Intangible Assets (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 15,541	$ 15,332	$ 4,796
Other intangible assets	6,500	6,800
Intangible assets subject to amortization	3,500	3,805
Intangible assets not subject to amortization	3,000
Amortization of Purchased Intangibles	$ 260	$ 19	$ 171