Entity Central Index Key Document And Entity Information Document And Entity Information [Abstract] Document Type Document Type Amendment Flag Amendment Flag Current Fiscal Year End Date Current Fiscal Year End Date 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 Filer Category Entity Filer Category Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Common Stock, Shares Outstanding Entity Common Stock Shares Outstanding Statement Of Financial Position [Abstract] Assets Assets [Abstract] Current assets: Assets Current [Abstract] Cash and cash equivalents Cash And Cash Equivalents At Carrying Value Short-term investments Short Term Investments Accounts receivable Accounts Receivable Net Current Prepaid research and development contracts Prepaid Expense Current Other current assets Other Assets Current Total current assets Assets Current Furniture and equipment, net Property Plant And Equipment Net Deposits Deposits Assets Noncurrent Total assets Assets Liabilities, redeemable convertible preferred stock, and stockholders´ equity (deficit) Liabilities And Stockholders Equity [Abstract] Current liabilities: Liabilities Current [Abstract] Accounts payable and accrued expenses Accounts Payable And Accrued Liabilities Current Convertible notes Convertible Notes Payable Current Total current liabilities Liabilities Current Commitments and contingencies (Note 11) Commitments And Contingencies Redeemable convertible preferred stock (all classes) Temporary Equity Carrying Amount Attributable To Parent Stockholders’ equity (deficit): Stockholders Equity [Abstract] Common stock, $0.0001 par value per share; 300,000,000 and 17,440,436 shares authorized and 27,070,038 and 1,240,925 shares issued and outstanding at June 30, 2017 and December 31, 2016 respectively. Common Stock Value Additional paid-in capital Additional Paid In Capital Common Stock Accumulated deficit Retained Earnings Accumulated Deficit Total stockholders’ equity (deficit) Stockholders Equity Total liabilities, redeemable convertible preferred stock, and stockholders’ equity (deficit) Liabilities And Stockholders Equity 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 Grant income. Income Statement [Abstract] Operating expenses: Operating Expenses [Abstract] Research and development Research And Development Expense General and administrative General And Administrative Expense Total operating expenses Operating Expenses Loss from operations Operating Income Loss Grant income Grant Income Interest income (expense), net Interest Income Expense Nonoperating Net Other income, net Other Nonoperating Income Expense Total other income (expense) Nonoperating Income Expense Net loss and comprehensive loss Net Income Loss Reconciliation to net loss attributable to common stockholders: Net Income Loss Available To Common Stockholders Basic [Abstract] Net loss and comprehensive loss Extinguishment of preferred stock Preferred Stock Redemption Discount Accretion of preferred stock to redemption value Temporary Equity Accretion To Redemption Value Adjustment Net Loss attributable to common stockholders Net Income Loss Available To Common Stockholders Basic Net loss per share attributable to common stockholders, basic and diluted Earnings Per Share Basic And Diluted Weighted average number of common shares used in computing net loss per share attributable to common stockholders, basic and diluted Weighted Average Number Of Share Outstanding Basic And Diluted Temporary equity value conversion of convertible securities. Temporary equity shares conversion of convertible securities. Stock issued during period shares conversion of convertible notes and accrued interest. Adjustments to additional paid in capital share exchange in connection with merger. Share exchange during period shares in connection with merger. Statement Of Stockholders Equity [Abstract] Statement [Table] Statement [Table] Redeemable Convertible Preferred Stock Statement Class Of Stock [Axis] Class of Stock Class Of Stock [Domain] Redeemable Convertible Preferred Stock Redeemable Convertible Preferred Stock [Member] Common Stock Statement Equity Components [Axis] Equity Component Equity Component [Domain] Common Stock 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] Redeemable convertible preferred stock, Balance Redeemable convertible preferred stock, Balance, Shares Temporary Equity Shares Outstanding Balance Balance, Shares Shares Outstanding Redeemable convertible preferred stock, Adjustment of redeemable convertible preferred stock to redemption value Temporary Equity Accretion To Redemption Value Adjustment of redeemable convertible preferred stock to redemption value Redeemable convertible preferred stock, Conversion of preferred stock Temporary Equity Value Conversion Of Convertible Securities Redeemable convertible preferred stock, Conversion of preferred stock, Shares Temporary Equity Shares Conversion Of Convertible Securities Conversion of preferred stock Stock Issued During Period Value Conversion Of Convertible Securities Conversion of preferred stock, Shares Stock Issued During Period Shares Conversion Of Convertible Securities Conversion of convertible notes and accrued interest Adjustments To Additional Paid In Capital Convertible Debt With Conversion Feature Conversion of convertible notes and accrued interest, Shares Stock Issued During Period Shares Conversion Of Convertible Notes And Accrued Interest Share exchange in connection with Merger Adjustments To Additional Paid In Capital Share Exchange In Connection With Merger Share exchange in connection with Merger, Shares Share Exchange During Period Shares In Connection With Merger Issuance of common stock, net of issuance costs Stock Issued During Period Value New Issues Issuance of common stock, net of issuance costs, Shares Stock Issued During Period Shares New Issues Issuance of common stock upon exercise of stock options Stock Issued During Period Value Stock Options Exercised Issuance of common stock upon exercise of stock options, Shares Stock Issued During Period Shares Stock Options Exercised Forfeiture of restricted stock Stock Issued During Period Value Restricted Stock Award Forfeitures Forfeiture of restricted stock, Shares Stock Issued During Period Shares Restricted Stock Award Forfeited Share-based compensation expense Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value Net loss Redeemable convertible preferred stock, Balance Redeemable convertible preferred stock, Balance, Shares Balance Balance, Shares Accretion of preferred stock to redemption value. Extinguishment of preferred stock. Noncash Financing Items. Statement Of Cash Flows [Abstract] Operating activities: Net Cash Provided By Used In Operating Activities Continuing Operations [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] Depreciation Depreciation Stock-based compensation Share Based Compensation Amortization of debt issuance costs Amortization Of Financing Costs Interest expense related to convertible note conversion Paid In Kind Interest Changes in operating assets and liabilities: Increase Decrease In Operating Capital [Abstract] Accounts receivable Increase Decrease In Accounts Receivable Prepaid expenses and current other assets Increase Decrease In Prepaid Deferred Expense And Other Assets Accounts payable and other current liabilities Increase Decrease In Accounts Payable And Other Operating Liabilities Net cash used in operating activities Net Cash Provided By Used In Operating Activities Continuing Operations Investing activities: Net Cash Provided By Used In Investing Activities Continuing Operations [Abstract] Purchase of furniture and equipment Payments To Acquire Property Plant And Equipment Net cash used in investing activities Net Cash Provided By Used In Investing Activities Continuing Operations Financing activities: Net Cash Provided By Used In Financing Activities Continuing Operations [Abstract] Proceeds from exercise of stock options Proceeds From Stock Options Exercised Proceeds from issuances of convertible notes Proceeds From Convertible Debt Cash paid for debt issuance costs Payments Of Debt Issuance Costs Proceeds from sale of common stock Proceeds From Issuance Of Common Stock Cash paid in connection with the sale of common stock Payments Of Stock Issuance Costs Net cash provided by financing activities Net Cash Provided By Used In Financing Activities Continuing Operations Net increase (decrease) in cash and cash equivalents Cash And Cash Equivalents Period Increase Decrease Cash and cash equivalents at beginning of year Cash and cash equivalents, six months ended Non-cash financing activities Noncash Financing Items [Abstract] Conversion of preferred stock into common stock Conversion Of Stock Amount Converted1 Conversion of notes and accrued interest into common stock Debt Conversion Converted Instrument Amount1 Accretion of preferred stock to redemption value Accretion Of Preferred Stock To Redemption Value Extinguishment of preferred stock Extinguishment Of Preferred Stock Organization Consolidation And Presentation Of Financial Statements [Abstract] Nature of Organization and Operations Organization Consolidation And Presentation Of Financial Statements Disclosure [Text Block] Accounting Policies [Abstract] Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Related Party Transactions [Abstract] Related-Party Arrangements Related Party Transactions Disclosure [Text Block] Payables And Accruals [Abstract] Accounts Payable and Accrued Expenses Accounts Payable And Accrued Liabilities Disclosure [Text Block] Debt Disclosure [Abstract] Notes Payable to Investors Debt Disclosure [Text Block] The entire disclosure for terms, amounts, nature of changes, rights and privileges, dividends, and other matters related to common stock. Preferred Stock and Common Stock [Abstract] Common Stock Common Stock [Text Block] Equity [Abstract] Preferred Stock Preferred Stock [Text Block] Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] Stock-Based Compensation Disclosure Of Compensation Related Costs Share Based Payments [Text Block] Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] Earnings Per Share [Abstract] Net Loss per Share Earnings Per Share [Text Block] Commitments And Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments Disclosure [Text Block] Disclosure of employee stock purchase plan. Employee Stock Purchase Plan Disclosure Of Employee Stock Purchase Plan [Text Block] Basis of Presentation Basis Of Accounting Policy