XML 96 R78.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Income Taxes Operating Loss Carryforwards (Details) - USD ($) $ in Millions | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | ---
U.K. |  |
Operating Loss Carryforwards [Line Items] |  |
Operating loss carryforwards | $ 675 | $ 325
Capital Loss Carryforwards | 415 | 294
U.S. Federal |  |
Operating Loss Carryforwards [Line Items] |  |
Operating loss carryforwards | 36 | 193
U.S. State |  |
Operating Loss Carryforwards [Line Items] |  |
Operating loss carryforwards | 412 | 474
Other |  |
Operating Loss Carryforwards [Line Items] |  |
Operating loss carryforwards | 392 | 350
Capital Loss Carryforwards | $ 232 | $ 218

X
- Definition The sum of domestic, foreign and state and local capital loss carryforwards, before tax effects, available to reduce future taxable income under enacted tax laws. + References No definition available. + Details
Name: | aon_CapitalLossCarryforwards
Namespace Prefix: | aon_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32559-109319 + Details
Name: | us-gaap_OperatingLossCarryforwards
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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: | us-gaap_OperatingLossCarryforwardsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_IncomeTaxAuthorityAxis=us-gaap_DomesticCountryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeTaxAuthorityAxis=us-gaap_InternalRevenueServiceIRSMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeTaxAuthorityAxis=us-gaap_StateAndLocalJurisdictionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeTaxAuthorityAxis=aon_OtherCountryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |