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 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 Interactive Data Current Entity Interactive Data Current 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 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 Title of 12(b) Security Security12b Title Trading Symbol Trading Symbol Security Exchange Name Security Exchange Name The amount expected to be received within one year or the normal operating cycle, if longer, as part of a refundable tax incentive program for research and development activities. Statement Of Financial Position [Abstract] Assets Assets [Abstract] Current assets: Assets Current [Abstract] Cash and cash equivalents Cash And Cash Equivalents At Carrying Value Marketable debt securities Available For Sale Securities Debt Securities Current Tax incentive receivable Tax Incentive Receivable Current Prepaid expenses and other current assets Prepaid Expense And Other Assets Current Total current assets Assets Current Property and equipment, net Property Plant And Equipment Net Operating lease right-of-use assets Operating Lease Right Of Use Asset Restricted cash Restricted Cash Noncurrent Other assets Other Assets Noncurrent Total assets Assets Liabilities and Stockholders' Equity Liabilities And Stockholders Equity [Abstract] Current liabilities: Liabilities Current [Abstract] Accounts payable Accounts Payable Current Accrued expenses Accrued Liabilities Current Accrued restructuring costs Restructuring Reserve Current Operating lease liabilities, current Operating Lease Liability Current Notes payable, current Notes Payable Current Total current liabilities Liabilities Current Notes payable, long-term Long Term Notes Payable Operating lease liabilities Operating Lease Liability Noncurrent Total liabilities Liabilities Commitments and contingencies (Note 7) Commitments And Contingencies Stockholders' equity: Stockholders Equity [Abstract] Preferred stock; $0.001 par value per share; 5,000,000 shares authorized as of March 31, 2020 and December 31, 2019; no shares issued and outstanding as of March 31, 2020 and December 31, 2019 Preferred Stock Value Common stock, $0.001 par value per share; 115,000,000 shares authorized as of March 31, 2020 and December 31, 2019; 37,469,596 and 37,446,498 shares issued and outstanding as of March 31, 2020 and December 31, 2019, respectively Common Stock Value Additional paid-in capital Additional Paid In Capital Common Stock Accumulated deficit Retained Earnings Accumulated Deficit Accumulated other comprehensive income Accumulated Other Comprehensive Income Loss Net Of Tax Total stockholders' equity Stockholders Equity Total liabilities and stockholders' equity Liabilities And Stockholders Equity Preferred stock, par value per share 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 per share 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 The aggregate total of expenses and expense reversals during the period allocated to research and development. Income Statement [Abstract] Revenue Revenues Operating expenses: Operating Expenses [Abstract] Research and development Research And Development Income Expense General and administrative General And Administrative Expense Restructuring charges Restructuring Charges Total operating expenses Operating Expenses Loss from operations Operating Income Loss Other income (expense): Other Income And Expenses [Abstract] Interest income Investment Income Interest Interest expense Interest Expense Other income Other Nonoperating Income Expense Foreign currency transaction (losses) gains, net Foreign Currency Transaction Gain Loss Before Tax Total other (expense) income, net Nonoperating Income Expense Net loss Net Income Loss Net loss per share, basic and diluted Earnings Per Share Basic And Diluted Weighted average common shares outstanding, basic and diluted Weighted Average Number Of Share Outstanding Basic And Diluted Comprehensive loss: Comprehensive Income Net Of Tax [Abstract] Net loss Other comprehensive (loss) income: Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent [Abstract] Unrealized (loss) gain on marketable debt securities Other Comprehensive Income Availableforsale Securities Adjustment Net Of Tax Portion Attributable To Parent Total other comprehensive (loss) income Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent Total comprehensive loss Comprehensive Income Net Of Tax The number of shares issued during the period upon exercise of stock options and stock purchase plans. The value of stock issued during the period upon exercise of stock options and stock purchase plans. 