Retirement Benefit Plans (Weighted Average Assumptions used to Determine Benefit Obligations) (Details)	Dec. 31, 2019	Dec. 31, 2018
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate (as a percent)	3.07%	4.12%
SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate (as a percent)	2.82%	3.95%
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate (as a percent)	2.50%	3.69%