Defined Benefit Pension Plans (Weighted-Average Assumptions Used) (Details)	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Qualified Pension Plan [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Equivalent single discount rate for benefit obligations	3.69%	4.18%
Equivalent single discount rate for service cost	3.76%	4.29%
Equivalent single discount rate for interest cost	3.42%	3.73%
Expected long-term return on plan assets	6.75%	6.75%
Rate of compensation increase	3.75%	3.75%
Non-Qualified Retirement Plans [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Equivalent single discount rate for benefit obligations	3.58%	3.96%
Equivalent single discount rate for service cost	3.79%	4.25%
Equivalent single discount rate for interest cost	3.22%	3.36%
Rate of compensation increase	3.75%	3.75%