Acquisitions (Details) $ in Millions	9 Months Ended		12 Months Ended	21 Months Ended
	Sep. 30, 2015 USD ($) business	Sep. 30, 2014 USD ($) business	Dec. 31, 2014 USD ($) business	Sep. 30, 2015 USD ($)
Business Combinations [Abstract]
Business combinations that were achieved in stages, with non-controlling interests acquired in previous years		2
Number of Businesses Acquired	2	5	8
Total consideration transferred | $	$ 609	$ 389	$ 575
Goodwill, Acquired During Period | $	$ 465			$ 507