Condensed Consolidated Statements of Financial Position (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
CURRENT ASSETS
Cash and cash equivalents	$ 323	$ 272
Short-term investments	510	785
Receivables, net	3,164	3,183
Fiduciary assets	11,795	10,838
Other current assets	415	427
Total Current Assets	16,207	15,505
Goodwill	8,896	8,770
Intangible assets, net	3,203	3,276
Fixed assets, net	808	783
Investments	211	239
Other non-current assets	946	979
TOTAL ASSETS	30,271	29,552
CURRENT LIABILITIES
Fiduciary liabilities	11,795	10,838
Short-term debt and current portion of long-term debt	286	337
Accounts payable and accrued liabilities	1,432	1,832
Other current liabilities	739	753
Total Current Liabilities	14,252	13,760
Long-term debt	4,168	4,155
Pension, other post retirement, and post employment liabilities	2,072	2,192
Other non-current liabilities	1,363	1,325
TOTAL LIABILITIES	21,855	21,432
EQUITY
Common stock-$1 par value Authorized: 750 shares (issued: 2012 - 386.4; 2011 - 386.4)	386	386
Additional paid-in capital	3,913	4,021
Retained earnings	8,770	8,594
Treasury stock at cost (shares: 2012 - 60.0; 2011 - 61.6)	(2,472)	(2,553)
Accumulated other comprehensive loss	(2,239)	(2,370)
TOTAL AON STOCKHOLDERS' EQUITY	8,358	8,078
Noncontrolling interests	58	42
TOTAL EQUITY	8,416	8,120
TOTAL LIABILITIES AND EQUITY	$ 30,271	$ 29,552