Entity Central Index Key Cover [Abstract] Document Type Document Type Amendment Flag Amendment Flag Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Trading Symbol Trading Symbol Entity Registrant Name Entity Registrant Name Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Well-known Seasoned Issuer Entity Well Known Seasoned Issuer Entity Current Reporting Status Entity Current Reporting Status Entity Voluntary Filers Entity Voluntary Filers Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Shell Company Entity Shell Company Entity Common Stock, Shares Outstanding Entity Common Stock Shares Outstanding Entity Public Float Entity Public Float Entity File Number Entity File Number Entity Tax Identification Number Entity Tax Identification Number Entity Address, Address Line One Entity Address Address Line1 Entity Address, Address Line Two Entity Address Address Line2 Entity Address, City or Town Entity Address City Or Town Entity Address, State or Province Entity Address State Or Province Entity Address, Postal Zip Code Entity Address Postal Zip Code City Area Code City Area Code Local Phone Number Local Phone Number Document Annual Report Document Annual Report Document Transition Report Document Transition Report Entity Incorporation, State or Country Code Entity Incorporation State Country Code Entity Interactive Data Current Entity Interactive Data Current Title of 12(b) Security Security12b Title Security Exchange Name Security Exchange Name Carrying amount as of the balance sheet date, which is the fair value of the acquired in-process technology, adjusted for any amortization recognized after market feasibility has been achieved and for any impairment charges. Accrued liabilities and other liabilities 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 Prepaid expense and other current assets Prepaid Expense And Other Assets Current Total current assets Assets Current Goodwill Goodwill In-process research and development In Process Research And Development Property and equipment, net Property Plant And Equipment Net Other long-term 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 liabilities and other current liabilities Accrued Liabilities And Other Liabilities Current Total current liabilities Liabilities Current Long-term deferred revenue Deferred Revenue Noncurrent Deferred tax liability Deferred Tax Liabilities Noncurrent Other long-term liabilities Other Liabilities Noncurrent Total liabilities Liabilities Commitments and contingencies Commitments And Contingencies Stockholders’ equity: Stockholders Equity [Abstract] Common stock, $0.001 par value; 100,000,000 shares authorized at December 31, 2019 and December 31, 2018; 43,908,065 and 42,081,306 shares issued and outstanding at December 31, 2019 and December 31, 2018, respectively Common Stock Value Additional paid-in capital Additional Paid In Capital Common Stock Accumulated other comprehensive 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 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 Research, development and patents expense. Income Statement [Abstract] Operating expenses: Operating Expenses [Abstract] Research, development and patents Research Development And Patents Expense General and administrative General And Administrative Expense Total operating expenses Operating Expenses Operating loss Operating Income Loss Interest income Interest Income Other Other expense, net Other Nonoperating Income Expense Loss before income taxes Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest Income tax (expense) Income Tax Expense Benefit Net loss applicable to common stockholders Net Income Loss Basic and diluted net loss per common share Earnings Per Share Basic And Diluted Shares used to compute basic and diluted net loss per common share Weighted Average Number Of Share Outstanding Basic And Diluted Net loss applicable to common stockholders Other comprehensive income, net of tax: Other Comprehensive Income Loss Net Of Tax Period Increase Decrease [Abstract] Foreign currency translation adjustments Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax Comprehensive loss Comprehensive Income Net Of Tax Stock issued during period shares under at-the-market equity distribution and sales agreements. Stock issued during period value under at-the-market equity distribution and sales agreements. Stock issued during period upon exercise of warrants. Stock issued during period value upon exercise of warrants. Statement Of Stockholders Equity [Abstract] Statement [Table] Statement [Table] Equity Components Statement Equity Components [Axis] Equity Component Equity Component [Domain] Common stock Common Stock [Member] Additional paid-in capital Additional Paid In Capital [Member] Accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income [Member] Accumulated deficit Retained Earnings [Member] Statement [Line Items] Statement [Line Items] Balance Balance, shares Shares Outstanding Share-based compensation Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value Issuance of shares under an employee stock purchase plan (ESPP) Stock Issued During Period Value Employee Stock Purchase Plan Issuance of shares under an employee stock purchase plan (ESPP), shares Stock Issued During Period Shares Employee Stock Purchase Plans Issuance of common stock under public offering, net of offering costs Stock Issued During Period Value New Issues Issuance of common stock under public offering, net of offering costs, shares Stock Issued During Period Shares New Issues Issuance of common stock under at-the-market equity distribution and sales agreements, net of offering costs Stock Issued During Period Value Under At The Market Equity Distribution And Sales Agreements Issuance of common stock under at-the-market equity distribution and sales agreements, net of offering costs, shares Stock Issued During Period Shares Under At The Market Equity Distribution And Sales Agreements Issuance of common stock for option exercises Stock Issued During Period Value Stock Options Exercised Issuance of common stock for option exercises, shares Stock Issued During Period Shares Stock Options Exercised Exercise of warrants Stock Issued During Period Value Upon Exercise Of Warrants Exercise of warrants, shares Stock Issued During Period Upon Exercise Of Warrants Net loss Foreign currency translation adjustments Balance Balance, shares Increase decrease in receivables prepaid deferred expense and other current and long-term assets. Amount of increase (decrease) in deferred tax liability, deferred revenue and other long term liabilities. Proceeds from issuance of common stock, exercise of common stock options and warrants, net of issuance costs. 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] Non-cash share-based compensation Share Based Compensation Depreciation and amortization Depreciation Depletion And Amortization Change in joint venture investment Income Loss From Equity Method Investments Changes in assets and liabilities: Increase Decrease In Operating Capital [Abstract] Receivables, prepaid expenses and other current and long-term assets Increase Decrease In Receivables Prepaid Deferred Expense And Other Current And Long Term Assets Accounts payable, accrued liabilities and other current liabilities Increase Decrease In Operating Liabilities Deferred tax liability, deferred revenue and other long-term liabilities Increase Decrease In Deferred Tax Liability Deferred Revenue And Other Long Term Liabilities 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] Proceeds from dissolution of joint venture Proceeds From Divestiture Of Interest In Joint Venture Acquisitions of property and equipment Payments To Acquire Property Plant And Equipment Net cash (used in) provided by 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, exercise of common stock options and warrants, net of issuance costs Proceeds From Issuance Of Common Stock Exercise Of Common Stock Options And Warrants Net Of Issuance Costs Proceeds from issuance of equity under ESPP Proceeds From Stock Plans Net cash provided by financing activities Net Cash Provided By Used In Financing Activities Effects of foreign exchange rates on cash Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations Net increase in cash and cash equivalents Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect Cash and cash equivalents, beginning of period Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations Cash and cash equivalents, end of period Supplemental disclosure of cash flow information: Supplemental Cash Flow Information [Abstract] Income taxes paid Income Taxes Paid Documents Incorporated by Reference Documents Incorporated By Reference [Text Block] Accounting Policies [Abstract] Organization and Summary of Significant Accounting Policies Organization Consolidation Basis Of Presentation Business Description And Accounting Policies [Text Block] Revenue From Contract With Customer [Abstract] Revenue Recognition Revenue From Contract With Customer [Text Block] Fair Value Disclosures [Abstract] Fair Value Measurements Fair Value Measurement Inputs Disclosure [Text Block] Organization Consolidation And Presentation Of Financial Statements [Abstract] Balance Sheet Details Supplemental Balance Sheet Disclosures [Text Block] Commitments And Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments And Contingencies Disclosure [Text Block] Equity Method Investments And Joint Ventures [Abstract] Joint Venture Equity Method Investments Disclosure [Text Block] Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] Share-based Compensation Disclosure Of Compensation Related Costs Share Based Payments [Text Block] Equity [Abstract] Stockholders' Equity Stockholders Equity Note Disclosure [Text Block] Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] Compensation And Retirement Disclosure [Abstract] Employee Savings Plan Pension And Other Postretirement Benefits Disclosure [Text Block] Subsequent Events [Abstract] Subsequent Events Subsequent Events [Text Block] Principles of Consolidation Consolidation Policy [Text Block] Segment Reporting Segment Reporting Policy Policy [Text Block] Use of Estimates Use Of Estimates Cash and Cash Equivalents Cash And Cash Equivalents Policy [Text Block] Concentrations and Credit Risk Concentration Risk Credit Risk Fair Value of Financial Instruments Fair Value Of Financial Instruments Policy In process research and development, long lived assets and goodwill policy. IPR&D, Long-Lived Assets and Goodwill In Process Research And Development Long Lived Assets And Goodwill Policy Policy [Text Block] Research development and patents expense. Research, Development and Patents Research Development And Patents Expense Policy [Text Block] Share-Based Compensation Share Based Compensation Option And Incentive Plans Policy Net Loss Per Share Earnings Per Share Policy [Text Block] Recent Accounting Pronouncements New Accounting Pronouncements Policy Policy [Text Block] Revenue Recognition Policy Revenue Recognition Policy [Text Block] Property and Equipment Net Property Plant And Equipment [Text Block] Accrued Liabilities Schedule Of Accrued Liabilities Table [Text Block] Schedule of information related to right-of-use assets and related lease liabilities. Schedule of Information Related to Right-of-Use Assets and Related Lease Liabilities Schedule Of Information Related To Right Of Use Assets And Related Lease Liabilities Table [Text Block] Estimated Future Annual Minimum Lease Payments under Non-Cancelable Building and Copier Leases Operating Leases Of Lessee Disclosure [Text Block] Summary of Stock Option Activity and Related Information Schedule Of Share Based Compensation Stock Options Activity Table [Text Block] Weighted-Average Assumptions for Stock Option Schedule Of Share Based Payment Award Stock Options Valuation Assumptions Table [Text Block] Weighted-Average Assumptions for ESPP Schedule Of Share Based Payment Award Employee Stock Purchase Plan Valuation Assumptions Table [Text Block] Summary of Stock-based Compensation Expenses Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Text Block] Summary of Activity Under the ATM Agreements Schedule Of Sale Of Stock By Subsidiary Or Equity Method Investee Disclosure [Text Block] Common Stock Reserved for Future Issuance Schedule Of Stockholders Equity Table [Text Block] Reconciliation of Loss before Income Taxes for Domestic and Foreign Locations Schedule Of Income Before Income Tax Domestic And Foreign Table [Text Block] Reconciliation of Income Tax Benefit (Expense) Schedule Of Components Of Income Tax Expense Benefit Table [Text Block] Components of Deferred Income Taxes Schedule Of Deferred Tax Assets And Liabilities Table [Text Block] Reconciliation of Federal Statutory Income Tax Rate to Effective Income Tax Rate Schedule Of Effective Income Tax Rate Reconciliation Table [Text Block] Basis of presentation and summary of significant accounting policies. Basis of presentation and summary of significant accounting policies. Basis Of Presentation And Summary Of Significant Accounting Policies [Table] Basis Of Presentation And Summary Of Significant Accounting Policies [Table] Statistical Measurement Range [Axis] Statistical Measurement Range [Member] Minimum Minimum [Member] Maximum Maximum [Member] Adjustments for New Accounting Pronouncements Adjustments For New Accounting Pronouncements [Axis] Type of Adoption Type Of Adoption [Member] ASU 2016-02 Accounting Standards Update201602 [Member] Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items] Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items] Number of operating segment Number Of Operating Segments Cash insured amount Cash F D I C Insured Amount Number of reportable unit Number Of Reporting Units Research and development costs Research And Development Expense Patents expense. Patent-related expenses Patents Expense Stock option, vesting period Share Based Compensation Arrangement By Share Based Payment Award Award Vesting Period1 