Retirement Benefits (Schedule Of Assumption Used Calculating Benefit Obligation) (Details)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Weighted-average assumptions used to determine net periodic benefit cost, Expected return on plan assets	8.25%
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average assumptions used to determine benefit obligations, Discount rate	5.20%	5.80%
Weighted-average assumptions used to determine benefit obligations, Salary scale (ultimate)	3.78%	3.78%
Weighted-average assumptions used to determine net periodic benefit cost, Discount rate	5.80%	6.10%
Weighted-average assumptions used to determine net periodic benefit cost, Salary scale (ultimate)	3.78%	3.78%
Weighted-average assumptions used to determine net periodic benefit cost, Expected return on plan assets	8.50%	8.50%
Retiree Medical And Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average assumptions used to determine benefit obligations, Discount rate	4.89%	5.69%
Weighted-average assumptions used to determine net periodic benefit cost, Discount rate	5.69%	5.90%
Weighted-average assumptions used to determine net periodic benefit cost, Expected return on plan assets	8.50%	8.50%