Condensed Consolidated Statements of Stockholder's Equity (Unaudited) - USD ($)	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Treasury Stock [Member]
Balance at Dec. 31, 2019	$ 34,893,000	$ 50,000	$ 41,576,000	$ (6,153,000)	$ (580,000)
Balance (in shares) at Dec. 31, 2019		4,933,063
Net income	183,000			183,000
Exercise of stock options	58,000		58,000
Exercise of stock options (in shares)		14,000
At-the-market stock sales, net of costs	3,254,000	$ 3,000	3,251,000
At-the-market stock sales, net of costs (in shares)		263,725
Stock-based compensation	10,000		10,000
Balance at Mar. 31, 2020	38,398,000	$ 53,000	44,895,000	(5,970,000)	(580,000)
Balance (in shares) at Mar. 31, 2020		5,210,788
Balance at Dec. 31, 2019	34,893,000	$ 50,000	41,576,000	(6,153,000)	(580,000)
Balance (in shares) at Dec. 31, 2019		4,933,063
Net income	438,000
Balance at Jun. 30, 2020	38,695,000	$ 53,000	44,937,000	(5,715,000)	(580,000)
Balance (in shares) at Jun. 30, 2020		5,212,054
Balance at Mar. 31, 2020	38,398,000	$ 53,000	44,895,000	(5,970,000)	(580,000)
Balance (in shares) at Mar. 31, 2020		5,210,788
Net income	255,000			255,000
Exercise of stock options	5,000	$ 1,266,000	5,000
Stock-based compensation	37,000		37,000
Balance at Jun. 30, 2020	38,695,000	$ 53,000	44,937,000	(5,715,000)	(580,000)
Balance (in shares) at Jun. 30, 2020		5,212,054
Balance at Dec. 31, 2020	$ 39,765,000	$ 53,000	45,477,000	(5,185,000)	(580,000)
Balance (in shares) at Dec. 31, 2020	5,272,204	5,272,204
Net income	$ 27,000			27,000
Stock-based compensation	78,000		78,000
Balance at Mar. 31, 2021	39,870,000	$ 53,000	45,555,000	(5,158,000)	(580,000)
Balance (in shares) at Mar. 31, 2021		5,272,204
Balance at Dec. 31, 2020	$ 39,765,000	$ 53,000	45,477,000	(5,185,000)	(580,000)
Balance (in shares) at Dec. 31, 2020	5,272,204	5,272,204
Net income	$ 9,000
Balance at Jun. 30, 2021	$ 39,871,000	$ 53,000	45,574,000	(5,176,000)	(580,000)
Balance (in shares) at Jun. 30, 2021	5,272,204	5,272,204
Balance at Mar. 31, 2021	$ 39,870,000	$ 53,000	45,555,000	(5,158,000)	(580,000)
Balance (in shares) at Mar. 31, 2021		5,272,204
Net income	(18,000)			(18,000)
Stock-based compensation	19,000		19,000
Balance at Jun. 30, 2021	$ 39,871,000	$ 53,000	$ 45,574,000	$ (5,176,000)	$ (580,000)
Balance (in shares) at Jun. 30, 2021	5,272,204	5,272,204