Defined Benefit Pension Plans (Weighted-Average Assumptions Used) (Details)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
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	3.42%	4.38%
Equivalent single discount rate for service cost	3.54%	4.44%
Equivalent single discount rate for interest cost	3.07%	4.12%
Expected long-term return on plan assets	5.75%	5.75%
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	3.30%	4.28%
Equivalent single discount rate for service cost	3.62%	4.48%
Equivalent single discount rate for interest cost	2.93%	3.98%
Rate of compensation increase	3.75%	3.75%