Equity Incentive Plans (Summary Of Exercisable Options) (Details) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2020 USD ($) $ / shares shares
Options outstanding (in shares)	109,875
Weighted avg. life remaining (in years)	3 years 6 months
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ / shares	$ 55.67
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value | $	$ 0
Forty Four Point Sixty Two To Forty Nine Point Nine Nine [Member]
Options outstanding (in shares)	27,215
Weighted avg. life remaining (in years)	1 year 7 months 6 days
Fifty To Fifty Nine Point Nine Nine Member
Options outstanding (in shares)	29,793
Weighted avg. life remaining (in years)	3 years 6 months
Sixty To Sixty Five Point Five Zero Member
Options outstanding (in shares)	50,719
Weighted avg. life remaining (in years)	4 years 4 months 24 days
Seventy To Seventy Six Point Six Three [Member]
Options outstanding (in shares)	2,148
Weighted avg. life remaining (in years)	6 years 9 months 18 days