Acquisitions (Pro-Forma Information) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Business Combinations [Abstract]
Revenue	$ 3,349	$ 3,256	$ 10,416	$ 10,232
Net income attributable to the Company	$ 392	$ 372	$ 1,466	$ 1,320
Basic net income per share:
Basic net income per share attributable to the Company (in dollars per share)	$ 0.77	$ 0.72	$ 2.85	$ 2.54
Diluted net income per share:
Diluted net income per share attributable to the Company (in dollars per share)	$ 0.76	$ 0.71	$ 2.82	$ 2.52