Accounting Policies [Abstract] Accounting Policies [Abstract] Accounts Payable, Current Accounts payable Accounts Receivable, Net, Current Accounts receivable Accrued Liabilities and Other Liabilities Accrued and other liabilities Accrued Liabilities, Current Clinical trial material expenses Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Less: accumulated depreciation Additional common stock issued on exercise of option by underwriters. Additional Common Stock Issued On Exercise Of Option By Underwriters Additional common stock issued on exercise of option by Underwriters Additional Paid in Capital, Common Stock Additional paid-in capital Additional Paid-in Capital [Member] Additional Paid-in Capital [Member] Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Stock-based compensation Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs Stock issuance costs Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net loss to net cash used in operating activities: Allocated Share-based Compensation Expense Stock-based compensation Allowance for lease improvement. Allowance For Lease Improvement Lease improvement allowance maximum amount Amended Facility Lease Agreement [Member] Amended Facility Lease Agreement [Member] Amended Facility Lease Agreement [Member] Amendment Flag Amendment Flag Amortization of Financing Costs Amortization of deferred financing costs Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Antidilutive securities excluded from computation of earnings per share, shares Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Assets Total assets Assets [Abstract] Assets Assets, Current Total current assets Assets, Current [Abstract] Current assets: Assets, Fair Value Disclosure Assets at fair value Assets, Fair Value Disclosure [Abstract] Assets: Astra Zeneca [Member] Astra Zeneca [Member] AstraZeneca [Member] Award Type [Axis] Award Type [Axis] Basis of Accounting, Policy [Policy Text Block] Basis of Presentation Business And Basis Of Presentation [Table] Business And Basis Of Presentation [Table] Business And Basis Of Presentation [Table] Capital Expenditures Incurred but Not yet Paid Acquisition of property and equipment included in accounts payable and accrued liabilities Capital Units, Authorized Shares authorized Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents at end of period Cash and cash equivalents at beginning of period Cash and cash equivalents Cash and cash equivalents original maturity dates. Cash And Cash Equivalents Original Maturity Dates Cash and cash equivalents original maturity dates Cash and Cash Equivalents, Period Increase (Decrease) Net increase in cash and cash equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Cash and Cash Equivalents Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Restricted Cash Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Supplementary disclosure of non-cash financing information: Cash Overdraft [Policy Text Block] Cash Overdraft [Policy Text Block] Cash overdrafts Certificates of Deposit [Member] Certificates of Deposit [Member] Class of Stock Disclosures [Abstract] Class of Stock Disclosures [Abstract] Class of Stock [Domain] Class of Stock [Domain] Class of Stock [Line Items] Class of Stock [Line Items] Class of Warrant or Right, Exercise Price of Warrants or Rights Exercise price of the warrants Purchase price for warrants Class of warrant or right expiration date description. Class Of Warrant Or Right Expiration Date Description Warrants description Class of Warrant or Right, Number of Securities Called by Warrants or Rights Warrants issued to purchase common stock Class of warrant or right number of warrants exercised. Class Of Warrant Or Right Number Of Warrants Exercised Number of warrants exercised Class of warrant or right threshold ownership percentage. Class of Warrant or Right, Threshold Ownership Percentage Maximum warrants ownership percentage by each holder of warrants Clinical Operations Consulting Arrangement [Member] Clinical Operations Consulting Arrangement [Member] Clinical Operations Consulting Arrangement [Member] Collaborative arrangement consideration. Collaborative Arrangement Consideration Amount of reimbursement paid for certain research and development expenses in consideration of acceleration of transfer of information and materials Collaborative Arrangement Disclosure [Text Block] Collaboration and Licensing Agreements Collaborative arrangement maximum contingent payment amount based on termination agreement. Collaborative Arrangement Maximum Contingent Payments Amount Aggregate amount payable under termination agreement Collaborative arrangement up front payment. Collaborative Arrangement Up Front Payment Amount of upfront payment for return of licenses Commitments and Contingencies Commitments and contingencies (Note 12) Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Text