Benefit Plans (Actuarial Assumptions for Net Cost or Benefit) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.95%	4.15%
Expected long term rate of return	7.50%	7.50%	7.50%
Rate of compensation increases			3.92%
Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.75%	2.75%	2.50%
Maximum | Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Discount rate			4.00%
Minimum | Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Discount rate			3.85%