Retirement Plans (Schedule Of Net Periodic Benefit Cost (Credit) For Pension And Postretirement Plans) (Details) - Pension Plan [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 1	$ 2
Expected return on plan assets	(3)	(3)
Amortization of net actuarial (gain) loss	0	1
Net periodic benefit cost (credit)	(1)	1
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	$ 1	$ 1