Stockholders' Equity	3 Months Ended
Mar. 31, 2020
Equity [Abstract]
Stockholders' Equity	Note 11. Stockholders’ Equity In September 2018, the Company filed with the SEC a new $75 million shelf registration statement on Form S-3 (the “2018 Shelf Registration Statement”) (File No. 333-227236) that allows the Company to issue any combination of common stock, preferred stock or warrants to purchase common stock or preferred stock. This shelf registration was declared effective on October 12, 2018 and will expire three years from that date. Aspire Purchase Agreement On October 28, 2019, Company, entered into a common stock purchase agreement (the “2019 Aspire Purchase Agreement”) with Aspire Capital Fund, LLC (“Aspire Capital”) which provides that, upon the terms and subject to the conditions and limitations set forth therein, Aspire Capital is committed to purchase up to an aggregate of $10.0 million of shares of the Company’s common stock over the 24-month term of the 2019 Aspire Purchase Agreement. During 2019, the Company sold and issued an aggregate of 0.5 million shares under the 2019 Aspire Purchase Agreement, receiving approximately $0.7 million. During the first quarter of 2020 through March 5, 2020 when the Company delivered notice to Aspire terminating the 2019 Aspire Purchase Agreement, the Company sold 1.0 million shares of common stock under the Aspire Purchase Agreement, receiving approximately $1.6 million in additional gross proceeds. Capital on Demand^TM Sales Agreement On December 4, 2018, the Company entered into a Capital on Demand^TM Sales Agreement (the “Capital on Demand Agreement”) with JonesTrading Institutional Services LLC, as sales agent (“JonesTrading”), pursuant to which the Company may offer and sell, from time to time, through JonesTrading shares of Common Stock having an aggregate offering price of up to $16.0 million. The Shares will be issued pursuant to Celsion’s previously filed and effective Registration Statement on Form S-3 (File No. 333-227236), the base prospectus dated October 12, 2018, filed as part of such Registration Statement, and the prospectus supplement dated December 4, 2018, filed by Celsion with the Securities and Exchange Commission. During 2019, the Company sold and issued an aggregate of 0.5 million shares under the Capital on Demand Agreement, receiving approximately $1.0 million in gross proceeds. The Company did not sell any shares under the Capital on Demand Agreement during 2020. As of March 31, 2020, the Company has approximately $15 million available under the Capital on Demand Agreement. Registered Direct Offering On February 27, 2020, we entered into a Securities Purchase Agreement (the “Purchase Agreement”) with several institutional investors, pursuant to which we agreed to issue and sell, in a registered direct offering (the “February 2020 Offering”), an aggregate of 4,571,428 shares (the “Shares”) of our common stock at an offering price of $1.05 per share for gross proceeds of approximately $4.8 million before the deduction of the Placement Agent fees and offering expenses. The Shares were offered by the Company pursuant to a registration statement on Form S-3 (File No. 333-227236). The Purchase Agreement contains customary representations, warranties and agreements by the Company and customary conditions to closing. In a concurrent private placement (the “Private Placement”), the Company agreed to issue to the investors that participated in the Offering, for no additional consideration, warrants, to purchase up to 2,971,428 shares of Common Stock (the “Original Warrants”). The Original Warrants were initially exercisable six months following their date of issue and were set to expire on the five-year anniversary of such initial exercise date. The Warrants had an exercise price of $1.15 per share subject to adjustment as provided therein. On March 12, 2020 the Company entered into private exchange agreements (the “Exchange Agreements”) with holders the Warrants. Pursuant to the Exchange Agreements, in return for a higher exercise price of $1.24 per share of Common Stock, the Company issued new warrants to the Investors to purchase up to 3,200,000 shares of Common Stock (the “Exchange Warrants”) in exchange for the Original Warrants. The Exchange Warrants, like the Original Warrants, are initially exercisable six months following their issuance (the “Initial Exercise Date”) and expire on the five-year anniversary of their Initial Exercise Date. Other than having a higher exercise price, different issue date, Initial Exercise Date and expiration date, the terms of the Exchange Warrants are identical to those of the Original Warrants.

