Entity Central Index Key Development and other revenue. Total amount of revenue recognized for license and development services under the collaboration agreement as of a given date. 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 Common Stock, Shares Outstanding Entity Common Stock Shares Outstanding Restricted time deposits noncurrent. Represents the long-term portion of the outstanding principal and accrued interest of advances in the form note agreements received by the entity to fund various product development efforts. Statement Of Financial Position [Abstract] Assets Assets [Abstract] Current assets: Assets Current [Abstract] Cash and cash equivalents Cash And Cash Equivalents At Carrying Value Short-term investments Available For Sale Securities Debt Securities Current Accounts receivable ($4,452 and $4,004 from a related party) Accounts Receivable Net Current Prepaid expenses and other current assets Prepaid Expense And Other Assets Current Total current assets Assets Current Restricted time deposits Restricted Time Deposits Noncurrent Long-term investments Available For Sale Securities Noncurrent Property and equipment, net Property Plant And Equipment Net Other assets Other Assets Noncurrent Total assets Assets Liabilities, stockholders’ equity and non-controlling interests Liabilities And Stockholders Equity [Abstract] Current liabilities: Liabilities Current [Abstract] Accounts payable Accounts Payable Current Accrued liabilities ($592 and $272 to a related party) Accrued Liabilities Current Deferred revenue Deferred Revenue Current Total current liabilities Liabilities Current Long-term portion of lease financing obligations Finance Lease Liability Noncurrent Product development obligations Accrued Product Development Costs Deferred rent Deferred Rent Credit Noncurrent Deferred revenue, net of current Deferred Revenue Noncurrent Other long-term liabilities Other Liabilities Noncurrent Total liabilities Liabilities Commitments and Contingencies Commitments And Contingencies Stockholders’ equity: Stockholders Equity Including Portion Attributable To Noncontrolling Interest [Abstract] Preferred stock, $0.01 par value; 125,000 shares authorized; no shares issued and outstanding at March 31, 2018 and December 31, 2017 Preferred Stock Value Common stock, $0.01 par value; 225,000 shares authorized at March 31, 2018 and December 31, 2017; 83,421 and 82,498 shares issued and outstanding at March 31, 2018 and December 31, 2017 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 Non-controlling interests Minority Interest Total equity Stockholders Equity Including Portion Attributable To Noncontrolling Interest Total liabilities, stockholders’ equity and non-controlling interests Liabilities And Stockholders Equity Accounts receivable from related party Accounts Receivable Related Parties Current Accrued liabilities to related party Due To Related Parties Current 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 Interest and other net. Income Statement [Abstract] Revenue: Revenues [Abstract] License revenue (includes $0 and $0 from a related party) Licenses Revenue Development and other revenue (includes $5,172 and $4,686 from a related party) Development And Other Revenue Total revenue Revenues 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 Interest and other, net Interest And Other Net [Abstract] Interest expense Interest Expense Interest income and other, net Interest And Other Income Total interest and other, net Interest Income Expense Nonoperating Net Loss before income taxes Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest Provision for income taxes Income Tax Expense Benefit Net loss Net Income Loss Net loss per share - basic and diluted Earnings Per Share Basic And Diluted Weighted average number of common shares used to calculate net loss per share - basic and diluted Weighted Average Number Of Share Outstanding Basic And Diluted Revenue from multiple-deliverable arrangements that include licensing fees and services revenue and the amount of consideration recognized during the period for milestones. Licensing revenue is consideration received from another party for the right to use, but not own, certain of the entity's intangible assets. Licensing arrangements include, but are not limited to, rights to use a patent, copyright, technology, manufacturing process, software or trademark. Licensing fees are generally, but not always, fixed as to amount and not dependent upon the revenue generated by the licensing party. An entity may receive licensing fees for licenses that also generate royalty payments to the entity. Services revenue may be derived by providing other, non-specified, services during the reporting period. Revenue recognized from co-development services, manufacturing of clinical supplies, committee services and information services and other revenue. Statement [Table] Statement [Table] Type of Arrangement and Non-arrangement Transactions Type Of Arrangement [Axis] Arrangements and Non-arrangement Transactions Arrangements And Nonarrangement Transactions [Member] Astellas agreements. Astellas Agreement [Member] Astellas Collaboration Agreement [Member] Statement [Line Items] Statement [Line Items] License and milestone revenue from a related party License Fees And Milestones Revenue Collaboration services and other revenue from a related party Collaboration Services And Other Revenue Statement Of Income And Comprehensive Income [Abstract] Net loss Other comprehensive income (loss): 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 Available-for-sale investments: Other Comprehensive Income Available For Sale Securities Adjustment Net Of Tax Period Increase Decrease [Abstract] Unrealized gain (loss) on investments, net of tax effect Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax Reclassification from accumulated other comprehensive loss Other Comprehensive Income Loss Reclassification Adjustment From A O C I For Sale Of Securities Net Of Tax Net change in unrealized gain on available-for-sale investments Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax Other comprehensive loss, net of taxes Other Comprehensive Income Loss Net Of Tax Comprehensive loss Comprehensive Income Net Of Tax Increase (decrease) in the obligation recognized by the entity related to lease agreements for which the entity is determined to be the owner of the asset leased for accounting purposes and not legal purposes. Statement Of Cash Flows [Abstract] Operating activities Net Cash Provided By Used In Operating Activities Continuing Operations [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 Depreciation Amortization of premium on investments Investment Income Amortization Of Premium Unrealized loss (gain) on short-term investments Unrealized Gain Loss On Investments Gain on disposal of property and equipment Gain Loss On Disposition Of Assets Stock-based compensation Share Based Compensation Realized gain on sales of available-for-sale securities Availableforsale Securities Gross Realized Gain Loss Excluding Other Than Temporary Impairments Changes in operating assets and liabilities: Increase Decrease In Operating Capital [Abstract] Accounts receivable Increase Decrease In Accounts Receivable Prepaid expenses and other current assets Increase Decrease In Prepaid Deferred Expense And Other Assets Other assets Increase Decrease In Other Operating Assets Accounts payable Increase Decrease In Accounts Payable Accrued liabilities Increase Decrease In Accrued Liabilities Deferred revenue Increase Decrease In Deferred Revenue Lease financing liability Increase Decrease In Lease Financing Liability Other long-term liabilities Increase Decrease In Other Noncurrent Liabilities Net cash used in operating activities Net Cash Provided By Used In Operating Activities Continuing Operations Investing activities Net Cash Provided By Used In Investing Activities Continuing Operations [Abstract] Purchases of property and equipment Payments To Acquire Property Plant And Equipment Proceeds from sale of property and equipment Proceeds From Sale Of Property Plant And Equipment Purchases of available-for-sale securities Payments To Acquire Available For Sale Securities Proceeds from sales of available-for-sale securities Proceeds From Sale Of Available For Sale Securities Proceeds from maturities of available-for-sale securities Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities Net cash provided by investing activities Net Cash Provided By Used In Investing Activities Continuing Operations Financing activities Net Cash Provided By Used In Financing Activities Continuing Operations [Abstract] Repayments of lease liability Repayments Of Long Term Capital Lease Obligations Cash paid for payroll taxes on restricted stock unit releases Payments Related To Tax Withholding For Share Based Compensation Proceeds from issuance of common stock Proceeds From Issuance Of Common Stock Net cash provided by financing activities Net Cash Provided By Used In Financing Activities Continuing Operations Effect of exchange rate change on cash and cash equivalents Effect Of Exchange Rate On Cash And Cash Equivalents Continuing Operations Net decrease in cash and cash equivalents Cash And Cash Equivalents Period Increase Decrease Total cash and cash equivalents at beginning of period Total cash and cash equivalents at end of period Accounting Policies [Abstract] Significant Accounting Policies Significant Accounting Policies [Text Block] Organization Consolidation And Presentation Of Financial Statements [Abstract] Collaboration Agreements Collaborative Arrangement Disclosure [Text Block] Fair Value Disclosures [Abstract] Fair Value Measurements Fair Value Disclosures [Text Block] Balance Sheet Components Supplemental Balance Sheet Disclosures [Text Block] Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] Stock-Based Compensation Disclosure Of Compensation Related Costs Share Based Payments [Text Block] Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] Related Party Transactions [Abstract] Related Party Transactions Related Party Transactions Disclosure [Text Block] Description of operations policy. Description of Operations Description Of Operations Policy Policy [Text Block] Basis of presentation and principles of consolidation policy. Basis of Presentation and Principles of Consolidation Basis Of Presentation And Principles Of Consolidation Policy Policy [Text Block] Revenue Recognition Revenue Recognition Policy [Text Block] Investments Investment Policy [Text Block] Use of Estimates Use Of Estimates Recently issued and adopted accounting guidance. Recently Issued and Adopted Accounting Guidance Recently Issued And Adopted Accounting Guidance Policy [Text Block] Recently issued accounting guidance not yet adopted. Recently Issued Accounting Guidance Not Yet Adopted Recently Issued Accounting Guidance Not Yet Adopted Policy [Text Block] Collaboration Arrangements Collaborative Arrangement Accounting Policy Other revenues policy. Other Revenues Other Revenues Policy [Text Block] Deferred Revenue Revenue Recognition Deferred Revenue Schedule of Adoption of New Revenue Standards Schedule Of New Accounting Pronouncements And Changes In Accounting Principles [Text Block] Schedule of Impacts to Accumulated Other Comprehensive Loss and Accumulated Deficit Upon Adoption of Guidance Schedule Of Error Corrections And Prior Period Adjustments [Text Block] Tabular disclosure of the recognition of revenue by the different types of revenue under a collaboration agreement. Geographical Statement Geographical [Axis] Geographical Segment Geographical [Domain] Japan [Member] JAPAN Europe [Member] Europe [Member] United States/Rest of World and China. U.S./RoW and China [Member] United States Rest Of World And China [Member] Summary of Revenue Recognized under Agreement Revenue Recognition By Type Table [Text Block] Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue Revenue Recognition Multiple Deliverable Arrangements Table [Text Block] Fair Values of Financial Assets Measured on Recurring Basis Fair Value Assets Measured On Recurring Basis [Text Block] Fair Values of Financial Liabilities Carried at Historical Cost Fair Value Liabilities Measured On Recurring And Nonrecurring Basis Table [Text Block] Schedule of Cash and Cash Equivalents Schedule Of Cash And Cash Equivalents Table [Text Block] Summary of Amortized Cost, Gross Unrealized Holding Gains or Losses, and Fair Value of Available-for-Sale Investments Schedule Of Available For Sale Securities Reconciliation Table [Text Block] Schedule of Accrued Liabilities Schedule Of Accrued Liabilities Table [Text Block] Schedule of Allocated Stock-Based Compensation Expense Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Text Block] Schedule of share based payment award stock options and employee stock purchase plan valuation assumptions. Schedule of Assumptions used to Estimate Fair Value of Stock Options Granted and Purchases under 2014 Employee Share Purchase Plan Schedule Of Share Based Payment Award Stock Options And Employee Stock Purchase Plan Valuation Assumptions Table [Text Block] Accounting policy. Accounting policy. Accounting Policy [Table] Accounting Policy [Table] Adjustments for Change in Accounting Principle Adjustments For Change In Accounting Principle [Axis] Adjustments for Change in Accounting Principle Change In Accounting Principle [Member] New revenue standards. New Revenue Standards [Member] New Revenue Standards [Member] Income Statement Location Income Statement Location [Axis] Income Statement Location Income Statement Location [Domain] Revenue [Member] Sales [Member] Adjustments for New Accounting Pronouncements Adjustments For New Accounting Pronouncements [Axis] Type of Adoption Type Of Adoption [Member] ASU 2014-09 [Member] Accounting Standards Update201409 [Member] Equity Components Statement Equity Components [Axis] Equity Component Equity Component [Domain] Accumulated Deficit [Member] Retained Earnings [Member] Accounting Policy [Line Items] Accounting Policy [Line Items] Number of operating segment Number Of Operating Segments Short term investments maximum maturity period. Long term investments minimum maturity period. Short term investments Maturity Short Term Investments Maximum Maturity Period Long term Investments Maturity Long Term Investments Minimum Maturity Period New Accounting Pronouncements And Changes In Accounting Principles [Abstract] New Accounting Pronouncements Or Change In Accounting Principle [Table] New Accounting Pronouncements Or Change In Accounting Principle [Table] Initial Application Period Cumulative Effect Transition Initial Application Period Cumulative Effect Transition [Axis] Initial Application Period Cumulative Effect Transition Initial Application Period Cumulative Effect Transition [Domain] As Previously Reported [Member] Calculated Under Revenue Guidance In Effect Before Topic606 [Member] New Revenue Standards Adjustment [Member] Difference Between Revenue Guidance In Effect Before And After Topic606 [Member] New Accounting Pronouncements Or Change In Accounting Principle [Line Items] New Accounting Pronouncements Or Change In Accounting Principle [Line Items] Statement of Operations License revenue Development and other revenue Balance Sheet Accumulated deficit Increase (reduction) in revenue New Accounting Pronouncement Or Change In Accounting Principle Effect Of Adoption Quantification Increase in accumulative deficit Cumulative Effect Of New Accounting Principle In Period Of Adoption Impact of change in accounting principle upon adoption of ASU 2016-01 [Member] ASU 2016-01 [Member] Accounting Standards Update201601 [Member] U.S. federal statutory income tax rate Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate Represents the amount of fixed and determinable non-contingent upfront payments included under the collaborative agreement as arrangement consideration.