Document and Entity Information	3 Months Ended
	Mar. 31, 2013
Document and Entity Information
Entity Registrant Name	Aon plc
Entity Central Index Key	0000315293
Document Type	10-Q
Document Period End Date	Mar. 31, 2013
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	309,126,345
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q1