Block] Commitments and Contingencies Common Stock [Member] Common Stock [Member] Common Stock, Par or Stated Value Per Share Common stock, par value Common Stock, Shares Authorized Common stock, shares authorized Common Stock, Shares, Issued Common stock, shares issued Sale and issuance of common stock Common Stock, Shares, Outstanding Common stock, shares outstanding Common Stock, Value, Issued Common stock, $0.0001 par value; 300,000,000 shares authorized as of December 31, 2015 and December 31, 2014, respectively; 25,964,886 and 18,589,245 shares issued and outstanding as of December 31, 2015 and December 31, 2014, respectively. Compensation Related Costs, Policy [Policy Text Block] Stock-Based Compensation Comprehensive Income, Policy [Policy Text Block] Comprehensive Loss Concentration Risk, Credit Risk, Policy [Policy Text Block] Concentration of Credit Risk Construction in Progress [Member] Construction in Progress [Member] Conversion of Stock, Amount Converted Conversion of convertible preferred stock to common stock at closing of initial public offering Convertible preferred stock converted to common stock, value Conversion of Stock, Shares Converted Convertible preferred stock converted to common stock, shares Convertible Preferred Stock [Member] Convertible Preferred Stock [Member] Convertible Preferred Stock, Shares Issued upon Conversion Company issued warrants The entire disclosure for terms, amounts, nature of changes, rights and privileges, dividends, and other matters related to convertible preferred stock. Convertible Preferred Stock [Text Block] Convertible Preferred Stock Convertible preferred stock warrant liability. Convertible Preferred Stock Warrant Liability Convertible preferred stock warrant liability Convertible Preferred Stock Warrant Liability Policy [Text Block] Convertible Preferred Stock Warrant Liability Policy [Text Block] Convertible Preferred Stock Warrant Liability Cost of Services, Amortization Amortization of deferred compensation for services Counterparty Name [Axis] Counterparty Name [Axis] Current Fiscal Year End Date Current Fiscal Year End Date Deferred Compensation Arrangement with Individual, Common Stock Reserved for Future Issuance Common stock reserved Deferred Compensation Arrangement with Individual, Shares Authorized for Issuance Number of shares authorized for issuance Deferred Revenue, Current Deferred revenue, current portion Deferred Revenue Disclosure [Abstract] Deferred Revenue Disclosure [Abstract] Deferred Revenue, Noncurrent Deferred revenue, non-current Deferred tax asset liability not recognized estimated future increase (decrease) to equity upon recognition, stock compensation. Deferred Tax Asset Liability Not Recognized Estimated Future Increase (Decrease) to Equity Upon Recognition, Stock Compensation Estimated increase in equity due to deferred tax assets upon realization Deferred Tax Assets, Deferred Income Deferred revenue Deferred Tax Assets, Gross Gross deferred tax assets Deferred Tax Assets, Net Net deferred tax assets Deferred Tax Assets, Net of Valuation Allowance Total deferred tax assets Deferred Tax Assets, Net [Abstract] Deferred tax assets: Deferred Tax Assets, Operating Loss Carryforwards Net operating loss carryforwards Deferred Tax Assets, Other Other Deferred Tax Assets, Tax Credit Carryforwards, Research Research credits Deferred Tax Assets, Valuation Allowance Valuation allowance Deferred Tax Liabilities, Net Deferred tax liabilities Depreciation Depreciation expense Depreciation, Depletion and Amortization, Nonproduction Depreciation and amortization expense Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Equity Incentive Plans Document And Entity Information [Abstract] Document And Entity Information [Abstract] Document And Entity Information [Abstract] Document Fiscal Period Focus Document Fiscal Period Focus Document Fiscal Year Focus Document Fiscal Year Focus Document Period End Date Document Period End Date Document Type Document Type Domestic Tax Authority [Member] Federal Tax Authority [Member] Drafts Payable Overdraft Payable Earnings Per Share [Abstract] Earnings Per Share [Abstract] Earnings Per Share, Basic Basic Earnings Per Share, Basic and Diluted Net loss per common share, basic and diluted Net loss per share - basic and diluted Earnings Per Share, Basic and Diluted [Abstract] Net (loss) income per share: Earnings Per Share, Diluted Diluted Earnings Per Share, Policy [Policy Text Block] Net Loss per Share Earnings Per Share [Text Block] Net Loss per Share Effective Income Tax Rate Reconciliation, Percent Income tax provision Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Expected income tax provision at the federal statutory rate Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent Change in valuation allowance Effective Income Tax Rate Reconciliation, Nondeductible