Condensed Consolidated Statements of Income (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Revenue
Commissions, fees and other	$ 2,908		$ 2,829
Fiduciary investment income	7		12
Total revenue	2,915		2,841
Expenses
Compensation and benefits	1,725		1,661
Other general expenses	780		778
Total operating expenses	2,505		2,439
Operating income	410		402
Interest income	1		3
Interest expense	(52)		(59)
Other income	9		0
Income before income taxes	368		346
Income taxes	96		97
Net income	272		249
Less: Net income attributable to noncontrolling interests	11		11
Net income attributable to Aon shareholders	$ 261		$ 238
Basic net income per share attributable to Aon shareholders (in dollars per share)	$ 0.82		$ 0.72
Diluted net income per share attributable to Aon shareholders (in dollars per share)	$ 0.82		$ 0.71
Cash dividends per share paid on ordinary shares (in dollars per share)	$ 0.16		$ 0.15
Weighted average ordinary shares outstanding - basic (in shares)	316.4	[1]	332.4	[1]
Weighted average ordinary shares outstanding - diluted (in shares)	320.0		336.6

[1] Includes 4.2 million and 4.9 million of participating securities for the three months ended March 31, 2013 and 2012, respectively.