Condensed Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($)	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total
Balance (in shares) at Dec. 31, 2019	12,885,273
Balance at Dec. 31, 2019	$ 129,000	$ 708,000	$ 32,390,000	$ 33,227,000
Net income	$ 0	0	5,342,000	5,342,000
Common stock repurchased and retired (in shares)	(35,100)
Common stock repurchased and retired	$ 0	(125,000)	0	(125,000)
Stock-based compensation expense	$ 0	91,000	0	91,000
Options exercised (in shares)	712,839
Options exercised	$ 7,000	1,834,000	0	1,841,000
Balance (in shares) at Mar. 31, 2020	13,563,012
Balance at Mar. 31, 2020	$ 136,000	2,508,000	37,732,000	40,376,000
Balance (in shares) at Dec. 31, 2019	12,885,273
Balance at Dec. 31, 2019	$ 129,000	708,000	32,390,000	33,227,000
Net income				11,561,000
Balance (in shares) at Jun. 30, 2020	13,587,847
Balance at Jun. 30, 2020	$ 136,000	2,694,000	43,951,000	46,781,000
Balance (in shares) at Mar. 31, 2020	13,563,012
Balance at Mar. 31, 2020	$ 136,000	2,508,000	37,732,000	40,376,000
Net income	0	0	6,220,000	6,220,000
Stock-based compensation expense	$ 0	92,000	0	92,000
Options exercised (in shares)	24,835
Options exercised	$ 0	94,000	0	94,000
Balance (in shares) at Jun. 30, 2020	13,587,847
Balance at Jun. 30, 2020	$ 136,000	2,694,000	43,951,000	$ 46,781,000
Balance (in shares) at Dec. 31, 2020	13,419,847			13,419,847	[1]
Balance at Dec. 31, 2020	$ 135,000	409,000	59,476,000	$ 60,020,000	[1]
Net income	$ 0	0	3,719,000	3,719,000
Common stock repurchased and retired (in shares)	(186,000)
Common stock repurchased and retired	$ (2,000)	(817,000)	(1,547,000)	(2,366,000)
Stock-based compensation expense	$ 0	101,000	0	101,000
Options exercised (in shares)	89,494
Options exercised	$ 1,000	307,000	0	308,000
Balance (in shares) at Mar. 31, 2021	13,323,341
Balance at Mar. 31, 2021	$ 134,000	0	61,648,000	$ 61,782,000
Balance (in shares) at Dec. 31, 2020	13,419,847			13,419,847	[1]
Balance at Dec. 31, 2020	$ 135,000	409,000	59,476,000	$ 60,020,000	[1]
Net income				$ 5,390,000
Options exercised (in shares)				124,494
Balance (in shares) at Jun. 30, 2021	13,208,341			13,208,341
Balance at Jun. 30, 2021	$ 132,000	0	62,130,000	$ 62,262,000
Balance (in shares) at Mar. 31, 2021	13,323,341
Balance at Mar. 31, 2021	$ 134,000	0	61,648,000	61,782,000
Net income	$ 0	0	1,671,000	1,671,000
Common stock repurchased and retired (in shares)	(150,000)
Common stock repurchased and retired	$ (2,000)	(151,000)	(1,189,000)	(1,342,000)
Stock-based compensation expense	$ 0	68,000	0	68,000
Options exercised (in shares)	35,000
Options exercised	$ 0	83,000	0	$ 83,000
Balance (in shares) at Jun. 30, 2021	13,208,341			13,208,341
Balance at Jun. 30, 2021	$ 132,000	$ 0	$ 62,130,000	$ 62,262,000

[1] The condensed consolidated balance sheet as of December 31, 2020 has been prepared using information from the audited consolidated balance sheet as of that date.