The following table summarizes the stock option activity for the nine months ended September 30, 2021 (Details)	9 Months Ended
	Sep. 30, 2021 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total outstanding and vested and expected to vest at beginning	6,508,296
Total outstanding and vested and expected to vest at ending	5,844,239
Vested at ending	5,844,239
2009 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total outstanding and vested and expected to vest at beginning	6,508,296
Options outstanding, weighted average exercise price, beginning balance | $ / shares	$ 4.29
Options outstanding, weighted average remaining contractual term at beginning	5 years 7 months 6 days
Options canceled/expired	(664,057)
Options canceled/expired, weighted average exercise price | $ / shares	$ 4.05
Total outstanding and vested and expected to vest at ending	5,844,239
Options outstanding, weighted average exercise price, ending balance | $ / shares	$ 4.32
Options outstanding, weighted average remaining contractual term at ending	3 years 10 months 17 days
Vested at ending	5,844,239
Option vested, weighted average exercise price at ending | $ / shares	$ 4.32
Options vested, weighted average remaining contractual term at ending	3 years 10 months 17 days