Policy [Text Block] Segment Information Segment Reporting Policy Policy [Text Block] Use of Estimates Use Of Estimates Cash and Cash Equivalents Cash And Cash Equivalents Policy [Text Block] Short-Term Investments. Short-Term Investments Short Term Investments Policy [Text Block] Grant Income. Grant Income Grant Income Policy [Text Block] Research and Development Costs Research And Development Expense Policy Patents. Patents Patents Policy Policy [Text Block] Income Taxes Income Tax Policy [Text Block] Net Loss Per Share Earnings Per Share Policy [Text Block] Stock-Based Compensation Share Based Compensation Option And Incentive Plans Policy Fair Value of Financial Instruments Fair Value Of Financial Instruments Policy Concentrations of Credit Risk and Off-Balance Sheet Risk Concentration Risk Credit Risk Comprehensive Loss Comprehensive Income Policy Policy [Text Block] Furniture and Equipment Property Plant And Equipment Policy [Text Block] Recent Accounting Pronouncements New Accounting Pronouncements Policy Policy [Text Block] Schedule of Assets Measured on Recurring Basis Fair Value Assets Measured On Recurring Basis [Text Block] Related Party Related Party Transactions By Related Party [Axis] Related Party Related Party [Domain] Akebia Therapeutics, Inc. Akebia [Member] Akebia Therapeutics Inc [Member] Summary of activities included in statements of operations and comprehensive loss Schedule Of Comprehensive Income Loss Table [Text Block] Schedule of Accounts Payable and Accrued Expenses Schedule Of Accounts Payable And Accrued Liabilities Table [Text Block] Summary of stock option activity Schedule Of Share Based Compensation Stock Options Activity Table [Text Block] Summary of restricted stock activity Schedule Of Sharebased Compensation Restricted Stock And Restricted Stock Units Activity Table [Text Block] Summary of recognized compensation cost related to employee and non-employee stock-based compensation activity Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Text Block] Stock options valuation assumptions Schedule Of Share Based Payment Award Stock Options Valuation Assumptions Table [Text Block] Schedule of computation of basic and diluted net loss per share Schedule Of Earnings Per Share Basic And Diluted Table [Text Block] Schedule of weighted average common stock equivalents excluded from calculation of diluted net loss per share Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Text Block] Schedule of future payments related to operating leases Schedule Of Future Minimum Rental Payments For Operating Leases Table [Text Block] Schedule Of Stock By Class [Table] Schedule Of Stock By Class [Table] Legal Entity Legal Entity [Axis] Entity Entity [Domain] Zeta Acquisition Corp. II. Zeta Acquisition Corp. II [Member] Zeta Acquisition Corp I I [Member] Range Range [Axis] Range Range [Member] Minimum [Member] Minimum [Member] Class Of Stock [Line Items] Class Of Stock [Line Items] Preferred stock, shares authorized Preferred Stock Shares Authorized Preferred stock, par value Preferred Stock Par Or Stated Value Per Share Capital stock conversion basis ratio. Capital stock conversion basis ratio Capital Stock Conversion Basis Ratio Warrants issuance term. Number of shares surrendered for cancellation Stock Repurchased And Retired During Period Shares Common stock issued to private placement Common stock issued to private placement, price per share Shares Issued Price Per Share Net proceeds of common stock issued to private placement Issuance of warrants term Warrants Issuance Term Number of warrants issued to purchase common stock Class Of Warrant Or Right Number Of Securities Called By Each Warrant Or Right Warrants issued to purchase common stock, exercise price Class Of Warrant Or Right Exercise Price Of Warrants Or Rights1 Percentage of Interest owned in the combined enterprise Business Acquisition Percentage Of Voting Interests Acquired Summary of significant accounting policies. Summary of significant accounting policies. Summary Of Significant Accounting Policies [Table] Summary Of Significant Accounting Policies [Table] Maximum [Member] Maximum [Member] Summary Of Significant Accounting Policies [Line Items] Summary Of Significant Accounting Policies [Line Items] Number of operating segment Number Of Operating Segments Significant uncertain tax positions Liability For Uncertain Tax Positions Current 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] Fair Value, Measurement Frequency Fair Value Measurement Frequency [Domain] Fair Value, Measurements, Recurring [Member] Fair Value Measurements Recurring [Member] Fair Value, Hierarchy Fair Value By Fair Value Hierarchy Level [Axis] Fair Value Hierarchy 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] 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] Assets: Assets Fair Value Disclosure [Abstract] Cash and cash equivalents Cash And Cash Equivalents Fair Value Disclosure Short-term investments Investments Fair Value Disclosure Total assets Assets Fair Value Disclosure Number of financial institutions. Number of principal financial institutions in cash deposit Number Of Financial Institutions Furniture and equipment estimated useful lives Property Plant And Equipment Useful Life Schedule