Equity Compensation Plans (Schedule Of Assumption Of Fair Value Options On The Date Of Grant Using Black-Scholes Option Pricing Model) (Details) - Stock Options	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, minimum	21.10%	19.70%	17.60%
Expected volatility, maximum	26.90%	20.00%	18.20%
Weighted average expected volatility	21.20%	19.70%	17.60%
Expected term (in months)	60 months	64 months	68 months
Risk - free interest rate, minimum	0.40%	1.70%	2.60%
Risk - free interest rate, maximum	1.50%	2.60%	2.90%
Expected dividend yield	2.40%	2.00%	1.80%