Selected Quarterly Financial Data and Supplemental Information(Details) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016 USD ($) $ / shares	Sep. 30, 2016 USD ($) $ / shares	Jun. 30, 2016 USD ($) $ / shares	Mar. 31, 2016 USD ($) $ / shares	Dec. 31, 2015 USD ($) $ / shares	Sep. 30, 2015 USD ($) $ / shares	Jun. 30, 2015 USD ($) $ / shares	Mar. 31, 2015 USD ($) $ / shares	Dec. 31, 2016 USD ($) $ / shares	Dec. 31, 2015 USD ($) $ / shares	Dec. 31, 2014 USD ($) $ / shares	Feb. 16, 2017 stockholder
Subsequent Event [Line Items]
Revenue | $	$ 3,364	$ 3,135	$ 3,376	$ 3,336	$ 3,338	$ 3,115	$ 3,225	$ 3,215	$ 13,211	$ 12,893	$ 12,951
Operating income | $	633	572	726	733	594	461	629	735	2,664	2,419	2,301
Income from continuing operations | $	441	384	480	490	380	329	429	498	1,795	1,636	1,471
Discontinued operations, net of tax | $	0	0	0	0	1	2	0	(3)	0	0	26
Net income attributable to the Company | $	$ 436	$ 379	$ 472	$ 481	$ 375	$ 323	$ 419	$ 482	$ 1,768	$ 1,599	$ 1,465
Basic Per Share Data:
Continuing operations	$ 0.85	$ 0.73	$ 0.91	$ 0.92	$ 0.72	$ 0.61	$ 0.78	$ 0.90	$ 3.41	$ 3.01	$ 2.64
Discontinued operations, net of tax	0.00	0.00	0.00	0.00	0.00	0.00	0.00	(0.01)
Net income attributable to the Company	0.85	0.73	0.91	0.92	0.72	0.61	0.78	0.89	3.41	3.01	2.69
Diluted Per Share Data:
Continuing operations	0.84	0.73	0.90	0.91	0.71	0.60	0.77	0.89	3.38	2.98	2.61
Discontinued operations, net of tax	0.00	0.00	0.00	0.00	0.00	0.01	0.00	(0.01)
Net income attributable to the Company	0.84	0.73	0.90	0.91	0.71	0.61	0.77	0.88	$ 3.38	$ 2.98	$ 2.65
Dividends Paid Per Share	$ 0.34	$ 0.34	$ 0.31	$ 0.31	$ 0.31	$ 0.31	$ 0.28	$ 0.28
Subsequent Event
Diluted Per Share Data:
Stockholders of record | stockholder												5,718