Type of Arrangement and Non-arrangement Transactions [Axis] Aratana Agreement [Member] Business Acquisition [Axis] Aratana Therapeutics [Member] Amgen Agreement [Member] Amgen [Member] Equity Components [Axis] Warrants [Member] Award Type [Axis] Restricted Stock Units (RSUs) [Member] Related Party [Axis] Especificos Stendhal SA de CV [Member] Warrant Liability [Member] Fair Value Hierarchy and NAV [Axis] Fair Value, Inputs, Level 1 [Member] Fair Value, Hierarchy [Axis] Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 3 [Member] Global BioPharma, Inc [Member] Subsequent Event Type [Axis] Subsequent Event [Member] Scenario [Axis] October 2013 Through January 2019 [Member] Restatement [Axis] Adjustments [Member] Balances Without Adoption of ASC 606 [Member] Employee Stock Awards [Member] Director Stock Awards [Member] Plan Name [Axis] 2018 Employee Stock Purchase Plan [Member] Income Statement Location [Axis] Research and Development [Member] General and Administrative [Member] Range [Axis] Minimum [Member] Maximum [Member] Antidilutive Securities [Axis] Warrants [Member] Stock Options [Member] Restricted Stock Units [Member] February 8, 2019 [Member] Document And Entity Information Entity Registrant Name Entity Central Index Key Document Type Document Period End Date Amendment Flag Current Fiscal Year End Date Entity Filer Category Entity Small Business Flag Entity Emerging Growth Company Entity Ex Transition Period Entity Common Stock, Shares Outstanding Trading Symbol Document Fiscal Period Focus Document Fiscal Year Focus Statement of Financial Position [Abstract] ASSETS Current Assets: Cash and cash equivalents Restricted cash Accounts receivable Deferred expenses Prepaid expenses and other current assets Total current assets Property and equipment (net of accumulated depreciation) Intangible assets (net of accumulated amortization) Other assets Total assets LIABILITIES AND STOCKHOLDERS' EQUITY Current liabilities: Accounts payable Accrued expenses Deferred revenue Common stock warrant liability Other current liabilities Total current liabilities Deferred revenue Other liabilities Total liabilities Commitments and contingencies - Note 10 Stockholders' equity: Preferred stock, $0.001 par value; 5,000,000 shares authorized; Series B Preferred Stock; 0 shares issued and outstanding at January 31, 2019 and October 31, 2018 Liquidation preference of $0 at January 31, 2019 and October 31, 2018 Common stock - $0.001 par value; 170,000,000 shares authorized, 69,734,259 and 69,556,452 shares issued and outstanding at January 31, 2019 and October 31, 2018, respectively Additional paid-in capital Accumulated deficit Total stockholders' equity Total liabilities and stockholders' equity Preferred stock, par value Preferred stock, shares authorized Series B Preferred stock, shares issued Series B Preferred stock, shares outstanding Preferred stock, liquidation preference value Common stock, par value Common stock, shares authorized Common stock, shares issued Common stock, shares outstanding Income Statement [Abstract] Revenue Operating expenses: Research and development expenses General and administrative expenses Total operating expenses Income (loss) from operations Other income (expense): Interest income, net Net changes in fair value of derivative liabilities Other expense Net income (loss) before benefit for income taxes Income tax expense Net income (loss) Net income (loss) per common share, basic and diluted Weighted average number of common shares outstanding, basic Weighted average number of common shares outstanding, diluted Statement of Cash Flows [Abstract] OPERATING ACTIVITIES Net income (loss) Adjustments to reconcile net income (loss) to net cash used in operating activities: Stock compensation Employee stock purchase plan expense Gain on change in value of warrants Loss on disposal of property and equipment Write-off of intangible assets Depreciation expense Amortization expense of intangible assets Net amortization of premiums and discounts Change in operating assets and liabilities: Accounts receivable Prepaid expenses and other current assets Income tax receivable Other assets Accounts payable and accrued expenses Deferred revenue Other liabilities Net cash used in operating activities INVESTING ACTIVITIES Purchases of short-term investment securities Proceeds from maturities of short-term investment securities Purchase of property and equipment Cost of intangible assets Net cash (used in) provided by investing activities FINANCING ACTIVITIES Net proceeds of issuance of common stock Proceeds from employee stock purchase plan Tax withholdings paid related to net share settlement of equity awards Employee tax withholdings paid on equity awards Tax shares sold to pay for employee tax withholdings on equity awards Net cash provided by financing activities Net (decrease) increase in cash, cash equivalents and restricted cash Cash, cash equivalents and restricted cash at beginning of year Cash, cash equivalents and restricted cash at end of year The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the condensed balance sheets that sum to the total of the same such amounts shown in the condensed statements of cash flows: Total cash, cash equivalents and restricted cash shown in condensed statements of cash flows SUPPLEMENTAL CASH FLOW INFORMATION Cash paid for taxes SUPPLEMENTAL DISCLOSURE OF NON-CASH AND FINANCING ACTIVITIES Property and equipment included in accounts payable and accrued expenses Organization, Consolidation and Presentation of Financial Statements [Abstract] Nature of Operations Accounting Policies [Abstract] Summary of Significant Accounting Policies and Basis of Presentation Property, Plant and Equipment [Abstract] Property and Equipment Goodwill and Intangible Assets Disclosure [Abstract] Intangible Assets Payables and Accruals [Abstract] Accrued Expenses Common Stock Purchase Warrants And Warrant Liability Common Stock Purchase Warrants and Warrant Liability Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Share Based Compensation Earnings Per Share [Abstract] Net Income (Loss) Per Share Collaboration And Licensing Agreements Collaboration and Licensing Agreements Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Income Tax Disclosure [Abstract] Income Taxes Fair Value Disclosures [Abstract] Fair Value Subsequent Events [Abstract] Subsequent Events Basis of Presentation/Estimates Reclassification Concentration of Credit Risk Restricted Cash and Letters of Credit Revenue Recognition Collaborative Arrangements Recent Accounting Standards Recently Adopted Accounting Standards Schedule of Reclassifications to Balance Sheet and Income Statement Schedule of Property and Equipment Summary of Intangible Assets Schedule of Accrued Expenses Schedule of Warrants Activity