Retirement Plans (Schedule Of Net Periodic Benefit Cost (Credit) For Pension And Postretirement Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 4
Settlement loss - net periodic benefit cost (credit)	3	$ 2	$ 0
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	10
Net gain (loss) in AOCI expected to be recognized in next year	(2)
Defined Benefit Plan, Benefit Obligation	154	165	173
Interest cost	6	7	7
Expected return on plan assets	(11)	(11)	(12)
Defined Benefit Plan, Amortization of Gain (Loss)	4	6	6
Defined Benefit Plan, Actuarial Net (Gains) Losses	2	(2)
Defined Benefit Plan, Benefit Obligation, Benefits Paid	19	13
Defined Benefit Plan, Fair Value of Plan Assets	168	161	157
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)	26	13
Defined Benefit Plan, Plan Assets, Contributions by Employer	0	4
Defined Benefit Plan, Funded (Unfunded) Status of Plan	14	(4)
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position	14	(4)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	2	4	1
Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax	(28)	(48)
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax	(28)	(48)
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	10
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	10
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	10
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	9
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	45
Supplemental Employee Retirement Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	2
Net gain (loss) in AOCI expected to be recognized in next year	0
Defined Benefit Plan, Benefit Obligation	10	10	10
Interest cost	1	1	1
Defined Benefit Plan, Amortization of Gain (Loss)	0	0	0
Defined Benefit Plan, Actuarial Net (Gains) Losses	0	0
Defined Benefit Plan, Benefit Obligation, Benefits Paid	1	1
Defined Benefit Plan, Fair Value of Plan Assets	0	0	0
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)	0	0
Defined Benefit Plan, Plan Assets, Contributions by Employer	1	1
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(10)	(10)
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position	(10)	(10)
Settlement loss - net periodic benefit cost (credit)	0	0	0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	1	1	1
Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax	(2)	(2)
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax	(2)	(2)
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	1
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	1
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	1
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	1
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	3
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	0
Net gain (loss) in AOCI expected to be recognized in next year	0
Defined Benefit Plan, Benefit Obligation	1	1	1
Interest cost	0	0	0
Defined Benefit Plan, Amortization of Gain (Loss)	0	0	0
Defined Benefit Plan, Actuarial Net (Gains) Losses	0	0
Defined Benefit Plan, Benefit Obligation, Benefits Paid	0	0
Defined Benefit Plan, Fair Value of Plan Assets	0	0	0
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)	0	0
Defined Benefit Plan, Plan Assets, Contributions by Employer	0	0
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(1)	(1)
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position	(1)	(1)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	0	0	$ 0
Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax	0	0
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax	0	$ 0
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	0
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	0
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	0
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	0
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	$ 0