Note 10 - Leases  | 
3 Months Ended | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Mar. 31, 2021  | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Leases of Lessee Disclosure [Text Block] | 
 We currently lease approximately   5,000  square feet of office space at 4995  Bradenton Avenue, Dublin, Ohio, as our principal offices, at a monthly base rent of approximately $3,000.  The current least term expires in  June 2023. 
In addition, we currently lease approximately   25,000  square feet of office space at 5600  Blazer Parkway, Dublin, Ohio, formerly our principal offices, at a monthly base rent of approximately $27,000  in 2021.  The current lease term expires in  October 2022  with an option to extend for an additional five  years. The Company does not  intend to renew this lease. In  June 2017,  the Company executed a sublease arrangement for the Blazer Parkway space, providing for monthly sublease payments to Navidea of approximately $39,000  through  October 2022. 
We also currently lease a vehicle at a monthly payment of approximately   $300,  expiring in  September 2021,  and office equipment at a monthly payment of approximately $100,  expiring in  October 2024. 
Total operating lease expense was   $46,000  and $51,000  for the three -month periods ended  March 31, 2021  and 2020,  respectively, and was recorded in selling, general and administrative expenses on our consolidated statements of operations.The following table presents information about the amount, timing and uncertainty of cash flows arising from the Company's operating leases as of    March 31, 2021. 
 
 
 Cash paid for amounts included in the present value of operating lease liabilities was  
$93,000  and $91,000  during the three -month periods ended  March 31, 2021  and 2020,  respectively, and is included in operating cash flows. | 
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