Retirement Benefits (Schedule of Weighted Average Assumptions) (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2011	Dec. 31, 2011 Pension Plans, Defined Benefit [Member]	Dec. 31, 2010 Pension Plans, Defined Benefit [Member]	Dec. 31, 2009 Pension Plans, Defined Benefit [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member]	Dec. 31, 2010 Other Postretirement Benefit Plans, Defined Benefit [Member]	Dec. 31, 2009 Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate			5.00%	5.60%	5.90%	5.10%	5.80%	6.00%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate			5.60%	5.90%	6.70%	5.80%	6.00%	6.90%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase			3.70%	3.70%	3.70%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase			3.70%	3.70%	4.10%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets			8.50%	8.80%	8.80%	8.80%	9.00%	9.00%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year		7.40%
Defined Benefit Plan, Direction and Pattern for Assumed Health Care Cost Trend Rate		0.30%
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate	5.00%
Defined Benefit Plan, Year that Rate Reaches Ultimate Trend Rate	2020