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, 2019	Mar. 31, 2018
Earnings Per Share[Abstract]
Earnings	$ 44,667	$ 44,996
Diluted Earnings	$ 44,667	$ 44,996
Earnings, Shares	15,954	16,100
Dilutive stock options, Shares	494	680
Nonvested stock awards, Shares	77	107
Diluted Earnings, Shares	16,525	16,887
Earnings per Share, Earnings	$ 2.80	$ 2.79
Earnings per Share, Diluted earnings	$ 2.70	$ 2.66