Stockholders' Equity Note Disclosure [Text Block] | Note 11. Stockholders’ Equity In September 2015, the Company filed with the SEC a $75 million shelf registration statement on Form S-3 (File No. 333-206789) that allows the Company to issue any combination of common stock, preferred stock or warrants to purchase common stock or preferred stock (the 2015 Registration Statement). This shelf registration was declared effective on September 25, 2015. On June 13, 2016, the Company entered into a Securities Purchase Agreement (the June 2016 Purchase Agreement) with an investor, pursuant to which the Company issued and sold, in a registered direct offering (the June 2016 Offering), an aggregate of 2,311,764 shares of common stock, par value $0.01 per share, of the Company at an offering price of $1.36 per share. In addition, the Company sold Pre-Funded Series B Warrants (the Pre-Funded Series B Warrants) to purchase 2,100,000 shares of common stock (and the shares of common stock issuable upon exercise of the Pre-Funded Series B Warrants), in lieu of shares of common stock to the extent that the purchase of common stock would cause the beneficial ownership of the Purchaser, together with its affiliates and certain related parties, to exceed 9.99% of our common stock. The Company offered these shares and warrants under the June 2016 Purchase Agreement pursuant to the 2015 Registration Statement. The Company received gross proceeds of approximately $6.0 million before the deduction of the placement agent fee and offering expenses in the June 2016 Offering. During the third quarter of 2016, 250,000 shares of common stock were issued in connection with the exercise of some of the Pre-Funded Series B Warrants. As of September 30, 2016, 1,850,000 of the Series B Pre-Funded warrants remain outstanding. In a concurrent private placement (the June 2016 Private Placement), the Company issued to the investor Series A warrants (the June 2016 Series A Warrants), each to purchase 0.5 share of common stock, Series C warrants (the June 2016 Series C Warrants), each to purchase one share of common stock, and Series D warrants (the June 2016 Series D Warrants), each to purchase 0.5 share of common stock (collectively the June 2016 Warrants). The June 2016 Series A Warrants are initially exercisable six months following issuance and terminate five and one-half years following issuance. The June 2016 Series C Warrants are initially exercisable six months following issuance and terminate one year following issuance. The June 2016 Series D Warrants only become exercisable ratably upon the exercise of the June 2016 Series C Warrants, are initially exercisable six months following issuance, and terminate five and one-half years following issuance. The June 2016 Warrants have an exercise price of $1.40 per share and are exercisable to purchase an aggregate of 8,823,528 shares of common stock. Subject to limited exceptions, a holder of a June 2016 Warrant will not have the right to exercise any portion of its warrants if the holder, together with its affiliates, would beneficially own in excess of 4.99% of the number of shares of common stock outstanding immediately after giving effect to such exercise (the “Beneficial Ownership Limitation”); provided, however, that upon 61 days’ prior notice to the Company, the holder may increase or decrease the Beneficial Ownership Limitation, provided that in no event shall the Beneficial Ownership Limitation exceed 9.99%. The June 2016 Warrants and the shares of our common stock issuable upon the exercise of the June 2016 Warrants are not being registered under the Securities Act of 1933, as amended (the “Securities Act”), are not being offered pursuant to the Registration Statement and are being offered pursuant to the exemption provided in Section 4(a)(2) under the Securities Act and Rule 506(b) promulgated thereunder. On October 31, 2016 we filed a registration statement on Form S-1 to provide for the resale of the shares of common stock issuable upon the exercise of the June 2016 Warrants and will be obligated to use our commercially reasonable efforts to keep such registration statement effective until the earliest of (i) the date on which all of the shares of commons stock issuable upon the exercise of the June 2016 Warrants have been sold under the registration statement or Rule 144 under the Securities Act, (ii) the date on which the shares of common stock issuable upon the exercise of the June 2016 Warrants may be sold without volume or manner-of-sale restrictions pursuant to Rule 144 under the Securities Act and (iii) the termination of the June 2016 Warrants. Under the June 2016 Purchase Agreement, the Company is prohibited, for a period of six months after the closing, from effecting or entering into an agreement to issue common stock or any other securities that are at any time convertible into, or exercisable or exchangeable for, or otherwise entitle the holder thereof to receive, common stock to the extent such issuance or sale involves certain variable conversion, exercise or exchange prices or such agreement provides for sale of securities