Investments [Abstract]
Investments
Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block]
Stockholders' Equity Note [Abstract]
Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table]
Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table]
Equity Components [Axis]
Equity Components [Axis]
Equity Component [Domain]
Equity Component [Domain]
Warrant
Warrant [Member]
Award Type [Axis]
Award Type [Axis]
Equity Award [Domain]
Equity Award [Domain]
Employee stock option
Employee Stock Option [Member]
Restricted stock units (RSUs)
Restricted Stock Units (RSUs) [Member]
Plan Name [Axis]
Plan Name [Axis]
Plan Name [Domain]
Plan Name [Domain]
The 2013 Plan
The 2013 Plan [Member]
The 2013 Plan [Member]
The 2013 Employee Stock Purchase Plan
The 2013 Employee Stock Purchase Plan [Member]
The 2013 Employee Stock Purchase Plan Member.
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for future issuance (in shares)
Common Stock, Capital Shares Reserved for Future Issuance
Maturing in one year or less
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, within One Year, Fair Value
Total debt investments
Debt Securities, Available-for-sale
Common stock of U.S. corporation
Equity Securities, FV-NI
Total investments
Available-For-Sale Securities, Debt Securities And Equity Securities, FV-NI
Available-For-Sale Securities, Debt Securities And Equity Securities, FV-NI
Schedule of Investments [Table]
Schedule of Investments [Table]
Investment Type [Axis]
Investment Type [Axis]
Investments [Domain]
Investments [Domain]
Corporate bonds
Corporate Bond Securities [Member]
Commercial paper
Commercial Paper [Member]
U.S. Treasury securities
US Treasury Securities [Member]
Schedule of Investments [Line Items]
Schedule of Investments [Line Items]
Amortized Cost
Available-for-sale Securities, Amortized Cost Basis
Amortized Cost
Debt Securities, Available-for-sale, Amortized Cost
Gross Unrealized Gains
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax
Gross Unrealized Gains
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax
Gross Unrealized Losses
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax
Gross Unrealized Losses
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax
Estimated Fair Value
Available-for-sale Securities
Estimated Fair Value
Accounting Policies [Abstract]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]
Schedule of Prepaid and Other Current Assets
Schedule Of Prepaid Expenses And Other Current Assets [Table Text Block]
Schedule of prepaid expenses and other current assets [Table TextBlock].
Schedule of Accrued Liabilities
Schedule of Accrued Liabilities [Table Text Block]
Selected Quarterly Financial Information [Abstract]
Selected Quarterly Financial Data (Unaudited)
Quarterly Financial Information [Text Block]
Commitments and Contingencies Disclosure [Abstract]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019
Operating Leases, Future Minimum Payments Due Current, Future Minimum Sublease Rentals
Operating Leases, Future Minimum Payments Due Current, Future Minimum Sublease Rentals
2020
Operating Leases, Future Minimum Payments Due In Two Years, Future Minimum Sublease Rentals
Operating Leases, Future Minimum Payments Due In Two Years, Future Minimum Sublease Rentals
2021
Operating Leases, Future Minimum Payments Due In Three Years, Future Minimum Sublease Rentals
Operating Leases, Future Minimum Payments Due In Three Years, Future Minimum Sublease Rentals
Total future minimum sublease rentals
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals
Expected volatility
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate
Expected term (in years)
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term
Weighted-average risk-free interest rate
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate
Expected dividend yield
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate
Weighted-average fair value per option (in usd per share)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value
Schedule of Shares Reserved for Future Issuance
Schedule of shares reserved for future issuance [Table Text Block]
Schedule of shares reserved for future issuance [Table Text Block]
Schedule of Fair Value Assumptions, Stock Options
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]
Summary of Activity Related to Stock Options
Share-based Compensation, Stock Options, Activity [Table Text Block]
Schedule of Other Information Regarding Stock Options
Schedule of Other Information Regarding Stock Options [Table Text Block]
[Table Text Block] for Schedule of Other Information Regarding Stock Options [Table]
Schedule of Share-based Compensation, Shares Authorized
Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block]
Schedule of Fair Value Assumptions, Employee Stock Purchase Plan
Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions [Table Text Block]
Summary of Activity Related to Restricted Stock Units
Schedule of Unvested Restricted Stock Units Roll Forward [Table Text Block]
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]
Total intrinsic value of options exercised
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value
Total fair value of shares vested
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value
Income Tax Disclosure [Abstract]
Operating Loss Carryforwards [Table]
Operating Loss Carryforwards [Table]
Income Tax Authority [Axis]
Income Tax Authority [Axis]
Income Tax Authority [Domain]
Income Tax Authority [Domain]
Federal
UNITED STATES
State
State and Local Jurisdiction [Member]
Foreign
Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards
Operating Loss Carryforwards
Operating loss carryforwards, subject to expiration
Operating Loss Carryforward, Subject to Expiration
Operating Loss Carryforward, Subject to Expiration
Operating loss carryforwards, not subject to expiration
Operating Loss Carryforward, Not Subject to Expiration
Operating Loss Carryforward, Not Subject to Expiration
Tax credit carryforward
Tax Credit Carryforward, Amount
Undistributed earnings of foreign subsidiary
Undistributed Earnings of Foreign Subsidiaries
Loss limitation ownership change benchmark amount
Loss Limitation Ownership Change Benchmark
Loss limitation ownership change benchmark amount in regards to any losses incurred prior to such date.
