Summary Of Significant Accounting Policies (Schedule Of Assumptions For Valuing Stock Options Granted) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	2.50%	2.40%	2.30%
Weighted average volatility percentage	43.80%	38.30%	38.30%
Weighted average risk-free interest rate	0.80%	2.40%	2.80%
Weighted average exercise price at date of grant (also weighted average market price at date of grant):	$ 11.90	$ 18.48	$ 19.35
Officers
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Holding period (years):	5 years	5 years	5 years
Weighted average exercise price at date of grant (also weighted average market price at date of grant):	$ 14.41	$ 18.48	$ 19.35