Of Related Party Transactions By Related Party [Table] Schedule Of Related Party Transactions By Related Party [Table] Restructuring Type Restructuring Cost And Reserve [Axis] Type of Restructuring Type Of Restructuring [Domain] Employee Costs [Member] Employee Severance [Member] Facility-related reimbursement. Facility Related Reimbursement [Member] Facility Related Reimbursement [Member] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Accrued project costs current. Accounts payable Accounts Payable Current Professional fees Accrued Professional Fees Current Accrued bonus Accrued Bonuses Current Accrued interest Interest Payable Current Accrued vacation Accrued Vacation Current Accrued project costs Accrued Project Costs Current Other Other Accrued Liabilities Current Total accounts payable and accrued expenses Debt Instrument [Table] Debt Instrument [Table] Short-term Debt, Type Short Term Debt Type [Axis] Short-term Debt, Type Short Term Debt Type [Domain] Convertible Note Financing [Member] Convertible Notes Payable [Member] Additional convertible note financings. Additional Convertible Note Financings [Member] Additional Convertible Note Financings [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Convertible notes payable Debt Instrument Face Amount Conversion description Debt Instrument Convertible Terms Of Conversion Feature Unamortized debt issuance costs Unamortized Debt Issuance Expense Conversion ratio Debt Instrument Convertible Conversion Ratio1 Debt instrument, accrued interest rate Debt Instrument Interest Rate Stated Percentage Debt issuance cost Deferred Finance Costs Gross Maturity date Debt Instrument Maturity Date Gross proceeds from sale of capital stock Proceeds From Issuance Or Sale Of Equity Convertible Notes [Member] Dividends common stock declared or paid Dividends Common Stock Cash Number of shares of common stock in lock-up agreements. Restricted period for shares of common stock in lock-up agreements. Restricted percentage of common stock for holders of specified shares. Number of shares of common stockholders with specified percentage restriction. Number of shares of common stock in lock-up agreements Number Of Shares Of Common Stock In Lock Up Agreements Restricted period for shares of common stock in lock-up agreements Restricted Period For Shares Of Common Stock In Lock Up Agreements Restricted percentage of common stock for holders of 915,000 shares Restricted Percentage Of Common Stock For Holders Of Specified Shares Number of shares of common stockholders with 80% restriction Number Of Shares Of Common Stockholders With Specified Percentage Restriction Percentage of common stockholder agreed not to effect short sale after merger. Period agreed by common stockholder not to effect short sale after merger. Percentage of common stockholder agreed not to effect short sale after merger Percentage Of Common Stockholder Agreed Not To Effect Short Sale After Merger Period agreed by common stockholder not to effect short sale after merger Period Agreed By Common Stockholder Not To Effect Short Sale After Merger Class of warrant or right term. Class of warrant or right expiration date. Warrants outstanding Class Of Warrant Or Right Outstanding Warrants exercise price per share Warrants term Class Of Warrant Or Right Term Warrants expiration date Class Of Warrant Or Right Expiration Date Temporary Equity Disclosure [Abstract] Temporary Equity By Class Of Stock [Table] Temporary Equity By Class Of Stock [Table] Series A redeemable convertible preferred stock. Series A Redeemable Convertible Preferred Stock [Member] Series A Redeemable Convertible Preferred Stock [Member] Series A1 redeemable convertible preferred stock. Series A1 Redeemable Convertible Preferred Stock [Member] Series A1 Redeemable Convertible Preferred Stock [Member] Series A2 redeemable convertible preferred stock. Series A2 Redeemable Convertible Preferred Stock [Member] Series A2 Redeemable Convertible Preferred Stock [Member] Series A and series A1 redeemable convertible preferred stock. Series A Redeemable Convertible Preferred Stock and Series A1 Redeemable Convertible Preferred Stock [Member] Series A And Series A1 Redeemable Convertible Preferred Stock [Member] Temporary Equity [Line Items] Temporary Equity [Line Items] Preferred stock, shares issued Preferred Stock Shares Issued Preferred stock, shares outstanding Preferred Stock Shares Outstanding Redeemable convertible preferred stock, shares authorized Temporary Equity Shares Authorized Redeemable convertible preferred stock, shares issued Temporary Equity Shares Issued Redeemable convertible preferred, shares outstanding Redeemable convertible preferred stock voting rights. Percentage of redeemable convertible preferred stock voting rights. Redeemable convertible preferred stock, voting rights Redeemable Convertible Preferred Stock Voting Rights Percentage of redeemable convertible preferred stock voting rights Percentage Of Redeemable Convertible Preferred Stock Voting Rights Number of board of directors appointed by redeemable convertible preferred shares holders. Number of board of directors appointed by redeemable convertible preferred shares holders under certain circumstances. Number of board of directors appointed by common shares holders. Number of board of directors appointed by common shares holders under certain circumstances. Number of board of directors appointed by redeemable convertible preferred shares holders Number Of Board Of Directors Appointed By Redeemable Convertible Preferred Shares Holders Number of board of directors appointed by redeemable convertible preferred shares holders under certain circumstances Number Of Board Of Directors Appointed By Redeemable Convertible Preferred Shares Holders Under Certain Circumstances Number of board of directors appointed by common shares holders Number Of Board Of Directors Appointed By Common Shares Holders Number of board of directors appointed by common shares holders under certain circumstances Number Of Board Of Directors Appointed By Common Shares Holders Under Certain Circumstances Redeemable convertible preferred stock dividend rate percentage. Redeemable convertible preferred stock, dividend rate, percentage Redeemable Convertible Preferred Stock Dividend Rate Percentage Redeemable convertible preferred stock dividends per share declared. Redeemable convertible preferred stock distribution to be paid Redeemable Convertible Preferred Stock Dividends Per Share Declared Redeemable convertible preferred stock conversion percentage. Redeemable convertible preferred stock conversion percentage Redeemable Convertible Preferred Stock Conversion Percentage Redeemable convertible preferred stock conversion basis percentage. Share Price Share Price Proceeds from Issuance Initial Public Offering Proceeds From Issuance Initial Public Offering Redeemable convertible preferred stock conversion basis percentage Redeemable Convertible Preferred Stock Conversion Basis Percentage Redeemable convertible preferred stock redemption date. Number of installments payable. Annual installment payable commencing period. Redeemable convertible preferred stock redemption date Redeemable Convertible Preferred Stock Redemption Date Number of installments payable Number Of Installments Payable Annual installment payable commencing period Annual Installment Payable Commencing Period Share based compensation arrangement by share based payment award number of additional shares authorized annual percentage. 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 Eleven Equity Incentive Plan. 2011 Equity Incentive Plan [Member] Two Thousand Eleven Equity Incentive Plan [Member] 2017 stock option and incentive plan. 2017 Stock Option and Incentive Plan [Member] Two Thousand Seventeen Stock Option And Incentive Plan [Member] Award Type Award Type [Axis] Equity Award Share Based Compensation Arrangements By Share Based Payment Award Award Type And Plan Name [Domain] Stock Option [Member] Employee Stock Option [Member] Vesting Vesting [Axis] Vesting Vesting [Domain] One-year Anniversary [Member] Share Based Compensation Award Tranche One [Member] Restricted Stock [Member] Restricted Stock [Member] Share Based Compensation Arrangement By Share Based Payment Award [Line Items] Share Based Compensation Arrangement By Share Based Payment Award [Line Items] Merger exchange rate Aggregate number of common stock Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number Common stock shares available for issuance Common Stock Capital Shares Reserved For Future Issuance Percentage applied to the outstanding shares as annual increase in number of shares authorized for issuance Share Based Compensation Arrangement By Share Based Payment Award Number Of Additional Shares Authorized Annual Percentage Number of awards granted Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross Vesting period Share Based Compensation Arrangement By Share Based Payment Award Award Vesting Period1 Vesting percentage Sharebased Compensation Arrangement By Sharebased Payment Award Award Vesting Rights Percentage Term of options to be granted Sharebased Compensation Arrangement By Sharebased Payment Award Expiration Period Shares, Outstanding at beginning balance Shares, Exercised Shares, Expired/cancelled Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period Shares, Outstanding at ending balance Shares, Expected to vest Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Number Shares, Options exercisable Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number Weighted Average Exercise Price, Outstanding at beginning balance Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price Weighted Average Exercise Price, Granted Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price Weighted Average Exercise Price, Exercised Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price Weighted Average Exercise Price, Expired/cancelled Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period Weighted Average Exercise Price Weighted Average Exercise Price, Outstanding at ending balance Weighted Average Exercise Price, Expected to vest Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Weighted Average Exercise Price Weighted Average Exercise Price, Options exercisable Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Exercise Price Weighted Average Remaining Contractual Term, Outstanding Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 Weighted Average Remaining