Entity Central Index Key Cover [Abstract] Document Type Document Type Amendment Flag Amendment Flag Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Trading Symbol Trading Symbol Entity Registrant Name Entity Registrant Name Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Current Reporting Status Entity Current Reporting Status Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Shell Company Entity Shell Company Entity Common Stock, Shares Outstanding Entity Common Stock Shares Outstanding Entity Interactive Data Current Entity Interactive Data Current Title of 12(b) Security Security12b Title Security Exchange Name Security Exchange Name Entity File Number Entity File Number Entity Incorporation, State or Country Code Entity Incorporation State Country Code Entity Tax Identification Number Entity Tax Identification Number Entity Address, Address Line One Entity Address Address Line1 Entity Address, Address Line Two Entity Address Address Line2 Entity Address, City or Town Entity Address City Or Town Entity Address, State or Province Entity Address State Or Province Entity Address, Postal Zip Code Entity Address Postal Zip Code City Area Code City Area Code Local Phone Number Local Phone Number Document Quarterly Report Document Quarterly Report Document Transition Report Document Transition Report Statement Of Financial Position [Abstract] Assets Assets [Abstract] Current assets: Assets Current [Abstract] Cash and cash equivalents Cash And Cash Equivalents At Carrying Value Prepaid expenses and other current assets Prepaid Expense And Other Assets Current Total current assets Assets Current Other assets Other Assets Noncurrent Total assets Assets Liabilities and stockholders’ equity Liabilities And Stockholders Equity [Abstract] Current liabilities: Liabilities Current [Abstract] Accounts payable, accrued expenses and other Accounts Payable And Accrued Liabilities Current Total current liabilities Liabilities Current Total liabilities Liabilities Commitments and contingencies Commitments And Contingencies Stockholders’ equity: Stockholders Equity [Abstract] Preferred stock, $0.01 par value: 10,000 shares authorized at March 31, 2022 and December 31, 2021; no shares issued or outstanding at March 31, 2022 or December 31, 2021 Preferred Stock Value Common stock, $0.01 par value: 30,000 shares authorized at March 31, 2022 and December 31, 2021; 13,410 shares issued and outstanding at March 31, 2022 and December 31, 2021 Common Stock Value Additional paid-in capital Additional Paid In Capital Common Stock Accumulated deficit Retained Earnings Accumulated Deficit Total stockholders’ equity Stockholders Equity Total liabilities and stockholders’ equity Liabilities And Stockholders Equity Preferred stock, par value Preferred Stock Par Or Stated Value Per Share Preferred stock, shares authorized Preferred Stock Shares Authorized Preferred stock, shares issued Preferred Stock Shares Issued Preferred stock, shares outstanding Preferred Stock Shares Outstanding Common stock, par value Common Stock Par Or Stated Value Per Share Common stock, shares authorized Common Stock Shares Authorized Common stock, shares issued Common Stock Shares Issued Common stock, shares outstanding Common Stock Shares Outstanding Statement Of Income And Comprehensive Income [Abstract] Operating expenses: Operating Expenses [Abstract] General and administrative expenses General And Administrative Expense Gain on sale of assets Gain Loss On Disposition Of Assets1 Total operating expenses Operating Expenses Loss from operations Operating Income Loss Net loss and comprehensive loss Comprehensive Income Net Of Tax Net loss per common share - basic and diluted Earnings Per Share Basic And Diluted Weighted-average common shares used to compute basic and diluted net loss per common share Weighted Average Number Of Share Outstanding Basic And Diluted Statement Of Stockholders Equity [Abstract] Statement [Table] Statement [Table] Equity Components Statement Equity Components [Axis] Equity Component Equity Component [Domain] Common Stock [Member] Common Stock [Member] Additional Paid-In Capital [Member] Additional Paid In Capital [Member] Accumulated Deficit [Member] Retained Earnings [Member] Statement [Line Items] Statement [Line Items] Balance Balance (in shares) Shares Outstanding Exercise of stock options Stock Issued During Period Value Stock Options Exercised Exercise of stock options (in shares) Stock Issued During Period Shares Stock Options Exercised Stock-based compensation Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value Net loss Profit Loss Balance Balance (in shares) Gain on sale of in progress research and development asset. Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and nonemployees. Proceeds from sale of in progress research and development asset. Statement Of Cash Flows [Abstract] Cash flows from operating activities Net Cash Provided By Used In Operating Activities [Abstract] Adjustments to reconcile net loss to net cash used in operating activities Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities [Abstract] Gain on sale of in process research and development Gain On Sale Of In Process Research And Development Asset Stock-based compensation expense Allocated Share Based Compensation Expense Including Non Employees Changes in operating assets and liabilities: Increase Decrease In Operating Capital [Abstract] Prepaid expenses and other assets Increase Decrease In Prepaid Deferred Expense And Other Assets Accounts payable, accrued expenses and other Increase Decrease In Accounts Payable And Accrued Liabilities Net cash used in operating activities Net Cash Provided By Used In Operating Activities Cash flows from investing activities Net Cash Provided By Used In Investing Activities [Abstract] Proceeds from sale of in process research and development Proceeds From Sale Of In Progress Research And Development Asset Net cash provided by investing activities Net Cash Provided By Used In Investing Activities Cash flows from financing activities Net Cash Provided By Used In Financing Activities [Abstract] Proceeds from exercise of stock options Proceeds From Stock Options Exercised Net cash provided by financing activities Net Cash Provided By Used In Financing Activities Net increase (decrease) in cash and cash equivalents Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect Cash and cash equivalents, beginning of period Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Cash and cash equivalents, end of period Organization Consolidation And Presentation Of Financial Statements [Abstract] Nature of the Business Nature Of Operations Accounting Policies [Abstract] Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Fair Value Disclosures [Abstract] Fair Value of Financial Instruments Fair Value Disclosures [Text Block] Payables And Accruals [Abstract] Accounts Payable, Accrued Expenses and Other Accounts Payable And Accrued Liabilities Disclosure [Text Block] Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] Stock-Based Compensation Disclosure Of Compensation Related Costs Share Based Payments [Text Block] Earnings Per Share [Abstract] Net Loss Per Common Share Earnings Per Share [Text Block] Accounting Changes And Error Corrections [Abstract] Recent Accounting Pronouncements New Accounting Pronouncements And Changes In Accounting Principles [Text Block] Basis of Presentation Basis Of Accounting Policy Policy [Text Block] Unaudited Interim Financial Information Comparability Of Prior Year Financial Data Use of Estimates Use Of Estimates Recent Accounting Pronouncements New Accounting Pronouncements Policy Policy [Text Block] Summary of Assets Measured at Fair Value on a Recurring Basis Fair Value Assets Measured On Recurring Basis [Text Block] Schedule of Accounts Payable, Accrued Expenses and Other Schedule Of Accounts Payable And Accrued Liabilities Table [Text Block] Schedule of Outstanding Options Excluded from Computation of Diluted Loss Per Share Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Text Block] Contingent milestone payments receivable. Summary of significant accounting policies. Summary of significant accounting policies. Summary Of Significant Accounting Policies [Table] Summary Of Significant Accounting Policies [Table] Counterparty Name Counterparty Name [Axis] Counterparty Name Repurchase Agreement Counterparty Name [Domain] Ipsen S.A. Ipsen [Member] Ipsen S A [Member] Scenario Statement Scenario [Axis] Scenario Scenario Unspecified [Domain] First Line Treatment of Metastatic Adenocarcinoma of Pancreas [Member] First Line Treatment Of Metastatic Adenocarcinoma Of Pancreas [Member] After Failure of First Line Chemotherapy [Member] After Failure Of First Line Chemotherapy [Member] Additional Indication [Member] Additional Indication [Member] Collaborative Arrangement and Arrangement Other than Collaborative Type Of Arrangement [Axis] Collaborative Arrangement and Arrangement Other than Collaborative Arrangements And Nonarrangement Transactions [Member] Asset sale agreement. Asset Sale Agreement [Member] Asset Sale Agreement [Member] Statistical Measurement Range [Axis] Statistical Measurement Range [Member] Maximum [Member] Maximum [Member] Minimum [Member] Minimum [Member] Fourteener oncology inc member. 