Expense, Percent Nondeductible expenses Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Other Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent State taxes, net of federal benefit Effective Income Tax Rate Reconciliation, Tax Credit, Percent Tax credits Employee-related Liabilities, Current Accrued compensation and benefits Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Unrecognized stock based compensation expense Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Unrecognized stock based compensation expense, weighted-average remaining recognition period Employee Stock Option [Member] Options to Purchase Common Stock [Member] Employee stock purchase plan initial offering period commenced period. Employee Stock Purchase Plan Initial Offering Period Commenced Period Employee stock purchase plan initial offering commenced period Employee stock purchase plan initial offering period ending period. Employee Stock Purchase Plan Initial Offering Period Ending Period Employee stock purchase plan initial offering ending period Entity Central Index Key Entity Central Index Key Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity Current Reporting Status Entity Current Reporting Status Entity Filer Category Entity Filer Category Entity Incorporation, Date of Incorporation Date of incorporation Entity Incorporation, State Country Name Place of incorporation Entity Public Float Entity Public Float Entity Registrant Name Entity Registrant Name Entity Voluntary Filers Entity Voluntary Filers Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Equity [Abstract] Equity [Abstract] Equity Component [Domain] Equity Component [Domain] Executive Officer Spouse [Member] Executive Officer Spouse [Member] Spouse of Executive Officer [Member] Expense Related to Distribution or Servicing and Underwriting Fees Underwriting discounts and commissions and expenses Fair Value Adjustment of Warrants Change in fair value of preferred stock warrant liability Change in fair value of preferred stock warrant liability 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] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table Text Block] Summary of Fair Value Measurements of Company's Financial Assets and Liabilities Fair Value, Assets, Level 1 to Level 2 Transfers, Amount Transfer of assets from Level 1 to Level 2 Fair Value, Assets, Level 2 to Level 1 Transfers, Amount Transfer of assets from Level 2 to Level 1 Asset Class [Domain] Asset Class [Domain] Fair Value Assumptions, Exercise Price Estimated fair value of common stock Asset Class [Axis] Asset Class [Axis] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Fair Value Disclosures [Text Block] Fair Value Measurements Fair Value, Inputs, Level 1 [Member] Level 1 [Member] Fair Value, Inputs, Level 2 [Member] Level 2 [Member] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value Measurement, Policy [Policy Text Block] Fair Value Measurements Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Fair Value, Measurements, Recurring [Member] Fair Value, Recurring [Member] Fair value of preferred stock warrant liability, probability of initial public offering scenario, percentage. Fair Value Of Preferred Stock Warrant Liability Probability Of Initial Public Offering Scenario Percentage Fair value of preferred stock warrant liability, probability of IPO scenario, percentage Fair value of preferred stock warrant liability, probability of merger scenario, percentage. Fair Value Of Preferred Stock Warrant Liability Probability Of Merger Scenario Percentage Fair value of preferred stock warrant liability, probability of merger scenario, percentage Fair value of preferred stock warrant liability, probability of stay private scenario, percentage. Fair Value Of Preferred Stock Warrant Liability Probability Of Stay Private Scenario Percentage Fair value of preferred stock warrant liability, probability of stay private scenario, percentage Gain (Loss) on Disposition of Property Plant Equipment Loss from disposal of fixed assets General and Administrative Expense General and administrative General and Administrative Expense [Member] General and Administrative [Member] Gross Proceeds From Issuance Of Common Stock Gross Proceeds From Issuance Of Common Stock Gross proceeds from issuance of common stock Impairment of Long-Lived Assets Held-for-use Impairment loss of long lived assets Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block] Impairment of Long-Lived Assets Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest Loss before provision for income taxes Income Statement [Abstract] Income Statement [Abstract] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Income Tax Disclosure [Line Items] Income Tax Disclosure [Line Items] Income Tax Disclosure [Line Items] Income Tax Disclosure [Table] Income Tax Disclosure [Table] Income Tax Disclosure [Table] Income Tax Disclosure [Text Block] Income Taxes Income Taxes Paid, Net Income taxes paid Income Tax Expense (Benefit) Benefit from (provision for) income taxes Income Tax, Policy [Policy Text Block] Income Taxes Increase (Decrease) in Accounts Payable Accounts payable Increase (Decrease) in Accounts Receivable Accounts receivable Increase (Decrease) in Deferred Revenue Deferred revenue Increase (Decrease) in Employee Related Liabilities Accrued compensation and benefits Increase (Decrease) in Operating Capital [Abstract] Changes in operating assets and liabilities: Increase (Decrease) in Other Accrued Liabilities Accrued and other liabilities Increase (Decrease) in Other Operating Liabilities Other long-term liabilities Increase (Decrease) in Prepaid Expense and Other Assets Prepaid expenses and other assets Increase In Shares Reserved For Issuance Maximum Shares To Be Issued Up On Exercise Of Stock Options Increase In Shares Reserved For Issuance Maximum Shares To Be Issued Up On Exercise Of Stock Options Increase in shares reserved for issuance, maximum shares to be issued up on exercise of stock options Investment Warrants, Exercise Price Warrants exercise price per share IPO [Member] IPO [Member] Laboratory Equipment [Member] Laboratory Equipment [Member] Laboratory Equipment [Member] Lease Arrangement, Type [Axis] Lease Arrangement, Type [Axis] Lease Arrangement, Type [Domain] Lease Arrangement, Type [Domain] Lease Expiration Date Lease expiration date Leasehold Improvements [Member] Leasehold Improvements [Member] Liabilities Total liabilities Liabilities and Equity Total liabilities and stockholders' equity Liabilities and Equity [Abstract] Liabilities and stockholders' equity Liabilities, Current Total current liabilities Liabilities, Current [Abstract] Current liabilities: License and Services Revenue Revenue recognized Licenses Revenue Licensing revenue Long-term Purchase Commitment, Amount Purchase commitments Loss Contingencies [Line Items] Loss Contingencies [Line Items] Loss Contingencies [Table] Loss Contingencies [Table] Maximum [Member] Maximum [Member] Minimum [Member] Minimum [Member] Minimum Tax Credit Carryforward [Member] Minimum Tax Credit Carryforward [Member] Minimum Tax Credit Carryforward [Member] Money Market Funds [Member] Money Market Funds [Member] Net Cash Provided by (Used in) Financing Activities, Continuing Operations Net cash provided by (used in) financing activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Financing activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Investing activities Net Cash Provided by (Used in) Operating Activities, Continuing Operations Net cash (used in) provided by operating activities Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Operating activities Net exercise and conversion of preferred stock warrants to common stock in connection with initial public offering in shares. Net Exercise And Conversion Of Preferred Stock Warrants To Common Stock In Connection With Initial Public Offering Shares Net exercise and conversion of preferred stock warrants to common stock in connection with initial public offering, shares Net Income (Loss) Attributable to Parent Net (loss) income Net loss Net Income (Loss) Attributable to Parent [Abstract] Numerator: Net income (loss) and comprehensive income (loss). Net Income Loss And Comprehensive Income Loss Net loss and comprehensive loss New Accounting Pronouncements, Policy [Policy Text Block] Recent Accounting Pronouncements Non Employee Stock Option [Member] Non Employee Stock Option [Member] Non Employee Stock Option [Member] Non royalty consideration percentage. Non Royalty Consideration Percentage Percentage of non-royalty revenue received Number of Operating Segments Number of operating segments Office Equipment And Furniture [Member] Office Equipment And Furniture [Member] Office Equipment And Furniture [Member] Operating Expenses Operating expenses Total operating expenses Operating Expenses [Abstract] Operating expenses: Operating Income (Loss) Loss from operations Operating Leases, Future Minimum Payments Due Total Operating Leases, Future Minimum Payments Due, Next Twelve Months 2016 Operating Leases, Future Minimum Payments, Due in Four Years 2019 Operating Leases, Future Minimum Payments, Due in Three Years 2018 Operating Leases, Future Minimum Payments, Due in Two Years 2017 Operating Leases, Rent Expense, Net Rent expense under operating leases Operating Loss Carryforwards Net operating loss carryforwards Operating Loss Carry Forwards Expiration Year Term Operating Loss Carry Forwards Expiration Year Term Operating loss carryforward expiration year Organization And Basis Of Presentation [Line Items] Organization And Basis Of Presentation [Line Items] Organization And Basis Of Presentation [Line Items] Organization And Basis Of Presentation [Table] Organization