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Short-term investments Available-for-sale Securities, Current Equity Component [Domain] Concentration Risk, Credit Risk, Policy [Policy Text Block] Common Stock [Member] Equity Components [Axis] us-gaap_IncreaseDecreaseInDeferredRevenue Deferred revenue us-gaap_DebtInstrumentUnamortizedDiscount Debt Instrument, Unamortized Discount us-gaap_ComprehensiveIncomeNetOfTax Comprehensive loss Accelerated Non-Cash Stock Option Expense [Member] This item represents accelerated non-cash stock option expense. us-gaap_IncreaseDecreaseInOtherAccruedLiabilities Other accrued liabilities us-gaap_IncreaseDecreaseInEmployeeRelatedLiabilities Accrued payroll and employee liabilities Use of Estimates, Policy [Policy Text Block] New Accounting Pronouncements, Policy [Policy Text Block] Shares excluded (in shares) us-gaap_IncreaseDecreaseInAccountsPayable Accounts payable Shares used in computing basic and diluted net loss per share (in shares) Basic and diluted net loss per share (in dollars per share) us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax Available-for-sale, gross unrealized losses us-gaap_SharePrice Share Price Available-for-sale, gross unrealized gains Available-for-sale, amortized cost Consolidation, Policy [Policy Text Block] Basis of Accounting [Text Block] Line of Credit Facility, Lender [Domain] Lender Name [Axis] Cash and cash equivalents Cash and cash equivalents at beginning of year Cash and cash equivalents at end of year us-gaap_CashEquivalentsAtCarryingValue Cash Equivalents, at Carrying Value Selling and Marketing Expense [Member] us-gaap_RestructuringAndRelatedCostExpectedCost1 Restructuring and Related Cost, Expected Cost Scenario, Unspecified [Domain] General and Administrative Expense [Member] hrtx_DebtInstrumentConversionRatioShares Debt Instrument Conversion Ratio Shares Number of shares per $1,000 of principal of note. us-gaap_RestructuringAndRelatedCostExpectedCostRemaining1 Restructuring and Related Cost, Expected Cost Remaining hrtx_DebtInstrumentConversionRatioMultipleOfPrincipal Debt Instrument Conversion Ratio Multiple of Principal The multiple of principal used in calculating the number of shares converted from the notes. Scenario [Axis] hrtx_BeneficialOwnershipAfterConversion Beneficial Ownership after Conversion Percentage amount the holder would beneficially own of the company's outstanding common stock. hrtx_NoticePeriodAssociatedWithBeneficialOwnershipPercentageLimitationConvertibleNotes Notice Period Associated with Beneficial Ownership Percentage Limitation Convertible Notes Notice period associated with beneficial ownership percentage limitation, convertible notes. Debt Conversion, Name [Domain] hrtx_CommonSharesRegisteredForResaleInConnectionWithConvertibleNotes Common Shares Registered for Resale in Connection with Convertible Notes Common shares registered for resale in connection with convertible notes. Debt Conversion Description [Axis] Debt Disclosure [Text Block] Restructuring Plan [Domain] us-gaap_ProceedsFromIssuanceOfLongTermDebt Proceeds from Issuance of Long-term Debt Restructuring Plan [Axis] Employee Severance [Member] us-gaap_ProceedsFromConvertibleDebt Proceeds from Convertible Debt Cost of Sales [Member] Income Statement Location [Domain] Restructuring Type [Axis] Income Statement Location [Axis] Type of Restructuring [Domain] Research and Development Expense [Member] hrtx_ImpactOnBasicAndDilutedNetLossPerCommonShareInDollarsPerShare Impact on basic and diluted net loss per share (in dollars per share) Impact on basic and diluted net loss per common share in dollars per shar Other comprehensive loss: Restructuring and Related Activities Disclosure [Text Block] Significant Accounting Policies [Text Block] Accounting Policies [Abstract] Statement of Financial Position [Abstract] us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets Prepaid expenses and other current assets Stockholders' Equity Note Disclosure [Text Block] Statement of Cash Flows [Abstract] Domestic Corporate Debt Securities [Member] hrtx_ConvertibleDebtIssuableInConnectionWithPrivatePlacement1 Convertible Debt Issuable in Connection with Private Placement Convertible debt issuable in connection with private placement. us-gaap_AllocatedShareBasedCompensationExpense Share-based compensation expense Restructuring Plan [Member] The plan intended to facilitate the transition of Heron from a research and development company to a late stage clinical development and commercial organization. us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses Available-for-sale Securities, Gross Realized Losses Products and Services [Domain] Products and Services [Axis] Valuation Allowances and Reserves [Table Text Block] Tabular disclosure of a schedule of allowance and reserve accounts where the valuation and qualifying accounts are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs. us-gaap_AvailableForSaleSecuritiesGrossRealizedGains Available-for-sale Securities, Gross Realized Gains Provision Amount of increase in the allowances and reserves, which consist of the valuation and qualifying accounts that are either netted against the cost of an asset or that reflect a liability established to represent expected future costs, from provisions of amounts previously written off or reestablishment of reserves that had previously been utilized. us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised Number of shares exercised (in shares) us-gaap_IncreaseDecreaseInAccountsReceivable Accounts receivable us-gaap_NotesPayableRelatedPartiesNoncurrent Notes Payable, Related Parties, Noncurrent Number of shares granted (in shares) Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Cash, Cash Equivalents, and Short-Term Investments [Policy Text Block] Disclosure of accounting policy regarding cash, cash equivalents and short-term investments. Cash includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the customer may deposit additional funds at any time and effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid Investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Short-term investments, exclusive of cash equivalents, generally consist of marketable securities intended to be sold within one year (or the normal operating cycle if longer) and may include trading securities, available-for-sale securities, or held-to-maturity securities (if maturing within one year), as applicable. us-gaap_StockIssuedDuringPeriodSharesNewIssues Stock Issued During Period, Shares, New Issues us-gaap_DeferredTaxAssetsValuationAllowance Deferred Tax Assets, Valuation Allowance Employee Related Liabilities [Member] Relates to employees who are being retained until the first quarter of 2017 and is being recognized on a straight-line basis over the retention period. us-gaap_LiabilitiesAndStockholdersEquity Total liabilities and stockholders’ equity (deficit) Accumulated deficit Retained Earnings (Accumulated Deficit) Net product sales Accumulated other comprehensive loss us-gaap_PolicyTextBlockAbstract Accounting Policies Accrued clinical liabilities Carrying value as of the balance sheet date of clinical obligations incurred and payable. Foreign Corporate Debt Securities [Member] us-gaap_IncreaseDecreaseInInventories Inventory hrtx_IncreaseDecreaseInClinicalLiabilities Accrued clinical liabilities The increase (decrease) during the reporting period in the aggregate amount of obligations related to clinical liabilities. Allowance for Sales Returns [Member] SUSTOL [Member] Represents the product SUSTOL. us-gaap_DeferredTaxAssetsGross Deferred Tax Assets, Gross Available-for-sale Securities [Table Text Block] Major Types of Debt and Equity Securities [Domain] Statement [Table] Major Types of Debt and Equity Securities [Axis] Allowance for Distributor Fees [Member] A valuation allowance for the amount of distributor fees on products sold. In Case of Debt Conversion [Member] When the debt principal is converted into the underlying securities. Allowance for Rebates and Chargebacks [Member] A valuation allowance for the amount of rebates and chargebacks of products sold. hrtx_DebtInstrumentConvertibleNumberSharesOfEquityInsturments Debt Instrument, Convertible, Number Shares of Equity Insturments The number of shares of equity instruments that the holder of the debt instrument would receive if the debt was converted to equity. Financing activities: Income Statement [Abstract] Class of Stock [Axis] Award Type [Axis] Equity Award [Domain] Private Placement 2011 [Member] Private placement 2011 [member us-gaap_ValuationAllowancesAndReservesBalance Balance Balance us-gaap_ValuationAllowancesAndReservesDeductions Payments/credits Prepaid expenses and other current assets us-gaap_DisclosureTextBlockAbstract Notes to Financial Statements us-gaap_LiabilitiesCurrent Total current liabilities us-gaap_InventoryRawMaterialsNetOfReserves Inventory, Raw Materials, Net of Reserves Revenues: us-gaap_InventoryFinishedGoodsNetOfReserves Inventory, Finished Goods, Net of Reserves Valuation Allowances and Reserves [Domain] Earnings Per Share, Policy [Policy Text Block] Valuation Allowances and Reserves Type [Axis] Fair Value, Measurements, Recurring [Member] us-gaap_PaymentsForProceedsFromInvestments Maturities of short-term investments us-gaap_OperatingExpenses Total operating expenses Comprehensive Income, Policy [Policy Text Block] Fair Value, Measurement Frequency [Domain] Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Measurement Frequency [Axis] Change in operating assets and liabilities: Share-based Compensation, Stock Options, Activity [Table Text Block] General and administrative Dividend yield us-gaap_PaidInKindInterest Paid-in-Kind Interest Risk-free interest rate Volatility us-gaap_OperatingIncomeLoss Loss from operations Deferred revenue Deferred Revenue, Current Expected life (years) (Year) Amendment Flag us-gaap_InventoryWriteDown Inventory Write-down Common stock us-gaap_PaymentsForRestructuring Payments for Restructuring Convertible Debt [Member] Other assets Income Tax Disclosure [Text Block] us-gaap_ShareBasedCompensation Stock-based compensation expense us-gaap_GainLossOnSaleOfPropertyPlantEquipment Loss on disposal of property and equipment Current Fiscal Year End Date us-gaap_InterestExpenseDebtExcludingAmortization Interest Expense, Debt, Excluding Amortization Document Fiscal Period Focus Amortization of debt discount Amortization of Debt Discount (Premium) Document Fiscal Year Focus Document Period End Date us-gaap_AssetImpairmentCharges Asset Impairment Charges us-gaap_RestructuringCharges Restructuring Charges Document Type Number of shares outstanding, weighted average remaining contractual term (Year) Accounts payable Document Information [Line Items] Document Information [Table] Accrued payroll and employee liabilities us-gaap_AssetsCurrent Total current assets Long-term Debt, Type [Axis] Entity Filer Category Entity Current Reporting Status United States Commercial Paper [Member] Unsecured promissory note (generally negotiable) that provides institutions with short-term funds that originates in the United States. Entity Voluntary Filers Long-term Debt, Type [Domain] Entity Well-known Seasoned Issuer us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice Number of shares outstanding, weighted average exercise price (in dollars per share) Number of shares outstanding, weighted average exercise price (in dollars per share) Foreign Commercial Paper [Member] Unsecured promissory note (generally negotiable) that provides institutions with short-term funds that originates in countries outside of the United States. hrtx_AmortizationOfShorttermInvestmentPremium (Accretion of discount) amortization of premium on short-term investments Amount of noncash expense included in interest expense to amortize short-term investment premium associated with the related investments. us-gaap_PaymentsToAcquireAvailableForSaleSecurities Purchases of short-term investments Number of shares expired and forfeited, weighted average exercise price (in dollars per share) Number of shares granted, weighted average exercise price (in dollars per share) us-gaap_DepreciationAndAmortization Depreciation and amortization Other accrued liabilities Number of shares exercised, weighted average exercise price (in dollars per share) Adjustments to reconcile net loss to net cash used for operating activities: Entity Central Index Key Entity Registrant Name Assets, fair value Entity [Domain] Tang Capital [Member] Represents Tang Capital Partners, LP. 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Term Loan [Member] The promissory note entered by the entity classified as a term loan. us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod Number of shares expired and forfeited (in shares) hrtx_ProceedsFromIssuanceOfLongtermDebtSubjectToAchievementOfCorporateMilestone Proceeds from Issuance of Long-term Debt, Subject to Achievement of Corporate Milestone The cash inflow from a debt that is subject to the achievement of a corporate milestone. us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1 Class of Warrant or Right, Exercise Price of Warrants or Rights us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights Class of Warrant or Right, Number of Securities Called by Warrants or Rights Current liabilities: Entity Common Stock, Shares Outstanding (in shares) Interest paid Additional paid-in capital us-gaap_Assets Total assets Cash and money market funds Inventory Inventory, Net Stockholders’ equity (deficit): Revenue Recognition, Policy [Policy Text Block] Trading Symbol us-gaap_PaymentsToAcquirePropertyPlantAndEquipment Purchases of property and equipment Business Description and Basis of Presentation [Text Block] us-gaap_NetIncomeLoss Net loss Net loss us-gaap_StockholdersEquity Total stockholders’ equity (deficit) us-gaap_DebtInstrumentTerm Debt Instrument, Term us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized us-gaap_Liabilities Total liabilities us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1 Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Sales and marketing US Government Agencies Debt Securities [Member] Cost of product sales Cost of Goods Sold Warrant [Member] us-gaap_DebtInstrumentIncreaseDecreaseOtherNet Debt Instrument, Increase (Decrease), Other, Net Operating activities: Antidilutive Securities, Name [Domain] Employee Stock Option [Member] Convertible Debt Securities [Member] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block] Antidilutive Securities [Axis] Accounts receivable, net Statement [Line Items] Research and development us-gaap_CashCashEquivalentsAndShortTermInvestments Cash, Cash Equivalents, and Short-term Investments us-gaap_DebtInstrumentConvertibleBeneficialConversionFeature Debt Instrument, Convertible, Beneficial Conversion Feature us-gaap_InterestExpense Interest Expense Interest expense, net hrtx_StockIssuedDuringPeriodSharesStockOptionsExercisedNet Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Net Number of share options (or share units) exercised during the current period, net of shares retained for cashless exercises. Supplemental disclosure of cash flow information: Unrealized gains (losses) on short-term investments Fair Value Disclosures [Text Block] Current assets: Property and equipment, net Accounting Standards Update 2016-09 [Member] us-gaap_DebtInstrumentInterestRateStatedPercentage Debt Instrument, Interest Rate, Stated Percentage Sale of Stock [Domain] us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease Net increase (decrease) in cash and cash equivalents us-gaap_TableTextBlock Notes Tables Sale of Stock [Axis] us-gaap_DebtInstrumentFeeAmount Debt Instrument, Fee Amount us-gaap_DebtInstrumentFaceAmount Debt Instrument, Face Amount us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations Net cash provided by financing activities us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations Net cash (used for) provided by investing activities Inventory, Policy [Policy Text Block] us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations Net cash (used for) provided by operating activities