Annual limitation of operating loss carryforwards
Operating Loss Carryforward, Annual Limitations
Operating Loss Carryforward, Annual Limitations
Penalties and interest accrued
Income Tax Examination, Penalties and Interest Accrued
Effect of change in federal tax rate
Effective Income Tax Rate Reconciliation, Tax Cuts And Jobs Act Of 2017, Change In Enacted Tax Rate Amount
Effective Income Tax Rate Reconciliation, Tax Cuts And Jobs Act Of 2017, Change In Enacted Tax Rate Amount
2019
Operating Leases, Future Minimum Payments Due, Next Twelve Months
2020
Operating Leases, Future Minimum Payments, Due in Two Years
2021
Operating Leases, Future Minimum Payments, Due in Three Years
Total future minimum rental payments
Operating Leases, Future Minimum Payments Due
Range [Axis]
Range [Axis]
Range [Domain]
Range [Domain]
Minimum
Minimum [Member]
Maximum
Maximum [Member]
Exercise Price Range [Axis]
Exercise Price Range [Axis]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Domain]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Domain]
1.57 to 7.57
Exercise Price Range, $1.53 to 7.57 [Member]
Exercise Price Range, $1.53 to 7.57
7.58 to 8.06
Exercise Price Range, $7.58 to 8.06 [Member]
Exercise Price Range, $7.58 to 8.06
8.07 to 18.75
Exercise Price Range, $8.07 to 18.75 [Member]
Exercise Price Range, $8.07 to 18.75 [Member]
18.76 to 39.17
Exercise Price Range, $18.76 to 39.17 [Member]
Exercise Price Range, $18.76 to 39.17
39.18 to 53.74
Exercise Price Range, $39.18 to 53.74 [Member]
Exercise Price Range, $39.18 to 53.74
1.57 to 53.74
Exercise Price Range, $1.53 to 53.74 [Member]
Exercise Price Range, $1.53 to 53.74
Share-based compensation, lower range limit (in usd per share)
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit
Share-based compensation, upper range limit (in usd per share)
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit
Share-based compensation, number of outstanding options (in shares)
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options
Share-based compensation, outstanding options, weighted average remaining contractual term
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term
Share-based compensation, outstanding options, weighted average exercise price (in usd per share)
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price
Share-based compensation, number of exercisable options (in shares)
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Exercisable Options
Share-based compensation, exercisable options, weighted average exercise price (in usd per share)
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price
Statement of Stockholders' Equity [Abstract]
Statement [Table]
Statement [Table]
Common Stock
Common Stock [Member]
Additional Paid-in Capital
Additional Paid-in Capital [Member]
Accumulated Other Comprehensive Gain (Loss)
AOCI Attributable to Parent [Member]
Accumulated Deficit
Retained Earnings [Member]
Statement [Line Items]
Statement [Line Items]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance
Stockholders' Equity Attributable to Parent
Share-based compensation
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition
Exercise of stock options
Stock Issued During Period, Value, Stock Options Exercised
Employee stock purchase plan purchases
Stock Issued During Period, Value, Employee Stock Purchase Plan
Issuance of common stock, net of issuance costs
Stock Issued During Period, Value, New Issues
Comprehensive loss:
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Unrealized gain (loss) on investments, net
Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, after Tax
Net loss
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest
Comprehensive loss
Comprehensive Income (Loss), Net of Tax, Attributable to Parent
Ending Balance
Reconciliation of the Difference between the Benefit for Income Taxes and Income Taxes at the Statutory U.S. Federal Income Tax Rate
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]
Components of Deferred Tax Assets and Liabilities
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]
Summary of Uncertain Tax Benefit
Summary of Income Tax Contingencies [Table Text Block]
Contractors [Abstract]
Long-term Purchase Commitment [Table]
Long-term Purchase Commitment [Table]
Investment, Name [Axis]
Investment, Name [Axis]
Investment, Name [Domain]
Investment, Name [Domain]
ContraVir Investment
ContraVir Investment [Member]
ContraVir Investment [Member]
Scenario [Axis]
Scenario [Axis]
Scenario, Unspecified [Domain]
Scenario, Unspecified [Domain]
Scenario, Forecast
Scenario, Forecast [Member]
Product and Service [Axis]
Product and Service [Axis]
Product and Service [Domain]
Product and Service [Domain]
Brincidofovir
Brincidofovir [Member]
Brincidofovir [Member].