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] Accumulated Other Comprehensive Loss [Member] Accumulated Other Comprehensive Income [Member] Statement [Line Items] Statement [Line Items] Beginning balance Beginning balance, shares Shares Outstanding Issuance of common stock upon exercise of stock options and employee stock purchase plan Stock Issued During Period Value Stock Options Exercised And Employee Stock Purchase Plan Issuance of common stock upon exercise of stock options and employee stock purchase plan, shares Stock Issued During Period Shares Stock Options Exercised And Employee Stock Purchase Plans Issuance of restricted stock units Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures Issuance of restricted stock units, shares Stock Issued During Period Shares Restricted Stock Award Net Of Forfeitures Stock-based compensation expense Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value Unrealized gain (loss) on marketable debt securities Ending balance Ending balance, shares The increase (decrease) during the reporting period in tax incentive receivable, which represents the amount due from tax authorities. Statement Of Cash Flows [Abstract] Cash flows from operating activities: Net Cash Provided By Used In Operating Activities [Abstract] Net loss Profit Loss 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] Stock-based compensation expense Share Based Compensation Depreciation expense Depreciation Loss on disposal of fixed assets Gain Loss On Disposition Of Assets Unrealized foreign currency transaction losses (gains) Foreign Currency Transaction Gain Loss Unrealized Amortization of discount on marketable debt securities Investment Income Net Amortization Of Discount And Premium Changes in operating assets and liabilities: Increase Decrease In Operating Capital [Abstract] Prepaid expenses and other current assets Increase Decrease In Prepaid Deferred Expense And Other Assets Tax incentive receivable Increase Decrease In Tax Incentives Receivable Accounts payable Increase Decrease In Accounts Payable Accrued restructuring costs Increase Decrease In Restructuring Reserve Accrued expenses Increase Decrease In 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 sales and maturities of marketable debt securities Proceeds From Sale And Maturity Of Available For Sale Securities Purchases of marketable debt securities Payments To Acquire Available For Sale Securities Debt Purchases of property and equipment Payments To Acquire Property Plant And Equipment 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] Repayment of notes payable Repayments Of Notes Payable Proceeds from exercise of common stock options and employee stock purchase plan Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans Including Stock Options Net cash (used in) provided by financing activities Net Cash Provided By Used In Financing Activities Net increase (decrease) in cash, cash equivalents and restricted cash Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect Cash, cash equivalents and restricted cash at beginning of period Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations Cash, cash equivalents and restricted cash at end of period Supplemental disclosure of non-cash investing and financing activities: Cash Flow Noncash Investing And Financing Activities Disclosure [Abstract] Property and equipment included in accounts payable Capital Expenditures Incurred But Not Yet Paid Supplemental disclosure of cash flow information: Supplemental Cash Flow Information [Abstract] Cash paid for interest Interest Paid Net Accounting Policies [Abstract] Nature of the Business and Basis of Presentation Business Description And Basis Of Presentation [Text Block] Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Fair Value Disclosures [Abstract] Fair Value Measurements and Marketable Debt Securities Fair Value Disclosures [Text Block] Payables And Accruals [Abstract] Accrued Expenses Accounts Payable Accrued Liabilities And Other Liabilities Disclosure Current [Text Block] Debt Disclosure [Abstract] Notes Payable Debt Disclosure [Text Block] Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] Stock-Based Awards Disclosure Of Compensation Related Costs Share Based Payments [Text Block] Commitments And Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments And Contingencies Disclosure [Text Block] Compensation And Retirement Disclosure [Abstract] Retirement Plan Pension And Other Postretirement Benefits Disclosure [Text Block] Research And Development [Abstract] Australia Research and Development Tax Incentive Research Development And Computer Software Disclosure [Text Block] Restructuring And Related Activities [Abstract] Restructuring Restructuring And Related Activities Disclosure [Text Block] Use