Stockholders' Equity

3 Months Ended

Mar. 31, 2020

Note 11. Stockholders’ Equity

In September 2018, the Company filed with the SEC a new $75 million shelf registration statement on Form S-3 (the “2018 Shelf Registration Statement”) (File No. 333-227236) that allows the Company to issue any combination of common stock, preferred stock or warrants to purchase common stock or preferred stock. This shelf registration was declared effective on October 12, 2018 and will expire three years from that date.

Aspire Purchase Agreement

On October 28, 2019, Company, entered into a common stock purchase agreement (the “2019 Aspire Purchase Agreement”) with Aspire Capital Fund, LLC (“Aspire Capital”) which provides that, upon the terms and subject to the conditions and limitations set forth therein, Aspire Capital is committed to purchase up to an aggregate of $10.0 million of shares of the Company’s common stock over the 24-month term of the 2019 Aspire Purchase Agreement.

During 2019, the Company sold and issued an aggregate of 0.5 million shares under the 2019 Aspire Purchase Agreement, receiving approximately $0.7 million. During the first quarter of 2020 through March 5, 2020 when the Company delivered notice to Aspire terminating the 2019 Aspire Purchase Agreement, the Company sold 1.0 million shares of common stock under the Aspire Purchase Agreement, receiving approximately $1.6 million in additional gross proceeds.

Capital on Demand^TM Sales Agreement

On December 4, 2018, the Company entered into a Capital on Demand^TM Sales Agreement (the “Capital on Demand Agreement”) with JonesTrading Institutional Services LLC, as sales agent (“JonesTrading”), pursuant to which the Company may offer and sell, from time to time, through JonesTrading shares of Common Stock having an aggregate offering price of up to $16.0 million.

The Shares will be issued pursuant to Celsion’s previously filed and effective Registration Statement on Form S-3 (File No. 333-227236), the base prospectus dated October 12, 2018, filed as part of such Registration Statement, and the prospectus supplement dated December 4, 2018, filed by Celsion with the Securities and Exchange Commission. During 2019, the Company sold and issued an aggregate of 0.5 million shares under the Capital on Demand Agreement, receiving approximately $1.0 million in gross proceeds. The Company did not sell any shares under the Capital on Demand Agreement during 2020. As of March 31, 2020, the Company has approximately $15 million available under the Capital on Demand Agreement.

Registered Direct Offering

On February 27, 2020, we entered into a Securities Purchase Agreement (the “Purchase Agreement”) with several institutional investors, pursuant to which we agreed to issue and sell, in a registered direct offering (the “February 2020 Offering”), an aggregate of 4,571,428 shares (the “Shares”) of our common stock at an offering price of $1.05 per share for gross proceeds of approximately $4.8 million before the deduction of the Placement Agent fees and offering expenses. The Shares were offered by the Company pursuant to a registration statement on Form S-3 (File No. 333-227236). The Purchase Agreement contains customary representations, warranties and agreements by the Company and customary conditions to closing. In a concurrent private placement (the “Private Placement”), the Company agreed to issue to the investors that participated in the Offering, for no additional consideration, warrants, to purchase up to 2,971,428 shares of Common Stock (the “Original Warrants”). The Original Warrants were initially exercisable six months following their date of issue and were set to expire on the five-year anniversary of such initial exercise date. The Warrants had an exercise price of $1.15 per share subject to adjustment as provided therein. On March 12, 2020 the Company entered into private exchange agreements (the “Exchange Agreements”) with holders the Warrants. Pursuant to the Exchange Agreements, in return for a higher exercise price of $1.24 per share of Common Stock, the Company issued new warrants to the Investors to purchase up to 3,200,000 shares of Common Stock (the “Exchange Warrants”) in exchange for the Original Warrants. The Exchange Warrants, like the Original Warrants, are initially exercisable six months following their issuance (the “Initial Exercise Date”) and expire on the five-year anniversary of their Initial Exercise Date. Other than having a higher exercise price, different issue date, Initial Exercise Date and expiration date, the terms of the Exchange Warrants are identical to those of the Original Warrants.