Accounting Policies [Abstract] Accounting Policies [Abstract] Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block] Accrued and Other Liabilities Accounts Payable, Current Accounts payable Accrued clinical trial expenses. Accrued Clinical Trial Expenses Accrued clinical trial expenses Accrued contract manufacturing costs. Accrued Contract Manufacturing Costs Accrued contract manufacturing Accrued Liabilities and Other Liabilities Accrued and other liabilities Accrued liabilities and other liabilities Accrued Liabilities And Other Liabilities [Line Items] Accrued Liabilities And Other Liabilities [Line Items] Accrued Liabilities And Other Liabilities [Line Items] Accrued Liabilities And Other Liabilities [Table] Accrued Liabilities And Other Liabilities [Table] Accrued Liabilities And Other Liabilities [Table] Accrued Liabilities, Current Clinical trial material accrual Clinical trial material expenses, accrued Accrued professional and consultant fees current. Accrued Professional And Consultant Fees Current Accrued professional and consulting services Additional Paid in Capital, Common Stock Additional paid-in capital Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net loss to net cash used in operating activities: Allocated Share-based Compensation Expense Stock-based compensation Allowance for lease improvement. Allowance For Lease Improvement Lease improvement allowance maximum amount Amended Facility Lease Agreement [Member] Amended Facility Lease Agreement [Member] Amended Facility Lease Agreement [Member] Amendment Flag Amendment Flag Amortization of Financing Costs Amortization of deferred financing costs Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Anti-dilutive securities excluded from computation of diluted net loss per share attributable to common stockholders Assets Total assets Assets [Abstract] Assets Assets, Current Total current assets Assets, Current [Abstract] Current assets: Assets, Fair Value Disclosure Assets at fair value Assets, Fair Value Disclosure [Abstract] Assets: Astra Zeneca [Member] Astra Zeneca [Member] AstraZeneca [Member] Award Type [Axis] Award Type [Axis] Capital Expenditures Incurred but Not yet Paid Acquisition of property and equipment included in accounts payable and accrued liabilities Capital Leases, Future Minimum Payments Due Minimum lease payments for extended lease Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents at end of period Cash and cash equivalents at beginning of period Cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Net increase (decrease) in cash and cash equivalents Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Supplemental noncash financing activities: Certificates of Deposit [Member] Certificates of Deposit [Member] Class of Warrant or Right, Exercise Price of Warrants or Rights Purchase price for warrants Class of warrant or right expiration date description. Class Of Warrant Or Right Expiration Date Description Warrants description Class of Warrant or Right, Number of Securities Called by Warrants or Rights Warrants issued to purchase common stock Class of warrant or right number of warrants exercised. Class Of Warrant Or Right Number Of Warrants Exercised Number of warrants exercised Class of warrant or right threshold ownership percentage. Class of Warrant or Right, Threshold Ownership Percentage Maximum warrants ownership percentage by each holder of warrants Collaborative Arrangement Disclosure [Text Block] Collaboration and Licensing Agreements Commitments and Contingencies Commitments and contingencies Common Stock, Par or Stated Value Per Share Common stock, par value Common Stock, Shares Authorized Common stock, shares authorized Common Stock, Shares, Issued Common stock, shares issued Common Stock, Shares, Outstanding Common stock, shares outstanding Common Stock, Value, Issued Common stock, $0.0001 par value; 300,000,000 shares authorized as of March 31, 2016 and December 31, 2015, respectively; 34,630,148 and 25,964,886 shares issued and outstanding as of March 31, 2016 and December 31, 2015, respectively. Cost of Services, Amortization Amortization of deferred compensation for services Counterparty Name [Axis] Counterparty Name [Axis] Current Fiscal Year End Date Current Fiscal Year End Date Deferred Revenue Disclosure [Abstract] Deferred Revenue Disclosure [Abstract] Depreciation Depreciation expense Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Stock-Based Compensation Document And Entity Information [Abstract] Document And Entity Information [Abstract] Document And Entity Information [Abstract] Document Fiscal Period Focus Document Fiscal Period Focus Document Fiscal Year Focus Document Fiscal Year Focus Document Period End Date Document Period End Date Document Type Document Type Earnings Per Share [Abstract] Earnings Per Share [Abstract] Earnings Per Share, Basic and Diluted Net loss per common share, basic and diluted Net loss per share-basic and diluted Earnings Per Share [Text Block] Net Loss Per Share Employee-related Liabilities, Current Accrued compensation and benefits Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Unrecognized stock based compensation expense Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Unrecognized stock based compensation expense, weighted-average remaining recognition period Employee Stock Option [Member] Options to Purchase Common Stock [Member] Employee Stock Purchase Plan [Member] Employee Stock Purchase Plan [Member] Employee Stock Purchase Plan [Member] Entity Central Index Key Entity Central Index Key Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity Filer Category Entity Filer Category Entity Registrant Name Entity Registrant Name Equity [Abstract] Equity [Abstract] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table Text Block] Summary of Fair Value Measurements of Company's Financial Assets Fair Value, Assets, Level 1 to Level 2 Transfers, Amount Transfer of assets from Level 1 to Level 2 Fair Value, Assets, Level 2 to Level 1 Transfers, Amount Transfer of assets from Level 2 to Level 1 Asset Class [Domain] Asset Class [Domain] Asset Class [Axis] Asset Class [Axis] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Fair Value Disclosures [Text Block] Fair Value Measurements Fair Value, Inputs, Level 1 [Member] Level 1 [Member] Fair Value, Inputs, Level 2 [Member] Level 2 [Member] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value Measurement, Policy [Policy Text Block] Fair Value Measurements Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Fair Value, Measurements, Recurring [Member] Fair Value, Recurring [Member] Gain (Loss) on Disposition of Property Plant Equipment Loss from disposal of fixed assets General and Administrative Expense General and administrative General and Administrative Expense [Member] General and Administrative [Member] Gross Proceeds From Issuance Of Common Stock Gross Proceeds From Issuance Of Common Stock Gross proceeds from issuance of common stock Health Care Costs, Policy [Policy Text Block] Clinical Trial Accruals Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest Loss before provision for income taxes Income Statement [Abstract] Income Statement [Abstract] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Income Taxes Paid, Net Cash paid during the period for income taxes Income Tax Expense (Benefit) Provision for income taxes Increase (Decrease) in Accounts Payable Accounts payable Increase (Decrease) in Accounts Receivable Accounts receivable Increase (Decrease) in Deferred Revenue Deferred revenue Increase (Decrease) in Employee Related Liabilities Accrued compensation and benefits Increase (Decrease) in Operating Capital [Abstract] Changes in operating assets and liabilities: Increase (Decrease) in Other Accrued Liabilities Accrued and other liabilities Increase (Decrease) in Prepaid Expense and Other Assets Prepaid expenses and other assets Investment Warrants, Exercise Price Warrants exercise price per share Lease Arrangement, Type [Axis] Lease Arrangement, Type [Axis] Lease Arrangement, Type [Domain] Lease Arrangement, Type [Domain] Lease Expiration Date Lease expiration date Liabilities Total liabilities Liabilities and Equity Total liabilities and stockholders' equity Liabilities and Equity [Abstract] Liabilities and stockholders' equity Liabilities, Current Total current liabilities Liabilities, Current [Abstract] Current liabilities: Licenses Revenue Licensing revenue Maximum [Member] Maximum [Member] Money Market Funds [Member] Money Market Funds [Member] Net Cash Provided by (Used in) Financing Activities, Continuing Operations Net cash provided by financing activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Financing activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Investing activities Net Cash Provided by (Used in) Operating Activities, Continuing Operations Net cash used in operating activities Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Operating activities Net Income (Loss) Attributable to Parent Net loss Net Income (Loss) Attributable to Parent [Abstract] Numerator: Net income (loss) and comprehensive income (loss). Net Income Loss And Comprehensive Income Loss Net loss and comprehensive loss New Accounting Pronouncements, Policy [Policy Text Block] Recent Accounting Pronouncements Operating Expenses Total operating expenses Operating Expenses [Abstract] Operating expenses: Operating Income (Loss) Loss from operations Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block] Organization and Basis of Presentation Other Assets, Noncurrent Other assets Other Liabilities, Current Other Other Liabilities, Noncurrent Other long-term