Accounting Policies [Abstract] Accounting Policies [Abstract] Accounts Payable and Accrued Liabilities Disclosure [Text Block] Accrued Expenses Accounts Payable, Current Accounts payable Accrued Liabilities, Current Accrued expenses Accrued expenses Accrued Professional Fees, Current Accrued professional fees Carrying value as of the balance sheet date of obligations incurred through that date and payable for expenses related to research and development. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Accrued Research And Development Expense Current Accrued research and development expenses Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive loss Additional Paid in Capital, Common Stock Additional paid-in capital Adjustments, Noncash Items, 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 expense Total stock-based compensation expense Amendment Flag Amendment Flag Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Securities excluded from computation of earnings per share Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Assets Total assets Assets [Abstract] Assets Assets, Current Total current assets Assets, Current [Abstract] Current assets: Assets, Fair Value Disclosure Total cash equivalents and marketable securities AUSTRALIA Australia [Member] Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax Gross Unrealized Gains Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax Gross Unrealized Losses Available-for-sale Debt Securities, Amortized Cost Basis Amortized Cost Available-for-sale Securities, Debt Securities Fair Value Marketable Securities Available-for-sale Securities, Gross Realized Gain (Loss) Premium on purchases of marketable securities Available-for-sale Securities [Table Text Block] Summary of Marketable Securities Award Type [Axis] Award Type [Axis] Business Description and Basis of Presentation [Text Block] Nature of the Business and Basis of Presentation Capital Loss Carryforward [Member] Capital Loss Carryforward [Member] 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, Fair Value Disclosure Cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Net increase in cash and cash equivalents Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Supplemental disclosure of non-cash investing and financing activities: Commercial Paper, Not Included with Cash and Cash Equivalents Due Within One Year [Member] Commercial Paper, Not Included with Cash and Cash Equivalents Due Within One Year [Member] Commercial Paper (Due within 1 Year) [Member] Commercial Paper, Not Included with Cash and Cash Equivalents [Member] Commercial Paper [Member] Commitment And Contingencies [Line Items] Commitment And Contingencies [Line Items] Commitment And Contingencies [Line Items] Commitment And Contingencies [Table] Commitment And Contingencies [Table] Commitment And Contingencies [Table] Commitments and Contingencies Commitments and contingencies (Note 7) Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Text Block] 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, $0.001 par value; 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Effective Income Tax Rate Reconciliation Tax Refunds Related To Research And Development Percentage of refundable tax incentive Employee-related Liabilities, Current Accrued payroll and related expenses Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Unrecognized stock-based compensation cost Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Stock-based compensation recognized weighted average period 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 Incorporation, Date of Incorporation Entity incorporation date Entity Registrant Name Entity Registrant Name Equity [Abstract] Equity [Abstract] Equity Method Investments And Cost Method Investments [Abstract] Equity Method Investments And Cost Method Investments [Abstract] Equity Method Investments And Cost Method Investments [Abstract] Fair Value, Assets, Level 1 to Level 2 Transfers, Amount Transfer from level 1 to level 2, financial assets Fair Value, Assets, Level 2 to Level 1 Transfers, Amount Transfer from level 2 to level 1, financial assets Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Table Text Block] Summary of Cash Equivalents and Marketable Securities Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value, Inputs, Level 1 [Member] Quoted Prices in Active Markets, (Level 1) [Member] Fair Value, Inputs, Level 2 [Member] Significant Other Observable Inputs (Level 2) [Member] Fair Value Measurement, Policy [Policy Text Block] Fair Value Measurements Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Follow On Offering [Member] Follow On Offering [Member] Follow-on Offering [Member] Foreign Currency Transaction Gain (Loss), before Tax Foreign currency