Retirement Plans (Projected Benefit Obligation) (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Weighted average assumptions used to determine the benefit obligation at year end:
Discount rate	3.55%	4.53%	3.93%	4.40%
Rate of increase in compensation levels	3.50%	3.50%	3.50%
Weighted average assumptions used to determine net pension cost:
Discount rate	4.53%	3.93%	4.40%
Rate of increase in compensation levels	3.50%	3.50%	3.50%
Expected long-term rate of return on plan assets	5.50%	5.50%	5.50%