of Estimates Use Of Estimates Marketable Debt Securities Marketable Securities Policy Net Loss Per Share Earnings Per Share Policy [Text Block] Risks and uncertainties. Risks and Uncertainties Risks And Uncertainties Policy [Text Block] Recently Issued and Adopted Accounting Pronouncements New Accounting Pronouncements Policy Policy [Text Block] Summary of Common Stock Equivalents Outstanding Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Text Block] Summary of Cash Equivalents and Marketable Debt Securities Fair Value Assets Measured On Recurring And Nonrecurring Basis Table [Text Block] Summary of Marketable Debt Securities Schedule Of Available For Sale Securities Reconciliation Table [Text Block] Schedule of Accrued Expenses Schedule Of Accrued Liabilities Table [Text Block] Tabular disclosure of notes payable. Includes, but is not limited to, current and long-term portions. Schedule of Notes Payable Schedule Of Notes Payable Table [Text Block] Summary of Stock-Based Compensation Expense Related to Stock Options, Restricted Common Stock and ESPP Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Text Block] Schedule of Future Minimum Lease Payments for Operating Leases Lessee Operating Lease Liability Maturity Table [Text Block] Schedule of Components of Leases Expense Lease Cost Table [Text Block] Schedule of weighted average remaining lease term and weighted average discount rate of operating leases. Schedule of Weighted Average Remaining Lease Term and Weighted Average Discount Rate of Operating Leases Schedule Of Weighted Average Remaining Lease Term And Weighted Average Discount Rate Of Operating Leases Table [Text Block] Summary of Accrued Restructuring Costs Schedule Of Restructuring Reserve By Type Of Cost [Text Block] Summary of Restructuring Charges by Category Schedule Of Restructuring And Related Costs [Text Block] Organization Consolidation And Presentation Of Financial Statements [Abstract] Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items] Organization Consolidation And Presentation Of Financial Statements Disclosure [Table] Organization Consolidation And Presentation Of Financial Statements Disclosure [Table] Organization Consolidation And Presentation Of Financial Statements Disclosure [Table] Business Acquisition Business Acquisition [Axis] Business Acquisition, Acquiree Business Acquisition Acquiree [Domain] Chondrial therapeutics inc. Chondrial Therapeutics Inc. [Member] Chondrial Therapeutics Inc [Member] Collaborative Arrangement and Arrangement Other than Collaborative Type Of Arrangement [Axis] Collaborative Arrangement and Arrangement Other than Collaborative Arrangements And Nonarrangement Transactions [Member] Company stockholders prior to merger. Company Stockholders Prior to Merger [Member] Company Stockholders Prior To Merger [Member] Equity Interest Type Equity Interest Issued Or Issuable By Type [Axis] Equity Interest Issued or Issuable, Type Equity Interest Issued Or Issuable Type [Domain] Chondrial security holders. Chondrial Security Holders [Member] Chondrial Security Holders [Member] Statistical Measurement Range [Axis] Statistical Measurement Range [Member] Maximum [Member] Maximum [Member] Minimum [Member] Minimum [Member] Sale of Stock Subsidiary Sale Of Stock [Axis] Sale of Stock Sale Of Stock Name Of Transaction [Domain] Follow-on offerings. Public Offering [Member] Follow On Offerings [Member] Long-term Debt, Type Longterm Debt Type [Axis] Long-term Debt, Type Longterm Debt Type [Domain] Term Loan [Member] Term Loan [Member] Term Loan [Member] Subsequent Event Type Subsequent Event Type [Axis] Subsequent Event Type Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent Event [Member] Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items] Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items] Entity incorporation date Entity Incorporation Date Of Incorporation Date of merger agreement. The percentage of outstanding shares of the company's common stock on a fully diluted basis that are expected to be owned immediately following the merger. The Company's valuation, as defined in the merger agreement, based on projected net cash, cash equivalents and marketable securities balance minus outstanding liabilities, subject to adjustment. The additional enterprise value added to the base value of the Company in order to determine the value in the merger agreement. The amount of net cash held by the Company, as presented in a range of values, that will determine whether an adjustment will be made to the ownership percentages as part of a merger agreement. If the Company's net cash is between the minimum and maximum thresholds, no adjustment will be made. The amount of daily reduction in target net cash, lower target net cash and upper target net cash from the date identified through the closing date of the merger, dependent on the Company's actual net cash balance. The amount of daily increase in the valuation of the company being merged into from the date identified through the closing date of the merger, dependent on the Company's actual net cash balance. Date of merger agreement Date Of Merger Agreement Percentage of expected diluted common shares immediately after merger Percentage Of Outstanding Shares Of Common Stock Owned After Merger Common stock, value immediately after merger Common Stock Value Outstanding Adjusted ownership value prior to closing merger Adjusted Ownership Value Prior To Closing Merger Additional enterprise value Additional Enterprise Value Net cash threshold Net Cash Threshold Cash valuation reduction Cash Valuation Reduction Increase in valuation of ownership Increase In Valuation Of Ownership Merger agreement termination fee to be paid by either party to other party upon termination of agreement. The amount of third party expenses that may be required to be paid to the other party in the event of termination of the merger agreement. Merger agreement termination fee to be paid by either party to other party upon termination of agreement Merger Agreement Termination Fee To Be Paid By Either Party To Other Party Upon Termination Of Agreement Additional third party expenses to be paid by either party to other party upon termination of merger agreement Third Party Expenses Required To Pay To Other Party The minimum amount of net cash required to be held as a condition of the merger agreement. Merger agreement minimum required net cash thresholds Merger Agreement Minimum Required Net Cash Thresholds Beneficiary interest percentage in outstanding common stock Variable Interest Entity Ownership Percentage The minimum default amount over which the lender may exercise remedies against the Company. Net proceeds from sale of securities. Accumulated deficit Net proceeds from sale of securities Net Proceeds From Sale Of Securities Issuance of common stock Stock Issued During Period Shares New Issues Share price per share Shares Issued Price Per Share Net proceeds from public offering, after underwriting discount, commission and offering expenses Proceeds From Issuance Of Common Stock Aggregate principal balance Debt Instrument Face Amount Loan agreement minimum liquidity required Restricted Cash And Investments Credit facility default amount Line Of Credit Facility Debt Default Minimum Amount Total cash, cash equivalents and marketable securities Cash Cash Equivalents And Short Term Investments Bid price of share as per rule Share Price Earnings Per Share [Abstract] 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] Options to Purchase Common Stock [Member] Employee Stock Option [Member] Unvested Restricted Common Stock [Member] Restricted Stock [Member] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] Total potentially dilutive shares Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table] Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table] Significant Other Observable Inputs (Level 2) [Member] Fair Value By Fair Value Hierarchy Level [Axis] Fair Value Hierarchy and NAV Fair Value Measurements Fair Value Hierarchy [Domain] Quoted Prices in Active Markets, (Level 1) [Member] Fair Value Inputs Level1 [Member] Significant Other Observable Inputs (Level 2) [Member] Fair Value Inputs Level2 [Member] Significant Unobservable Inputs (Level 3) [Member] Fair Value Inputs Level3 [Member] Investment Type Investment Type [Axis] Investments Investment Type Categorization [Member] Money Market Funds [Member] Money Market Funds [Member] U.S. Government Securities [Member] U S Government Corporations And Agencies Securities [Member] Corporate Bonds [Member] Corporate Bond Securities [Member] Commercial Paper [Member] Commercial Paper [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 Total cash equivalents and marketable debt securities Assets Fair Value Disclosure Debt Securities Available For Sale [Table] Debt Securities Available For Sale [Table] Corporate Bonds (Due within 1 Year) [Member] Commercial Paper (Due within 1 Year) [Member] U.S. Government Securities (Due within 1 Year) [Member] Schedule of Available-for-sale Securities [Line Items] Schedule Of Available For Sale Securities [Line Items] Amortized Cost Available For Sale Debt Securities Amortized Cost Basis Gross Unrealized Gains Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax Gross Unrealized Losses Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax Fair Value Allowance for credit losses Debt