Employee Benefits (Schedule Of Fair Value Of Pension Plan Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Allocation Percentage of Assets, Long-Term	60.00%
Defined Benefit Plan, Target Allocation Percentage of Assets, Short-Term	40.00%
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	60.00%
Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	40.00%
Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 650	$ 614
Domestic Plan [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	264	190
Domestic Plan [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	386	424
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	18	16
Foreign Plan [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5	5
Foreign Plan [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13	11
Cash and Cash Equivalents [Member] | Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Cash and Cash Equivalents [Member] | Domestic Plan [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Cash and Cash Equivalents [Member] | Domestic Plan [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Cash and Cash Equivalents [Member] | Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5	5
Cash and Cash Equivalents [Member] | Foreign Plan [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5	5
Cash and Cash Equivalents [Member] | Foreign Plan [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Common Stock [Member] | Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21	17
Common Stock [Member] | Domestic Plan [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21	17
Common Stock [Member] | Domestic Plan [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Common Stock [Member] | Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Common Stock [Member] | Foreign Plan [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Common Stock [Member] | Foreign Plan [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Large-Cap Mutual Funds [Member] | Domestic Plan [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	222	217
Large-Cap Mutual Funds [Member] | Domestic Plan [Member] | Level 1 [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	49	50
Large-Cap Mutual Funds [Member] | Domestic Plan [Member] | Level 2 [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	173	167
Large-Cap Mutual Funds [Member] | Foreign Plan [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2	2
Large-Cap Mutual Funds [Member] | Foreign Plan [Member] | Level 1 [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Large-Cap Mutual Funds [Member] | Foreign Plan [Member] | Level 2 [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2	2
Small-Cap Mutual Funds [Member] | Domestic Plan [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	34	31
Small-Cap Mutual Funds [Member] | Domestic Plan [Member] | Level 1 [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	9	8
Small-Cap Mutual Funds [Member] | Domestic Plan [Member] | Level 2 [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	25	23
Small-Cap Mutual Funds [Member] | Foreign Plan [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Small-Cap Mutual Funds [Member] | Foreign Plan [Member] | Level 1 [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Small-Cap Mutual Funds [Member] | Foreign Plan [Member] | Level 2 [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International Mutual Funds [Member] | Domestic Plan [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	119	107
International Mutual Funds [Member] | Domestic Plan [Member] | Level 1 [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	69	53
International Mutual Funds [Member] | Domestic Plan [Member] | Level 2 [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	50	54
International Mutual Funds [Member] | Foreign Plan [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5	4
International Mutual Funds [Member] | Foreign Plan [Member] | Level 1 [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International Mutual Funds [Member] | Foreign Plan [Member] | Level 2 [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5	4
Bond Mutual Funds [Member] | Domestic Plan [Member] | Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	241	227
Bond Mutual Funds [Member] | Domestic Plan [Member] | Level 1 [Member] | Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	116	62
Bond Mutual Funds [Member] | Domestic Plan [Member] | Level 2 [Member] | Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	125	165
Bond Mutual Funds [Member] | Foreign Plan [Member] | Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6	5
Bond Mutual Funds [Member] | Foreign Plan [Member] | Level 1 [Member] | Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Bond Mutual Funds [Member] | Foreign Plan [Member] | Level 2 [Member] | Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6	5
Short Term Investment Funds [Member] | Domestic Plan [Member] | Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13	15
Short Term Investment Funds [Member] | Domestic Plan [Member] | Level 1 [Member] | Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Short Term Investment Funds [Member] | Domestic Plan [Member] | Level 2 [Member] | Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13	15
Short Term Investment Funds [Member] | Foreign Plan [Member] | Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Short Term Investment Funds [Member] | Foreign Plan [Member] | Level 1 [Member] | Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Short Term Investment Funds [Member] | Foreign Plan [Member] | Level 2 [Member] | Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Discretionary range within asset allocations	10.00%