Entity Central Index Key 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 Accounts payable and accrued liabilities related parties current. Statement Of Financial Position [Abstract] Assets Assets [Abstract] Current assets: Assets Current [Abstract] Cash and cash equivalents Cash And Cash Equivalents At Carrying Value Short-term investments Available For Sale Securities Current Accounts receivable, related party Accounts Receivable Related Parties Current Prepaid expenses and other current assets Prepaid Expense And Other Assets Current Total current assets Assets Current Property and equipment, net Property Plant And Equipment Net Other long-term assets Other Assets Noncurrent Total assets Assets Liabilities and Stockholders' Equity Liabilities And Stockholders Equity [Abstract] Current liabilities: Liabilities Current [Abstract] Accounts payable and accrued expenses Accounts Payable And Accrued Liabilities Current Accounts payable and accrued expenses, related party Accounts Payable And Accrued Liabilities Related Parties Current Current portion of long-term debt, net Long Term Debt Current Total current liabilities Liabilities Current Long-term debt, net Long Term Debt Noncurrent Other long-term liabilities Other Liabilities Noncurrent Total liabilities Liabilities Stockholders' equity: Stockholders Equity [Abstract] Preferred stock, $0.0001 par value; 10,000 shares authorized; no shares issued and outstanding Preferred Stock Value Common stock, $0.0001 par value; 200,000 shares authorized; 21,375 and 21,368 shares issued as of June 30, 2017 and December 31, 2016, respectively; and 19,988 and 19,348 shares outstanding as of June 30, 2017 and December 31, 2016, respectively, excluding 1,387 and 2,020 shares subject to repurchase as of June 30, 2017 and December 31, 2016, respectively Common Stock Value Additional paid-in capital Additional Paid In Capital Common Stock Accumulated other comprehensive loss Accumulated Other Comprehensive Income Loss Net Of Tax Accumulated deficit Retained Earnings Accumulated Deficit Total stockholders' equity Stockholders Equity Total liabilities and stockholders' equity Liabilities And Stockholders Equity 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 Number of shares, subject to repurchase Stock Repurchase Program Number Of Shares Authorized To Be Repurchased Research and development expense excluding related party transactions. Related party transaction research and development expense. General and administrative expense excluding related party transactions. Related party transaction general and administrative expenses. Management fee income related party. Income Statement [Abstract] Operating Expenses: Operating Expenses [Abstract] Research and development Research And Development Expense Excluding Related Party Transactions Research and development, related party Related Party Transaction Research And Development Expense General and administrative General And Administrative Expense Excluding Related Party Transactions General and administrative, related party Related Party Transaction General And Administrative Expenses Total operating expenses Operating Expenses Other Income (Expense): Nonoperating Income Expense [Abstract] Management fee income, related party Management Fee Income Related Party Interest income Investment Income Interest Interest expense Interest Expense Total other income Nonoperating Income Expense Net loss Net Income Loss Net loss per share, basic and diluted Earnings Per Share Basic And Diluted Weighted average number of shares used in computing net loss per share, basic and diluted Weighted Average Number Of Share Outstanding Basic And Diluted Comprehensive Loss: Comprehensive Income Net Of Tax [Abstract] Other comprehensive income (loss): Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent [Abstract] Unrealized (loss) gain on marketable securities Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax Comprehensive loss Comprehensive Income Net Of Tax Increase decrease in accounts payable and accrued expenses excluding related party transactions. Increase decrease in accounts payable and accrued expenses related party. 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] Share-based compensation expense Share Based Compensation Non-cash interest expense Amortization Of Financing Costs Depreciation expense Depreciation Amortization of discount on marketable securities Accretion Amortization Of Discounts And Premiums Investments Changes in operating assets and liabilities: Increase Decrease In Operating Capital [Abstract] Accounts receivable, related party Increase Decrease In Accounts Receivable Related Parties Prepaid expenses and other current assets Increase Decrease In Prepaid Deferred Expense And Other Assets Other long-term assets Increase Decrease In Other Noncurrent Assets Accounts payable and accrued expenses Increase Decrease In Accounts Payable And Accrued Expenses Excluding Related Party Transactions Accounts payable and accrued expenses, related party Increase Decrease In Accounts Payable And Accrued Expenses Related Party 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] Maturities of marketable securities Proceeds From Sale And Maturity Of Marketable Securities Purchases of marketable securities Payments To Acquire Marketable 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] Proceeds from issuance of common stock, net Proceeds From Issuance Of Common Stock Proceeds from issuance of long-term debt, net Proceeds From Issuance Of Long Term Debt Proceeds from exercise of stock options Proceeds From Stock Options Exercised Net cash provided by financing activities Net Cash Provided By Used In Financing Activities Continuing Operations Net increase (decrease) in cash and cash equivalents Cash And Cash Equivalents Period Increase Decrease Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Supplemental disclosure of cash flow information: Supplemental Cash Flow Information [Abstract] Interest paid Interest Paid Accounting Policies [Abstract] Organization and Basis of Presentation Business Description And Basis Of Presentation [Text Block] Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Investments All Other Investments [Abstract] Investments Investments In Debt And Marketable Equity Securities And Certain Trading Assets Disclosure [Text Block] Fair Value Disclosures [Abstract] Fair Value Measurements Fair Value Measurement Inputs Disclosure [Text Block] Payables And Accruals [Abstract] Accounts Payable and Accrued Liabilities Accounts Payable And Accrued Liabilities Disclosure [Text Block] Debt Disclosure [Abstract] Long-Term Debt Debt Disclosure [Text Block] Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] Equity Incentive Plan Disclosure Of Compensation Related Costs Share Based Payments [Text Block] Related Party Transactions [Abstract] Related Party Transactions Related Party Transactions Disclosure [Text Block] Comprehensive Loss Comprehensive Income Policy Policy [Text Block] Net Loss per Share Earnings Per Share Policy [Text Block] Recent Accounting Pronouncements New Accounting Pronouncements Policy Policy [Text Block] Summary of Number of Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Text Block] Investments Measured at Fair Value on Recurring Basis Schedule Of Available For Sale Securities Reconciliation Table [Text Block] Schedule Of Fair Value Measurements, By Major Security Type Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Table [Text Block] Accounts Payable and Accrued Liabilities Schedule Of Accounts Payable And Accrued Liabilities Table [Text Block] Future Minimum Payments under Term Loan Facility Schedule Of Maturities Of Long Term Debt Table [Text Block] Summary of Share-based Compensation Expense Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Text Block] Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Table] Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Table] Antidilutive Securities Antidilutive Securities Excluded From Computation Of Earnings Per Share By Antidilutive Securities [Axis] Antidilutive Securities, Name Antidilutive Securities Name [Domain] Unvested restricted stock awards. Unvested Restricted Stock Awards Unvested Restricted Stock Awards [Member] Stock option employee non-employee and consultant. Stock Options Stock Option Employee Non Employee And Consultant [Member] Warrants Warrant [Member] Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] Potentially dilutive securities Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount Maturity of available for sale investments. Cash equivalents fair value disclosure. Schedule Of Available For Sale Securities [Table] Schedule Of Available For Sale Securities [Table] Measurement Frequency Fair Value By Measurement Frequency [Axis] Fair Value, Measurement Frequency Fair Value Measurement Frequency [Domain] Fair Value Measurements on Recurring Basis Fair Value Measurements Recurring [Member] Investment Type Investment Type [Axis] Investments Investment Type Categorization [Member] Money Market Funds Money Market Funds [Member] Government Agency Securities U S Government Agencies Debt Securities [Member] Commercial Paper Commercial Paper [Member] U.S. Treasury Securities U S Treasury Securities [Member] Corporate Debt Securities Corporate Debt Securities [Member] Government Sponsored Enterprise Securities U S Government Sponsored Enterprises Debt Securities [Member] Schedule Of Available For Sale Securities [Line Items] Schedule Of Available For Sale Securities [Line Items] Maturities (years) Available For Sale Securities Maturity Description Cash equivalents, Amortized Cost Cash Equivalents At Carrying Value Cash equivalents, Fair Value Cash Equivalents Fair Value Disclosure Cash equivalents and short term investments amortized cost. Cash equivalents and short term investments. Short-term investments, Amortized Cost Available For Sale Securities Amortized Cost Short-term investments, Unrealized Gains Available For Sale Securities Accumulated Gross Unrealized Gain Before Tax Short-term investments, Unrealized Losses Available For Sale Securities Accumulated Gross Unrealized Loss Before Tax Cash equivalents and Short-term investments, Amortized Cost Cash Equivalents And Short Term Investments Amortized Cost Cash equivalents and Short-term investments, Fair Value Cash Equivalents And Short Term Investments Short term investments maturities description. Available-for-sale securities, realized gains or losses Available For Sale Securities Gross Realized Gain Loss Net Marketable securities gross unrealized loss positions for less than twelve months Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value Short-term investments maturities, description Short Term Investments Maturities Description Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table] Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table] Fair Value, Hierarchy Fair Value By Fair Value Hierarchy Level [Axis] Fair Value Hierarchy Fair Value Measurements Fair Value Hierarchy [Domain] Level 1 Fair Value Inputs Level1 [Member] Level 2 Fair Value Inputs Level2 [Member] Asset Class Fair Value By Asset Class [Axis] Asset Class Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation By Asset Class [Domain] Government sponsored enterprise securities. Government Sponsored Enterprise Securities Government Sponsored Enterprise Securities [Member] Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] Cash equivalents Cash equivalents and short-term investments Accounts payable Accounts Payable Current Accrued compensation and benefits Employee Related Liabilities Current Other accrued expenses Other Accrued Liabilities Current Total accounts payable and accrued expenses additional borrowing description. Description required debt amount. Debt instrument minimum draw amount. Debt Instrument [Table] Debt Instrument [Table] Debt Instrument Debt Instrument [Axis] Debt Instrument, Name Debt Instrument Name [Domain] Term A loan. Term A Loan Term A Loan [Member] Term B loan. Term B Loan Term B Loan [Member] Range Range [Axis] Range Range [Member] Minimum Minimum [Member] Scenario Statement Scenario [Axis] Scenario, Unspecified Scenario Unspecified [Domain] Transaction occurring assumption one. Transaction Occurring Assumption One Transaction Occurring Assumption One [Member] Transaction occurring assumption two. Transaction Occurring Assumption Two Transaction Occurring Assumption Two [Member] Transaction occurring assumption Three. Transaction Occurring Assumption Three Transaction Occurring Assumption Three [Member] Variable Rate Variable Rate [Axis] Variable Rate Variable Rate [Domain] Base Rate Base Rate [Member] Term Loans. Term Loans Term Loans [Member] Long-term Debt, Type Longterm Debt Type [Axis] Long-term Debt, Type Longterm Debt Type [Domain] Term loan amendment agreement. Loan Amendment Term Loan Amendment Agreement [Member] Term loan warrants. Term Loan Warrants Term Loan Warrants [Member] Maximum Maximum [Member] Lender Name Line Of Credit Facility [Axis] Line of Credit Facility, Lender Line Of Credit Facility Lender [Domain] Silicon Valley bank. Silicon Valley Bank Silicon Valley Bank [Member] Oxford Finance LLC. Oxford Finance LLC Oxford Finance L L C [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Maximum borrowing capacity under term loans Line Of Credit Facility Maximum Borrowing Capacity Principal amount outstanding on loan Debt Instrument Carrying Amount