Potentially dilutive outstanding securities excluded from diluted net loss per common share Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount Right-of-use assets Operating Lease Right Of Use Asset Lease liabilities for operating leases Operating Lease Liability Cumulative-effect adjustment to accumulated deficit Cumulative Effect On Retained Earnings Net Of Tax1 Revenue Recognition [Abstract] Revenue Recognition Milestone Method [Table] Revenue Recognition Milestone Method [Table] Related Party Related Party Transactions By Related Party [Axis] Related Party Related Party [Domain] Kissei Pharmaceutical Co., Ltd. Kissei Pharmaceutical Co., Ltd Kissei Pharmaceutical Co Ltd [Member] Revenue Recognition Milestone Method [Line Items] Revenue Recognition Milestone Method [Line Items] Deferred revenue related to research and development services Revenue relating to research and development services Research And Development Arrangement Contract To Perform For Others Compensation Earned 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 Fair Value Inputs Level1 [Member] Cash and Cash Equivalents Cash And Cash Equivalents [Axis] Cash and Cash Equivalents Restricted Cash And Cash Equivalents Cash And Cash Equivalents [Member] Money Market Funds Money Market Funds [Member] Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] Cash equivalents, fair value Cash And Cash Equivalents Fair Value Disclosure Property Plant And Equipment [Abstract] Leasehold improvements Leasehold Improvements Gross Furniture and equipment Furniture And Fixtures Gross Software Capitalized Computer Software Gross Property and equipment, gross, total Property Plant And Equipment Gross Less accumulated depreciation and amortization Accumulated Depreciation Depletion And Amortization Property Plant And Equipment Property and equipment, net Property, plant, and equipment disclosure. Property, Plant, and Equipment Disclosure [Table] Property Plant And Equipment Disclosure [Table] Property Plant And Equipment Disclosure [Table] Property Plant And Equipment Disclosure [Line Items] Property Plant And Equipment Disclosure [Line Items] Property and equipment, useful lives Property Plant And Equipment Useful Life Accrued research and development expense current. Payables And Accruals [Abstract] Accrued compensation Employee Related Liabilities Current Research and development costs Accrued Research And Development Expense Current Professional services fees Accrued Professional Fees Current Other Other Accrued Liabilities Current Total accrued liabilities and other current liabilities Operating lease expiration date, month and year. Lessee operating lease extended term of contract. Loss Contingencies [Table] Loss Contingencies [Table] Geographical Statement Geographical [Axis] Geographical Segment Geographical [Domain] U.S UNITED STATES Tokyo, Japan JAPAN Research and Development Arrangement, Contract to Perform for Others, Type Research And Development Arrangement Contract To Perform For Others By Type [Axis] Research and Development Arrangement, Contract to Perform for Others, Type Research And Development Arrangement Contract To Perform For Others Type [Domain] Licensing Agreements License Agreement Terms [Member] Product development. Product Development Product Development [Member] Development milestone. Development Milestone Development Milestone [Member] Commercialization milestone. Commercialization Milestone Commercialization Milestone [Member] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Operating lease term Lessee Operating Lease Term Of Contract Operating lease expiration date Lease Expiration Date1 Operating lease expiration date, month and year Operating Lease Expiration Date Month And Year Operating lease, auto-renewal term Lessee Operating Lease Renewal Term Operating lease, extension term Lessee Operating Lease Extended Term Of Contract Lessee, operating lease, existence of option to extend Lessee Operating Lease Existence Of Option To Extend Total operating lease liabilities Cash paid for operating lease liabilities Operating Lease Payments Operating lease costs Operating Lease Cost Right-of-use assets obtained in exchange for new operating lease obligations Right Of Use Asset Obtained In Exchange For Operating Lease Liability Maturities of operating lease liabilities as of December 31, 2019 were as follows: Operating Lease Liabilities Payments Due [Abstract] 2020 Lessee Operating Lease Liability Payments Due Next Twelve Months 2021 Lessee Operating Lease Liability Payments Due Year Two Lessee, Operating Lease, Liability, Payments, Due Lessee Operating Lease Liability Payments Due Less imputed interest Lessee Operating Lease Liability Undiscounted Excess Amount Current operating lease liabilities Operating Lease Liability Current Operating Lease, Liability, Current, Statement of Financial Position [Extensible List] Operating Lease Liability Current Statement Of Financial Position Extensible List Long-term operating lease liabilities Operating Lease Liability Noncurrent Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List] Operating Lease Liability Noncurrent Statement Of Financial Position Extensible List Total operating lease liabilities Weighted-average remaining lease term Operating Lease Weighted Average Remaining Lease Term1 Discount rate Lessee Operating Lease Discount Rate 2019 Operating Leases Future Minimum Payments Due Current 2020 Operating Leases Future Minimum Payments Due In Two Years 2021 Operating Leases Future Minimum Payments Due In Three Years 2022 Operating Leases Future Minimum Payments Due In Four Years 2023 Operating Leases Future Minimum Payments Due In Five Years Total minimum payments Operating Leases Future Minimum Payments Due Potential future milestone payments. Research and development expense Future potential milestone payments Potential Future Milestone Payments Schedule Of Equity Method Investments [Table] Schedule Of Equity Method Investments [Table] Investment, Name Schedule Of Equity Method Investment Equity Method Investee Name [Axis] Investment, Name Equity Method Investee Name [Domain] Zhejiang Sunmy Bio Medical Co Ltd. Zhejiang Sunmy Bio Medical Co Ltd Zhejiang Sunmy Bio Medical Co Ltd [Member] Beijing Medfron Medical Technologies Co Ltd. Beijing Medfron Medical Technologies Co Ltd Beijing Medfron Medical Technologies Co Ltd [Member] Schedule Of Equity Method Investments [Line Items] Schedule Of Equity Method Investments [Line Items] Investment in joint venture, percentage Equity Method Investment Ownership Percentage Proceed from dissolution of joint venture and liquidation of investments 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 thirteen equity incentive plan. 2013 Plan Two Thousand Thirteen Equity Incentive Plan [Member] Subsequent Event Type Subsequent Event Type [Axis] Subsequent Event Type Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Award Type Award Type [Axis] Award Type Share Based Compensation Arrangements By Share Based Payment Award Award Type And Plan Name [Domain] Performance Options Performance Shares [Member] Two thousand four plan. 2004 Plan Two Thousand Four Plan [Member] Stock Option Employee Stock Option [Member] Sale of Stock Subsidiary Sale Of Stock [Axis] Sale of Stock Sale Of Stock Name Of Transaction [Domain] 2007 Employee Stock Purchase Plan Employee Stock [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share Based Compensation Arrangement By Share Based Payment Award [Line Items] Common stock reserved for future issuance Common Stock Capital Shares Reserved For Future Issuance Shares available for future grant Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant Increase in number of shares of common stock reserved for issuance Share Based Compensation Arrangement By Share Based Payment Award Number Of Additional Shares Authorized Number of vested shares Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Number of vested shares, percentage Sharebased Compensation Arrangement By Sharebased Payment Award Award Vesting Rights Percentage Options granted expiration term Sharebased Compensation Arrangement By Sharebased Payment Award Expiration Period Number of Option Shares Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Roll Forward Stock Options, Beginning Balance Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number Stock Options, Granted Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross Stock Options, Exercised Stock Options, Cancelled Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period Stock Options, Ending Balance Stock Options, Exercisable at December 31, 2019 Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number Weighted Average Exercise Price, 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, Cancelled Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period Weighted Average Exercise Price Weighted Average Exercise Price, Ending Balance Weighted Average Exercise Price, Exercisable at December 31, 2019 Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Exercise Price Stock Options, Non-vested, Beginning Balance Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Number Of Shares Stock Options, Vested Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested Number Of Shares Stock Options, Forfeitures Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Options Forfeited Number Of Shares Stock Options, Non-vested, Ending Balance Weighted Average Grant-Date Fair Value, Non-vested, Beginning Balance Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Weighted Average Grant Date Fair Value Weighted Average Grant-Date Fair Value, Granted Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value Weighted Average Grant-Date Fair Value, Vested Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested Weighted Average Grant Date Fair Value Weighted Average Grant-Date Fair Value, Forfeitures Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Options Forfeited Weighted Average Grant Date Fair Value Weighted Average Grant-Date Fair Value, Non-vested, Ending Balance Aggregate intrinsic value Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value Weighted average contractual life, options outstanding Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 Weighted average contractual life, options exercisable Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Weighted Average Remaining Contractual Term1 Total intrinsic value of options outstanding Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value Total intrinsic value of options exercisable Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Intrinsic Value1 Stock issuance limit under employee stock purchase plan description. Employee stock purchase plan offering period. Annual increase in shares reserved for issuance. Annual increase in shares reserved for issuance as percentage of outstanding shares of common stock. Shares reserved, description Stock Issuance Limit Under Employee Stock Purchase Plan Description Increase in shares reserved for issuance Annual Increase In Shares Reserved For Issuance Increase in shares reserved for issuance as percentage of outstanding shares Annual Increase In Shares Reserved For Issuance As Percentage Of Outstanding Shares Of Common Stock Percentage of employee compensation for purchase of common stock under ESPP Share Based Compensation Arrangement By Share Based Payment Award Maximum Employee Subscription Rate Common stock fair market value, percentage Sharebased Compensation Arrangement By Sharebased Payment Award Purchase Price Of Common Stock Percent Employee stock purchase plan offering period Employee Stock Purchase Plan Offering Period Shares issued under ESPP Employee Stock Purchase Plan Weighted-average assumptions for stock options and ESPP Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions And Methodology [Abstract] Risk-free interest rate Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate Expected volatility of common stock Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate Dividend yield Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate Expected option term (in years) Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1 Weighted-average fair value, per option Income Statement Location Income Statement Location [Axis] Income Statement Location Income Statement Location [Domain] Research and development and patents expense. Research, Development and Patents Research And Development And Patents Expense [Member] General and Administrative General And Administrative Expense [Member] Total stock-based compensation expense Allocated Share Based Compensation Expense Unamortized compensation cost Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Unamortized compensation cost, vesting period Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1 Percentage of commission on gross proceeds from sale of common stock, maximum. Agreement termination date. Counterparty Name Counterparty Name [Axis] Counterparty Name Repurchase Agreement Counterparty Name [Domain] MLV. MLV M L V Co L L C [Member] 2015 at market issuance sales agreement. 2015 at-the-market issuance sales agreement Two Thousand Fifteen At Market Issuance Sales Agreement [Member] 2019 at market issuance sales agreement 2019 at-the-market issuance sales agreement Two Thousand Nineteen At Market Issuance Sales Agreement [Member] B. Riley FBR, Inc. B. Riley FBR B Riley F B R Inc [Member] Warrants Warrant [Member] Underwritten public offering Over Allotment Option [Member] Stock purchase agreement, aggregate amount of common stock agreed to be purchased Common Stock Shares Subscriptions Sales commission as a percentage of gross proceeds Percentage Of Commission On Gross Proceeds From Sale Of Common Stock Maximum Agreement termination date Agreement Termination Date Proceeds from issuance of common stock net. Schedule Of Subsidiary Or Equity Method Investee [Table] Schedule Of Subsidiary Or Equity Method Investee [Table] At market issuance sales agreement. At-the-market issuance sales agreement At Market Issuance Sales Agreement [Member] Minimum Subsidiary Or Equity Method Investee [Line Items] Subsidiary Or Equity Method Investee [Line Items] Gross proceeds Proceeds From Issuance Of Common Stock Net proceeds Proceeds From Issuance Of Common Stock Net Shares sold Price range Sale Of Stock Price Per Share Common stock issued upon exercise of warrants Proceeds from warrant exercises Proceeds From Warrant Exercises Warrants, outstanding Class Of Warrant Or Right Outstanding Financial Instrument Financial Instrument [Axis] Financial Instruments Transfers And Servicing Of Financial Instruments Types Of Financial Instruments [Domain] 2004 Plan and 2013 Plan Stock Compensation Plan [Member] Additional share issuance option term. Additional share issuance to underwriters. Issuance of common stock, net of offering costs (in shares) Shares purchase & equity issuance, price per share amount Shares Issued Price Per Share Gross proceeds from issuance of common stock Proceeds From Issuance Initial Public Offering Net proceeds from issuance of common stock Additional share issuance option term Additional Share Issuance Option Term Additional shares which underwriters can purchase on option Additional Share Issuance To Underwriters United States Income Loss From Continuing Operations Before Income Taxes Domestic Foreign Income Loss From Continuing Operations Before Income Taxes Foreign Federal Current Federal Tax Expense Benefit State Current State And Local Tax Expense Benefit Foreign Current Foreign Tax Expense Benefit Total current income tax benefit (expense) Current Income Tax Expense Benefit Federal Deferred Federal Income Tax Expense Benefit State Deferred State And Local Income Tax Expense Benefit Foreign Deferred Foreign Income Tax Expense Benefit Total deferred income tax benefit (expense) Deferred Income Tax Expense Benefit Total income tax benefit (expense) Deferred tax assets right-of-use asset. Deferred tax liabilities right-of-use liability. Deferred tax assets liabilities before valuation allowance. Deferred tax assets: Deferred Tax Assets Net [Abstract] Net operating loss carryforwards Deferred Tax Assets Operating Loss Carryforwards Capitalized licenses Deferred Tax Assets Tax Deferred Expense Research tax credits Deferred Tax Assets Tax Credit Carryforwards Research Stock options Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost Other, net Deferred Tax Assets Other Right-of-use asset Deferred Tax Assets Right Of Use Asset Total deferred tax assets Deferred Tax Assets Gross Deferred tax liabilities Deferred Tax Liabilities [Abstract] Right-of-use liability Deferred Tax Liabilities Right Of Use Liability In process R&D Deferred Tax Liabilities Deferred Expense Capitalized Research And Development Costs Total deferred tax liabilities Deferred Income Tax Liabilities Net deferred tax assets Deferred Tax Assets Liabilities Before Valuation Allowance Valuation allowance Deferred Tax Assets Valuation Allowance Net deferred tax liability Deferred Tax Liabilities Operating loss carryforwards, expiration year. Research and development credits, expiration year. Income Tax [Line Items] Income Tax [Table] Income Tax [Table] Income Tax [Table] Income Tax Authority Income Tax Authority [Axis] Income Tax Authority Income Tax Authority [Domain] Federal Domestic Country [Member] California State And Local Jurisdiction [Member] Income Tax [Line Items] Income Tax [Line Items] Net operating loss carryforwards Operating Loss Carryforwards Net operating loss carryforwards, expiration year Operating Loss Carryforwards Expiration Year Research tax credit carry forwards Tax Credit Carryforward Amount Research and development credits, expiration period Research And Development Credits Expiration Year Effective Income Tax Rate Reconciliation, Permanent Differences Federal statutory income tax rate Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate State income taxes, net of federal benefit Effective Income Tax Rate Reconciliation State And Local Income Taxes Tax credits Effective Income Tax Rate Reconciliation Tax Credits Change in valuation allowance Effective Income Tax Rate Reconciliation Change In Deferred Tax Assets Valuation Allowance Permanent differences Effective Income Tax Rate Reconciliation Permanent Differences Stock compensation Effective Income Tax Rate Reconciliation Nondeductible Expense Share Based Compensation Cost Other Effective Income Tax Rate Reconciliation Other Adjustments Provision for income taxes Effective Income Tax Rate Continuing Operations Postemployment Benefits [Abstract] Discretionary contributions to employee savings plan Defined Contribution Plan Employer Discretionary Contribution Amount