Document and Entity Information [Abstract] Statement [Table] Statement [Line Items] Entity Registrant Name Entity Central Index Key Document Type Document Period End Date Amendment Flag Current Fiscal Year End Date Entity Current Reporting Status Entity Filer Category Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Period Focus Statement of Financial Position [Abstract] Assets [Abstract] Assets Assets, Current [Abstract] Current assets: Cash Cash at end of period Cash at beginning of period Prepaid Expense and Other Assets, Current Prepaid and other current assets Assets, Current Total current assets Property, Plant and Equipment, Net Equipment, net Other Assets, Noncurrent Other assets Assets Total assets Liabilities and Equity [Abstract] Liabilities and stockholders? equity Liabilities, Current [Abstract] Current liabilities: Accounts Payable, Current Accounts payable Accrued Liabilities, Current Accounts Payable and Other Accrued Liabilities, Current Accrued expenses and other current liabilities Long-term Debt, Current Maturities Loan payable, current portion Loan payable, current portion Represents the liabilities associated with warrants Warrant Liability Warrant liability Liabilities, Current Total current liabilities Long-term Debt, Excluding Current Maturities Loan payable, long-term Liabilities Total liabilities Stockholders' Equity Attributable to Parent [Abstract] Stockholders? equity: Preferred Stock, Value, Issued Preferred stock, $0.0001 par value per share (10,000,000 shares authorized, none issued and outstanding at March 31, 2018 and December 31, 2017, respectively) Common Stock, Value, Issued Common stock, $0.0001 par value per share (150,000,000 shares authorized, 26,252,562 and 25,492,992 shares issued and outstanding at June 30, 2018 and December 31, 2017, respectively) Additional Paid in Capital Additional paid-in capital Retained Earnings (Accumulated Deficit) Accumulated deficit Stockholders' Equity Attributable to Parent Total stockholders' equity Liabilities and Equity Total liabilities and stockholders' equity 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 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 Income Statement [Abstract] Operating Expenses [Abstract] Operating expenses: Research and Development Expense Research and development General and Administrative Expense General and administrative Operating Expenses Total operating expenses Operating Income (Loss) Loss from operations Investment Income, Net Interest and amortization of debt discount/premium (expense) income Fair Value Adjustment of Warrants Change in fair value of warrant liability Change in fair value of warrants Net Income (Loss) Attributable to Parent Net loss Net loss Earnings Per Share, Basic and Diluted Net loss per common share, basic and diluted Weighted Average Number of Shares Outstanding, Basic and Diluted Weighted average common shares outstanding, basic and diluted Statement of Cash Flows [Abstract] Net Cash Provided by (Used in) Operating Activities [Abstract] Cash flows from operating activities Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net loss 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: Share-based Compensation Stock-based compensation expense Amortization of Debt Discount (Premium) Amortization of debt discount Depreciation Increase (Decrease) in Operating Capital [Abstract] Changes in operating assets and liabilities: The increase (decrease) during the reporting period in the value of prepaid expenses and other current assets not separately disclosed in the statement of cash flows, for example, deferred expenses, intangible assets, or income taxes. Increase (Decrease) in Prepaid Expense and Other Assets, Current Prepaid expenses and other current assets Increase (Decrease) in Other Noncurrent Assets Other assets Increase (Decrease) in Accounts Payable Accounts payable Increase (Decrease) in Accrued Liabilities Accrued expenses Net Cash Provided by (Used in) Operating Activities Net cash used in operating activities Net Cash Provided by (Used in) Investing Activities [Abstract] Cash flows from investing activities Payments to Acquire Property, Plant, and Equipment Purchases of equipment Net Cash Provided by (Used in) Investing Activities Net cash used in investing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Cash flows from financing activities Proceeds from (Repayments of) Notes Payable Repayment of principal on term loan Proceeds from Issuance of Common Stock Procceds from issuance of common stock upon financing, net Proceeds from Stock Options Exercised Proceeds from issuance of common stock upon exercise of options Proceeds from Warrant Exercises Proceeds issuance of common stock upon exercise of warrants Net Cash Provided by (Used in) Financing Activities Net cash provided by financing activities Cash and Cash Equivalents, Period Increase (Decrease) Net (decrease) increase in cash Nature of Business and Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Nature of Business and Basis of Presentation Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Summary of Significant Accounting Policies