Contractual Term, Expected to vest Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested And Expected To Vest Outstanding Weighted Average Remaining Contractual Term1 Weighted Average Remaining Contractual Term, Options exercisable Sharebased Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Exercisable Options Weighted Average Remaining Contractual Term2 Aggregate Intrinsic Value, Outstanding Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value Aggregate Intrinsic Value, Expected to vest Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Aggregate Intrinsic Value Aggregate Intrinsic Value, Options exercisable Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Intrinsic Value1 Compensation expense for stock options Allocated Share Based Compensation Expense Unrecognized compensation cost related to stock options Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Stock Options Weighted average period expected to be recognized Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1 Shares, Nonvested beginning balance Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number Shares, Granted Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Shares, Vested Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Shares, Forfeited Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period Shares, Nonvested ending balance Weighted Average Grant Date Fair Value, Nonvested beginning balance Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value Weighted Average Grant Date Fair Value, Granted Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value Weighted Average Grant Date Fair Value, Vested Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value Weighted Average Grant Date Fair Value, Forfeited Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value Weighted Average Grant Date Fair Value, Nonvested ending balance Unrecognized compensation cost related to restricted stock grants Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Share Based Awards Other Than Options Disclosure Of Share Based Compensation Arrangements By Share Based Payment Award [Abstract] Disclosure Of Share Based Compensation Arrangements By Share Based Payment Award [Abstract] Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Table] Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Table] 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] Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] Stock-based compensation expense Weighted-average fair value of options granted Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Weighted Average Grant Date Fair Value Expected term (years) Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1 Risk-free interest rate Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate Expected volatility Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate Expected dividend yield Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate Current income tax expense or benefit Current Income Tax Expense Benefit Deferred income tax expense or benefit Deferred Income Tax Expense Benefit Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Table] Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Table] Convertible Preferred Stock (If Converted) [Member] Convertible Preferred Stock [Member] Notes and accrued interest. Notes and Accrued Interest (If Converted) [Member] Notes And Accrued Interest [Member] Antidilutive Securities Antidilutive Securities Excluded From Computation Of Earnings Per Share By Antidilutive Securities [Axis] Antidilutive Securities, Name Antidilutive Securities Name [Domain] Unvested Restricted Stock [Member] Warrants to Purchase Common Stock [Member] Warrant [Member] Weighted Average [Member] Weighted Average [Member] Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] Total amount of anti-dilutive securities excluded from computation of earnings per share Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount Area of lease property. Lease allowances for tenant improvements. Area of lease property Area Of Lease Property Lease expiration date Lease Expiration Date1 Total operating leases rent expense Operating Leases Rent Expense Net Lease agreement allowances for tenant improvements Lease Allowances For Tenant Improvements Deferred rent included in accrued expenses Deferred Rent Credit Current Non-cancellable future minimum operating lease payments Operating Leases Future Minimum Payments Due Operating leases future minimum payments due in three years and thereafter. Operating leases, 2017 Operating Leases Future Minimum Payments Due Current Operating leases, 2018 Operating Leases Future Minimum Payments Due In Two Years Operating leases, 2019 and Thereafter Operating Leases Future Minimum Payments Due In Three Years And Thereafter Operating leases, Total Number of shares reserved for issuance annual increased percentage. Sale of Stock Subsidiary Sale Of Stock [Axis] Sale of Stock Sale Of Stock Name Of Transaction [Domain] Employee Stock Purchase Plan [Member] Employee Stock [Member] Maximum number of shares provided for issuance Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Authorized Percentage of annual increase in number of shares reserved for issuance Number Of Shares Reserved For Issuance Annual Increased Percentage