Financial Instrument [Axis]
Corporate Debt Securities [Member]
Measurement Frequency [Axis]
Fair Value, Measurements, Recurring [Member]
Fair Value Hierarchy and NAV [Axis]
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member]
Significant Other Observable Inputs (Level 2) [Member]
Significant Unobservable Inputs (Level 3) [Member]
Business Acquisition [Axis]
EGEN Inc [Member]
Type of Arrangement and Non-arrangement Transactions [Axis]
Purchase Agreement [Member]
Finite-Lived Intangible Assets by Major Class [Axis]
Noncompete Agreements [Member]
Contingent Consideration by Type [Axis]
Ovarian Cancer [Member]
Range [Axis]
Maximum [Member]
Award Type [Axis]
Stock Options [Member]
Restricted Stock Awards [Member]
Minimum [Member]
Legal Entity of Counterparty, Type [Axis]
Hisun [Member]
Horizon Credit Agreement [Member]
Debt Instrument [Axis]
Class of Warrant or Right [Axis]
Horizon Warrants [Member]
Variable Rate [Axis]
LIBOR plus [Member]
Legal Entity [Axis]
IPR&D Drug Technology Platforms [Member]
Plan Name [Axis]
Inducement Option Grants [Member]
Title of Individual [Axis]
Five New Employees [Member]
Equity Components [Axis]
Common Stock [Member]
Additional Paid in Capital [Member]
Treasury Stock [Member]
Accumulated Other Comprehensive Income [Member]
Accumulated Deficit [Member]
Hisun Agreement [Member]
Investment Type [Axis]
Short-term Investments [Member]
Property, Plant and Equipment, Type [Axis]
Machinery and Equipment [Member]
Furniture and Fixtures [Member]
Leasehold Improvements [Member]
Income Tax Authority [Axis]
Federal Income Tax [Member]
2018 Aspire Purchase Agreements [Member]
Capital on DemandTM Sales Agreement [Member]
License Agreement [Member]
Duke University [Member]
Investor [Member]
Warrant Exchange Agreements [Member]
U.S. Federal and State Tax [Member]
Asset Class [Axis]
Goodwill [Member]
IPR&D [Member]
Capital on Demand Agreement [Member]
Geographical [Axis]
New Jersey [Member]
2018 Stock Incentive Plan [Member]
2007 Stock Incentive Plan [Member]
Exercise Price Range [Axis]
Exercise Price One [Member]
Exercise Price Two [Member]
New Jersey [Member]
Glioblastoma Multiforme Brain Cancer [Member]
2018 Aspire Purchase Agreements [Member]
Equity Stock Awards [Member]
Inducement Awards [Member]
Income Statement Location [Axis]
Research and Development Expense [Member]
General and Administrative Expense [Member]
Amended Asset Purchase Agreement [Member]
Related Party Transaction [Axis]
10 Business Days of Achieving Milestone [Member]
Within One Year of Achieving Milestone [Member]
Fair Value Earnout Milestone Liability [Member]
Amended Asset Purchase Agreement Option Payment 2 [Member]
EGWU, Inc [Member]
1st Lease Amendment [Member]
First Year [Member]
2nd Lease Amendment [Member]
EGEN Asset Purchase Agreement [Member]
Adjustments for New Accounting Pronouncements [Axis]
Accounting Standards Update 2016-02 [Member]
Final Year [Member]
All Other Warrants [Member]
Aspire Purchase Agreement [Member]
2019 Aspire Purchase Agreements [Member]
Amended Asset Purchase Agreement Option Payment 1 [Member]
Subsequent Event Type [Axis]
Subsequent Event [Member]
Sale of Stock [Axis]
Controlled Equity Offering SM Sales Agreement [Member]
Securities Purchase Agreement [Member]
Original Warrants [Member]
Private Exchange Agreements [Member]
Warrant [Member]
February 2020 Offering [Member]
60 Month Lease [Member]
Operating Leases [Member]
Document And Entity Information
Entity Registrant Name
Entity Central Index Key
Document Type
Document Period End Date
Amendment Flag
Current Fiscal Year End Date
Entity Well-known Seasoned Issuer
Entity Voluntary Filer
Entity Current Reporting Status
Entity Interactive Data Current
Entity Filer Category
Entity Small Business Flag
Entity Emerging Growth Company
Entity Shell Company
Entity Public Float
Entity Common Stock, Shares Outstanding
Document Fiscal Period Focus
Document Fiscal Year Focus
Statement of Financial Position [Abstract]
ASSETS
Current assets:
Cash and cash equivalents
Investment in debt securities - available for sale, at fair value
Accrued interest receivable on investment securities
Advances and deposits on clinical programs and other current assets
Total current assets
Property and equipment (at cost, less accumulated depreciation and amortization)
Other assets:
Deferred income tax asset
In-process research and development, net
Goodwill
Operating lease right-of-use assets, net
Other intangible assets, net
Deposits and other assets
Total other assets
Total assets
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities:
Accounts payable - trade
Other accrued liabilities
Notes payable - current portion, net of deferred financing costs
Operating lease liability - current portion
Deferred revenue - current portion
Total current liabilities
Earn-out milestone liability
Note Payable, net of deferred financing costs
Operating lease liability - non-current portion
Deferred revenue - non-current portion
Other liabilities - non-current
Total liabilities
Commitments and contingencies
Stockholders' equity:
Preferred Stock - $0.01 par value (100,000 shares authorized, and no shares issued or outstanding at December 31, 2019 and 2018)
Common stock - $0.01 par value (112,500,000 shares authorized; 23,256,152 and 18,832,168 shares issued at December 31, 2019 and 2018, respectively, and 23,255,818 and 18,831,834 shares outstanding at December 31, 2019 and 2018, respectively)
Additional paid-in capital
Accumulated other comprehensive gain
Accumulated deficit
Total stockholders' equity before treasury stock
Treasury stock, at cost (334 shares at December 31, 2019 and 2018)
Total stockholders' equity
Total liabilities and stockholders' equity
Preferred stock, par value
Preferred stock, shares authorized
Preferred stock, shares issued
Preferred stock, shares outstanding
Common stock, par value
Common stock, shares authorized
Common stock, shares issued
Common stock, shares outstanding
Treasury stock, shares
Income Statement [Abstract]
Technology development and licensing revenue
Operating expenses:
Research and development
General and administrative
Total operating expenses
Loss from operations
Other income (expense):
Gain from change in earn-out milestone liability
Fair value of warrants issued in connection with amendment to modify GEN-1 earn-out milestone payments
Impairment of in-process research and development
Investment income, net
Interest expense
Other income
Total other income (expense)
Net loss before income tax benefit
Income tax benefit
Net loss
Net loss per common share - basic and diluted
Weighted average common shares outstanding - basic and diluted
Statement of Comprehensive Income [Abstract]
Net loss
Changes in:
Realized (gain) loss on investment securities recognized in investment income, net
Unrealized gain (loss) on investment securities
Other comprehensive income (loss)
Comprehensive loss
Statement of Cash Flows [Abstract]
Cash flows from operating activities:
Adjustments to reconcile net loss to net cash from operating activities:
Depreciation and amortization
Change in fair value of earn-out milestone liability
Fair value of warrants issued in connection with amendment to modify the GEN-1 earn-out milestone payments
Stock-based compensation
Shares issues in upon vesting of stock awards
Deferred income tax asset
Shares issued in exchange for services
Impairment of in-process research and development
Amortization of deferred finance charges and debt discount associated with note payable
Change in deferred rent liability
Net changes in:
Interest receivable on investments
Advances and deposits on clinical programs and other current assets
Other assets
Accounts payable - trade
Deferred revenue
Other accrued liabilities
Net cash used in operating activities
Cash flows from investing activities:
Purchases of investment in debt securities
Proceeds from sale and maturity of investment in debt securities
Purchases of property and equipment
Net cash provided by (used in) investing activities
Cash flows from financing activities:
Proceeds from issuance of common stock equity, net of issuance costs
Proceeds from note payable, net of issuance costs
Net cash provided by financing activities
(Decrease) Increase in cash and cash equivalents
Cash and cash equivalents at beginning of period
Cash and cash equivalents at end of period
Supplemental disclosures of cash flow information:
Cash (paid for) received from:
Interest
Income tax benefit
Cash paid for amounts included in measurement of lease liabilities:
Operating cash flows from lease payments
