Condensed Consolidated Statements of Income (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Revenue
Commissions, fees and other	$ 2,913		$ 2,891		$ 5,854		$ 5,799
Fiduciary investment income	6		6		12		13
Total revenue	2,919		2,897		5,866		5,812
Expenses
Compensation and benefits	1,708		1,712		3,459		3,437
Other general expenses	766		803		1,493		1,583
Total operating expenses	2,474		2,515		4,952		5,020
Operating income	445		382		914		792
Interest income	2		2		4		3
Interest expense	(65)		(48)		(123)		(100)
Other (expense) income	(2)		6		(1)		15
Income before income taxes	380		342		794		710
Income taxes	67		90		145		186
Net income	313		252		649		524
Less: Net income attributable to noncontrolling interests	9		11		20		22
Net income attributable to Aon shareholders	$ 304		$ 241		$ 629		$ 502
Basic net income per share attributable to Aon shareholders	$ 1.02		$ 0.77		$ 2.09		$ 1.59
Diluted net income per share attributable to Aon shareholders	$ 1.01		$ 0.76		$ 2.07		$ 1.58
Cash dividends per share paid on ordinary shares	$ 0.251		$ 0.18		$ 0.425		$ 0.33
Weighted average ordinary shares outstanding - basic (in shares)	298.5	[1]	313.7	[1]	301.0	[1]	315.0	[1]
Weighted average ordinary shares outstanding - diluted (in shares)	301.6		317.1		304.4		318.6

[1] Includes 3.0 million and 4.0 million of participating securities for the three months ended June 30, 2014 and 2013, respectively, and 3.2 million and 4.1 million of participating securities for the six months ended June 30, 2014 and 2013, respectively.