XML 88 R74.htm IDEA: XBRL DOCUMENT
v3.19.1

Share-Based Compensation Plans - Performance Share Awards Narrative (Details) - Performance Shares | 3 Months Ended
--- | ---
Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Vesting conditions period (in years) | 3 years
Minimum |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Shares issued, percent | 0.00%
Maximum |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Shares issued, percent | 200.00%

X
- Definition Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued, Percent + References No definition available. + Details
Name: | aon_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedPercent
Namespace Prefix: | aon_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Share-based Compensation Arrangement by Share-based Payment Award, Vesting Conditions Period + References No definition available. + Details
Name: | aon_SharebasedCompensationArrangementbySharebasedPaymentAwardVestingConditionsPeriod
Namespace Prefix: | aon_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

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_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_AwardTypeAxis=us-gaap_PerformanceSharesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |