Name:	aon_OperatingLeasesFutureMinimumPaymentsDueNetOfSubleaseRentalIncomeCurrent
Namespace Prefix:	aon_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The total of future contractually required payments, net of sublease rental income, on leases defined as operating.

No definition available.

Name:	aon_OperatingLeasesFutureMinimumPaymentsNetOfSubleaseRentalIncomeDue
Namespace Prefix:	aon_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments, net of sublease rental income, due within the fifth year of the balance sheet date relating to leases defined as operating.

No definition available.

Name:	aon_OperatingLeasesFutureMinimumPaymentsNetOfSubleaseRentalIncomeDueInFiveYears
Namespace Prefix:	aon_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

No definition available.

Name:	aon_OperatingLeasesFutureMinimumPaymentsNetOfSubleaseRentalIncomeDueInFourYears
Namespace Prefix:	aon_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments, net of sublease rental income due within the third year of the balance sheet date relating to leases defined as operating.

No definition available.

Name:	aon_OperatingLeasesFutureMinimumPaymentsNetOfSubleaseRentalIncomeDueInThreeYears
Namespace Prefix:	aon_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments, net of sublease rental income, due after the fifth year from the balance sheet date on leases defined as operating.

No definition available.

Name:	aon_OperatingLeasesFutureMinimumPaymentsNetOfSubleaseRentalIncomeDueThereafter
Namespace Prefix:	aon_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments, net of sublease rental income, due within the second year of the balance sheet date relating to leases defined as operating.

No definition available.

Name:	aon_OperatingLeasesFutureMinimumPaymentsNetOfSubleaseRentalsDueInTwoYears
Namespace Prefix:	aon_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Represents the percentage of entity's lease obligations for the use of office space.

No definition available.

Name:	aon_PercentageOfLeaseObligationsRelatedToOfficeSpace
Namespace Prefix:	aon_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Rental expense incurred for leased assets including furniture and equipment which has not been recognized in costs and expenses applicable to sales and revenues; for example, cost of goods sold or other operating costs and expenses.

No definition available.

Name:	us-gaap_LeaseAndRentalExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_LeasesOperatingAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsDueAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_OperatingLeasesRentExpenseAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6453985&loc=d3e41499-112717

Name:	us-gaap_OperatingLeasesRentExpenseNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The total amount of sublease rental income recognized during the period that reduces the entity's rent expense incurred under operating leases.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Topic 840

-SubTopic 10

-Section 55

-Paragraph 40

-Subparagraph (Note 3)

-Name Accounting Standards Codification

-URI http://asc.fasb.org/extlink&oid=6584154&loc=d3e38371-112697