Non-cash financing and investing activities
Fair value of warrants issued in connection with amendment to modify the GEN-1 earn-out milestone payments
Fair value of common stock issued as equity issuance costs and charged against paid in capital
Fair value of warrants issued in connection with the debt facility
Fair value of stock issued in exchange for cancelation of warrants
Right of use assets obtained in exchange for lease liabilities
Operating leases
Realized and unrealized gains and losses, net, on investment in debt securities
Statement [Table]
Statement [Line Items]
Balance
Balance, shares
Sale of equity through ATM and common stock purchase agreement
Sale of equity through ATM and common stock purchase agreement, shares
Common stock issuance in exchange for cancellation of common stock warrants
Common stock issuance in exchange for cancellation of common stock warrants, shares
Common stock and warrants to purchase common stock issued in connection with equity and debt facilities
Common stock and warrants to purchase common stock issued in connection with equity and debt facilities, shares
Common stock issued in connection with equity facilities
Common stock issued in connection with equity facilities, shares
Realized and unrealized gains and losses, net, on investments securities
Stock-based compensation expense
Issuance of restricted stock
Issuance of restricted stock, shares
Sale of equity through equity financing facilities
Sale of equity through equity financing facilities, shares
Common stock warrants issued in connection with amendment to modify GEN-1 earn-out milestone payments
Balance
Balance, shares
Accounting Policies [Abstract]
Summary of Significant Accounting Policies
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Financial Condition
Investments, Debt and Equity Securities [Abstract]
Investments in Debt Securities Available For Sale
Fair Value Disclosures [Abstract]
Fair Values of Financial Instruments
Intangible Assets, Net (Including Goodwill) [Abstract]
Intangible Assets
Property, Plant and Equipment [Abstract]
Property and Equipment
Payables and Accruals [Abstract]
Other Accrued Liabilities
Debt Disclosure [Abstract]
Notes Payable
Income Tax Disclosure [Abstract]
Income Taxes
Equity [Abstract]
Stockholders' Equity
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation
Hercules Warrant [Member]
Earn-out Milestone Liability
Warrants and Rights Note Disclosure [Abstract]
Warrants
Postemployment Benefits [Abstract]
Celsion Employee Benefit Plans
Leases [Abstract]
Leases
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies
Licenses of Intellectual Property and Patents
Technology Development And Licensing Agreements
Technology Development and Licensing Agreements
Subsequent Events [Abstract]
Subsequent Events
Description of Business
Basis of Presentation
Use of Estimates
Revenue Recognition
Cash and Cash Equivalents
Fair Value of Investment in Debt Securities
Short Term Investments
Property and Equipment
Deposits
In-Process Research and Development, Other Intangible Assets and Goodwill
Impairment or Disposal of Long-Lived Assets
Comprehensive Income (Loss)
Research and Development
Net Loss Per Common Share
Income Taxes
Stock-Based Compensation
Recent Accounting Pronouncements
Short-term Investments [Abstract]
Schedule of Cost, Fair Value and Maturities of Short Term Investments
Summary of Investment Securities Gross Unrealized Gains (Losses)
Summary of Net Realized Losses On Sales of Available for Sale Securities and Investment Income Interest and Dividends
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis
Schedule of Future Amortization Amounts During the Remaining Life
Schedule of Fair Value of Assets Acquired
Summary of Property and Equipment
Schedule of Other Accrued Liabilities
Schedule of Future Principle Payments, Net of Unamortized Debt Discounts
Schedule of Income Tax Provision (Benefit)
Schedule of Effective Income Tax Rate Reconciliation
Schedule of Deferred Tax Assets and Liabilities
Summary of Stock Option Awards
Summary of Non-vested Restricted Stock Awards
Summary of Stock Options Outstanding
Schedule of Assumptions Used to Determine Fair Value of Options Granted
Schedule of Changes in Earn-out Milestone Liability
Summary of Warrant Activity
Schedule of Weighted Average Remaining Contractual Terms
