Computation Of Basic And Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share [Abstract]
Net income	$ 14,503	$ 15,301	$ 48,108	$ 22,785
Weighted average common shares outstanding - Basic	1,894	1,892	1,894	1,892
Incremental shares outstanding assuming the exercise of dilutive stock options and SARs (share settled)	6	3	5	4
Weighted average common shares outstanding - Diluted	1,900	1,895	1,899	1,896
Basic Earnings per Common Share	$ 7.66	$ 8.09	$ 25.40	$ 12.04
Diluted Earnings per Common Share	$ 7.63	$ 8.07	$ 25.34	$ 12.02