12. Unaudited Quarterly Financial Information (Details) - USD ($)		3 Months Ended												12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018		Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2018		Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Total revenue		$ 2,582,000	$ 3,079,000	$ 3,121,000	$ 2,923,000	$ 3,043,000		$ 3,275,000		$ 3,177,000		$ 2,953,000		$ 11,704,624		$ 12,447,947		$ 9,838,408
Operating income		224,000	835,000	801,000	754,000	541,000		714,000		703,000		699,000		2,613,588		2,656,996		2,943,732
Valuation allowance for receivables						(2,800,000)		(1,296,000)		0		0		(1,300,000)		(4,095,805)		(440,000)
Net income (loss) before income taxes from continuing operations		(1,283,000)	615,000	580,000	627,000	(2,428,000)		(755,000)		550,000		539,000		539,023		(2,094,012)		854,968
Net income (loss) from continuing operations						(3,277,000)		(562,000)		412,000		403,000		(378,065)		(3,024,409)		(3,291,491)
Loss from discontinued operations						(38,000)		0		0		0		0		(37,800)		(93,436)
Net income (loss)		$ (1,763,000)	$ 467,000	$ 441,000	$ 476,000	$ (3,315,000)		$ (562,000)		$ 412,000		$ 403,000		$ (378,065)		$ (3,062,209)		$ (3,384,927)
Net income (loss) from continuing operations per common share
Basic						$ (0.15)		$ (0.03)		$ 0.02		$ 0.02		$ (.02)		$ (0.14)		$ (0.16)
Diluted	[1]					(0.15)		(0.02)		0.02		0.02		(0.02)		(0.14)		(0.16)
Net income (loss) per common share
Basic		$ (.08)	$ (0.02)	$ (0.02)	$ (0.02)	(0.15)		(0.03)		0.02		0.02		(.02)		(0.14)		(0.16)
Diluted		$ (.08)	$ (0.02)	$ (0.02)	$ (0.02)	$ (0.15)	[1]	$ (0.02)	[1]	$ 0.02	[1]	$ 0.02	[1]	$ (0.02)	[1]	$ (0.14)	[1]	$ (0.16)	[1]

[1] Net loss per share is shown the same as basic loss per share because the underlying dilutive securities have anti-dilutive effect.