Schedule of Lease Payments and Maturity of Our Operating Lease Liabilities
Collaborative Arrangement and Arrangement Other than Collaborative [Axis]
Accounts receivable
Contract liabilities
Depreciation
Number of shares of common stock issuable upon exercise of warrants and equity awards
Warrants exercise price
Number of shares of common stock issued in calculation basic loss per share
Tax benefits of EDA
Net proceeds from sale of net operating losses
Right-of-use assets
Related lease liabilities
Other liabilities
Statistical Measurement [Axis]
Cumulated net losses
Cash, investment securities and interest receivable
Future tax benefits
Raised in equity financing
Proceeds from available future sale of equity under common stock purchase agreement
Short-term investments - Fair Value
Short-term investments - Cost
Short-term investment maturities - Within 3 months, cost
Short-term investment maturities - Between 3-12 months, cost
Total, cost
Short-term investment maturities - Within 3 months, fair value
Short-term investment maturities - Between 3-12 months, fair value
Total, fair value
Investments in debt securities with unrealized gains, Less than 12 months , Fair Value
Investments in debt securities with unrealized losses, Less than 12 months, unrealized losses, Fair Value
Investment securities - available for sale, Fair Value
Investments in debt securities with unrealized gains, Less than 12 months, Unrealized Holding Gains (Losses)
Investments in debt securities with unrealized losses, Less than 12 months, Unrealized Holding Gains (Losses)
Unrealized Holding Gains (Losses)
Interest and dividends accrued and paid
Realized gains (losses
Investment income, net
Investment securities, available for sale
Indefinite lived intangible assets
Asset impairment charges, total
Business combination, consideration transferred, liabilities incurred
IPR&D costs
Finite-lived intangible assets, net
Finite-lived intangible assets acquired
Finite-lived intangible asset, useful life
Amortization expense
Finite-lived intangible assets, accumulated amortization
Goodwill, acquisition
2020
2021
Total
Intangible assets, beginning balance
Amortization
Impairment charge
Intangible assets, ending balance
Property and equipment gross
Less accumulated depreciation and amortization
Total
Estimated useful life
Amounts due to contract research organizations and other contractual agreements
Accrued payroll and related benefits
Accrued professional fees
Other
Total
Line of credit facility, maximum borrowing capacity
Proceeds from lines of credit, total
Interest rate
Debt effective interest rate
Percentage of outstanding principle balance, description
Class of warrant or right exercisable
Warrant exercise price
Debt instrument, unamortized discount, total
Financing fees and expenses
Loan origination fees
Percentage for original debt, amount
Interest expense, debt, total
Amortization of debt issuance costs
2020
2021
2022
2023 and thereafter
Subtotal of future principal payments
Unamortized debt issuance costs, net
Total
Income tax, description
Income tax, u.s. Corporate income tax rate
Deferred tax asset
Net operating losses
Net operating losses, unused
Net operating losses expiration, description
Net operating losses carryforward limits, description
Operating loss carry forwards, limitation on use
Operating loss carry forwards, limitation on use
Payments from sale of nols
Proceeds from sale of nols
Future tax benefits remaining under the nol program
Federal, Current
Federal, Deferred
State and Local, Current
State and Local, Deferred
Effective tax rate
Federal statutory rate
State taxes, net of federal tax benefit
Permanent differences
Other
Change in valuation allowance and deferred rate change, net
Effective tax rate
Net operating loss carryforwards
Other Deferred tax assets, net
Subtotal
Valuation allowance
Total deferred tax asset
Shelf registration statement amount
Aggregate offering price, additions
Aggregate offering price, term
Maximum number of shares purchased per business day
Aggregate offering price
Aggregate offering price, description
Aspire purchase agreement, terms
Maximum number of shares purchased per business day, additional
Stock issued during period, shares, new issues
Proceeds from issuance of common stock
