| Note 15 - Leases | 12 Months Ended | ||||||||||||||||||||||||||||||||||||||||||
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| Dec. 31, 2017 | |||||||||||||||||||||||||||||||||||||||||||
| Notes to Financial Statements | |||||||||||||||||||||||||||||||||||||||||||
| Leases of Lessee Disclosure [Text Block] | 
 We currently lease approximately  5,000square feet of office space at 4995Bradenton Avenue, Dublin, Ohio, as our principal offices. The current least term expires in  June 2020, at a monthly base rent of approximately $3,000.We  also lease approximately  2,000square feet of office space at 560Sylvan Avenue, Englewood Cliffs, New Jersey. The current lease term expires in  March 2018, at a monthly base rent of approximately $3,000. In addition, we  currently lease approximately  25,000square feet of office space at 5600Blazer Parkway, Dublin, Ohio, formerly our principal offices. The current lease term expires in  October 2022, at a monthly base rent of approximately $26,000during 2018.In  June 2017, the Company executed a sublease arrangement for the Blazer space, providing for monthly sublease payments to Navidea of approximately $39,000through  October 2022. As of   December 31, 2017, the future minimum lease payments for the years ending  December 31 are as follows: 
 Total rental expense was  $139,000, $187,000and $217,000for the years ended  December 31, 2017,  2016and 2015,respectively. See Note 1(l). | ||||||||||||||||||||||||||||||||||||||||||
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- References No definition available. 
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- Definition The entire disclosure for lessee entity's leasing arrangements including, but not limited to, all of the following: (a.) The basis on which contingent rental payments are determined, (b.) The existence and terms of renewal or purchase options and escalation clauses, (c.) Restrictions imposed by lease agreements, such as those concerning dividends, additional debt, and further leasing. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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