Retirement Benefits (Schedule of Weighted Average Assumptions) (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	3.90%	4.30%	4.00%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	4.30%	4.00%	4.90%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase	3.40%	3.40%	3.40%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase	3.40%	3.40%	3.40%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	7.40%	7.40%	8.10%
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	4.30%	4.50%	4.10%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	4.50%	4.10%	5.00%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	8.00%	8.00%	8.50%