And Basis Of Presentation [Table] Organization And Basis Of Presentation [Table] Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block] Organization and Basis of Presentation Other Assets, Noncurrent Other assets Other Liabilities, Noncurrent Other long-term liabilities Other Nonoperating Income (Expense) Other income (expense), net Payment received on termination of option and license agreement. Payment Received On Termination Of Option And License Agreement Payment received on termination and return of rights Payments to Acquire Property, Plant, and Equipment Purchases of property and equipment Percentage of royalties payments. Percentage Of Royalties Payments Percentage of royalty on net sales required to pay under the agreement Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] Preferred Stock, Par or Stated Value Per Share Preferred stock, par value Preferred Stock, Shares Authorized Preferred stock, shares authorized Preferred Stock, Shares Issued Preferred stock, shares issued Preferred Stock, Shares Outstanding Preferred stock, shares outstanding Preferred Stock [Text Block] Preferred Stock Warrants Preferred Stock, Value, Issued Preferred stock, $0.0001 par value; 5,000,000 shares authorized as of December 31, 2015 and December 31, 2014, respectively; no shares issued and outstanding as of December 31, 2015 and December 31, 2014, respectively. Prepaid Expense and Other Assets, Current Prepaid expenses and other current assets Private Placement [Member] Private Placement [Member] Proceeds from Issuance Initial Public Offering Net proceeds from the IPO Proceeds from Issuance of Common Stock Proceeds from issuance of common stock, net of issuance costs Net proceeds from offering Proceeds from issuance of common stock, net Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Excluding Stock Options Proceeds from issuance of shares Proceeds from License Fees Received Upfront payment received Proceeds from (Payments for) Other Financing Activities Other Proceeds from Stock Options Exercised Proceeds from issuance of common stock from exercise of options Property, Plant and Equipment [Abstract] Property, Plant and Equipment [Abstract] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment Disclosure [Text Block] Property and Equipment Property, Plant and Equipment, Gross Property and equipment, gross Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Property, Plant and Equipment, Net Property and equipment, net Total property and equipment, net Property, Plant and Equipment, Policy [Policy Text Block] Property and Equipment Property, Plant and Equipment [Table Text Block] Summary of Property and Equipment Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Useful Life Property and equipment, estimated useful lives Provision for Lease Losses Amount provided lessor with irrevocable letter of credit Quarterly Financial Information Disclosure [Abstract] Quarterly Financial Information Disclosure [Abstract] Quarterly Financial Information [Text Block] Selected Quarterly Financial Data (Unaudited) Range [Axis] Range [Axis] Range [Domain] Range [Domain] Reclassification of convertible preferred warrant liability to additional paid-in capital. Reclassification Of Convertible Preferred Warrant Liability To Additional Paid In Capital Reclassification of convertible preferred warrant liability to additional paid-in capital Reclassification of warrant liability to additional paid-in capital upon completion of initial public offering. Reclassification Of Warrant Liability To Additional Paid In Capital Upon Completion Of Initial Public Offering Net exercise and conversion of preferred stock warrants to common stock in connection with initial public offering, amount Recognition of Deferred Revenue Recognized deferred revenue Related Party [Domain] Related Party [Domain] Related Party Transaction, Amounts of Transaction Related party transactions Related Party Transaction [Axis] Related Party Transaction [Axis] Related Party Transaction [Domain] Related Party Transaction [Domain] Related Party Transaction, Expenses from Transactions with Related Party Research and development service expenses Related Party Transaction [Line Items] Related Party Transaction [Line Items] Related Party Transactions [Abstract] Related Party Transactions [Abstract] Related Party [Axis] Related Party [Axis] Related Party Transactions Disclosure [Text Block] Related Party Transactions Counterparty Name [Domain] Counterparty Name [Domain] Research and Development Expense Research and development Research and Development Expense [Member] Research and Development [Member] Research and Development Expense, Policy [Policy Text Block] Research and Development Costs Research Tax Credit Carryforward [Member] Research and Development Tax Credit [Member] Restricted Cash and Cash Equivalents, Noncurrent Restricted cash Restricted Stock [Member] Restricted Stock [Member] Retained Earnings (Accumulated Deficit) Accumulated deficit Retained Earnings [Member] Accumulated Deficit [Member] Revenue from Related Parties Collaborative development revenue Revenue Recognition, Multiple-deliverable Arrangements, Determination of Selling Price, Amount Maximum amount of obligation to supply clinical trial materials, drug substance and drug product Revenue Recognition, Multiple-deliverable Arrangements [Line Items] Revenue Recognition, Multiple-deliverable Arrangements [Line Items] Revenue Recognition, Multiple-deliverable Arrangements [Table] Revenue Recognition, Multiple-deliverable Arrangements [Table] Revenue Recognition, Policy [Policy Text Block] Revenue Recognition Revenues Total revenue Total revenue Revenues [Abstract] Revenue: Sale of Stock [Domain] Sale of Stock [Domain] Sanofi [Member] Sanofi [Member] Sanofi [Member] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Calculation of Anti-dilutive Potentially Dilutive Securities Not Included in Diluted Per Share Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Significant Components of the Company's Deferred Tax Assets Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Computation of Net Loss Per Common Share Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Reconciliation of Statutory Federal Income Tax Rate to the Company's Effective Tax Rate 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] Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block] Summary of Stock-Based Compensation Recognized Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Schedule of Future Minimum Payments Under the Noncancelable Operating Lease Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Schedule of Quarterly Financial Information [Table Text Block] Schedule of Selected Quarterly Financial Results from Operations Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Schedule of Share-based Compensation, Activity [Table Text Block] Summary of Activity Under 2008 Plan and 2014 Plan, Including Grants to Nonemployees and Restricted Stock Issued Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Summary of Weighted Average Assumptions to Estimate Fair Value of Stock Option Awards and Employee Stock Purchase Plan Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block] Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits Share-based Compensation Stock-based compensation Share-based Compensation Arrangement by Share-based Payment Award, Accelerated Vesting, Number Share-based award accelerated vesting number of shares Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Vesting period Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost Stock-based compensation charge Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Dividend yield Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Expected term ( years) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Risk-free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Weighted Average Expected Dividend Expected dividend yield Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Shares Available for Grant, Ending balance Shares Available for Grant, Beginning balance Shares available for future grant Share based compensation arrangement by share based payment award number of shares available for grant options authorized. Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant Options Authorized Shares Available for Grant, Options authorized Share based compensation arrangement by share based payment award number of shares available for grant options exercised in period. Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant Options Exercised In Period Shares Available for Grant, Options exercised Share based compensation arrangement by share based payment award number of shares available for grant options repurchased. Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant Options Repurchased Shares Available for Grant, Options repurchased Share based compensation arrangement by share based payment award options authorized in period gross. Share Based Compensation Arrangement By Share Based Payment Award Options Authorized In Period Gross Options Issued and Outstanding Number of Shares, Options authorized Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Aggregate Intrinsic Value, Vested Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Options Issued and Outstanding Number of Shares, Vested Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Options Issued and Outstanding Average Exercise Price per Share, Vested Share based compensation arrangement by share based payment award options expected to vest. Share Based Compensation Arrangement By Share Based Payment Award Options Expected To Vest Options Issued and Outstanding Number of Shares, Expected to vest Share based compensation arrangement by share based payment