Document and Entity Information	6 Months Ended
	Jun. 30, 2012
Document and Entity Information
Entity Registrant Name	Aon plc
Entity Central Index Key	0000315293
Document Type	10-Q
Document Period End Date	Jun. 30, 2012
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	322,406,542
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q2