Securities Available For Sale Allowance For Credit Loss Accrued payroll and related expenses Employee Related Liabilities Current Accrued professional fees Accrued Professional Fees Current Accrued other Other Accrued Liabilities Current Total accrued expenses Debt Instrument [Table] Debt Instrument [Table] Variable Rate Variable Rate [Axis] Variable Rate Variable Rate [Domain] Prime Rate [Member] Prime Rate [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Maximum borrowings under term loan Proceeds from issuance of notes payable Proceeds From Notes Payable The fee, as a percentage of the term loan, due as a final payment. Debt facility description Debt Instrument Description Debt maturity date Debt Instrument Maturity Date Debt facility interest rate description Debt Instrument Description Of Variable Rate Basis Debt facility variable interest at annual rate above prime rate Debt Instrument Basis Spread On Variable Rate1 Debt facility effective interest rate Debt Instrument Interest Rate Effective Percentage Debt facility fee percentage Debt Instrument Fee Percentage Charges to interest expense of debt outstanding Debt Instrument Increase Accrued Interest The amount of cash, cash equivalents and marketable securities the Company is required to maintain, as a percentage of the total outstanding principal balance of a loan. Percentage equivalent of cash, cash equivalents and marketable debt securities balance Restricted Cash And Investments As Percentage Of Outstanding Principal Amount The percentage of its cash, cash equivalents, and marketable securities that the Company is obligated to maintain a balance of. The percentage of the principal balance that the Company must immediately secure if it does not meet its balance obligations of cash, cash equivalents and marketable securities. Debt facility covenant description Debt Instrument Covenant Description Unrestricted cash, cash equivalents and marketable debt securities Percentage of cash, cash equivalents and marketable debt securities Cash Cash Equivalents And Short Term Investments Percentage Percentage of principal balance to be secured in restricted cash account for not to be considered an event of default Percentage Of Principal Balance To Be Secured In Restricted Cash Account The aggregate amount of cash permitted to be maintained by the Australian subsidiary. Aggregate value of cash maintained by Australian subsidiary, limit Debt Instrument Restrictive Covenants Investment In Subsidiaries Carrying value as of the balance sheet date of notes payable before accretion (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Debt Instruments [Abstract] Notes payable Notes Payable Less: current portion Notes payable, net of current portion Long Term Notes Payable Before Accretion Accretion related to final payment Debt Instrument Periodic Payment Terms Balloon Payment To Be Paid Notes payable, long term Interest expense on term loan Debt Instrument Periodic Payment Interest Debt facility effective interest rate Debt Instrument Interest Rate During Period Compensation Related Costs [Abstract] 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] Two thousand fourteen stock option and incentive plan. 2014 Stock Option and Incentive Plan [Member] Two Thousand Fourteen Stock Option And Incentive Plan [Member] Two thousand and fourteen employee stock purchase plan. 2014 Employee Stock Purchase Plan [Member] Two Thousand And Fourteen Employee Stock Purchase Plan [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share Based Compensation Arrangement By Share Based Payment Award [Line Items] Shares available for grant Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant Shares added to plan Share Based Compensation Arrangement By Share Based Payment Award Options Other Increases Decreases In Period Income Statement Location Income Statement Location [Axis] Income Statement Location Income Statement Location [Domain] Research and Development [Member] Research And Development Expense [Member] General and Administrative [Member] General And Administrative Expense [Member] Total stock-based compensation expense Allocated Share Based Compensation Expense Area of office space. Date which rent payments for lease or group of leases is set to begin, in CCYY-MM-DD format. Other Commitments [Table] Other Commitments [Table] Entity By Location Entity By Location [Axis] Location Location [Domain] Boston Boston [Member] Boston [Member] Geographical Statement Geographical [Axis] Geographical Segment Geographical [Domain] Massachusetts [Member] MASSACHUSETTS Legal Entity Legal Entity [Axis] Entity Entity [Domain] Shigo Center Plaza Owners LLC. Shigo Center Plaza Owners LLC [Member] Shigo Center