Expense Reimbursement
Expense Reimbursement [Member]
Expense Reimbursement [Member]
Fees
Fees [Member]
Fees
License and Service
License and Service [Member]
Type of Arrangement and Non-arrangement Transactions [Axis]
Type of Arrangement and Non-arrangement Transactions [Axis]
Arrangements and Non-arrangement Transactions [Domain]
Arrangements and Non-arrangement Transactions [Domain]
Regents of University of California
Regents Of University Of California [Member]
Regents Of University Of California [Member].
BARDA
BARDA [Member]
BARDA [Member]
Second Option Segment
BARDA Second Option Segment [Member]
BARDA Second Option Segment [Member]
Third Option Segment
BARDA Third Option Segment [Member]
BARDA Third Option Segment [Member]
ContraVir Pharmaceuticals
ContraVir Pharmaceuticals [Member]
ContraVir Pharmaceuticals [Member]
The Regents of the University of Michigan
The Regents of the University of Michigan [Member]
The Regents of the University of Michigan
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment [Line Items]
Stock issued during period, issued for services (in shares)
Stock Issued During Period, Shares, Issued for Services
Milestone payments
Milestone Payments Aggregate
Payments for certain milestones achieved.
Sublicense fee percentage
Sublicense Fee Percentage
Sublicense fee percentage.
Sublicense fee amount payable fee percentage
Sublicense Fee Amount Payable Fee Percentage
Sublicense fee amount, payable fee percentage.
Royalties percentage
Royalties Percentage
Royalties percentage.
Number of extension periods
Number Of Extension Periods
The number of extension periods.
Contract revenue
Revenue from Contract with Customer, Including Assessed Tax
Number of extension periods
Number Of Extension Periods Through Which Revenue Has Been Recognized
Number Of Extension Periods Through Which Revenue Has Been Recognized
Short-term investments
Short-term Investments
Future licenses revenue
Future Licenses Revenue
Future Licenses Revenue
License agreement, termination notice period
License Agreement, Termination Notice
License Agreement, Termination Notice
Cost of sales
Cost of Goods and Services Sold
Statement of Financial Position [Abstract]
Preferred stock, par value (in USD per share)
Preferred Stock, Par or Stated Value Per Share
Preferred stock, shares authorized (in shares)
Preferred Stock, Shares Authorized
Preferred stock, shares issued (in shares)
Preferred Stock, Shares Issued
Preferred stock, shares outstanding (in shares)
Preferred Stock, Shares Outstanding
Common stock, par value (in USD per share)
Common Stock, Par or Stated Value Per Share
Common stock, shares authorized (in shares)
Common Stock, Shares Authorized
Common stock, shares issued (in shares)
Common Stock, Shares, Issued
Common stock, shares outstanding (in shares)
Common Stock, Shares, Outstanding
Income Statement Location [Axis]
Income Statement Location [Axis]
Income Statement Location [Domain]
Income Statement Location [Domain]
Research and development expense
Research and Development Expense [Member]
General and administrative expense
General and Administrative Expense [Member]
Allocated share-based compensation expense
Allocated Share-based Compensation Expense
ASSETS
Assets [Abstract]
Current assets:
Assets, Current [Abstract]
Cash and cash equivalents
Cash and Cash Equivalents, at Carrying Value
Short-term investments, available-for-sale
Debt Securities, Available-for-sale, Current
Short-term investments, available-for-sale
Available-for-sale Securities, Current
Accounts receivable
Accounts Receivable, Net, Current
Prepaid expenses and other current assets
Prepaid Expense and Other Assets, Current
Total current assets
Assets, Current
Long-term investments
Debt Securities, Noncurrent
Property and equipment, net of accumulated depreciation
Property, Plant and Equipment, Net
Other long-term assets
Other Assets, Noncurrent
Total assets
Assets
LIABILITIES AND STOCKHOLDERS' EQUITY
Liabilities and Equity [Abstract]
Current liabilities:
Liabilities, Current [Abstract]
Accounts payable
Accounts Payable, Current
Accrued liabilities
Accrued Liabilities, Current
Total current liabilities
Liabilities, Current
Lease-related obligations
Other Liabilities, Noncurrent
Total liabilities
Liabilities
Stockholders’ equity:
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Preferred stock, $0.001 par value, 10,000,000 shares authorized at December 31, 2018 and 2017; no shares issued and outstanding as of December 31, 2018 and 2017
Preferred Stock, Value, Outstanding
