Consolidated Statements of Income (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Income Statement [Abstract]
Revenue	$ 3,215	$ 3,264
Expense:
Compensation and benefits	1,730	1,839
Other operating expenses	750	752
Operating expenses	2,480	2,591
Operating income	735	673
Interest income	3	5
Interest expense	(36)	(42)
Investment income	2	13
Income before income taxes	704	649
Income tax expense	206	192
Income from continuing operations	498	457
Discontinued operations, net of tax	(3)	(1)
Net income before non-controlling interests	495	456
Less: Net income attributable to non-controlling interests	13	13
Net income attributable to the Company	$ 482	$ 443
Basic net income per share
Basic net income per share - Continuing operations (usd per share)	$ 0.90	$ 0.81
Basic net income per share - Net income attributable to the Company (usd per share)	$ 0.89	$ 0.81
Diluted net income per share
Diluted net income per share - Continuing operations (usd per share)	$ 0.89	$ 0.80
Diluted net income per share - Net income attributable to the Company (usd per share)	$ 0.88	$ 0.80
Average number of shares outstanding
Average number of shares outstanding - Basic	539	548
Average number of shares outstanding - Diluted	545	556
Shares outstanding at March 31	538	549