Annual report pursuant to Section 13 and 15(d)

Note 1 - Organization and Summary of Significant Accounting Policies (Details Textual)

v3.21.1
Note 1 - Organization and Summary of Significant Accounting Policies (Details Textual)
 12 Months Ended
Apr. 26, 2019
$ / shares
shares
Dec. 31, 2020
USD ($)
$ / shares
shares
Dec. 31, 2019
USD ($)
$ / shares
shares
Jun. 30, 2019
shares
Apr. 25, 2019
shares
Jan. 01, 2019
USD ($)
Common Stock, Par or Stated Value Per Share (in dollars per share) | $ / shares $ 0.001 $ 0.001 $ 0.001      
Common Stock, Shares, Outstanding, Ending Balance (in shares) | shares 10,100,000 27,149,691 19,234,960   201,000,000  
Common Stock, Shares Authorized (in shares) | shares 300,000,000 300,000,000 300,000,000      
Notes Payable, Fair Value Disclosure   $ 745,000 $ 306,000      
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | shares   992,000        
Patent and Trademark Costs   $ 277,989 56,700      
Previously Capitalized Patent Costs Abandoned   9,000 58,000      
Impairment of Long-Lived Assets to be Disposed of   0 0      
Unrecognized Tax Benefits, Ending Balance   $ 0 0      
Open Tax Year   2017 2018 2019 2020        
Operating Lease, Right-of-Use Asset   $ 250,095 $ 281,688     $ 406,842
Operating Lease, Liability, Total   $ 590,957       998,602
Accounting Standards Update 2016-02 [Member]            
Operating Lease, Right-of-Use Asset           407,000
Operating Lease, Liability, Total           $ 407,000
Minimum [Member]            
Finite-Lived Intangible Asset, Useful Life (Year)   5 years        
Maximum [Member]            
Finite-Lived Intangible Asset, Useful Life (Year)   15 years        
The 2014 Plan [Member]            
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares) | shares   1,750,000        
The 2002 and 2014 Plan [Member]            
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year)   10 years        
The 2002 and 2014 Plan [Member] | Minimum [Member]            
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)   1 year        
The 2002 and 2014 Plan [Member] | Maximum [Member]            
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)   4 years        
Underwriting Agreement Warrants [Member]            
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | shares       600,000    
Class of Warrant or Right Percent of Common Stock Sold       7.50%    
Warrants and Rights Outstanding   $ 261,000        
Underwriting Agreement Warrants [Member] | Measurement Input, Price Volatility [Member]            
Warrants and Rights Outstanding, Measurement Input   0.886        
Underwriting Agreement Warrants [Member] | Measurement Input, Risk Free Interest Rate [Member]            
Warrants and Rights Outstanding, Measurement Input   0.018        
Underwriting Agreement Warrants [Member] | Measurement Input, Expected Dividend Payment [Member]            
Warrants and Rights Outstanding, Measurement Input   0        
Reverse Stock Split [Member]            
Stockholders' Equity Note, Stock Split, Conversion Ratio 20          
Navidea Biopharmaceuticals Limited [Member]            
Noncontrolling Interest, Ownership Percentage by Parent   100.00%        
Macrophage Therapeutics [Member]            
Noncontrolling Interest, Ownership Percentage by Parent   99.90%        
Navidea Europe [Member]            
Noncontrolling Interest, Ownership Percentage by Parent   100.00%