Restructuring Costs (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring Costs [Abstract]
Restructuring Reserve	$ 47	$ 25	$ 47	$ 1
Severance Costs		68	65
Defined Benefit Plan, Special termination Benefits cost		5	26
Loss on sale of business		9
Restructuring Charges	$ 80	$ 82	$ 91	$ 2