Entity Central Index Key Document and entity information. Document And Entity Information [Abstract] Document Type Document Type Amendment Flag Amendment Flag Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Trading Symbol Trading Symbol Entity Registrant Name Entity Registrant Name Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Common Stock, Shares Outstanding Entity Common Stock Shares Outstanding Accrued clinical expenses current. 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 securities Available For Sale Securities Debt Securities Current Accrued interest receivable Interest Receivable Prepaid expenses Prepaid Expense Current Total current assets Assets Current Property and equipment, net Property Plant And Equipment Net Operating lease right-of-use asset Operating Lease Right Of Use Asset 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 clinical trial expenses Accrued Clinical Expenses Current Other accrued liabilities Other Accrued Liabilities Current Total current liabilities Liabilities Current Long-term portion of operating lease liability Operating Lease Liability Noncurrent Other liabilities Other Liabilities Noncurrent Total liabilities Liabilities Commitments and contingencies Commitments And Contingencies Stockholders’ equity: Stockholders Equity [Abstract] Preferred stock, $0.0001 par value: 10,000,000 shares authorized; no shares issued and outstanding Preferred Stock Value Common stock, $0.0001 par value: 100,000,000 shares authorized; 68,694,043 and 59,456,493 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively Common Stock Value Additional paid-in capital Additional Paid In Capital Accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income Loss Net Of Tax Accumulated deficit Retained Earnings Accumulated Deficit Total stockholders’ equity Stockholders Equity Total liabilities and stockholders’ equity Liabilities And Stockholders Equity Preferred stock, par value Preferred Stock Par Or Stated Value Per Share Preferred stock, shares authorized Preferred Stock Shares Authorized Preferred stock, shares issued Preferred Stock Shares Issued Preferred stock, shares outstanding Preferred Stock Shares Outstanding Common stock, par value Common Stock Par Or Stated Value Per Share Common stock, shares authorized Common Stock Shares Authorized Common stock, shares issued Common Stock Shares Issued Common stock, shares outstanding Common Stock Shares Outstanding Income Statement [Abstract] Type of Revenue [Extensible List] Type Of Revenue Extensible List 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 Other income (expense): Nonoperating Income Expense [Abstract] Interest income Investment Income Interest Interest expense Interest Expense Other expense, net Other Nonoperating Income Expense Total other income (expense) Nonoperating Income Expense Net loss Net Income Loss Other comprehensive income (loss): Other Comprehensive Income Loss Net Of Tax Period Increase Decrease [Abstract] Unrealized gain (loss) on marketable securities Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax Total other comprehensive income (loss) Other Comprehensive Income Loss Net Of Tax Comprehensive loss Comprehensive Income Net Of Tax Basic net loss per common share Earnings Per Share Basic Diluted net loss per common share Earnings Per Share Diluted Weighted average common shares outstanding used to calculate basic net loss per common share Weighted Average Number Of Shares Outstanding Basic Weighted average common shares outstanding used to calculate diluted net loss per common share Weighted Average Number Of Diluted Shares Outstanding Increase decrease in interest receivable and other current assets. Proceeds from maturities of marketable securities. Proceeds from sale of marketable securities. Accrued financing costs. Cashless exercise of common stock for warrants liability. Statement Of Cash Flows [Abstract] 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] Depreciation and amortization Depreciation Depletion And Amortization Stock-based compensation expense Share Based Compensation Net accretion and amortization of investments in marketable securities Accretion Amortization Of Discounts And Premiums Investments Non-cash interest associated with debt discount accretion Amortization Of Debt Discount Premium Change in fair value of warrant liability Fair Value Adjustment Of Warrants Changes in assets and liabilities: Increase Decrease In Operating Capital [Abstract] Receivable from collaboration Increase Decrease In Accounts Receivable Interest receivable and other current assets Increase Decrease In Interest Receivable And Other Current Assets Prepaid expenses Increase Decrease In Prepaid Expense Other assets Increase Decrease In Other Operating Assets Accounts payable Increase Decrease In Accounts Payable Accrued liabilities Increase Decrease In Accrued Liabilities Accrued interest payable Increase Decrease In Interest Payable Net Net cash used in operating activities Net Cash Provided By Used In Operating Activities Investing activities Net Cash Provided By Used In Investing Activities [Abstract] Purchases of property and equipment Payments To Acquire Property Plant And Equipment Purchases of marketable securities Payments To Acquire Marketable Securities Proceeds from maturities of marketable securities Proceeds From