8. Common Stock (Details 3) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity [Abstract]
Balance of employee non-vested stock options outstanding	791,668	730,501	1,031,500
Stock options granted	410,500	395,000	410,000
Stock options vested	(418,333)	(258,833)	(380,999)
Stock options forfeited	(34,000)	(75,000)	(330,000)
Balance of employee non-vested stock options outstanding	749,835	791,668	730,501