Retirement Plans (Schedule Of Net Periodic Benefit Cost (Credit) For Pension And Postretirement Plans) (Details) - Pension Plan [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]
Interest cost	$ 2	$ 2	$ 5	$ 5
Expected return on plan assets	(3)	(3)	(9)	(9)
Amortization of net actuarial (gain) loss	1	1	4	5
Net periodic benefit cost (credit)	1	3	2	4
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	$ 1	$ 3	$ 2	$ 3