Segment Information (Tables)

3 Months Ended

Mar. 31, 2013

Segment Reporting [Abstract]

Schedule of total revenue by business segments

Aon’s total revenue is as follows (in millions):

	Three months ended March 31,
	2013			2012
Risk Solutions	$	1,971		$	1,905
HR Solutions	954			945
Intersegment elimination	(10		)	(9		)
Total revenue	$	2,915		$	2,841

Schedule of commissions, fees and other revenues by products

Commissions, fees and other revenues by product are as follows (in millions):

	Three months ended March 31,
	2013			2012
Retail brokerage	$	1,562		$	1,494
Reinsurance brokerage	402			399
Total Risk Solutions Segment	1,964			1,893
Consulting services	382			380
Outsourcing	581			568
Intrasegment	(9		)	(3		)
Total HR Solutions Segment	954			945
Intersegment	(10		)	(9		)
Total commissions, fees and other revenue	$	2,908		$	2,829

Schedule of fiduciary investment income by business segments

Fiduciary investment income by segment is as follows (in millions):

	Three months ended March 31,
	2013		2012
Risk Solutions	$	7	$	12
HR Solutions	—		—
Total fiduciary investment income	$	7	$	12

Schedule of reconciliation of segment income before tax to income from continuing operations before income taxes

A reconciliation of segment operating income before tax to income before income taxes is as follows (in millions):

	Three months ended March 31,
	2013			2012
Risk Solutions	$	403		$	366
HR Solutions	51			73
Segment income before income taxes	454			439
Unallocated expenses	(44		)	(37		)
Interest income	1			3
Interest expense	(52		)	(59		)
Other income	9			—
Income before income taxes	$	368		$	346