Common stock, $0.001 par value; 200,000,000 shares authorized at December 31, 2018 and 2017; 50,735,279 and 47,505,532 shares issued and outstanding at December 31, 2018 and 2017, respectively
Common Stock, Value, Outstanding
Additional paid-in capital
Additional Paid in Capital
Accumulated other comprehensive loss, net
Accumulated Other Comprehensive Income (Loss), Net of Tax
Accumulated deficit
Retained Earnings (Accumulated Deficit)
Total stockholders’ equity
Total liabilities and stockholders’ equity
Liabilities and Equity
Schedule of Future Minimum Rental Payments for Operating Leases
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]
Equity Award [Domain]
Number of Restricted Stock Units Outstanding
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Beginning Balance (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number
Granted (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period
Shares issuance (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period
Forfeited (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Forfeitures
Ending Balance (in shares)
Weighted-Average Grant-Date Fair Value
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Beginning Balance (in usd per share)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value
Granted (in usd per share)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value
Shares issuance (in usd per share)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Weighted Average Grant Date Fair Value
Forfeited (in usd per share)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value
Ending Balance (in usd per share)
Deferred tax assets:
Deferred Tax Assets, Gross [Abstract]
Domestic net operating loss carryforwards
Deferred Tax Assets, Operating Loss Carryforwards, Domestic
Foreign net operating loss carryforwards
Deferred Tax Assets, Operating Loss Carryforwards, Foreign
Research and development expenses
Deferred Tax Assets Tax Deferred Expense, Research and Development
Deferred Tax Assets Tax Deferred Expense, Research and Development.
Capitalized Section 174 expenses
Deferred Tax Assets, Tax Deferred Expense, Other
Research and development credits
Deferred Tax Assets, Tax Credit Carryforwards, Research
Accrued bonuses
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Employee Bonuses
Share-based compensation
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost
Other
Deferred Tax Assets, Other
Total gross deferred tax assets
Deferred Tax Assets, Gross
Valuation allowance
Deferred Tax Assets, Valuation Allowance
Total deferred tax assets
Deferred Tax Assets, Net of Valuation Allowance
Deferred tax liabilities:
Deferred Tax Liabilities, Gross [Abstract]
Other
Deferred Tax Liabilities, Other
Total deferred tax liabilities
Deferred Tax Liabilities, Gross
Total deferred tax assets and liabilities, net
Deferred Tax Assets, Net
Property, Plant and Equipment [Abstract]
Schedule of Property, Plant and Equipment [Table]
Property, Plant and Equipment [Table]
Property, Plant and Equipment, Type [Axis]
Property, Plant and Equipment, Type [Axis]
Property, Plant and Equipment, Type [Domain]
Property, Plant and Equipment, Type [Domain]
Lab equipment
Other Machinery and Equipment [Member]
Leasehold improvements
Leasehold Improvements [Member]
Computer equipment
Computer Equipment [Member]
Office furniture and equipment
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment [Line Items]
Property and equipment
Property, Plant and Equipment, Gross
Less accumulated depreciation
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment
Property and equipment, net of accumulated depreciation
Schedule of Quarterly Financial Information
Quarterly Financial Information [Table Text Block]
Amount
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income tax benefit at statutory rate
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount
State income taxes
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount
Research and development credits
Effective Income Tax Rate Reconciliation, Tax Credit, Research, Amount
Foreign rate differential
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount
Permanent items
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Amount
Provision to return adjustments
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount
Effect of change in state tax rate
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount
Removal of excess tax benefit
Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit, Amount
Increase in unrecognized tax benefits
Effective Income Tax Reconciliation Increase Due to Unrecognized Tax Benefits
Effective income tax reconciliation increase due to unrecognized tax benefits.