Plaza Owners L L C [Member] Sandiego. Sandiego [Member] Sandiego [Member] California [Member] CALIFORNIA Other Commitments [Line Items] Other Commitments [Line Items] Area of office space Area Of Office Space Operating lease term Lessee Operating Lease Term Of Contract Lease extension period Lessee Operating Lease Renewal Term Letter of credit Line Of Credit Operating lease, existence of option to extend Lessee Operating Lease Existence Of Option To Extend Lease rent payment start date Lease Rent Payment Start Date Total lease payments over the initial term Lessee Operating Lease Liability Payments Due Lease expiration date Lease Expiration Date1 Leases [Abstract] 2020 (April - December) Lessee Operating Lease Liability Payments Remainder Of Fiscal Year 2021 Lessee Operating Lease Liability Payments Due Year Two 2022 Lessee Operating Lease Liability Payments Due Year Three 2023 Lessee Operating Lease Liability Payments Due Year Four 2024 Lessee Operating Lease Liability Payments Due Year Five Thereafter Lessee Operating Lease Liability Payments Due After Year Five Total lease payments Less: imputed interest Lessee Operating Lease Liability Undiscounted Excess Amount Present value of lease liabilities Operating Lease Liability Lease expense Lease Cost Operating lease cost Operating Lease Cost Short-term lease cost Short Term Lease Cost Sublease income Sublease Income Total lease cost Weighted average remaining lease term in years Operating Lease Weighted Average Remaining Lease Term1 Weighted average discount rate Operating Lease Weighted Average Discount Rate Percent Additional right of use assets. Operating cash flows from operating leases Operating Lease Payments Additional right-of-use-assets Additional Right Of Use Assets Defined Contribution Plan [Table] Defined Contribution Plan [Table] Retirement Plan Type Retirement Plan Type [Axis] Retirement Plan Type Retirement Plan Type [Domain] Retirement 401K plan. Retirement 401K Plan [Member] Retirement401 K Plan [Member] Defined Contribution Plan Disclosure [Line Items] Defined Contribution Plan Disclosure [Line Items] Percentage of employer's contribution on employee's base salary Defined Contribution Plan Employer Matching Contribution Percent Contribution expense Defined Contribution Plan Cost Recognized The percentage to be refunded pertaining to the tax incentive for qualified research and development activities. Tax incentive receivable. The amount of reduction to research and development expense recorded in the income statement. The percentage of research and development costs to be reduced. Research and Development Tax Incentive [Line Items] Research and Development Expenses [Table] Research And Development Expenses [Table] Research And Development Expenses [Table] Consolidated Entities Consolidated Entities [Axis] Consolidated Entities Consolidated Entities [Domain] Zafgen Australia Pty Limited [Member] Subsidiaries [Member] Australia [Member] AUSTRALIA Research and Development Tax Incentive [Line Items] Research And Development Tax Incentive [Line Items] Percentage of refundable tax incentive Effective Tax Incentive Rate Related To Research And Development Reduction to research and development expenses Tax Incentive Research And Development Activities Percentage of reduction in research and development costs Percentage Reduction Research And Development Costs Research and development expense Research And Development Expense Unrealized foreign currency exchange gains (losses) Tax incentive receivable Tax Incentive Receivable Schedule Of Restructuring And Related Costs [Table] Schedule Of Restructuring And Related Costs [Table] Restructuring Type Restructuring Cost And Reserve [Axis] Type of Restructuring Type Of Restructuring [Domain] Other Employee Related Costs [Member] Other Restructuring [Member] Restructuring Cost And Reserve [Line Items] Restructuring Cost And Reserve [Line Items] Number of workforce reduction Restructuring And Related Cost Number Of Positions Eliminated Restructuring charges paid Payments For Restructuring Restructuring Reserve [Abstract] One-Time Employee Termination Benefits [Member] One Time Termination Benefits [Member] Contract Termination Costs [Member] Contract Termination [Member] Accrued restructuring costs as of December 31, 2019 Restructuring charges incurred during the period Restructuring And Related Cost Incurred Cost Amounts paid during the period Accrued restructuring costs as of March 31, 2020 Cash and Cash Equivalents Cash And Cash Equivalents [Axis] Cash and Cash Equivalents Restricted Cash And Cash Equivalents Cash And Cash Equivalents [Member] Cash [Member] Cash [Member] Non Cash [Member] Non-Cash [Member] Non Cash [Member]