Goodwill and Other Intangible Assets, net (Schedule of Goodwill and Net Carrying Amount of Intangible Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Balance at beginning of period	$ 5,307	$ 5,285
Acquisitions	0	22
Asset impairment	(111)	0
Balance of end of period	5,196	5,307	$ 5,285
Intangible Assets [Roll Forward]
Balance beginning of period	12,400	12,036
Acquisitions	15	385
Asset Impairment	(98)	0
Amortization	(38)	(21)	(21)
Balance end of period	$ 12,279	$ 12,400	$ 12,036