Change in valuation allowance
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount
Net benefit
Income Tax Expense (Benefit)
% of Pretax Earnings
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Income tax benefit at statutory rate
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent
State income taxes
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent
Research and development credits
Effective Income Tax Rate Reconciliation, Tax Credit, Research, Percent
Foreign rate differential
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Percent
Permanent items
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Percent
Provision to return adjustments
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent
Effect of change in federal tax rate
Effective Income Tax Rate Reconciliation, Tax Cuts And Jobs Act Of 2017, Change In Enacted Tax Rate, Percent
Effective Income Tax Rate Reconciliation, Tax Cuts And Jobs Act Of 2017, Change In Enacted Tax Rate, Percent
Effect of change in state tax rate
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent
Removal of excess tax benefit
Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit, Percent
Increase in unrecognized tax benefits
Effective Income Tax Reconciliation Increase Due to Unrecognized Tax Benefits Tax Rate
Effective income tax reconciliation increase due to unrecognized tax benefits, tax rate.
Change in valuation allowance
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent
Net benefit
Effective Income Tax Rate Reconciliation, Percent
Class of Stock [Axis]
Class of Stock [Axis]
Class of Stock [Domain]
Class of Stock [Domain]
Series F
Series F Preferred Stock [Member]
Sale of Stock [Axis]
Sale of Stock [Axis]
Sale of Stock [Domain]
Sale of Stock [Domain]
IPO
IPO [Member]
Private Placement
Private Placement [Member]
Performance Shares
Performance Shares [Member]
Share-based compensation, equity increase percentage
Share-Based Compensation, Evergreen Option Provision, Equity Increase
Share-Based Compensation, Evergreen Option Provision, Equity Increase
Share-based compensation, nonvested awards, compensation not yet recognized, stock options
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options
Unrecognized compensation costs, period of recognition
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition
Number of shares authorized to be granted (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized
Number of shares authorized, increase amount (in shares)
Increase (Decrease) in Number of Shares Authorized
Increase (decrease) in number of shares authorized.
Number of additional shares authorized (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized
Number of shares available for grant (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant
Percentage of pay that employee can contribute, maximum
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Employee Subscription Rate
Discount from market price, entry date
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Offering Date
Discount from market price, purchase date
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Purchase Date
Employee stock purchase plan, automatic reset participation period
Employee Stock Purchase Plan, Automatic Reset Purchase Period
Employee Stock Purchase Plan, Automatic Reset Purchase Period
Shares issued during period, employee stock purchase plans (in shares)
Stock Issued During Period, Shares, Employee Stock Purchase Plans
ESPP purchase period
Employee Stock Purchase Plan, Purchase Period
Employee Stock Purchase Plan, Purchase Period
Liability
Shares issued pursuant to vesting of RSUs (in shares)
Stock Issued During Period, Shares, Restricted Stock Award, Gross
Share-based compensation, nonvested awards, compensation cost not recognized
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized
Number of shares called by warrants (in share)
Class of Warrant or Right, Number of Securities Called by Warrants or Rights
Exercise price of warrants (in usd per share)
Class of Warrant or Right, Exercise Price of Warrants or Rights
Warrants outstanding and exercisable (in shares)
Class of Warrant or Right, Outstanding
Proceeds from exercise of all share-based payment arrangements
Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options
Tax benefit from share-based payment arrangements
