Consolidated Statements Of Changes In Shareholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Treasury Stock [Member]	Total
Balance at Dec. 31, 2017	$ 4,689	$ 40,396	$ 82,218	$ (6,028)	$ (6,131)	$ 115,144
Cumulative adjustment for fair value of equity securities			201	(201)
Net income (loss)			6,125			6,125
Other comprehensive income (loss)				(151)		(151)
Cash dividends declared			(4,598)			(4,598)
Acquisition of treasury stock					(88)	(88)
Treasury shares issued under employee stock purchase plan		38			60	98
Treasury shares issued under dividend reinvestment plan		659			758	1,417
Incentive stock options exercised	12	252				264
Stock option compensation expense		185				185
Balance at Dec. 31, 2018	4,701	41,530	83,946	(6,380)	(5,401)	118,396
Net income (loss)			16,115			16,115
Other comprehensive income (loss)				394		394
Cash dividends declared			(5,115)			(5,115)
Acquisition of treasury stock					(3,846)	(3,846)
Treasury shares issued under employee stock purchase plan		27			47	74
Treasury shares issued under dividend reinvestment plan		526			790	1,316
Incentive stock options exercised	9	185				194
Balance at Dec. 31, 2019	$ 4,710	$ 42,268	$ 94,946	$ (5,986)	$ (8,410)	$ 127,528