aon_ThreePointEightSevenFiveSeniorNoteDueinDecemberTwentyTwentyFiveMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |