Acquisitions and Dispositions (Pro-Forma Information) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Business Combinations [Abstract]
Revenue	$ 3,967	$ 3,940	$ 12,830	$ 12,842
Net income attributable to the Company	$ 306	$ 181	$ 1,445	$ 804
Basic net income per share attributable to the Company (in dollars per share)	$ 0.61	$ 0.36	$ 2.85	$ 1.59
Diluted net income per share attributable to the Company (in dollars per share)	$ 0.60	$ 0.36	$ 2.83	$ 1.57