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
Income Statement [Abstract]
Revenue	$ 3,300	$ 3,088	$ 6,564	$ 6,214
Expense:
Compensation and benefits	1,876	1,766	3,715	3,569
Other operating expenses	777	745	1,529	1,461
Operating expenses	2,653	2,511	5,244	5,030
Operating income	647	577	1,320	1,184
Interest income	5	4	10	8
Interest expense	(42)	(40)	(84)	(84)
Investment income	(2)	23	11	44
Income before income taxes	608	564	1,257	1,152
Income tax expense	168	164	360	340
Income from continuing operations	440	400	897	812
Discontinued operations, net of tax	(2)	(5)	(3)	7
Net income before non-controlling interests	438	395	894	819
Less: Net income attributable to non-controlling interests	7	7	20	18
Net income attributable to the Company	$ 431	$ 388	$ 874	$ 801
Basic net income per share
Basic net income per share - Continuing operations	$ 0.79	$ 0.71	$ 1.60	$ 1.45
Basic net income per share - Net income attributable to the Company	$ 0.78	$ 0.71	$ 1.59	$ 1.46
Diluted net income per share
Diluted net income per share - Continuing operations	$ 0.78	$ 0.70	$ 1.58	$ 1.42
Diluted net income per share - Net income attributable to the Company	$ 0.77	$ 0.69	$ 1.57	$ 1.44
Average number of shares outstanding
Average number of shares outstanding - Basic	549	551	548	549
Average number of shares outstanding - Diluted	556	559	556	558
Shares outstanding at June 30	546	549	546	549