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense
Sale of common stock, amount authorized
Sale of Stock, Authorized Amount
Sale of Stock, Authorized Amount
Common stock sold (in shares)
Sale of Stock, Number of Shares Issued in Transaction
Sale of common stock, weighted average price of shares sold (in usd per share)
Sale of Stock, Consideration Received Per Transaction
Sale of common stock, net offering proceeds
Sale of Stock, Consideration Received on Transaction
Statement of Cash Flows [Abstract]
Cash flows from operating activities:
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net 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 of property and equipment
Depreciation
Amortization of discount/premium on investments
Accretion (Amortization) of Discounts and Premiums, Investments
Share-based compensation
Share-based Compensation
Loss on sale of investments
Realized Investment Gains (Losses)
Unrealized loss on equity investment
Equity Securities, FV-NI, Unrealized Loss
Unrealized loss on equity investment
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities
Amortization of lease-related obligations
Increase (Decrease) in Deferred Liabilities
Changes in operating assets and liabilities:
Increase (Decrease) in Operating Capital [Abstract]
Accounts receivable
Increase (Decrease) in Accounts Receivable
Prepaid expenses and other assets
Increase (Decrease) in Prepaid Expense and Other Assets
Accounts payable and accrued liabilities
Increase (Decrease) in Accounts Payable and Accrued Liabilities
Net cash used in operating activities
Net Cash Provided by (Used in) Operating Activities
Cash flows from investing activities:
Net Cash Provided by (Used in) Investing Activities [Abstract]
Purchases of property and equipment
Payments to Acquire Property, Plant, and Equipment
Purchases of short-term investments
Payments to Acquire Short-term Investments
Purchases of long-term investments
Payments to Acquire Long-term Investments
Proceeds from sales of short-term investments
Proceeds from Sale of Short-term Investments
Proceeds from maturities of short-term investments
Proceeds from Maturities, Prepayments and Calls of Short-term Investments
Net cash provided by investing activities
Net Cash Provided by (Used in) Investing Activities
Cash flows from financing activities:
Net Cash Provided by (Used in) Financing Activities [Abstract]
Proceeds from exercise of stock options
Proceeds from Stock Options Exercised
Proceeds from employee stock purchase plan
Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Excluding Stock Options
Proceeds from issuance of common stock, net of commissions
Proceeds from Issuance of Common Stock
Payments of deferred offering costs
Payments of Stock Issuance Costs
Net cash provided by financing activities
Net Cash Provided by (Used in) Financing Activities
Net increase (decrease) in cash and cash equivalents
Cash and Cash Equivalents, Period Increase (Decrease)
Beginning of period
End of period
Supplemental disclosure of cash flow information
Supplemental Cash Flow Information [Abstract]
Non-cash addition to deferred offering costs
Noncash Or Part Noncash Addition To Stock Issuance Costs
Noncash Or Part Noncash Addition To Stock Issuance Costs
Schedule of Stock by Class [Table]
Schedule of Stock by Class [Table]
Subsequent Event Type [Axis]
Subsequent Event Type [Axis]
Subsequent Event Type [Domain]
Subsequent Event Type [Domain]
Subsequent Event
Subsequent Event [Member]
Adjustments for New Accounting Pronouncements [Axis]
Adjustments for New Accounting Pronouncements [Axis]
Type of Adoption [Domain]
Type of Adoption [Domain]
Accounting Standards Update 2016-02
Accounting Standards Update 2016-02 [Member]
Common stock of U.S. corporation
Fair Value Hierarchy and NAV [Axis]
Fair Value Hierarchy and NAV [Axis]
Fair Value, Measurements, Fair Value Hierarchy [Domain]
Fair Value Hierarchy and NAV [Domain]
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Inputs, Level 1 [Member]
Class of Stock [Line Items]
Class of Stock [Line Items]
Investments
Realized losses on available for sale debt securities
Debt Securities, Realized Gain (Loss)
Unrealized loss on equity investment
Unrealized loss on equity investment
Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, after Tax
Property and Equipment
Property and Equipment
Property And Equipment [Abstract].
