Note 4 - Fair Value  | 
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| Notes to Financial Statements | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Fair Value Disclosures [Text Block] | 
 The Company’s available-for-sale securities consist of certificates of deposit which are measured using Level   2  inputs.MT issued warrants to purchase MT common stock with certain characteristics including a net settlement provision that require the warrants to be accounted for as a derivative liability at fair value on the consolidated balance sheets. The estimated fair value of the MT warrants is   $63,000  at both  September 30, 2019  and  December 31, 2018,  is included in other liabilities on the accompanying consolidated balance sheets and will continue to be measured on a recurring basis.The following tables set forth, by level, financial assets and liabilities measured at fair value on a recurring basis.  
 
 
 
 There were   no  transfers in or out of our Level 1  or Level 2  liabilities during the nine -month periods ended  September 30, 2019  or 2018.   Changes in the estimated fair value of our Level 3  liabilities relating to unrealized gains (losses), if any, are recorded as changes in fair value of financial instruments in the consolidated statements of operations.  There was no  change in the estimated fair value of our Level 3  liabilities during the nine -month periods ended  September 30, 2019  and 2018. 
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