Restructuring Costs (Changes In Restructuring Reserve) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Restructuring Costs [Abstract]
Restructuring Reserve, Beginning Balance	$ 47	$ 1
Severance Costs	68	65
Cash payments during the period	(90)	(19)
Restructuring Reserve, Ending Balance	$ 25	$ 47