transaction gains (losses), net Foreign Currency Transaction Gain (Loss), Unrealized Unrealized foreign currency transaction gains (losses) Unrealized foreign currency transaction (gains) losses General and Administrative Expense General and administrative General and Administrative Expense [Member] General and Administrative [Member] Income Statement [Abstract] Income Statement [Abstract] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Income Taxes Receivable, Current Tax incentive receivable Income Taxes Receivable, Noncurrent Tax incentive receivable Income Taxes Receivable Tax incentive receivable Increase (Decrease) in Accounts Payable Accounts payable Increase (Decrease) in Accrued Liabilities Accrued expenses Increase (Decrease) in Operating Capital [Abstract] Changes in operating assets and liabilities: Increase (Decrease) in Prepaid Expense and Other Assets Prepaid expenses and other current assets The increase (decrease) during the reporting period in tax incentive receivable, which represents the amount due from tax authorities for refunds of overpayments or recoveries of taxes paid. 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Notes Payable Net Of Current Notes payable, net of current portion Numerator [Abstract] Numerator [Abstract] Numerator: Office Two [Member] Office Two [Member] Office Two [Member] Operating Expenses Total operating expenses Operating Expenses [Abstract] Operating expenses: Operating Income (Loss) Loss from operations Operating Lease Option For Extension Period Operating Lease Option For Extension Period Lease extension period Operating Leases, Future Minimum Payments Due Total Operating Leases, Future Minimum Payments, Due in Three Years 2017 Operating Leases, Future Minimum Payments, Due in Two Years 2016 Operating Leases, Future Minimum Payments, Remainder of Fiscal Year 2015 Operating Leases, Rent Expense, Net Operating lease, rental expense Operating Loss Carryforwards [Line Items] Operating Loss Carryforwards [Line Items] Operating Loss Carryforwards [Table] Operating Loss Carryforwards [Table] Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items] Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items] Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items] Organization Consolidation And Presentation Of Financial Statements Disclosure [Table] Organization Consolidation And Presentation Of Financial Statements Disclosure [Table] Organization Consolidation And Presentation Of Financial Statements Disclosure [Table] Other Accrued Liabilities, Current Accrued other Other Assets, Noncurrent Other assets Other Commitments [Axis] Other Commitments [Axis] Other Commitments [Domain] Other Commitments [Domain] Other Comprehensive Income (Loss), Net of Tax Total other comprehensive loss Other Comprehensive Income (Loss), Tax [Abstract] Other comprehensive loss: Other Income and Expenses [Abstract] Other income (expense): Paid-in-Kind Interest Non-cash interest expense Payables and Accruals [Abstract] Payables and Accruals [Abstract] Payments of Stock Issuance Costs Underwriting discounts, commissions and offering expenses Payments of deferred offering costs Payments to Acquire Marketable Securities Purchase of marketable securities Payments to Acquire Property, Plant, and Equipment Purchases of property and equipment Pension and Other Postretirement Benefits Disclosure [Text Block] Retirement Plan The percentage of research and development costs to be reduced. Percentage Reduction Research And Development Costs Percentage of reduction in research and development costs Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] Pre Commercialization Milestones [Member] Pre Commercialization Milestones [Member] Pre Commercialization Milestones [Member] 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; $0.001 par value; 5,000,000 shares authorized at March 31, 2015 and December 31, 2014; no shares issued and outstanding at March 31, 2015 and December 31, 2014 Prepaid Expense and Other Assets, Current Prepaid expenses and other current assets Proceeds from Issuance Initial Public Offering Proceeds from offering, net of commissions and underwriting discounts Proceeds from Issuance of Common Stock Proceeds from offering, net of commissions and underwriting discounts Proceeds from public offering, net Proceeds from Issuance of Redeemable Convertible Preferred Stock Proceeds from issuance of redeemable convertible preferred stock Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options Proceeds from exercise of common stock options and issuance of common stock pursuant to employee stock purchase plan Proceeds from Notes Payable Proceeds from issuance of notes payable, net of issuance costs Proceeds from Sale and Maturity of Available-for-sale Securities Proceeds from maturities of marketable securities Product Commercialization Milestones [Member] Product Commercialization Milestones [Member] Product Commercialization Milestones [Member] Property, Plant and Equipment, Net Property and equipment, net Name of Property [Axis] Name of Property [Axis] Name of Property [Domain] Name of Property [Domain] Research and Development [Abstract] Research and Development [Abstract] Research and Development Expense Research and development Research and Development Expense [Member] Research and Development [Member] Amount of expense reduction recorded related to a refundable tax incentive receivable. Research And Development Expenses Reduction Reduction to research and development expenses Research, Development, and Computer Software Disclosure [Text Block] Australia Research and Development Tax Incentive Retained Earnings (Accumulated Deficit) Accumulated deficit Revenues Revenue Sale of Stock [Domain] Sale of Stock [Domain] Schedule of Accrued Liabilities [Table Text Block] Schedule of Accrued Expenses Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Summary of Common Stock Equivalents Outstanding Schedule of Available-for-sale Securities [Line Items] Schedule of Available-for-sale Securities [Line Items] Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Computation of Basic and Diluted Earnings Per Share Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block] Summary of Stock-Based Compensation Expense Related to Stock Options and Restricted Common Stock Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Schedule of Future Minimum Lease Payments for Operating Leases Schedule of Maturities of Long-term Debt [Table Text Block] Schedule of Estimated Future Principal Payments Tabular disclosure of notes payable. Includes, but is not limited to, current and long-term portions. Schedule of Notes Payable [Table Text Block] Schedule of Notes Payable Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Geographical [Domain] Geographical [Domain] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Shares available for grant Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Shares available for grant Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares Number of outstanding unvested shares held by nonemployees Share-based Compensation Arrangement by Share-based Payment Award, Options, Other Increases (Decreases) in Period Shares added to plan Equity Award [Domain] Equity Award [Domain] Shares Issued, Price Per Share Common stock issued price per share Significant Accounting Policies [Text Block] Summary of Significant Accounting Policies Geographical [Axis] Geographical [Axis] Statement [Line Items] Statement [Line Items] Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Statement [Table] Statement [Table] 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, New Issues Common stock issued Number of shares of stock issued to underwriters for the exercise of the over allotment option. Stock Issued During Period Shares To Underwriters For Exercise Of Over Allotment Option Shares issued related to the exercise of over allotment option by underwriters Equity Option [Member] Options to Purchase Common Stock [Member] Subsequent Event [Member] Subsequent Event [Member] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Licensed Product [Member] Subsequent Licensed Product [Member] Subsequent Licensed Product [Member] Sale of Stock [Axis] Sale of Stock [Axis] Summary Of Significant Policies [Line Items] Summary Of Significant Policies [Line Items] Summary Of Significant Policies [Line Items] Summary Of Significant Policies [Table] Summary Of Significant Policies [Table] Summary Of Significant Policies [Table] Tax Credit Carryforward [Axis] Tax Credit Carryforward [Axis] Tax Credit Carryforward, Name [Domain] Tax Credit Carryforward, Name [Domain] Temporary Equity, Accretion to Redemption Value, Adjustment Accretion of redeemable convertible preferred stock to redemption values Accretion of redeemable convertible preferred stock to redemption value Trading Symbol Trading Symbol Two Thousand And Fifteen [Member] Two Thousand And Fifteen [Member] 2015 [Member] Two Thousand And Fourteen Employee Stock Purchase Plan [Member] Two Thousand And Fourteen Employee Stock Purchase Plan [Member] 2014 Employee Stock Purchase Plan [Member] Two Thousand And Seventeen [Member] Two Thousand And Seventeen [Member] 2017 [Member] Two Thousand And Sixteen [Member] Two Thousand And Sixteen [Member] 2016 [Member] Two Thousand Fourteen Stock Option [Member] Two Thousand Fourteen Stock Option [Member] 2014 Stock Option and Incentive Plan [Member] Unaudited Interim Financial Information Policy. 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