Pension Plan And Other Postretirement Benefits (Pension And Other Postretirement Benefit Costs) (Details) - Pension Benefits [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2	$ 3	$ 7	$ 9
Interest cost	2	1	4	4
Expected return on plan assets	(1)	(2)	(4)	(5)
Amortization of prior service cost
Amortization of net loss			1	1
Curtailment loss				1
Settlement loss		2		10
Net periodic benefit cost	$ 3	$ 4	$ 8	$ 20