Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Statement [Abstract]
Revenue	$ 3,225	$ 3,300	$ 6,440	$ 6,564
Expense:
Compensation and benefits	1,826	1,876	3,556	3,715
Other operating expenses	770	777	1,520	1,529
Operating expenses	2,596	2,653	5,076	5,244
Operating income	629	647	1,364	1,320
Interest income	3	5	6	10
Interest expense	(40)	(42)	(76)	(84)
Investment income (loss)	3	(2)	5	11
Income before income taxes	595	608	1,299	1,257
Income tax expense	166	168	372	360
Income from continuing operations	429	440	927	897
Discontinued operations, net of tax	0	(2)	(3)	(3)
Net income before non-controlling interests	429	438	924	894
Less: Net income attributable to non-controlling interests	10	7	23	20
Net income attributable to the Company	$ 419	$ 431	$ 901	$ 874
Basic net income per share
Basic net income per share - Continuing operations (usd per share)	$ 0.78	$ 0.79	$ 1.68	$ 1.60
Basic net income per share - Net income attributable to the Company (usd per share)	0.78	0.78	1.68	1.59
Diluted net income per share
Diluted net income per share - Continuing operations (usd per share)	0.77	0.78	1.66	1.58
Diluted net income per share - Net income attributable to the Company (usd per share)	$ 0.77	$ 0.77	$ 1.66	$ 1.57
Average number of shares outstanding
Average number of shares outstanding - Basic	535	549	537	548
Average number of shares outstanding - Diluted	541	556	543	556
Shares outstanding at June 30	531	546	531	546