13. Unaudited Quarterly Financial Information (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Total revenue	$ 3,043,000	$ 3,275,000	$ 3,177,000	$ 2,953,000	$ 2,646,000	$ 2,513,000	$ 2,466,000	$ 2,213,000	$ 12,447,947	$ 9,838,408	$ 7,836,485
Operating income	541,000	714,000	703,000	699,000	794,000	761,000	739,000	649,000	2,656,996	2,943,732	3,077,353
Valuation allowance for receivables - including Heyser case	(2,800,000)	(1,296,000)	0	0	(90,000)	(350,000)	0	0	4,095,805	440,000	1,103,521
Change in fair value of derivatives					458,000	(930,000)	315,000	(18,000)	0	(174,737)	(44,464)
Net income (loss) before income taxes from continuing operations	(2,428,000)	(755,000)	550,000	539,000	909,000	(1,120,000)	755,000	311,000	(2,094,012)	854,968	1,276,907
Net income (loss) from continuing operations	(3,277,000)	(562,000)	412,000	403,000	(3,017,000)	(1,047,000)	581,000	193,000	(3,024,409)	(3,291,491)	789,027
Loss from discontinued operations	(38,000)	0	0	0	36,000	(129,000)	0	0	(37,800)	(93,436)	(1,659,867)
Net income (loss)	$ (3,315,000)	$ (562,000)	$ 412,000	$ 403,000	$ (2,981,000)	$ (1,177,000)	$ 581,000	$ 193,000	$ (3,062,209)	$ (3,384,927)	$ (870,840)
Basic	$ (.15)	$ (.03)	$ 0.02	$ 0.02	$ (0.14)	$ (0.05)	$ 0.03	$ 0.01	$ (.14)	$ (.16)	$ 0.04
Diluted	(.15)	(.02)	0.02	0.02	(0.14)	(0.05)	0.02	0.01	(.14)	(.16)	0.04
Net income (loss) per common share
Basic	(.15)	(.03)	0.02	0.02	(0.14)	(0.06)	0.03	0.01	$ (0.14)	$ (0.16)	$ (0.04)
Diluted	$ (.15)	$ (.02)	$ 0.02	$ 0.02	$ (0.14)	$ (0.06)	$ 0.02	$ 0.01