Postretirement Benefits (Components Of Postretirement Benefit Expense) (Details) - Other Postretirement Benefits Plan [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1	$ 1	$ 1
Interest cost	11	11	11
Amortization of Gains (Losses)	8	5	6
Amortization of prior service credits	(3)	(4)	(10)
Net periodic pension expense	17	13	8
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	1
Interest cost	2	3	5
Amortization of Gains (Losses)	3	2	1
Amortization of prior service credits	(4)	(4)	(2)
Net periodic pension expense	$ 1	$ 1	$ 5