Consolidated Statements of Income (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Statement [Abstract]
Revenue	$ 3,141	$ 2,932	$ 9,705	$ 9,146
Expense:
Compensation and benefits	1,904	1,824	5,619	5,393
Other operating expenses	792	704	2,321	2,165
Operating expenses	2,696	2,528	7,940	7,558
Operating income	445	404	1,765	1,588
Interest income	6	5	16	13
Interest expense	(45)	(40)	(129)	(124)
Investment income	26	14	37	58
Income before income taxes	432	383	1,689	1,535
Income tax expense	127	123	487	463
Income from continuing operations	305	260	1,202	1,072
Discontinued operations, net of tax	(1)	(1)	(4)	6
Net income before non-controlling interests	304	259	1,198	1,078
Less: Net income attributable to non-controlling interests	7	6	27	24
Net income attributable to the Company	$ 297	$ 253	$ 1,171	$ 1,054
Basic net income per share
Basic net income per share - Continuing operations (usd per share)	$ 0.55	$ 0.46	$ 2.15	$ 1.91
Basic net income per share - Net income attributable to the Company (usd per share)	$ 0.55	$ 0.46	$ 2.14	$ 1.92
Diluted net income per share
Diluted net income per share - Continuing operations (usd per share)	$ 0.54	$ 0.45	$ 2.12	$ 1.88
Diluted net income per share - Net income attributable to the Company (usd per share)	$ 0.54	$ 0.45	$ 2.11	$ 1.89
Average number of shares outstanding
Average number of shares outstanding - Basic	544	549	547	549
Average number of shares outstanding - Diluted	551	558	554	558
Shares outstanding at September 30	542	547	542	547