CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($)	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Undistributed Gains from Sales of Properties Net of Losses [Member]	Undistributed (Losses) gains from Operations [Member]	Treasury Stock [Member]
Balance at Dec. 31, 2018	$ 21,033,055	$ 1,035,493	$ 24,157,986	$ 54,642,765	$ (58,473,808)	$ (340,281)
Balance (in shares) at Dec. 31, 2018		1,046,393				33,101
Net income (loss)	(11,116)	$ 0	0	0	(11,116)	$ 0
Balance at Mar. 31, 2019	21,021,939	$ 1,046,393	24,157,986	54,642,765	(58,484,924)	$ (340,281)
Balance (in shares) at Mar. 31, 2019		1,046,393				33,101
Balance at Dec. 31, 2018	21,033,055	$ 1,035,493	24,157,986	54,642,765	(58,473,808)	$ (340,281)
Balance (in shares) at Dec. 31, 2018		1,046,393				33,101
Net income (loss)	337,155
Retired 33,101 treasury shares	340,281
Balance at Sep. 30, 2019	21,379,090	$ 1,013,292	23,859,686	54,642,765	(58,136,653)	$ 0
Balance (in shares) at Sep. 30, 2019		1,013,292				0
Balance at Mar. 31, 2019	21,021,939	$ 1,046,393	24,157,986	54,642,765	(58,484,924)	$ (340,281)
Balance (in shares) at Mar. 31, 2019		1,046,393				33,101
Net income (loss)	9,550	$ 0	0	0	9,550	$ 0
Retired 33,101 treasury shares		$ (33,101)	(307,180)			$ 340,281
Retired 33,101 treasury shares (in shares)		(33,101)				(33,101)
Balance at Jun. 30, 2019	21,031,489	$ 1,013,292	23,850,806	54,642,765	(58,475,374)	$ 0
Balance (in shares) at Jun. 30, 2019		1,013,292				0
Net income (loss)	338,721	$ 0	0	0	338,721	$ 0
Non-employee stock option compensation	8,880	0	8,880	0	0	0
Balance at Sep. 30, 2019	21,379,090	$ 1,013,292	23,859,686	54,642,765	(58,136,653)	$ 0
Balance (in shares) at Sep. 30, 2019		1,013,292				0
Balance at Dec. 31, 2019	$ 20,805,159	$ 1,013,292	23,859,686	54,136,119	(58,203,938)	$ 0
Balance (in shares) at Dec. 31, 2019	1,013,292	1,013,292				0
Net income (loss)	$ (964,869)	$ 0	0	0	(964,869)	$ 0
Balance at Mar. 31, 2020	19,840,290	$ 1,013,292	23,859,686	54,136,119	(59,168,807)	$ 0
Balance (in shares) at Mar. 31, 2020		1,013,292				0
Balance at Dec. 31, 2019	$ 20,805,159	$ 1,013,292	23,859,686	54,136,119	(58,203,938)	$ 0
Balance (in shares) at Dec. 31, 2019	1,013,292	1,013,292				0
Net income (loss)	$ (909,859)
Retired 33,101 treasury shares	0
Balance at Sep. 30, 2020	$ 19,828,908	$ 1,013,292	23,859,686	54,136,119	(59,113,797)	$ (66,392)
Balance (in shares) at Sep. 30, 2020	1,007,248	1,013,292				6,044
Balance at Mar. 31, 2020	$ 19,840,290	$ 1,013,292	23,859,686	54,136,119	(59,168,807)	$ 0
Balance (in shares) at Mar. 31, 2020		1,013,292				0
Net income (loss)	125,863	$ 0	0	0	125,863	$ 0
Purchased treasury shares	(66,392)	$ 0	0	0	0	$ (66,392)
Purchased treasury shares (in shares)		0				6,044
Balance at Jun. 30, 2020	19,899,761	$ 1,013,292	23,859,686	54,136,119	(59,042,944)	$ (66,392)
Balance (in shares) at Jun. 30, 2020		1,013,292				6,044
Net income (loss)	(70,853)	$ 0	0	0	(70,853)	$ 0
Balance at Sep. 30, 2020	$ 19,828,908	$ 1,013,292	$ 23,859,686	$ 54,136,119	$ (59,113,797)	$ (66,392)
Balance (in shares) at Sep. 30, 2020	1,007,248	1,013,292				6,044