Fair Value Measurements Fair Value Disclosures [Text Block] Fair Value Measurements Accrued Expenses Accounts Payable and Accrued Liabilities Disclosure [Text Block] Accrued Expenses Debt Disclosure [Abstract] Long-term Debt [Text Block] Loan and Security Agreement Net Loss per Common Share Earnings Per Share [Text Block] Net Loss per Common Share Stockholders? Equity Stockholders' Equity Note Disclosure [Text Block] Stockholders' Equity Disclosure of accounting policy for significant risks and uncertainties. Significant Risks and Uncertainties, Policy, [Policy Text Block] Significant Risks and Uncertainties Use of Estimates, Policy [Policy Text Block] Use of Estimates Foreign Currency Transactions and Translations Policy [Policy Text Block] Foreign Currency Translation Segment Reporting, Policy [Policy Text Block] Segment and Geographic Information Cash and Cash Equivalents, Policy [Policy Text Block] Cash Equivalents Concentration Risk, Credit Risk, Policy [Policy Text Block] Concentration of Credit Risk Fair Value of Financial Instruments, Policy [Policy Text Block] Fair Value of Financial Instruments Research and Development Expense, Policy [Policy Text Block] Research and Development Costs Income Tax, Policy [Policy Text Block] Income Taxes Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] Stock Based Compensation Earnings Per Share, Policy [Policy Text Block] Basic and Diluted Net Loss per Common Share New Accounting Pronouncements, Policy [Policy Text Block] Recent Accounting Pronouncements Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Summary of changes in the fair value of Level 3 liabilities Schedule of Accrued Liabilities [Table Text Block] Schedule of accrued expenses Schedule of Long-term Debt Instruments [Table Text Block] Schedule of long-term debt and unamortized debt discount balances Schedule of Maturities of Long-term Debt [Table Text Block] Schedule of principal payments Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Computation of basic and diluted net loss per common share Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Schedule of potentially dilutive securities Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block] Schedule of stock option activity Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block] Schedule of stock-based compensation expense Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block] Schedule of warrant activity Represents the number of late-stage candidates included in the Company's product candidate portfolio. Number of Late-stage Product Candidates Number of late-stage candidates in Company's product candidate portfolio Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract] Segment and Geographic Information Number of Operating Segments Number of operating segments Cash Equivalents, at Carrying Value [Abstract] Cash Equivalents Cash Equivalents, at Carrying Value Cash Equivalents Risks and Uncertainties [Abstract] Concentration of Credit Risk Represents the number of financial institutions holding the Company's cash. Number of Financial Institutions Holding Deposits Number of financial institutions that hold the Company's cash Effective Income Tax Rate Reconciliation, Percent [Abstract] Income Taxes Effective Income Tax Rate Reconciliation, Percent Effective tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent U.S. federal statutory income tax rate Fair Value Measurements, Recurring and Nonrecurring [Table] Class of Warrant or Right [Axis] Class Of Warrant Or Right [Domain] Class of Warrant or Right [Domain] Represents common warrants. Common Warrants [Member] Common warrants Represents placement agent warrants. Placement Agent Warrants [Member] Placement agent warrants Scenario [Axis] Scenario Unspecified [Domain] Scenario, Unspecified [Domain] Represents a 10 percent increase in the share price. Share Price Change Ten Percent Increase [Member] 10% share price increase Represents a 10 percent decrease in the share price. Share Price Change Ten Percent Decrease [Member] 10% share price decrease Represents a 10 percent increase in the expected volatility. Expected Volatility Change Ten Percent Increase [Member] 10% expected volatility increase Represents a 10 percent decrease in the expected volatility. Expected Volatility Change Ten Percent Decrease [Member] 10% expected volatility decrease Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Number of warrants (or share units) issued during the current period. Warrants Issued In Period Warrants issued Class of Warrant or Right, Exercise Price of Warrants or Rights Ending balance (in dollars per share) Beginning balance (in dollars per share) Exercise price of warrants (in dollars per share) The fair value of outstanding warrants. Fair Value Of Warrants Fair value Share Price Fair Value Assumptions, Risk Free Interest Rate Risk-free interest rates Fair Value Assumptions, Expected Volatility Rate Expected volatility rate The increase (decrease) in the warrant liability. Warrant Liability Increase (Decrease) Increase (decrease) in warrant liability Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Liability Class [Axis] Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation By Liability Class [Domain] Fair Value by Liability Class [Domain] Note Warrant [Member] Warrant liability Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value End of period Beginning of period Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings Change in fair value Carrying value as of the balance sheet date of obligations incurred through that date and payable for 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, Current Research and development Employee-related Liabilities, Current Accrued compensation Other Accrued Liabilities, Current Other Debt Instrument [Axis] Debt Instrument Name [Domain] Debt Instrument, Name [Domain] Line Of Credit [Member] Term Loan Represents information pertaining to tranche one of the term loan. Line Of Credit Term Loan Tranche One [Member] Term Loan, Tranche One, triggered upon closing Represents information pertaining to tranches two and three of the term loan. Line Of Credit Term Loan Tranches Two And Three [Member] Term Loan, Tranches Two and Three Represents information pertaining to tranche two of the term loan. Line Of Credit Term Loan Tranche Two [Member] Term Loan, Tranche Two Represents information pertaining to tranche three of the term loan. Line Of Credit Term Loan Tranche Three [Member] Term Loan, Tranche Three Line of Credit Facility, Maximum Borrowing Capacity Maximum loan amount Debt Instrument, Face Amount Loan amount Represents the number of loan tranches pertaining to the debt instrument. Debt Instrument, Number of Loan Tranches Number of loan tranches Debt Instrument, Interest Rate, Stated Percentage Base interest rate Debt Instrument, Basis Spread on Variable Rate Interest rate spread The percent of principal due, as a final payment fee, at extinguishment of debt. Extinguishment of Debt, Fee, Percent of Principal Final payment fee, percent of principal Represents the prepayment premium due, as a percent of the outstanding principal, if prepayment occurs under condition one. Debt Instrument, Prepayment Premium, Percent of Outstanding Principal, Condition One Prepayment premium, percent of principal, if prepaid within two years The period of time during which prepayment premium condition one is in effect, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Debt Instrument, Prepayment Premium Condition One, Term Prepayment premium, condition one, term Represents the prepayment premium due, as a percent of the outstanding principal, if prepayment occurs under condition two. Debt Instrument, Prepayment Premium, Percent of Outstanding Principal, Condition Two Prepayment premium, percent of principal, if prepaid during the third year Represents the prepayment premium due, as a percent of the outstanding principal, if prepayment occurs under condition three. Debt Instrument, Prepayment Premium, Percent of Outstanding Principal, Condition Three Prepayment premium, percent of principal, if prepaid after the third year Interest Expense, Debt, Excluding Amortization Interest expense Amortization of Financing Costs Amortization of debt issuance costs Long-term Debt, Gross Total Long-term debt Debt Instrument, Unamortized Discount, Noncurrent Less debt discount, net of current portion Amount, after noncurrent portion of unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations. Long-term Debt, Net Noncurrent Debt Discount Long-term debt, net of debt discount Amount, after noncurrent portion of unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations. Long-term Debt Current, Net of Noncurrent Debt Discount Less current portion of long-term debt Current portion of long-term debt Debt Instrument, Unamortized Discount, Current Current portion of debt discount Class of Warrant or Right, Number of Securities Called by Warrants or Rights Common stock to be issued if warrants are exercised (in shares) Period during which warrants are active, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Class of Warrant or Right, Term Term of warrants (in years) Proceeds from Issuance of Long-term Debt Long-term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year 2018 Long-term Debt, Maturities, Repayments of Principal in Year Two 2019 Long-term Debt, Maturities, Repayments of Principal in Year Three 2020 Earnings Per Share, Basic and Diluted [Abstract] Basic and diluted net loss per common share: Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Antidilutive Securities [Axis] Antidilutive Securities Name [Domain] Antidilutive Securities, Name [Domain] Employee Stock Option [Member] Stock Options Warrant [Member] Warrants Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Antidilutive securities Subsidiary or Equity Method Investee, Sale of Stock by Subsidiary or Equity Investee [Table] Subsidiary, Sale of Stock [Line Items] The maximum aggregate amount issuable under the Shelf Registration Statement, which allows for the issuance of common stock, preferred stock, warrants, rights, debt securities, and units. Shelf Registration Statement, Maximum Aggregate Amount Issuable Shelf Registration Statement, maximum aggregate amount issuable