Computation Of Basic And Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Net income	$ 14,495	$ 5,500	$ 7,484	$ 12,126
Weighted average common shares outstanding - Basic	1,892	1,889	1,891	1,888
Incremental shares outstanding assuming the exercise of dilutive stock options and SARs (share settled)	3	7	4	8
Weighted average common shares outstanding - Diluted	1,895	1,896	1,895	1,896
Basic Earnings per Common Share	$ 7.66	$ 2.91	$ 3.96	$ 6.42
Diluted Earnings per Common Share	$ 7.65	$ 2.90	$ 3.95	$ 6.40