Acquisitions (Pro-Forma Information) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Business Combinations [Abstract]
Revenue	$ 3,496	$ 3,493	$ 7,011	$ 6,951
Net income attributable to the Company	$ 502	$ 470	$ 1,072	$ 950
Basic net income per share:
Basic net income per share attributable to the Company (in dollars per share)	$ 0.98	$ 0.90	$ 2.08	$ 1.82
Diluted net income per share:
Diluted net income per share attributable to the Company (in dollars per share)	$ 0.96	$ 0.89	$ 2.06	$ 1.81