Retirement Benefits and Trusteed Assets (Pension Plan - Assumptions used in Determining the PBO and Net Pension Costs) (Details) - Pension Plan	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Projected benefit obligation
Discount rate	4.50%	4.12%	4.95%
Rate of compensation increase	4.65%	4.65%	4.20%
Net pension costs
Discount rate	4.12%	4.95%	4.15%
Rate of compensation increase	4.65%	4.20%	4.20%
Expected long-term rate of return on plan assets	7.75%	7.75%	8.25%