Selected Quarterly Financial Data and Supplemental Information(Details) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015 USD ($) $ / shares	Sep. 30, 2015 USD ($) $ / shares	Jun. 30, 2015 USD ($) $ / shares	Mar. 31, 2015 USD ($) $ / shares	Dec. 31, 2014 USD ($) $ / shares	Sep. 30, 2014 USD ($) $ / shares	Jun. 30, 2014 USD ($) $ / shares	Mar. 31, 2014 USD ($) $ / shares	Dec. 31, 2015 USD ($) $ / shares	Dec. 31, 2014 USD ($) $ / shares	Dec. 31, 2013 USD ($) $ / shares	Feb. 18, 2016 stockholder
Subsequent Event [Line Items]
Revenue | $	$ 3,338	$ 3,115	$ 3,225	$ 3,215	$ 3,246	$ 3,141	$ 3,300	$ 3,264	$ 12,893	$ 12,951	$ 12,261
Operating income | $	594	461	629	735	536	445	647	673	2,419	2,301	2,077
Income from continuing operations | $	380	329	429	498	269	305	440	457	1,636	1,471	1,379
Discontinued operations, net of tax | $	1	2	0	(3)	30	(1)	(2)	(1)	0	26	6
Net income attributable to the Company | $	$ 375	$ 323	$ 419	$ 482	$ 294	$ 297	$ 431	$ 443	$ 1,599	$ 1,465	$ 1,357
Basic Per Share Data:
Continuing operations	$ 0.72	$ 0.61	$ 0.78	$ 0.90	$ 0.49	$ 0.55	$ 0.79	$ 0.81	$ 3.01	$ 2.64	$ 2.46
Discontinued operations, net of tax	0.00	0.00	0.00	(0.01)	0.05	0.00	(0.01)	0.00
Net income attributable to the Company	0.72	0.61	0.78	0.89	0.54	0.55	0.78	0.81	3.01	2.69	2.47
Diluted Per Share Data:
Continuing operations	0.71	0.60	0.77	0.89	0.48	0.54	0.78	0.80	2.98	2.61	2.42
Discontinued operations, net of tax	0.00	0.01	0.00	(0.01)	0.06	0.00	(0.01)	0.00
Net income attributable to the Company	0.71	0.61	0.77	0.88	0.54	0.54	0.77	0.80	$ 2.98	$ 2.65	$ 2.43
Dividends Paid Per Share	$ 0.31	$ 0.31	$ 0.28	$ 0.28	$ 0.28	$ 0.28	$ 0.25	$ 0.25
Subsequent Event
Diluted Per Share Data:
Stockholders of record | stockholder												5,927