at a price to be determined in the future. May 2015 Common Stock Offering On May 27, 2015, the Company entered into a Securities Purchase Agreement with certain investors, pursuant to which the Company sold and issued on June 1, 2015, in a registered direct offering (the May 2015 Offering), an aggregate of 3,000,000 shares of common stock at an offering price of $2.675 per share for gross proceeds of $8.0 million before the deduction of the placement agent fee and offering expenses. The Shares were offered by the Company pursuant to a registration statement on Form S-3 (File No. 333-183286), which was initially filed with the SEC on August 13, 2012, as amended on August 20, 2012, and was declared effective by the SEC on September 14, 2012 (the Shelf Registration Statement). In a concurrent private placement closed on June 1, 2015, the Company issued to the investors in the May 2015 Offering certain warrants (the May 2015 Warrants) at an exercise price of $2.60 per share. The May 2015 Warrants are exercisable to purchase 0.65 share of common stock for each share of common stock purchased in the May 2015 Offering for an aggregate of 1,950,000 shares of common stock. Each May 2015 Warrant will be exercisable on the date of its issuance until the five-year anniversary of the date of issuance. On July 10, 2015, the Company filed a registration statement for the resale of any shares of common stock issuable upon the exercise of the May 2015 Warrants on Form S-3 (File No. 333-205608) which was declared effective by the SEC on July 30, 2015. Under this purchase agreement, the Company was prohibited, for the period from the date of closing and ending September 1, 2015, from effecting or entering into an agreement to issue common stock or, for a period of five months after the closing, any other securities that are at any time convertible into, or exercisable or exchangeable for, or otherwise entitle the holder thereof to receive, common stock to the extent such issuance or sale involves certain variable conversion, exercise or exchange prices or such agreement provides for sale of securities at a price to be determined in the future. Controlled Equity Offering On February 1, 2013, the Company entered into a Controlled Equity Offering SM Sales Agreement (the “ATM Agreement”) with Cantor Fitzgerald & Co., as sales agent (“Cantor”), pursuant to which Celsion may offer and sell, from time to time, through Cantor, shares of our common stock having an aggregate offering price of up to $25.0 million (the “ATM Shares”) pursuant to the Company’s previously filed and effective Registration Statement on Form S-3. Under the ATM Agreement, Cantor may sell ATM Shares by any method deemed to be an “at-the-market” offering as defined in Rule 415 promulgated under the Securities Act of 1933, as amended, including sales made directly on The NASDAQ Capital Market, on any other existing trading market for the our common stock or to or through a market maker. From February 1, 2013 through September 30, 2016, the Company sold and issued an aggregate of 1,479,535 shares of common stock under the ATM Agreement, receiving approximately $7.4 million in net proceeds. The Company is not obligated to sell any ATM Shares under the ATM Agreement. Subject to the terms and conditions of the ATM Agreement, Cantor will use commercially reasonable efforts, consistent with its normal trading and sales practices and applicable state and federal law, rules and regulations and the rules of The NASDAQ Capital Market, to sell ATM Shares from time to time based upon the Company’s instructions, including any price, time or size limits or other customary parameters or conditions the Company may impose. In addition, pursuant to the terms and conditions of the ATM Agreement and subject to the instructions of the Company, Cantor may sell ATM Shares by any other method permitted by law, including in privately negotiated transactions. The ATM Agreement will terminate upon the earlier of (i) the sale of ATM Shares under the ATM Agreement having an aggregate offering price of $25 million and (ii) the termination of the ATM Agreement by Cantor or the Company. The ATM Agreement may be terminated by Cantor or the Company at any time upon 10 days' notice to the other party, or by Cantor at any time in certain circumstances, including the occurrence of a material adverse change in the Company. The Company pays Cantor a commission of 3.0% of the aggregate gross proceeds from each sale of ATM Shares and has agreed to provide Cantor with customary indemnification and contribution rights. The Company also reimbursed Cantor for legal fees and disbursements of $50,000 in connection with entering into the ATM Agreement. On October 2, 2015, we filed a prospectus supplement to the base prospectus that forms a part of the Shelf Registration Statement, filed on September 4, 2015 and declared effective by the SEC on September 25, 2015, pursuant to which we may offer and sell up to $7,500,000 of common stock from time to time under the ATM Agreement. The Company currently has approximately $17.4 million remaining under the ATM Agreement. |