14ner Sale [Member] Fourteener Oncology Inc [Member] Milestone achievement one member. Achievement of the Primary Endpoint in the First Registrational Clinical Study of Either MM-121 or MM-111 [Member] Milestone Achievement One [Member] Milestone achievement two member. Achievement of Various Regulatory Approval and Reimbursement-Based Milestones in the United States, Europe and Japan [Member] Milestone Achievement Two [Member] Milestone achievement three member. Achievement Various Cumulative Worldwide Net Sales Targets Between $100.0 million and $300.0 million for MM-121 and MM-111 [Member] Milestone Achievement Three [Member] Asset purchase option agreement. Asset Purchase Option Agreement [Member] Asset Purchase Option Agreement [Member] Legal Entity Legal Entity [Axis] Entity Entity [Domain] Celator Pharmaceuticals Inc [Member]. Celator Pharmaceuticals Inc [Member] Celator Pharmaceuticals Inc [Member] Pegascy SAS. Pegascy SAS [Member] Pegascy S A S [Member] Summary Of Significant Accounting Policies [Line Items] Summary Of Significant Accounting Policies [Line Items] Contingent milestone payments receivable Contingent Milestone Payments Receivable Upfront cash payment received. Additional payments receivable on achievement of certain milestone events. Upfront cash payment received Upfront Cash Payment Received Additional payments receivable on achievement of certain milestone events Additional Payments Receivable On Achievement Of Certain Milestone Events Cumulative worldwide net sales target Revenue From Contract With Customer Including Assessed Tax Cash payment received. Repayment received or receivable for expenses incurred on behalf of a client or customer, other than those reimbursements received by landlords from tenants. Transaction expenses. Consideration receivable. Option fee. Exercise period of option. Amount of gain (loss) on payment of option fee. Consideration received. Gain loss on payment of consideration. Cash payment received Cash Payment Received Reimbursement of expenses Reimbursement Revenues Transaction expenses Transaction Expenses Consideration receivable Consideration Receivable Option fee Option Fee Exercise period of option Exercise Period Of Option Gain related to option fee payment Gain Loss On Payment Of Option Fee Consideration received Consideration Received Gain related to payment of consideration Gain Loss On Payment Of Consideration Accumulated deficit Net loss from continuing operations Cash used in operating activities Cash, cash equivalents and marketable securities Cash Cash Equivalents And Short Term Investments Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table] Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table] Measurement Frequency Fair Value By Measurement Frequency [Axis] Measurement Frequency Fair Value Measurement Frequency [Domain] Recurring Basis [Member] Fair Value Measurements Recurring [Member] Level 2 [Member] Fair Value By Fair Value Hierarchy Level [Axis] Fair Value Hierarchy and NAV Fair Value Measurements Fair Value Hierarchy [Domain] Level 1 [Member] Fair Value Inputs Level1 [Member] Level 2 [Member] Fair Value Inputs Level2 [Member] Level 3 [Member] Fair Value Inputs Level3 [Member] Asset Class Fair Value By Asset Class [Axis] Asset Class Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation By Asset Class [Domain] Money Market Funds [Member] Money Market Funds [Member] Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] Cash equivalents Cash And Cash Equivalents Fair Value Disclosure Fair Value By Balance Sheet Grouping [Table] Fair Value By Balance Sheet Grouping [Table] Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items] Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items] Liabilities measured at fair value Liabilities Fair Value Disclosure Carrying value as of the balance sheet date of obligations incurred through that date arising from ongoing clinical trial activity. Accrued and other liabilities. Accounts payable Accounts Payable Current Accrued goods and services Accrued Liabilities Current Accrued clinical trial costs Accrued Clinical Trial Costs Others Accrued And Other Liabilities Total accounts payable, accrued expenses and other Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table] Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table] Plan Name Plan Name [Axis] Plan Name Plan Name [Domain] Stock Incentive Plan 2021 [Member]. Stock Incentive Plan 2021 [Member] Stock Incentive Plan2021 [Member] Income Statement Location Income Statement Location [Axis] Income Statement Location Income Statement Location [Domain] General and Administrative Expense [Member] General And Administrative Expense [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share Based Compensation Arrangement By Share Based Payment Award [Line Items] Shares of common stock available for grant (in shares) Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant Number of Options, Granted Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross Allocated Share Based Compensation Expense Allocated Share Based Compensation Expense Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Table] Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Table] Antidilutive Securities Antidilutive Securities Excluded From Computation Of Earnings Per Share By Antidilutive Securities [Axis] Antidilutive Securities, Name Antidilutive Securities Name [Domain] Outstanding Options to Purchase Common Stock [Member] Stock Compensation Plan [Member] Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] Outstanding options to purchase common stock Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount