0000001 - Document - Cover link:presentationLink link:calculationLink link:definitionLink 0000002 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS link:presentationLink link:calculationLink link:definitionLink 0000003 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) link:presentationLink link:calculationLink link:definitionLink 0000004 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS link:presentationLink link:calculationLink link:definitionLink 0000005 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS link:presentationLink link:calculationLink link:definitionLink 0000006 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY link:presentationLink link:calculationLink link:definitionLink 0000007 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS link:presentationLink link:calculationLink link:definitionLink 0000008 - Disclosure - Organization and Description of Business link:presentationLink link:calculationLink link:definitionLink 0000009 - Disclosure - Summary of Significant Accounting Policies link:presentationLink link:calculationLink link:definitionLink 0000010 - Disclosure - Fair Value Measurements link:presentationLink link:calculationLink link:definitionLink 0000011 - Disclosure - Balance Sheet Components link:presentationLink link:calculationLink link:definitionLink 0000012 - Disclosure - Research Collaboration and License Agreements link:presentationLink link:calculationLink link:definitionLink 0000013 - Disclosure - Commitments and Contingencies link:presentationLink link:calculationLink link:definitionLink 0000014 - Disclosure - Stock-Based Compensation link:presentationLink link:calculationLink link:definitionLink 0000015 - Disclosure - Income Taxes link:presentationLink link:calculationLink link:definitionLink 0000016 - Disclosure - Workforce Reduction link:presentationLink link:calculationLink link:definitionLink 0000017 - Disclosure - Subsequent Events link:presentationLink link:calculationLink link:definitionLink 9954471 - 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Disclosure - Summary of Significant Accounting Policies - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 9954480 - Disclosure - Summary of Significant Accounting Policies - Estimated Useful Life of Asset (Details) link:presentationLink link:calculationLink link:definitionLink 9954481 - Disclosure - Summary of Significant Accounting Policies - Computation of Net Loss Per Common Share (Details) link:presentationLink link:calculationLink link:definitionLink 9954482 - Disclosure - Summary of Significant Accounting Policies - Potentially Dilutive Securities Not Included in the Diluted Net Loss Per Share Calculations (Details) link:presentationLink link:calculationLink link:definitionLink 9954483 - Disclosure - Fair Value Measurements - Schedule of Cash and Cash Equivalents and Marketable Securities Classified as Available-for-sale Securities (Details) link:presentationLink link:calculationLink link:definitionLink 9954484 - Disclosure - Fair Value Measurements - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 9954485 - Disclosure - Fair Value Measurements - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) link:presentationLink link:calculationLink link:definitionLink 9954486 - Disclosure - Balance Sheet Components - Schedule of Reconciliation of Cash, Cash Equivalent and Restricted Cash (Details) link:presentationLink link:calculationLink link:definitionLink 9954487 - Disclosure - Balance Sheet Components - Schedule of Property and Equipment (Details) link:presentationLink link:calculationLink link:definitionLink 9954488 - Disclosure - Balance Sheet Components - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 9954489 - Disclosure - Balance Sheet Components - Schedule of Accrued Liabilities (Details) link:presentationLink link:calculationLink link:definitionLink 9954490 - Disclosure - Research Collaboration and License Agreements - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 9954491 - Disclosure - Research Collaboration and License Agreements - Schedule of Recognized Revenue from Collaboration and License Agreements (Details) link:presentationLink link:calculationLink link:definitionLink 9954492 - Disclosure - Commitments and Contingencies - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 9954493 - Disclosure - Commitments and Contingencies - Components of Lease Costs (Details) link:presentationLink link:calculationLink link:definitionLink 9954494 - Disclosure - Commitments and Contingencies - Operating Lease Liability Maturity (Details) link:presentationLink link:calculationLink link:definitionLink 9954495 - Disclosure - Stock-Based Compensation - Schedule of Activity under 2008 Plan and 2018 Plan (Details) link:presentationLink link:calculationLink link:definitionLink 9954496 - Disclosure - Stock-Based Compensation - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 9954497 - Disclosure - Stock-Based Compensation - Schedule of Stock Based Compensation Expense (Details) link:presentationLink link:calculationLink link:definitionLink 9954498 - Disclosure - Workforce Reduction (Details) link:presentationLink link:calculationLink link:definitionLink 9954499 - Disclosure - Subsequent Events (Details) link:presentationLink link:calculationLink link:definitionLink