Property and equipment, useful life
Property, Plant and Equipment, Useful Life
Impairment of long-lived assets
Impairment of Long-Lived Assets Held-for-use
Revenue Recognition
Disaggregation of Revenue [Abstract]
Number of base segments
Revenue, Performance Obligation, Total Number Of Base Segments
Revenue, Performance Obligation, Total Number Of Base Segments
Number of option segments
Revenue, Performance Obligation, Total Number Of Option Segments
Revenue, Performance Obligation, Total Number Of Option Segments
Number of contracts
Revenue, Performance Obligation, Total Number Of Contracts
Revenue, Performance Obligation, Total Number Of Contracts
Defined Contribution Plan [Abstract]
Defined Contribution Plan [Abstract]
Defined contribution plan, cost recognized
Defined Contribution Plan, Cost
Segments
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Number of operating segments
Number of Operating Segments
Leases
Assets and Liabilities, Lessee [Abstract]
Lease asset
Operating Lease, Right-of-Use Asset
Lease liability
Operating Lease, Liability
Income Taxes
Income Tax Disclosure [Text Block]
Accrued compensation
Accrued Salaries
Accrued research and development expenses
Accrued Development Liabilities
Accrued development liabilities.
Accrued indemnification claim
Accrued Indemnification Claim
Accrued Indemnification Claim
Other accrued liabilities
Other Accrued Liabilities, Current
Total accrued liabilities
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Table]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Table]
Measurement Frequency [Axis]
Measurement Frequency [Axis]
Fair Value, Measurement Frequency [Domain]
Fair Value, Measurement Frequency [Domain]
Fair value, measurements, recurring
Fair Value, Measurements, Recurring [Member]
Money market funds
Money Market Funds [Member]
Significant Other Observable Inputs (Level 2)
Fair Value, Inputs, Level 2 [Member]
Significant Unobservable Inputs (Level 3)
Fair Value, Inputs, Level 3 [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Cash equivalents
Cash and Cash Equivalents, Fair Value Disclosure
Short-term Investments
Long-term investments
Long-term Investments
Total assets
Assets, Fair Value Disclosure
Subsequent Events [Abstract]
Subsequent Events
Subsequent Events [Text Block]
Summary of Property and Equipment, net
Property, Plant and Equipment [Table Text Block]
The Business and Summary of Significant Accounting Policies
Basis of Presentation and Significant Accounting Policies [Text Block]
Expected volatility
Expected term (in years)
Weighted-average risk-free interest rate
Expected dividend yield
Basis of Presentation
Basis of Accounting, Policy [Policy Text Block]
Reclassifications
Reclassification, Policy [Policy Text Block]
Cash and Cash Equivalents
Cash and Cash Equivalents, Policy [Policy Text Block]
Investments and Unrealized Loss on Equity Investment
Investment, Policy [Policy Text Block]
Concentration of Credit Risk
Concentration Risk, Credit Risk, Policy [Policy Text Block]
Accounts Receivable
Receivables, Policy [Policy Text Block]
Fair Value of Financial Instruments
Fair Value of Financial Instruments, Policy [Policy Text Block]
Property and Equipment
Property, Plant and Equipment, Policy [Policy Text Block]
Impairment of Property and Equipment
Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]
Deferred Lease Obligation
Lessee, Leases [Policy Text Block]
Revenue Recognition
Revenue from Contract with Customer [Policy Text Block]
Research and Development Prepaids and Accruals
Clinical Trial Accruals [Policy Text Block]
The entire policy related to clinical trial accruals.
Research and Development Expenses
Research and Development Expense, Policy [Policy Text Block]
Interest Income and Other, Net
Interest and Other Income, Policy [Policy Text Block]
Interest and Other Income, Policy [Policy Text Block]
Income Taxes
Income Tax, Policy [Policy Text Block]
Share-Based Compensation
Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block]
401(k) Plan
Pension and Other Postretirement Plans, Nonpension Benefits, Policy [Policy Text Block]
Basic and Dilutive Net Loss Per Share of Common Stock
Earnings Per Share, Policy [Policy Text Block]
Segments
Segment Reporting, Policy [Policy Text Block]
Impact of Recently Issued Accounting Standards and Impact of Recently Adopted Accounting Standards
New Accounting Pronouncements, Policy [Policy Text Block]
Revenue
Revenues
Operating loss
Operating Income (Loss)
Net loss per share, basic and diluted (in USD per share)
Earnings Per Share, Basic and Diluted
Weighted-average shares outstanding, basic and diluted (in shares)
Weighted Average Number of Shares Outstanding, Basic and Diluted
Significant Agreements
Long-term Contracts or Programs Disclosure [Text Block]
Commitments and Contingencies
Commitments and Contingencies Disclosure [Text Block]
Fair Value, Less than 12 Months
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value
Fair Value, Less than 12 Months
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months
Unrealized Loss, Less than 12 Months
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss
Unrealized Loss, Less than 12 Months
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss
Fair Value, Greater than 12 Months
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value
Fair Value, Greater than 12 Months
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer
Unrealized Loss, Greater than 12 Months
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss
Unrealized Loss, Greater than 12 Months
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss
Fair Value, Total
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Fair Value, Total
Debt Securities, Available-for-sale, Unrealized Loss Position
Unrealized Loss, Total
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss
Unrealized Loss, Total
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss
Number of securities with unrealized losses, Less than 12 Months
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year
Number of securities with unrealized losses, Less than 12 Months
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions
Number of securities with unrealized losses, Greater than 12 Months
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year
Number of securities with unrealized losses, Greater than 12 Months
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions
Number of securities with unrealized losses, Total
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions
Number of securities with unrealized losses, Total
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions
Document And Entity Information [Abstract]
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
Entity Registrant Name
Entity Registrant Name
Entity Central Index Key
Entity Central Index Key
Entity Voluntary Filers
Entity Voluntary Filers
Entity Well-known Seasoned Issuer
Entity Well-known Seasoned Issuer
Entity Current Reporting Status
Entity Current Reporting Status
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
Entity Emerging Growth Company
Entity Shell Company
Entity Shell Company
Entity Public Float
Entity Public Float
Entity Common Stock, Shares Outstanding
Entity Common Stock, Shares Outstanding
Operating leases, rent expense
Operating Leases, Rent Expense, Net
Area of sublease property (in sqft)
Operating Leases, Area of Sublease Property
Operating Leases, Area of Sublease Property
Other Commitments [Table]
Other Commitments [Table]
Refundable Agreements
Refundable Agreements [Member]
Refundable Agreements [Member]
Other Commitments [Line Items]
Other Commitments [Line Items]
Provision for refundable amounts
Contract with Customer, Liability
Stockholders' Equity (Deficit)
Stockholders' Equity Note Disclosure [Text Block]
Prepaid research and development expenses
Prepaid Development Expenses
Prepaid development expenses.
Interest receivable
Interest Receivable
Prepaid insurance
Prepaid Insurance
Other prepaid expenses and current assets
Other Assets, Current
Total prepaid expenses and other current assets
Summary of Short-term and Long-term Investments
Debt Securities, Available-for-sale [Table Text Block]
Summary of Short-term and Long-term Investments
Available-for-sale Securities [Table Text Block]
Summary of Investments with Unrealized Losses, Aggregated by Investment Type and the Length of Time
Schedule of Unrealized Loss on Investments [Table Text Block]
Summary of the Scheduled Maturity of Company Investments
Investments Classified by Contractual Maturity Date [Table Text Block]
Income Statement [Abstract]
Revenues:
Revenues [Abstract]
Operating expenses:
Operating Expenses [Abstract]
Research and development
Research and Development Expense
General and administrative
General and Administrative Expense
Total operating expenses
Operating Expenses
Loss from operations
Other (expense) income:
Other Nonrecurring (Income) Expense [Abstract]
Interest income and other, net
Interest Income (Expense), Net
Net loss
Other comprehensive loss:
Other Comprehensive Income (Loss), Tax [Abstract]
Per share information:
Earnings Per Share [Abstract]
Net loss, basic and diluted (in USD per share)
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance
Unrecognized Tax Benefits
Increase related to current year tax positions
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions
Increase related to prior periods
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions
Ending balance
Property and Equipment
Property, Plant and Equipment Disclosure [Text Block]
Number of Options Outstanding
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning balance (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number
Granted (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures
Exercised (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period
Forfeited (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period
Ending balance (in shares)
Exercisable (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number
Vested and expected to vest (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number
Weighted-Average Exercise Price
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Beginning balance (in usd per share)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price
Granted (in usd per share)
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price
Exercised (in usd per share)
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price
Forfeited (in usd per share)
Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price
Ending balance (in usd per share)
Exercisable (in usd per share)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Exercise Price
Vested or expected to vest (in usd per share)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price
Additional Disclosure
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted-average remaining contractual life (in years)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term
Weighted-average remaining contractual life (in years), Exercisable
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term
Weighted-average remaining contractual life (in years), Vested or expected to vest
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term
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
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value
Total intrinsic value of options vested or expected to vest
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value