Revenues (Details) - USD ($)	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Accumulated deficit		$ (11,059,500)		$ (12,811,000)	$ (11,059,500)	$ (12,811,000)
Net earnings	$ 148,900	$ 85,400	$ 1,447,500	95,800	234,300	1,543,300
Cumulative effect of accounting change				$ 96,100		96,100
Accumulated deficit	(10,825,200)		11,171,600		(10,825,200)	11,171,600
Long-term receivable	$ 1,158,200		1,521,700		$ 1,158,200	$ 1,521,700	$ 1,352,200
Selling expense			$ 106,500