Acquisitions (Pro-Forma Information) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Business Combinations [Abstract]
Revenue	$ 3,748	$ 3,539	$ 7,770	$ 7,098
Net income attributable to the Company	$ 532	$ 503	$ 1,225	$ 1,072
Basic net income per share:
Basic net income per share attributable to the Company (in dollars per share)	$ 1.05	$ 0.98	$ 2.41	$ 2.08
Diluted net income per share:
Diluted net income per share attributable to the Company (in dollars per share)	$ 1.04	$ 0.97	$ 2.39	$ 2.06