liabilities Other Nonoperating Income (Expense) Other income (expense), net Payables and Accruals [Abstract] Payables and Accruals [Abstract] Payments to Acquire Property, Plant, and Equipment Purchases of property and equipment Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] Preferred Stock, Par or Stated Value Per Share Preferred stock, par value Preferred Stock, Shares Authorized Preferred stock, shares authorized Preferred Stock, Shares Issued Preferred stock, shares issued Preferred Stock, Shares Outstanding Preferred stock, shares outstanding Preferred Stock, Value, Issued Preferred stock, $0.0001 par value; 5,000,000 shares authorized as of March 31, 2016 and December 31, 2015, respectively; no shares issued and outstanding as of March 31, 2016 and December 31, 2015, respectively. Prepaid Expense and Other Assets, Current Prepaid expenses and other current assets Proceeds from Issuance of Common Stock Proceeds from issuance of common stock, net of issuance costs Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Excluding Stock Options Proceeds from issuance of shares under the ESPP Proceeds from License Fees Received Upfront payment received Proceeds from Stock Options Exercised Proceeds from exercise of stock options Property, Plant and Equipment, Net Property and equipment, net Purchase Rights [Member] Purchase Rights [Member] Purchase Rights [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Counterparty Name [Domain] Counterparty Name [Domain] Research and Development Expense Clinical trial material expenses paid Research and development Research and Development Expense (Excluding Acquired in Process Cost) Clinical trial material expenses Research and Development Expense [Member] Research and Development [Member] Restricted Cash and Cash Equivalents, Noncurrent Restricted cash Restricted Stock Units (RSUs) [Member] Restricted Stock Units (RSUs) [Member] Retained Earnings (Accumulated Deficit) Accumulated deficit Revenue from Related Parties Collaborative development revenue Revenue Recognition, Multiple-deliverable Arrangements, Determination of Selling Price, Amount Maximum amount of obligation to supply clinical trial materials, drug substance and drug product Revenue Recognition, Multiple-deliverable Arrangements [Line Items] Revenue Recognition, Multiple-deliverable Arrangements [Line Items] Revenue Recognition, Multiple-deliverable Arrangements [Table] Revenue Recognition, Multiple-deliverable Arrangements [Table] Revenues Total revenue Revenues [Abstract] Revenue: Schedule of Accounts Payable and Accrued Liabilities [Table Text Block] Schedule of Accrued Liabilities and Other Liabilities Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Computation of Basic and Diluted Earnings Per Share Attributable to Common Stockholders Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table] Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table] Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block] Summary of Stock-Based Compensation Recognized Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Share-based Compensation Stock-based compensation Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Equity Award [Domain] Equity Award [Domain] Shares Issued, Price Per Share Purchase price of common shares Significant Accounting Policies [Text Block] Summary of Significant Accounting Policies Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Stockholders' Equity Attributable to Parent Total stockholders' equity Stockholders' Equity Attributable to Parent [Abstract] Stockholders' equity: Stockholders' Equity Note Disclosure [Text Block] Stockholders Equity Stock Issued During Period, Shares, Employee Stock Purchase Plans Shares sold under ESPP Stock Issued During Period, Shares, New Issues Common stock sold and issued Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Shares purchased by employees on exercise of options Subsequent Event [Line Items] Subsequent Event [Line Items] Subsequent Event [Member] Subsequent Event [Member] Subsequent Events [Abstract] Subsequent Events [Abstract] Subsequent Events [Text Block] Subsequent Events Subsequent Event [Table] Subsequent Event [Table] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Supplemental Cash Flow Information [Abstract] Supplemental cash flow disclosure: Trading Symbol Trading Symbol Use of Estimates, Policy [Policy Text Block] Use of Estimates Warrant expiration term. Warrant Expiration Term Warrants expiration term Weighted Average Number of Shares Outstanding, Basic and Diluted Shares used to compute net loss per common share, basic and diluted Weighted average common shares outstanding-basic and diluted Weighted Average Number Of Shares Outstanding Basic And Diluted [Abstract] Weighted Average Number Of Shares Outstanding Basic And Diluted [Abstract] Denominator: