Consolidated Statements Of Income (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Income Statement [Abstract]
Revenue	$ 3,051	$ 2,884
Expense:
Compensation and benefits	1,796	1,721
Other operating expenses	728	691
Operating expenses	2,524	2,412
Operating Income	527	472
Interest income	6	7
Interest expense	(46)	(51)
Investment income (loss)	20	19
Income before income taxes	507	447
Income tax expense	153	128
Income from continuing operations	354	319
Discontinued operations, net of tax		12
Net income before non-controlling interest	354	331
Less: Net income attributable to non-controlling interests	7	6
Net income attributable to the Company	$ 347	$ 325
Basic net income per share
- Continuing operations	$ 0.64	$ 0.57
- Net income attributable to the Company	$ 0.64	$ 0.59
Diluted net income per share
- Continuing operations	$ 0.63	$ 0.56
- Net income attributable to the Company	$ 0.63	$ 0.58
Average number of shares outstanding
- Basic (in shares)	542	544
- Diluted (in shares)	551	552
Shares outstanding at March 31, (in shares)	546	548