Commission percentage for gross proceeds from common stock
Aggregate value available for issuance
Proceeds from sale equity
Sale of common stock, shares
Shares issued, price per share
Number of warrants to purchase common stock
Warrants term
Equity awards, number of stock authorized
Number of equity awards available for future issuance
Percentage of fair market value of shares
Percentage of outstanding stock determining factor for incentive stock price
Number of shares issued
Inducement option grant, exercise price per share
Option vested period
Options expiration period
Number of shares reserved for future issuance
Compensation cost
Unrecognized compensation cost related to non-vested stock based compensation
Stock based compensation cost expected to be recognized, weighted average period
Number Outstanding, Outstanding, Beginning Balance
Number Outstanding, Granted
Number Outstanding, Cancelled or expired
Number Outstanding, Ending Balance
Number Outstanding, Exercisable
Weighted Average Exercise Price, Outstanding, Beginning Balance
Weighted Average Exercise Price, Granted
Weighted Average Exercise Price, Cancelled or expired
Weighted Average Exercise Price, Outstanding, Ending Balance
Weighted Average Exercise Price, Exercisable
Weighted Average Remaining Contractual Term (years), Outstanding, Ending Balance
Weighted Average Remaining Contractual Term (years), Exercisable
Aggregate Intrinsic Value, Outstanding, Ending Balance
Aggregate Intrinsic Value, Exercisable
Number Outstanding, Non-vested stock awards outstanding, Beginning Balance
Number Outstanding, Non-vested stock awards outstanding, Granted
Number Outstanding, Non-vested stock awards outstanding, Vested and issued
Number Outstanding, Non-vested stock awards outstanding, Forfeited
Number Outstanding, Non-vested stock awards outstanding, Ending Balance
Weighted Average Grant Date Fair Value, Beginning Balance
Weighted Average Grant Date Fair Value, Granted
Weighted Average Grant Date Fair Value, Vested and issued
Weighted Average Grant Date Fair Value, Forfeited
Weighted Average Grant Date Fair Value, Ending Balance
Range of Exercise Prices, Upper
Range of Exercise Prices, Lower
Options Outstanding, Number
Options Outstanding, Weighted Average Remaining Contractual Term (in years)
Options Outstanding, Weighted Average Exercise Price
Options Exercisable, Number
Options Exercisable, Weighted Average Remaining Contractual Term (in years)
Options Exercisable, Weighted Average Exercise Price
Risk-free interest rate, minimum
Risk-free interest rate, maximum
Expected volatility, minimum
Expected volatility, maximum
Expected life (in years)
Expected dividend yield
Future earn-out payments
Fair value of acquisition consideration
Risk adjusted assessment of each milestone
Estimated time to achieve the milestone
Earnout milestone liability
Warrants to purchase common stock
Warrants strike price
Gain on non-cash benefit
Gain (loss) from change in fair value of earn out milestone liability
Earn-out liabilities, beginning balance
Non-cash gain from the adjustment for the change in fair value included in net loss
Earn-out liabilities, ending balance
Number of shares, warrant rights
Common stock shares issued
Number of Warrants Issued, Warrants Outstanding, Beginning Balance
Number of Warrants Issued, Warrants Issued
Number of Warrants Issued, Warrants cancelled in exchange for common stock
Number of Warrants Issued, Warrants Expired
Number of Warrants Issued, Warrants Outstanding, Ending Balance
Weighted Average Exercise Price, Warrants Outstanding, Beginning Balance
Weighted Average Exercise Price, Warrants Issued
Weighted Average Exercise Price, Warrants cancelled in exchange for common stock
Weighted Average Exercise Price, Warrants Expired
Weighted Average Exercise Price, Warrants Outstanding and Exercisable, Ending Balance
Aggregate Intrinsic Value of Outstanding Warrants
Weighted average remaining contractual terms (years)
Number of Warrants Issued
Weighted Average Exercise Price
Weighted Average Contractual Terms Remaining (in years)
Maximum annual contributions per employee, percent
Matching contributions of employee
Discretionary contribution
Discretionary contribution, rate
Lease description
Area of land
Lease, term of contract
Lease expiration date
