7. Common Stock (Details 3) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Equity [Abstract]
Balance of employee non-vested stock options outstanding	749,835	791,668	730,501
Stock options granted	415,000	410,500	395,000
Stock options vested	(337,499)	(418,333)	(258,833)
Stock options forfeited	(105,500)	(34,000)	(75,000)
Balance of employee non-vested stock options outstanding	721,836	749,835	791,668