Goodwill and Other Intangibles (Changes in the Carrying Amount of Goodwill) (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017
Goodwill [Roll Forward]
Balance as of January 1,		$ 9,089	$ 8,369
Goodwill acquired		116	370
Other adjustments	[1]	(28)	82
Balance at June 30,		$ 9,177	$ 8,821

[1] Primarily reflects the impact of foreign exchange.