Lease, renewal term
Lease, option to extend
Lease, rent payment
ROU asset
Operating lease liabilities
Increased ROU asset
Operating lease costs
Operating lease expense
Cash paid for operating leases, including operating cash flows
2020
2021
2022
2023
2024 and thereafter
Subtotal future lease payments
Less imputed interest
Total lease liabilities
Weighted average remaining life
Weighted average discount rate
Number of days before issuance factoring into average closing price
Amount of time after effective date of license agreement for registration rights to take place
Common stock, shares, issued
Common stock, value, issued
Number of trademark protection application pending for thermo dox
Non-refundable research and development fee
Deferred revenue
Deferred revenue amortization period
Upfront payment
Proceeds from offering
Represents Controlled Equity Offering Sales Agreement (the “ATM Agreement”) with Cantor Fitzgerald & Co., as sales agent.
Represents the additional aggregate offering price for shares of common stock that the Company may offer and sell through a sales agent.
Aggregate offering price, description.
Aggregate offering price, term.
Aggregate offering price.
Aspire Capital Fund, LLC [Member]
Aspire Purchase Agreement [Member]
The current amount of amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).
Amount of accumulated unrealized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position.
Capital on Demand Agreement [Member]
Capital on DemandTM Sales Agreement [Member]
The amount of cash, investment securities and interest receivable.
Common Stock Sales Agreement [Member]
Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) unrealized gain less than 12 months.
Amount of accumulated unrealized gain on investment in debt security measured at fair value with change in other comprehensive income (available-for-sale), unrealized gain for less than 12 months.
Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next rolling three to twelve months.
Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next rolling three to twelve months.
Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) with single maturity date and allocated without single maturity date, maturing in next rolling three months.
Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next rolling three months.
The amortization period for deferred revenue.
Duke University [Member]
EGEN Asset Purchase Agreement [Member]
Information pertaining to the business acquisition of EGEN, Inc.
EGEN Inc [Member]
EGWU, Inc [Member]
The amount of earn-out milestone liability as of the balance sheet.
The disclosure related to earn-out milestone liabilities.
Equity Stock Awards [Member]
The amount of estimated time to achieve the milestone.
Exercise Agreements [Member]
Exercise Price One [Member]
Exercise Price Two [Member]
Fair value of common stock issued as equity issuance costs and charged against paid in capital.
Fair value of warrants issued in connection with amendment to modify GEN-1 earn-out milestone payments.
Fair value of warrants issued in connection with amendment to modify the related earn-out milestone payments.
Represents the public offering on February 14, 2017.
February 14, 2017 Public Offering [Member]
Federal Income Tax [Member]
First Tranche [Member]
Gain (loss) from change in valuation of earn-out milestone liability.
The amount of gain (loss) from the change in the fair value of earn-out milestone liability.
The amount recognized in earnings related to the change in fair value during the period of milestone liability.
Glioblastoma Multiforme Brain Cancer [Member]
Represents a loan agreement with Hercules Technology Growth Capital, Inc. (“Hercules”).
Represents Hercules Technology Growth Capital, Inc..
Hercules Technology Growth Capital, Inc. [Member]
Represents Hercules Technology Growth Capital, Inc..
Hisun Agreement [Member]
Hisun [Member]
Horizon Credit Agreement [Member]
Horizon Technology Finance Corporation [Member]
Horizon Warrants [Member]
Huntsville Alabama [Member]
IPR&D Drug Technology Platforms [Member]
IPR&D [Member]
In Process R and D - GBM Two [Member]
Inducement Option Grants [Member]
Investor Warrants [Member]
Represents the information pertaining to the direct offering agreement on July 6, 2017.
