Annual report pursuant to Section 13 and 15(d)

Note 16 - Income Taxes - Net Operating Loss and Credit Carryforwards (Details)

v3.20.1
Note 16 - Income Taxes - Net Operating Loss and Credit Carryforwards (Details) - USD ($)
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]    
U.S. Net Operating Loss Carryforwards $ 142,183,037 $ 130,900,000
Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]    
U.S. R&D Credit Carryforwards $ 8,761,692 $ 8,700,000
Tax Year 2000 [Member]    
Expiration dates Dec. 31, 2020  
Tax Year 2000 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]    
U.S. Net Operating Loss Carryforwards  
Tax Year 2000 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]    
U.S. R&D Credit Carryforwards $ 71,713  
Tax Year 2001 [Member]    
Expiration dates Dec. 31, 2021  
Tax Year 2001 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]    
U.S. Net Operating Loss Carryforwards  
Tax Year 2001 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]    
U.S. R&D Credit Carryforwards $ 39,128  
Tax Year 2002 [Member]    
Expiration dates Dec. 31, 2022  
Tax Year 2002 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]    
U.S. Net Operating Loss Carryforwards  
Tax Year 2002 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]    
U.S. R&D Credit Carryforwards $ 5,350  
Tax Year 2003 [Member]    
Expiration dates Dec. 31, 2023  
Tax Year 2003 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]    
U.S. Net Operating Loss Carryforwards  
Tax Year 2003 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]    
U.S. R&D Credit Carryforwards $ 2,905  
Tax Year 2004 [Member]    
Expiration dates Dec. 31, 2024  
Tax Year 2004 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]    
U.S. Net Operating Loss Carryforwards  
Tax Year 2004 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]    
U.S. R&D Credit Carryforwards $ 22,861  
Tax Year 2005 [Member]    
Expiration dates Dec. 31, 2025  
Tax Year 2005 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]    
U.S. Net Operating Loss Carryforwards  
Tax Year 2005 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]    
U.S. R&D Credit Carryforwards $ 218,332  
Tax Year 2006 [Member]    
Expiration dates Dec. 31, 2026  
Tax Year 2006 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]    
U.S. Net Operating Loss Carryforwards  
Tax Year 2006 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]    
U.S. R&D Credit Carryforwards $ 365,541  
Tax Year 2007 [Member]    
Expiration dates Dec. 31, 2027  
Tax Year 2007 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]    
U.S. Net Operating Loss Carryforwards  
Tax Year 2007 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]    
U.S. R&D Credit Carryforwards $ 342,898  
Tax Year 2008 [Member]    
Expiration dates Dec. 31, 2028  
Tax Year 2008 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]    
U.S. Net Operating Loss Carryforwards  
Tax Year 2008 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]    
U.S. R&D Credit Carryforwards $ 531,539  
Tax Year 2009 [Member]    
Expiration dates Dec. 31, 2029  
Tax Year 2009 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]    
U.S. Net Operating Loss Carryforwards  
Tax Year 2009 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]    
U.S. R&D Credit Carryforwards $ 596,843  
Tax Year 2010 [Member]    
Expiration dates Dec. 31, 2030  
Tax Year 2010 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]    
U.S. Net Operating Loss Carryforwards  
Tax Year 2010 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]    
U.S. R&D Credit Carryforwards $ 1,094,449  
Tax Year 2011 [Member]    
Expiration dates Dec. 31, 2031  
Tax Year 2011 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]    
U.S. Net Operating Loss Carryforwards  
Tax Year 2011 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]    
U.S. R&D Credit Carryforwards $ 1,950,744  
Tax Year 2012 [Member]    
Expiration dates Dec. 31, 2032  
Tax Year 2012 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]    
U.S. Net Operating Loss Carryforwards $ 18,850,484  
Tax Year 2012 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]    
U.S. R&D Credit Carryforwards $ 468,008  
Tax Year 2013 [Member]    
Expiration dates Dec. 31, 2033  
Tax Year 2013 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]    
U.S. Net Operating Loss Carryforwards $ 37,450,522  
Tax Year 2013 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]    
U.S. R&D Credit Carryforwards $ 681,772  
Tax Year 2014 [Member]    
Expiration dates Dec. 31, 2034  
Tax Year 2014 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]    
U.S. Net Operating Loss Carryforwards $ 34,088,874  
Tax Year 2014 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]    
U.S. R&D Credit Carryforwards $ 816,116  
Tax Year 2015 [Member]    
Expiration dates Dec. 31, 2035  
Tax Year 2015 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]    
U.S. Net Operating Loss Carryforwards $ 25,073,846  
Tax Year 2015 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]    
U.S. R&D Credit Carryforwards $ 492,732  
Tax Year 2016 [Member]    
Expiration dates Dec. 31, 2036  
Tax Year 2016 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]    
U.S. Net Operating Loss Carryforwards $ 15,581,209  
Tax Year 2016 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]    
U.S. R&D Credit Carryforwards $ 262,257  
Tax Year 2017 [Member]    
Expiration dates Dec. 31, 2037  
Tax Year 2017 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]    
U.S. Net Operating Loss Carryforwards  
Tax Year 2017 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]    
U.S. R&D Credit Carryforwards $ 387,892  
Tax Year 2018 [Member]    
Expiration dates Dec. 31, 2038  
Tax Year 2018 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]    
U.S. Net Operating Loss Carryforwards  
Tax Year 2018 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]    
U.S. R&D Credit Carryforwards 197,547  
Tax Year 2019 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]    
U.S. Net Operating Loss Carryforwards 11,138,102  
Tax Year 2019 [Member] | Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]    
U.S. R&D Credit Carryforwards $ 213,065