| Note 2 - Liquidity | 9 Months Ended | ||
|---|---|---|---|
| Sep. 30, 2019 | |||
| Notes to Financial Statements | |||
| Substantial Doubt about Going Concern [Text Block] | 
 As disclosed in the Company’s Annual Report on Form  10-K and other filings, the Company is engaged in ongoing litigation with Capital Royalty Partners II L.P. (“CRG”) and is currently pursuing recovery of $4.1million and other damages. See Note 11. The Company was also engaged in litigation with Platinum-Montaur Life Sciences LLC (“Platinum-Montaur”), an affiliate of Platinum Management (NY) LLC, Platinum Partners Value Arbitrage Fund L.P. (“PPVA”), Platinum Partners Capital Opportunity Fund (“PPCO”), Platinum Partners Liquid Opportunity Master Fund L.P., Platinum Liquid Opportunity Management (NY) LLC, and Montsant Partners LLC (collectively, “Platinum”), in which Platinum-Montaur was seeking damages of approximately  $1.9million plus interest.  In  October 2018, the court granted judgment for Navidea and dismissed all claims in the case; however, in  November 2018, Platinum-Montaur filed a notice of appeal.  Oral argument on the appeal was held before the United States Court of Appeals for the Second Circuit (the “Second Circuit”) on  September 5, 2019 and the court will issue its decision in the near future. See Notes 9and 11. In addition, the Company is engaged in litigation with our former President and Chief Executive Officer, Dr. Michael Goldberg. See Notes  7and 11. On   June 18, 2019, the Company completed an underwritten public offering of 8,000,000shares (the “Shares”) of our Common Stock pursuant to an underwriting agreement (the “Underwriting Agreement”), dated  June 13, 2019, between the Company and H.C. Wainwright & Co., LLC (the “Underwriter”) at a price to the public of $0.75per share.  Of the 8,000,000total Shares, 4,000,000shares were placed with existing investor John K. Scott, Jr. (the “Investor”), at a price of $0.75per share. Pursuant to the Underwriting Agreement, the Underwriter purchased the remaining 4,000,000Shares from the Company at a price of $0.69375per share.  After underwriting discounts, commissions, fees and expenses paid to the Underwriter, the Company received net proceeds from the offering of $5,555,000.The Company intends to use the net proceeds from the offering to fund its research and development programs, including continuing to advance its Phase 2band Phase 3clinical trials of Tc99mtilmanocept in patients with rheumatoid arthritis, and for general working capital purposes and other operating expenses. In addition, the Company has experienced recurring net losses and has used significant cash to fund its operations. The Company has considerable discretion over the extent of development project expenditures and has the ability to curtail the related cash flows as needed. The   June 2019 underwritten public offering provided approximately $5.5million of additional working capital. The Company also has funds remaining under outstanding grant awards, and continues working to establish new sources of funding, including collaborations, potential equity investments, and additional grant funding that can augment the balance sheet. However, based on our current working capital and our projected cash burn, and without definitive agreements in place for additional funding, management believes that there is substantial doubt about the Company’s ability to continue as a going concern for at least twelvemonths following the filing of this Quarterly Report on Form 10-Q. |