June 2016 Warrants [Member]
Lawrenceville New Jersey [Member]
License Agreement [Member]
The entire disclosure for a contractual arrangement, in which the Company gave another party an exclusive license.
Loan Agreement [Member]
Maximum number of shares purchased per day.
Maximum number of shares purchased per day, additional.
Represents a securities purchase agreement with certain investors into which the entity entered in May 2015.
New Jersey [Member]
Represents the total number of Shares of common stock issuable upon exercise of warrants and equity awards.
Represents the October 2017 Underwritten Offering.
Oppenheimer & Co. Inc. [Member]
Ovarian Cancer [Member]
Percentage of fair market value of shares
Percentage of outstanding stock determining factor for incentive stock price.
Information relating to Pre-Funded Series BB Warrant.
Represents the information pertaining to the Pre-Funded Series CCC Warrants.
Purchase Agreement [Member]
Aspire purchase agreement, terms.
The percentage of risk-adjusted assessment of each milestone.
Sale of equity through equity financing facilities.
Sale of equity through equity financing facilities, shares.
The disclosure of transactions regarding the changes in earn-out liabilities during the period.
Second Tranche [Member]
Represents the information pertaining to the Series AAA Warrants.
Information relating to Series AA warrants.
Represents the information pertaining to the Series BBB Warrants.
Represents the information pertaining to Series DDD Warrants.
Weighted Average Exercise Price, Warrants issued
Shares issued in exchange for services.
Shelf Registration statement.
Sale of equity through ATM purchase agreement, shares.
Sale of equity through ATM purchase agreement.
Tax benefits of EDA
Tax Reform Act [Member]
Three New Employees [Member]
2018 Stock Incentive Plan [Member]
2007 Stock Incentive Plan [Member]
Represents the information pertaining to the 2015 Warrants.
Represents the information pertaining to the 2013 Warrants, 2014 Warrants, and June 2016 Warrants.
U.S. Federal and State Tax [Member]
Underwriting Agreement [Member]
Warrant Exchange Agreements [Member]
Warrants [Text Block]
Tabular disclosure of weighted average remaining contractual terms.
Aggregate value available for issuance.
Five New Employees [Member]
Inducement Awards [Member]
Earnout milestone liability.
Amended Asset Purchase Agreement [Member]
10 Business Days of Achieving Milestone [Member]
Within One Year of Achieving Milestone [Member]
Recognized Non-cash Benefit [Member]
Fair Value Earnout Milestone Liability [Member]
Amended Asset Purchase Agreement Option Payment 1 [Member]
Amended Asset Purchase Agreement Option Payment 2 [Member]
Recognized Non-cash Charge [Member]
Other Warrant [Member]
1st Lease Amendment [Member]
2nd Lease Amendment [Member]
Upfront payment.
Revenue Ratably Through 2022 [Member]
Reduction in Warrant [Member]
Commission percentage for gross proceeds from common stock.
First Year [Member]
Final Year [Member]
All Other Warrants [Member]
General and Administrative Expenses [Member]
Sharebased compensation arrangement by sharebased payment award non options outstanding intrinsic value.
Weighted average price at which grantees can acquire the shares reserved for issuance under the stock non-option equity plan.
Weighted average per share amount at which grantees can acquire shares of common stock by exercise of non-option equity.
Share based compensation arrangement by share based payment award non option equity instruments expired in period weighted average exercise price.
Fair value of warrants issued in connection with the debt facility.
Warrants strike price.
Common stock and warrants to purchase common stock issued in connection with equity and debt facilities.
Common stock and warrants to purchase common stock issued in connection with equity and debt facilities, shares.
2018 Aspire Purchase Agreements [Member]
2018 Aspire Purchase Agreements [Member]
2019 Aspire Purchase Agreements [Member]
Impairment of in-process research and development.
Common stock issuance in exchange for cancellation of common stock warrants.
Common stock issuance in exchange for cancellation of common stock warrants, shares.
Description of Business.
Deposits.
Net proceeds from sale of net operating losses
Net operating losses, unused.
