Consolidated Statements Of Income (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Revenue	$ 3,246	$ 3,115	$ 12,951	$ 12,261	$ 11,924
Expense:
Compensation and benefits			7,515	7,226	7,134
Other operating expenses			3,135	2,958	2,961
Operating expenses			10,650	10,184	10,095
Operating income	536	489	2,301	2,077	1,829
Interest income			21	18	24
Interest expense			(165)	(167)	(181)
Cost of extinguishment of debt			(137)	(24)	0
Investment income			37	69	24
Income before income taxes			2,057	1,973	1,696
Income tax expense			586	594	492
Income from continuing operations	269	307	1,471	1,379	1,204
Discontinued operations, net of tax	30	0	26	6	(3)
Net income before non-controlling interests			1,497	1,385	1,201
Less: Net income attributable to non-controlling interests			32	28	25
Net income attributable to the Company	$ 294	$ 303	$ 1,465	$ 1,357	$ 1,176
Basic Per Share Data:
Basic net income per share – Continuing operations (in dollars per share)	$ 0.49	$ 0.55	$ 2.64	$ 2.46	$ 2.16
Net income attributable to the Company (in dollars per share)	$ 0.54	$ 0.55	$ 2.69	$ 2.47	$ 2.16
Diluted Per Share Data:
Continuing operations (in dollars per share)	$ 0.48	$ 0.54	$ 2.61	$ 2.42	$ 2.13
Net income attributable to the Company (in dollars per share)	$ 0.54	$ 0.54	$ 2.65	$ 2.43	$ 2.13
Average number of shares outstanding
Basic (in shares)			545	549	544
Diluted (in shares)			553	558	552
Shares outstanding at December 31 (in shares)	540	547	540	547	545