Pension Plan And Other Postretirement Benefits (Pension And Other Postretirement Benefit Costs) (Details) - Pension Benefits [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3	$ 2	$ 5	$ 6
Interest cost	1	1	2	3
Expected return on plan assets	(2)	(1)	(3)	(3)
Amortization of prior service cost
Amortization of net loss		1	1	1
Curtailment loss		1		1
Settlement loss		8		8
Net periodic benefit cost	$ 2	$ 12	$ 5	$ 16