Quarterly Financial Data (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Data [Abstract]
Goodwill, Impairment Loss	$ 2,078		$ 2,748
Goodwill, Impairment Loss, Net of Tax	$ 1,822
Restructuring Charges		$ 80	82	$ 91	$ 2
Restructuring Charges, Net of Tax		52
Acquisition and integration costs		49	$ 25	$ 436	$ 236
Acquisition and integration costs, after tax		$ 48