award options expected to vest intrinsic value. Share Based Compensation Arrangement By Share Based Payment Award Options Expected To Vest Intrinsic Value Aggregate Intrinsic Value, Expected to Vest Share Based Compensation Arrangement By Share Based Payment Award Options Expected To Vest Weighted Average Exercise Price Share Based Compensation Arrangement By Share Based Payment Award Options Expected To Vest Weighted Average Exercise Price Options Issued and Outstanding Average Exercise Price per Share, Expected to vest Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period Options Issued and Outstanding Number, Options cancelled Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Options Issued and Outstanding Number of Shares, Options granted Shares Available for Grant, Options granted Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Weighted-average grant-date estimated fair value of options granted Share based compensation arrangement by share based payment award options issuance of common stock for services in period gross. Share Based Compensation Arrangement By Share Based Payment Award Options Issuance Of Common Stock For Services In Period Gross Options Issued and Outstanding Number of Shares, Issuance of common stock for services Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Aggregate Intrinsic Value, Ending balance Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Options Issued and Outstanding Number of Shares, Ending balance Options Issued and Outstanding Number of Shares, Beginning balance Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Options Issued and Outstanding Average Exercise Price per Share, Ending balance Options Issued and Outstanding Average Exercise Price per Share, Beginning balance Share-based Compensation Arrangement by Share-based Payment Award, Options Outstanding, Weighted Average Exercise Price, and Additional Disclosures [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Options Outstanding, Weighted Average Exercise Price, and Additional Disclosures [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Options Outstanding, Weighted Average Exercise Price, and Additional Disclosures [Abstract] Share based compensation arrangement by share based payment award options repurchased in period gross. Share Based Compensation Arrangement By Share Based Payment Award Options Repurchased In Period Gross Options Issued and Outstanding Number of Shares, Options repurchased Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value Fair value of options vested during period Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Outstanding Stock Maximum Possible increase in shares reserved for issuance as percentage of outstanding stock Share-based Compensation Arrangement by Share-based Payment Award, Per Share Weighted Average Price of Shares Purchased Weighted-average purchase price Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period Number of shares sold under the plan Equity Award [Domain] Equity Award [Domain] Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Options Issued and Outstanding Average Exercise Price per Share, Options exercised Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price Options Issued and Outstanding Average Exercise Price per Share, Options canceled Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Options Issued and Outstanding Average Exercise Price per Share, Options granted Share based compensation arrangements by share based payment award options issuance of common stock for services in period weighted average exercise price. Share Based Compensation Arrangements By Share Based Payment Award Options Issuance Of Common Stock For Services In Period Weighted Average Exercise Price Options Issued and Outstanding Average Exercise Price per Share, Issuance of common stock for services Share based compensation arrangements by share based payment award options repurchased in period weighted average exercise price. Share Based Compensation Arrangements by Share Based Payment Award Options Repurchased in Period Weighted Average Exercise Price Options Issued and Outstanding Average Exercise Price per Share, Options repurchased Shares Issued, Price Per Share Purchase price of common shares Shares, Outstanding Balance, shares Balance, shares Significant Accounting Policies [Text Block] Summary of Significant Accounting Policies State and Local Jurisdiction [Member] State Tax Authority [Member] Class of Stock [Axis] Class of Stock [Axis] Equity Components [Axis] Equity Components [Axis] Statement [Line Items] Statement [Line Items] Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] Stockholders' Equity Attributable to Parent Balance, amount Balance, amount Total stockholders' equity Stockholders' Equity Attributable to Parent [Abstract] Stockholders' equity: Stock Issued Services settled through the issuance