7. Common Stock (Details 3) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Equity [Abstract]
Non-vested stock options outstanding, beginning	731,336	721,836	749,835
Non-vested stock options granted	443,500	529,500	415,000
Non-vested stock options vested	(212,500)	(325,000)	(337,499)
Non-vested stock options forfeited	0	(195,000)	(105,500)
Non-vested stock options outstanding, ending	962,336	731,336	721,836