Schedule of Changes in Common Stock Options (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options outstanding, beginning of year	4,303,900	5,040,450
Options, Granted	649,850	526,500
Options, Exercised	(31,276)	(173,130)
Options, Expired	(765,000)	(1,016,870)
Options, Forfeited	(545,624)	(73,050)
Options outstanding, end of year	3,611,850	4,303,900
Options exercisable at year end	2,157,336	2,533,700
Weighted Average Exercise Price, Outstanding at beginning of year	$ 0.75	$ 0.97
Weighted Average Exercise Price, Granted	0.74	0.43
Weighted Average Exercise Price, Exercised	0.45	0.43
Weighted Average Exercise Price, Expired	2.00	1.74
Weighted Average Exercise Price, Forfeited	0.61	0.77
Weighted Average Exercise Price, Outstanding at end of year	0.51	0.75
Weighted Average Exercise Price, Options exercisable at end of year	0.46	0.96
Weighted-average fair value of options granted during the year	$ 0.50	$ 0.17