of common stock Stock Issued During Period, Shares, Conversion of Convertible Securities Conversion of convertible preferred stock to common stock in connection with initial public offering, shares Stock Issued During Period, Shares, Employee Stock Purchase Plans Issuance of common stock under employee stock purchase plan , shares Stock Issued During Period, Shares, Issued for Services Issuance of common stock for services (Shares) Issuance of common stock for services, shares Shares Available for Grant, Issuance of common stock for services Stock Issued During Period, Shares, New Issues Stock issued during period, shares, new issues Common stock sold and issued Issuance of common stock and warrants in connection with the private placement, shares Stock Issued During Period, Shares, Share-based Compensation, Forfeited Shares Available for Grant, Options canceled Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Exercise of stock options and vesting of early exercised stock options, net of repurchases, shares Options Issued and Outstanding Number of Shares, Options exercised Stock Issued During Period, Value, Conversion of Convertible Securities Conversion of convertible preferred stock to common stock in connection with initial public offering, amount Stock Issued During Period, Value, Employee Stock Purchase Plan Issuance of common stock under employee stock purchase plan ,amount Stock Issued During Period, Value, Issued for Services Issuance of common stock for services, amount Stock Issued During Period, Value, New Issues Issuance of common stock and warrants in connection with the private placement, net of expenses Stock Issued During Period, Value, Other Other Stock Issued During Period, Value, Stock Options Exercised Exercise of stock options and vesting of early exercised stock options, net of repurchases, amount Subsequent Event [Line Items] Subsequent Event [Line Items] Subsequent Event [Member] Subsequent Event [Member] Subsequent Events [Abstract] Subsequent Events [Abstract] Subsequent Events [Text Block] Subsequent Events Subsequent Event [Table] Subsequent Event [Table] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Sale of Stock [Axis] Sale of Stock [Axis] Supplemental Cash Flow Information [Abstract] Supplementary disclosure of cash flow information Tax Credit Carryforward, Amount Tax credit carryforwards Tax Credit Carryforward [Axis] Tax Credit Carryforward [Axis] Tax Credit Carry Forward Expiration Year Tax Credit Carry Forward Expiration Year Tax credit carryforward expiration year Tax Credit Carryforward, Name [Domain] Tax Credit Carryforward, Name [Domain] Text Block [Abstract] Text Block [Abstract] Trading Symbol Trading Symbol Two Thousand Eight Stock Incentive Plan [Member] Two Thousand Eight Stock Incentive Plan [Member] 2008 Stock Incentive Plan [Member] Two Thousand Fourteen Employee Stock Purchase Plan [Member] Two Thousand Fourteen Employee Stock Purchase Plan [Member] 2014 Employee Stock Purchase Plan [Member] 2014 Equity Incentive Award Plan [Member] Two Thousand Fourteen Equity Incentive Award Plan [Member] 2014 Equity Incentive Award Plan [Member] Unrecognized Tax Benefits Balance at end of year Balance at beginning of year Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued Accrued interest and penalties related to unrecognized tax benefits Unrecognized tax benefits increase (decreases) resulting from prior period tax positions. Unrecognized Tax Benefits Increase Decreases Resulting From Prior Period Tax Positions Additions (subtractions) based on tax positions related to prior year Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions Additions based on tax positions related to current year Unrecognized Tax Benefits that Would Impact Effective Tax Rate Unrecognized tax benefits that would affect the effective tax rate if recognized Use of Estimates, Policy [Policy Text Block] Use of Estimates Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount Increase (decrease) in deferred tax valuation allowance Variable Interests And Equity Method Investments Disclosure [Abstract] Variable Interests And Equity Method Investments Disclosure [Abstract] Variable Interests And Equity Method Investments Disclosure [Abstract] Warrant expiration term. Warrant Expiration Term Warrants expiration term Warrant [Member] Warrants to Purchase Convertible Preferred Stock [Member] Warrants To Purchase Common Stock [Member] Warrants To Purchase Common Stock [Member] Warrants to Purchase Common Stock [Member] Weighted Average Number of Shares Outstanding, Basic and Diluted Shares used to compute net loss per common share, basic and diluted Weighted average number of shares outstanding-basic and diluted Weighted Average Number Of Shares Outstanding Basic And Diluted [Abstract] Weighted Average Number Of Shares Outstanding Basic And Diluted [Abstract] Denominator: