Goodwill and Other Intangibles (Changes in the Carrying Amount of Goodwill) (Details) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017
Goodwill [Roll Forward]
Balance as of January 1,		$ 9,089	$ 8,369
Goodwill acquired		410	533
Other adjustments	[1]	(64)	198
Balance at September 30,		$ 9,435	$ 9,100

[1] Primarily reflects the impact of foreign exchange.