Net operating losses expiration, description.
Net operating losses carryforward limits, description.
Operating loss carry forwards, limitation on use
Proceeds from sale of NOLs.
Effective income tax rate reconciliation permanent differences.
Number of days before issuance factoring into average closing price.
Amount of time after effective date of license agreement for registration rights to take place.
Number of trademark protection application pending for thermo dox.
Asset Purchase Agreement [Member]
Cash Paid [Abstract]
Lease Contract Type [Axis]
Licenses of Intellectual Property and Patents [Text Block]
Number of shares of common stock issued in calculation basic loss per share.
Future tax benefits.
Proceeds from available future sale of equity under common stock purchase agreement.
Precentage of outstanding principle balance, description.
Raised in equity financing.
Payments from sale of net operating losses.
Future tax benefits remaining under the NOL Program.
Controlled Equity Offering SM Sales Agreement [Member]
Securities Purchase Agreement [Member]
Original Warrants [Member]
Private Exchange Agreements [Member]
Gain on non-cash benefit.
Weighted average remaining contractual term for non-option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.
Weighted average price at which grantees could have acquired the underlying shares with respect to non-options that were terminated.
Amount of discretionary contributions made by an employer as a percentage of each participants annual salary to a defined contribution plan.
February 2020 Offering [Member]
Amortization of deferred finance charges and debt discount associated with note payable.
60 Month Lease [Member]
Operating Leases [Member]
Cash paid for operating leases, including operating cash flows.
NEW JERSEY
AspirePurchaseAgreementsMember
Assets, Current
Assets, Noncurrent
Assets
Liabilities, Current
Liabilities
Stockholders' Equity before Treasury Stock
Treasury Stock, Value
Stockholders' Equity Attributable to Parent
Liabilities and Equity
Operating Expenses
Operating Income (Loss)
Nonoperating Income (Expense)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax
Comprehensive Income (Loss), Net of Tax, Attributable to Parent
Loss from change in valuation of earn-out milestone liability
Deferred Income Tax Expense (Benefit)
Increase (Decrease) in Accrued Investment Income Receivable
Increase (Decrease) in Prepaid Expense and Other Assets
Increase (Decrease) in Other Current Assets
Increase (Decrease) in Accounts Payable
Increase (Decrease) in Other Accrued Liabilities
Net Cash Provided by (Used in) Operating Activities
Payments to Acquire Available-for-sale Securities
Payments to Acquire Property, Plant, and Equipment
Net Cash Provided by (Used in) Investing Activities
Net Cash Provided by (Used in) Financing Activities
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations
Interest Paid, Excluding Capitalized Interest, Operating Activities
Shares, Outstanding
Property, Plant and Equipment, Policy [Policy Text Block]
Income Tax, Policy [Policy Text Block]
Share-based Payment Arrangement [Policy Text Block]
Cost
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value
Less than 12 months, unrealized gains, fair value
Less than 12 months, unrealized gains
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss
Unrealized gains (losses)
Amortization of Intangible Assets
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months
Long-term Debt, Maturities, Repayments of Principal in Year Two
Long-term Debt, Gross
Debt Instrument, Unamortized Discount (Premium), Net
Long-term Debt
OperatingLossCarryForwardsLimitationOnUse
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent
Effective Income Tax Rate Reconciliation, Percent
Deferred Tax Assets, Gross
Deferred Tax Assets, Valuation Allowance
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Number of Shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Number of Shares
Share-based Compensation Arrangement by Share-based Payment Award, Option, Nonvested, Weighted Average Exercise Price
clsn_EarnoutMilestoneLiability
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Forfeitures
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Expirations
ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingWeightedAverageExercisePrice
ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionsOutstandingIntrinsicValue
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months
Lessee, Operating Lease, Liability, Payments, Due Year Two
Lessee, Operating Lease, Liability, Payments, Due Year Three
Lessee, Operating Lease, Liability, Payments, Due
Lessee, Operating Lease, Liability, Undiscounted Excess Amount
Deferred Revenue