Earnings Per Share (Schedule Of Computation Of Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share[Abstract]
Earnings	$ 55,891	$ 44,667
Diluted earnings	$ 55,891	$ 44,667
Earnings, Shares	15,991	15,954
Dilutive stock options, Shares	446	494
Nonvested stock awards, Shares	79	77
Diluted earnings, Shares	16,516	16,525
Earnings, Earnings per Share	$ 3.50	$ 2.80
Diluted earnings, Earnings per Share	$ 3.38	$ 2.70