Maturities Of Marketable Securities Proceeds from sale of marketable securities Proceeds From Sale Of Marketable Securities Net cash used in investing activities Net Cash Provided By Used In Investing Activities Financing activities Net Cash Provided By Used In Financing Activities [Abstract] Proceeds from issuance of common stock, net of issuance costs Proceeds From Issuance Or Sale Of Equity Proceeds from issuance of common stock pursuant to equity award plans Proceeds From Stock Options Exercised Proceeds from issuance of common stock upon exercise of warrants Proceeds From Warrant Exercises Repayment of facility loan principal Repayments Of Long Term Lines Of Credit Net cash provided by financing activities Net Cash Provided By Used In Financing Activities Net increase in cash and cash equivalents Cash And Cash Equivalents Period Increase Decrease Cash and cash equivalents at beginning of period Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations Cash and cash equivalents at end of period Supplemental disclosure Supplemental Cash Flow Information [Abstract] Cash paid for interest Interest Paid Net Supplemental non-cash investing and financing activities Noncash Investing And Financing Items [Abstract] Accrued financing costs Accrued Financing Costs Issuance of common stock upon warrant exercises Cashless Exercise Of Common Stock For Warrants Liability Stock issued during period shares stock options and incentive awards exercised. Stock issued during period value stock options and awards incentive exercised. Stock issued during period shares stock warrants exercised. Stock issued during period value stock warrants exercised. 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 Other Comprehensive Income (Loss) [Member] Accumulated Other Comprehensive Income [Member] Accumulated Deficit [Member] Retained Earnings [Member] Statement [Line Items] Statement [Line Items] Balance at beginning of period Balance at beginning of period (in shares) Shares Outstanding Issuance of common stock upon exercise of stock options and incentive awards Stock Issued During Period Value Stock Options And Incentive Awards Exercised Issuance of common stock upon exercise of stock options and incentive awards (Shares) Stock Issued During Period Shares Stock Options And Incentive Awards Exercised Issuance of common stock upon exercise of warrants, value Stock Issued During Period Value Stock Warrants Exercised Issuance of common stock upon exercise of warrants (Shares) Stock Issued During Period Shares Stock Warrants Exercised Stock-based compensation expense Stock Issued During Period Value Share Based Compensation Issuance of common stock, value Stock Issued During Period Value New Issues Issuance of common stock, (in shares) Stock Issued During Period Shares New Issues Net loss Net unrealized gain (loss) on marketable securities Balance at end of period Balance at end of period (in shares) Stock issuance cost Adjustments To Additional Paid In Capital Stock Issued Issuance Costs Organization Consolidation And Presentation Of Financial Statements [Abstract] Organization and Description of Business Organization Consolidation And Presentation Of Financial Statements Disclosure [Text Block] Accounting Policies [Abstract] Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Other accrued liabilities, current disclosure. Other accrued liabilities current. Other Accrued Liabilities Current [Abstract] Other Accrued Liabilities Other Accrued Liabilities Current Disclosure [Text Block] Collaboration and License Agreements Collaborative Arrangement Disclosure [Text Block] Leases [Abstract] Leases Lessee Operating Leases [Text Block] Equity [Abstract] Stockholders' Equity Stockholders Equity Note Disclosure [Text Block] Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] Stock Plan and Stock-Based Compensation Disclosure Of Compensation Related Costs Share Based Payments [Text Block] Liquidity accounting. Liquidity Liquidity Accounting Policy [Text Block] Basis of Presentation Basis Of Accounting Policy Policy [Text Block] Use of Estimates Use Of Estimates Fair Value of Financial Instruments Fair Value Measurement Policy Policy [Text Block] Cash equivalents and investments. Cash, Cash Equivalents and Marketable Securities Cash Equivalents And Investments Policy [Text Block] Concentrations of Risk Concentration Risk Credit Risk Leases Lessee Leases Policy [Text Block] Common stock warrant liability. Common Stock Warrant Liabilities Common Stock Warrant Liability Policy [Text Block] Research and Development Expenses Research And Development Expense Policy Stock-Based Compensation Share Based Compensation Option And Incentive Plans Policy Net Loss Per Common Share Earnings Per Share Policy [Text Block] Recently Adopted and Issued Accounting Pronouncements New Accounting Pronouncements Policy Policy [Text Block] Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis Schedule Of Fair Value Assets And Liabilities Measured On Recurring Basis Table [Text Block] Schedule of Changes in Fair Value of Liabilities Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Text Block] Schedule of Amortized Cost, Unrealized Gain and Loss, and Fair Value of Available for Sale Marketable Securities Marketable Securities [Text Block] Computation of Basic and Diluted Net Loss per Share Schedule Of Earnings Per Share Basic And Diluted Table [Text Block] Anti-Dilutive Securities Excluded from the Computation of Diluted Net Loss per Share Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Text Block] Schedule of other accrued liabilities. Summary of Other Accrued Liabilities Schedule Of Other Accrued Liabilities Table [Text Block] Schedule of other information related to leases. Schedule of Information Related to Leases Schedule Of Information Related To Leases Table [Text Block] Summary of Maturities of Operating Lease Liabilities Lessee Operating Lease Liability Maturity Table [Text Block] Summary of Stock-Based Compensation Expense Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Text Block] Number of operating segments Number Of Operating Segments Cash flows from operating activities Cash and cash equivalents and marketable securities Cash Cash Equivalents And Short Term Investments Fair Value Disclosures [Abstract] Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table] Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table] Fair Value Hierarchy and NAV Fair Value By Fair Value Hierarchy Level [Axis] Fair Value Hierarchy and NAV Fair Value Measurements Fair Value Hierarchy [Domain] Level 1 [Member] Fair Value Inputs Level1 [Member] Level 2 [Member] Fair Value Inputs Level2 [Member] Level 3 [Member] Fair Value Inputs Level3 [Member] Investment Type Investment Type [Axis] Investments Investment Type Categorization [Member] Cash Equivalents [Member] Cash Equivalents [Member] Short-term Investments [Member] Short Term Investments [Member] Asset Class Fair Value By Asset Class [Axis] Asset Class Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation By Asset Class [Domain] Money Market Funds [Member] Money Market Funds [Member] U.S. and Foreign Commercial Paper [Member] Commercial Paper [Member] U.S. and Foreign Corporate Debt Securities [Member] Corporate Debt Securities [Member] Asset-backed Securities [Member] Asset Backed Securities [Member] U.S. Treasury Securities [Member] U S Treasury Securities [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] Total assets measured at fair value Assets Fair Value Disclosure Warrant exercised or expired period. Schedule Of Product Information [Table] Schedule Of Product Information [Table] Range Range [Axis] Range Range [Member] Maximum [Member] Maximum [Member] Minimum [Member] Minimum [Member] Adjustments for New Accounting Pronouncements Adjustments For New Accounting Pronouncements [Axis] Type of Adoption Type Of Adoption [Member] Accounting standards update two thousand eighteen eleven. ASU 2018-11 [Member] Accounting Standards Update Two Thousand Eighteen Eleven [Member] Product Information [Line Items] Product Information [Line Items] Warrants exercise or expiration period Warrant Exercised Or Expired Period Fair Value Instruments Classified In Shareholders Equity Measured On Recurring Basis Unobservable Input Reconciliation [Table] Fair Value Instruments Classified In Shareholders Equity Measured On Recurring Basis Unobservable Input Reconciliation [Table] Fair Value, Instruments Classified in Shareholders' Equity Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair Value Instruments Classified In Shareholders Equity Measured On Recurring Basis Unobservable Input Reconciliation [Line Items] Fair Value, Instruments Classified in Shareholders' Equity Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair Value Instruments Classified In Shareholders Equity Measured On Recurring Basis Unobservable Input Reconciliation Calculation Roll Forward Balance, beginning of period Fair Value Measurement With Unobservable Inputs Reconciliations Recurring Basis Liability Value Change in fair value Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Period Increase Decrease Settlement of financial instruments Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Settlements Balance, end of period Cash equivalent maturity description. Cash and cash equivalents, maturity description Cash Equivalent Maturity Description Short-term investment contractual maturity. Long-term investments maturity period. Short-term contractual maturities Short Term Investment Contractual Maturity Long-term contractual maturities Long Term Investments Maturity Period Schedule Of Available For Sale Securities [Table] Schedule Of Available For Sale Securities [Table] Financial Instrument Financial Instrument [Axis] Financial Instruments Transfers And Servicing Of Financial Instruments Types Of Financial Instruments [Domain] U.S. and Foreign Commercial Paper [Member] Commercial Paper Not Included With Cash And Cash Equivalents [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 Estimated Fair Value Number of operating leased facilities. Number of leased facilities Number Of Operating Leased Facilities Earnings Per Share [Abstract] Numerator: Net Income Loss [Abstract] Net loss allocated to common stock-basic Net Income Loss Available To Common Stockholders Basic Net loss allocated to common stock-diluted Net Income Loss Available To Common Stockholders Diluted Denominator: Weighted Average Number Of Shares Outstanding Diluted Disclosure Items [Abstract] Weighted average number of common stock shares outstanding - basic Weighted average number of common stock shares outstanding - diluted Net loss per share - basic: Net loss per share - diluted: 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] Employee or non employee stock options. Common Stock Options [Member] Employee Or Non Employee Stock Options [Member] Incentive stock awards. Incentive Awards [Member] Incentive Stock Awards [Member] Common stock warrant. Common Stock Warrants [Member] Common Stock Warrant [Member] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] Anti-dilutive securities excluded from the computation of diluted loss per share Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount Lessee, operating lease, description Lessee Operating Lease Description Derecognition of deferred rent. ROU assets Lease liabilities Operating Lease Liability Derecognition of the deferred rent Derecognition Of Deferred Rent Accrued professional fees and other, classified as current. Accrued compensation Employee Related Liabilities Current Accrued professional fees and other Accrued Professional Fees And Other Current Operating lease liability Operating Lease Liability Current Deferred rent Deferred Rent Credit Current Total other accrued liabilities Royalty percentage based on net sales. Schedule Of Collaborative Arrangements And Noncollaborative Arrangement Transactions [Table] Schedule Of Collaborative Arrangements And Noncollaborative Arrangement Transactions [Table] Counterparty Name Counterparty Name [Axis] Counterparty Name Repurchase Agreement Counterparty Name [Domain] Janssen Pharmaceutical N V. Janssen Pharmaceutical NV [Member] Janssen Pharmaceutical N V [Member] Janssen Pharmaceuticals Inc. Janssen Pharmaceuticals, Inc. [Member] Janssen Pharmaceuticals Inc [Member] Diatex Inc. DiaTex, Inc. [Member] Diatex Inc [Member] gaap:Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items] Percentage of royalty on net sales Royalty Percentage Based On Net Sales Royalty payment Payments For Royalties Accrued royalties Accrued Royalties Current And Noncurrent Number of development and license agreements. Number of development and license agreements Number Of Development And License Agreements Development payment. Development payment Development Payment Number of leased facilities operating leases. Area of office space. Lease start date. Lessee Lease Description [Table] Lessee Lease Description [Table] Lease Arrangement, Type Lease Arrangement Type [Axis] Lease Arrangement, Type Lease Arrangement Type [Domain] Lease facility. Lease Facility [Member] Lease Facility [Member] Income Statement Location Income Statement Location [Axis] Income Statement Location Income Statement Location [Domain] Operating Expense [Member] Operating Expense [Member] Lessee Lease Description [Line Items] Lessee Lease Description [Line Items] Number of leased facilities Number Of Leased Facilities Operating Leases Area of office space Area Of Office Space Lease start date Lease Start Date Weighted average remaining lease term Operating Lease Weighted Average Remaining Lease Term1 Lease, option to extend Lessee Operating Lease Option To Extend Weighted average lease discount rate Operating Lease Weighted Average Discount Rate Percent Lease costs Operating Lease Cost Rent expenses Operating Leases Rent Expense Net Commitments And Contingencies Disclosure [Abstract] Balance sheet Assets And Liabilities Lessee [Abstract] Operating lease right-of-use assets Operating lease liability (Other accrued liabilities) Total operating lease liability Cash flows Cash Flow Operating Activities Lessee [Abstract] Cash paid for amounts included in the measurement of lease liabilities Operating Lease Payments 2019 (from April to December) Lessee Operating Lease Liability Payments Remainder Of Fiscal Year 2020 Lessee Operating Lease Liability Payments Due Year Two 2021 Lessee Operating Lease Liability Payments Due Year Three 2022 Lessee Operating Lease Liability Payments Due Year Four 2023 Lessee Operating Lease Liability Payments Due Year Five Thereafter Lessee Operating Lease Liability Payments Due After Year Five Total undiscounted future minimum lease payments Lessee Operating Lease Liability Payments Due Less: Imputed interest Lessee Operating Lease Liability Undiscounted Excess Amount Less: Current portion of operating lease liability Common stock offering price Shares Issued Price Per Share Net proceeds from public offering Proceeds From Issuance Of Common Stock 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] Equity incentive plan two thousand and thirteen. 2013 Equity Incentive Plan [Member] Equity Incentive Plan Two Thousand And Thirteen [Member] Title of Individual Title Of Individual [Axis] Relationship to Entity Title Of Individual With Relationship To Entity [Domain] Employees, directors and consultant. Employees, Directors and Consultant [Member] Employees Directors And Consultant [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share Based Compensation Arrangement By Share Based Payment Award [Line Items] Increase in shares reserved for issuance Share Based Compensation Arrangement By Share Based Payment Award Number Of Additional Shares Authorized Number of option granted to employees Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross Shares available for grant Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant 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] 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]