Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Current Current Foreign Tax Expense (Benefit) Estimated lease payments Total Lessee, Operating Lease, Liability, to be Paid Net loss including noncontrolling interest Net loss Net loss including noncontrolling interest Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Variable Interest Entity, Primary Beneficiary Variable Interest Entity, Primary Beneficiary [Member] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Total State State and Local Income Tax Expense (Benefit), Continuing Operations Property, Plant and Equipment [Abstract] Property, Plant and Equipment [Abstract] Technology License Commitments Technology License Commitments [Member] Technology license commitments. Preferred stock, shares outstanding (in shares) Preferred Stock, Shares Outstanding Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Milestone payment receivable at start of phase two Milestone Payment Receivable At Start Of Phase Two Milestone payment receivable at start of phase two. Net loss (gain) from investments Gain (Loss) on Investments Total gross fixed assets Property, Plant and Equipment, Gross Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss [Abstract] Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss [Abstract] Fixed Assets Deferred Tax Liabilities, Property, Plant and Equipment Tax increment financing award Tax Increment Financing Award Tax Increment Financing Award Financial Instruments [Domain] Financial Instruments [Domain] Statistical Measurement [Domain] Statistical Measurement [Domain] Exercise of stock options (in shares) Exercised (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period Net deferred tax assets (liabilities) Deferred Tax Assets, Net Weighted-average discount rate Operating Lease, Weighted Average Discount Rate, Percent Share-based Payment Arrangement [Abstract] Share-Based Payment Arrangement [Abstract] Additional paid-in capital Additional Paid in Capital, Common Stock Current Current State and Local Tax Expense (Benefit) Net loss attributable to Arrowhead Pharmaceuticals, Inc. Net Income (Loss) Attributable to Parent Lessee Lease Description [Table] Lessee, Lease, Description [Table] Debt securities Debt Securities [Member] Subsequent Event Type Subsequent Event Type [Axis] Cash received as due under collaboration agreement Cash Received As Due Under Collaboration Agreement Cash received as due under collaboration agreement. Other Effective Income Tax Rate Reconciliation, Other Adjustments, Percent 2028 and thereafter Lessee, Operating Lease, Liability, to be Paid, after Year Five Equity Component Equity Component [Domain] Subsequent Event Type Subsequent Event Type [Domain] Net loss per share attriutable to Arrowhead Pharmaceuticals, Inc.: Earnings Per Share Reconciliation [Abstract] Additional office space for lease (in sq ft) Additional Land Subject To Lease Additional land subject to lease. Leases Lessee, Operating Leases [Text Block] Restricted Stock Units, Market-Based Restricted Stock Units, Market-Based [Member] Restricted Stock Units, Market-Based Lessee Lease Description [Line Items] Lessee, Lease, Description [Line Items] Plan Name Plan Name [Axis] Marketable debt securities, Fair Value Marketable debt securities Debt Securities, Available-for-Sale A R O H S D Agreement A R O H S D Agreement [Member] AROHSD agreement. Common stock shares value reserved for future issuance Common Stock Capital Shares Value Reserved For Future Issuance Common stock, capital shares value reserved for future issuance. Supplementary disclosures: Supplemental Cash Flow Information [Abstract] Unrecognized pre-tax compensation expense Share-Based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount Plan Name Plan Name [Domain] Total long-term liabilities Liabilities, Noncurrent Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Entity Address, State or Province Entity Address, State or Province Level 1 Fair Value, Inputs, Level 1 [Member] Weighted-Average Remaining Contractual Term, Outstanding Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Award Type Award Type [Axis] 2013 Plan Two Thousands Thirteen Incentive Plan [Member] Two thousands thirteen incentive plan. Planned area of site (in sq ft) Area of Land Net cash (used in) provided by operating activities Net Cash Provided by (Used in) Operating Activities Sales-related milestone payments Sales Related Milestone Payments Sales-related milestone payments. Contingent Consideration Contingent Consideration Policy [Policy Text Block] Disclosure of accounting policy for contingent consideration obligations related to acquisitions. Lease liabilities Operating Lease, Liability, Current Cancelled (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Expirations in Period Collaborative Arrangement Collaborative Arrangement, Accounting Policy [Policy Text Block] Lease Cost Lease, Cost [Abstract] Number of shares forfeited (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Forfeitures in Period Other Commitments [Domain] Other Commitments [Domain] Document Annual Report Document Annual Report Legal Entity [Axis] Legal Entity [Axis] Certificate of deposits Certificates of Deposit [Member] Number of distinct performance obligations Number Of Distinct Performance Obligations Number of distinct performance obligations. Percentage of commission to sales agent Percentage Of Commission On Aggregate Gross Proceeds From Sale Of Common Stock Percentage of commission on aggregate gross proceeds from sale of common stock. Weighted-average remaining lease term (in years) Operating Lease, Weighted Average Remaining Lease Term Share Based Compensation Arrangement By Share Based Payment Award [Line Items] Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] Geographical Geographical [Axis] CASH FLOWS FROM INVESTING ACTIVITIES: Net Cash Provided by (Used in) Investing Activities [Abstract] Amortization of note premiums Investment Income, Net, Amortization of Discount and Premium Commercial notes Commercial Notes [Member] Commercial Notes Common stock - issued for cash Stock Issued During Period, Value, New Issues Operating Leased Assets [Line Items] Operating Leased Assets [Line Items] Entity Common Stock Shares Outstanding Entity Common Stock, Shares Outstanding Fair Value Hierarchy and NAV Fair Value Hierarchy and NAV [Domain] Performance-Based Restricted Stock Units Restricted Stock Units, Performance-Based [Member] Restricted Stock Units, Performance-Based Summary of Property and Equipment Property, Plant and Equipment [Table Text Block] Revenue Recognition Revenue from Contract with Customer [Policy Text Block] Preferred stock, shares issued (in shares) Preferred Stock, Shares Issued Document Type Document Type Weighted- Average Exercise Price Per Share Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Office space leases (in sq ft) Land Subject to Ground Leases Property and equipment, useful life Property, Plant and Equipment, Useful Life Number of RSUs Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Finite-Lived Intangible Assets, Major Class Name Finite-Lived Intangible Assets, Major Class Name [Domain] Research Facility in San Diego Research Facility In San Diego [Member] Research Facility in San Diego. Development regulatory and sales milestones payments Development, regulatory and sales milestones payments Development Regulatory And Sales Milestones Payments Development regulatory and sales milestones payments. Beginning balance (in dollars per share) Ending balance (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Employee Benefit Plans Compensation and Employee Benefit Plans [Text Block] Asset Acquisition Asset Acquisition [Axis] Entity Shell Company Entity Shell Company Deferred Deferred Income Tax Expense (Benefit) Accrued expenses Increase (Decrease) in Accrued Liabilities Total Foreign Foreign Income Tax Expense (Benefit), Continuing Operations 2023 Lessee, Operating Lease, Liability, to be Paid, Year One Financial Instrument [Axis] Financial Instrument [Axis] Summary of Short-term, Long-term Investments and Marketable Securities Held To Maturity Securities And Marketable Securities Table [Table Text Block] Held to maturity securities and marketable securities. Subsequent Event Subsequent Event [Member] Document Period End Date Document Period End Date Computers, software, office equipment and furniture Furniture and Fixtures, Gross Total Assets Assets Income Statement Location [Axis] Income Statement Location [Axis] Shares issued Shares, Issued Accrued expenses Accrued Liabilities, Current Exercised (in dollars per share) Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price 2027 Lessee, Operating Lease, Liability, to be Paid, Year Five Net cash provided by financing activities Net Cash Provided by (Used in) Financing Activities Accounting Policies [Abstract] Accounting Policies [Abstract] Accrued payroll and benefits Employee-related Liabilities, Current Variable lease cost Variable Lease, Cost Other Commitments [Axis] Other Commitments [Axis] Loss before income tax expense and noncontrolling interest Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Cash received as due under collaboration agreement Cash Receivable As Upfront Payment Due Under Collaboration Agreement Cash receivable as upfront payment due under collaboration agreement. Valuation allowance against deferred tax assets Percentage Of Valuation Allowance Percentage of valuation allowance. Assumptions Used to Value Stock Options Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Schedule of Company's Current Pipeline Schedule of Current Products [Table Text Block] Schedule of Current Products Federal: Federal Income Tax Expense (Benefit), Continuing Operations [Abstract] Janssen Janssen Pharmaceuticals Incorporation [Member] Janssen Pharmaceuticals, Incorporation. Operating lease liabilities Increase (Decrease) in Operating Lease Liability Comprehensive loss Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Provisions for Income Taxes Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Award Type Award Type [Domain] Valuation allowance Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent Weighted average period to recognize pre-tax compensation expense Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Weighted-Average Remaining Contractual Term, Exercisable Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Schedule of Finite-Lived Intangible Assets Schedule of Finite-Lived Intangible Assets [Table Text Block] Common stock - restricted stock units vesting Stock Issued During Period, Value, Restricted Stock Award, Gross Initial transaction price Initial Transaction Price Initial transaction price. Entity Registrant Name Entity Registrant Name Common stock - issued for cash (in shares) Stock Issued During Period, Shares, New Issues Subsequent Events Subsequent Events [Text Block] Expected dividend yield Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Dividend Rate Deconsolidation of Ablaris Therapeutics, Inc. Noncontrolling Interest, Increase From Deconsolidation Noncontrolling Interest, Increase From Deconsolidation Patents Patents [Member] Audit Information [Abstract] Audit Information Entity Address, City or Town Entity Address, City or Town Commercial milestone payments at first commercial sale Commercial Milestone Payments At First Commercial Sale Commercial milestone payments at first commercial sale. Leases [Abstract] Leases [Abstract] Operating expenses: Operating Expenses [Abstract] Total noncontrolling interest and stockholders' equity Beginning balance Ending balance Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Net Operating Losses Deferred Tax Assets, Operating Loss Carryforwards Minimum Minimum [Member] Restricted cash Restricted Cash and Cash Equivalents, Current Noncontrolling interest Stockholders' Equity Attributable to Noncontrolling Interest Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Entity Emerging Growth Company Entity Emerging Growth Company Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Olpasiran and ARO-AMG1 Agreement Olpasiran And A R O A M G1 Agreement [Member] Olpasiran and ARO-AMG1 agreement. Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Auditor Name Auditor Name Fair Value Measurements Fair Value Disclosures [Text Block] Additional remaining development regulatory and sales milestones payments Additional Remaining Development Regulatory And Sales Milestones Payments Additional remaining development regulatory and sales milestones payments. 2021 Plan Two Thousand Twenty One Incentive Plan [Member] Two thousand twenty one incentive plan. Trading Symbol Trading Symbol Entity File Number Entity File Number Intangible Assets Intangible Assets Disclosure [Text Block] 2026 Finite-Lived Intangible Asset, Expected Amortization, Year Four Deferred revenue, net of current portion Contract with Customer, Liability, Noncurrent Leasehold improvements Leasehold Improvements, Gross Increase for prior period tax positions Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions Deferred Deferred Foreign Income Tax Expense (Benefit) Title of Individual [Axis] Title of Individual [Axis] Granted (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period Restricted Stock Units (RSUs) Restricted Stock Units (RSUs) [Member] Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Money market instruments Cash and Cash Equivalents, Fair Value Disclosure License Agreement License Agreement [Member] License agreement. Proceeds from investment in joint venture Proceeds from upfront capital Proceeds from Contributed Capital Accounts payable Increase (Decrease) in Accounts Payable Visirna Therapeutics, Inc. Visirna Therapeutics, Inc. [Member] Visirna Therapeutics, Inc. Organization and Significant Accounting Policies Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Text Block] Milestone payment Milestone Payment Earned Milestone payment earned. Subsequent Events [Abstract] Subsequent Events [Abstract] Volatility, maximum Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum Long-term investments, Held to maturity, Fair Value Debt Securities, Held-to-Maturity, Fair Value, Noncurrent Investments Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Income Taxes Income Tax Disclosure [Text Block] Deferred Deferred State and Local Income Tax Expense (Benefit) Amortization expense Amortization of Intangible Assets Interest paid Interest Paid, Excluding Capitalized Interest, Operating Activities Basic (in dollars per share) Earnings Per Share, Basic 2025 Lessee, Operating Lease, Liability, to be Paid, Year Three Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] State taxes Deferred Tax Liabilities State Taxes Amount of deferred tax liability attributable to taxable temporary differences from state tax deductions. Construction in progress Construction in Progress, Gross Schedule Of Held To Maturity Securities And Marketable Securities [Table] Schedule Of Held To Maturity Securities And Marketable Securities [Table] Schedule of held to maturity securities and marketable securities. Capitalized Research & Development Deferred Tax Assets In Process Research And Development Cost Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from in-process research and development costs. Short-term investments Short-term investments, Held to maturity, Adjusted Bases Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss, Current Counterparty Name Counterparty Name [Domain] Olpasiran Agreement Olpasiran Agreement [Member] Olpasiran agreement. Total Arrowhead Pharmaceuticals, Inc. stockholders' equity Stockholders' Equity Attributable to Parent Prepaid expenses Prepaid Expense, Current Foreign: Foreign Income Tax Expense (Benefit), Continuing Operations [Abstract] Forfeited (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Entity Interactive Data Current Entity Interactive Data Current Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Milestone payment receivable upon achievement of phase two and first patient dosed in phase three Milestone Payment Receivable Upon Achievement Of Phase Two And First Patient Dosed In Phase Three Milestone payment receivable upon achievement of phase two and first patient dosed in phase three. Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] 2025 Finite-Lived Intangible Asset, Expected Amortization, Year Three Money market instruments Money Market Funds [Member] Proceeds from sale of marketable debt securities Proceeds from Sale of Debt Securities, Available-for-Sale Drug Manufacturing Facility Drug Manufacturing Facility [Member] Drug manufacturing facility. Accumulated Deficit Retained Earnings [Member] Unrecognized pre-tax compensation expense Share-Based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount California Alternative Minimum Tax Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax 2004 Equity Incentive Plan, 2013 Equity Incentive Plan, 2021 Equity Incentive Plan and Inducement Grants Two Thousand Four Equity Incentive Plan Two Thousand Thirteen Equity Incentive Plan Two Thousand Twenty One Equity Incentive Plan And Inducement Grants [Member] Two thousand four equity incentive plan two thousand thirteen equity incentive plan Two thousand twenty one equity incentive plan and inducement grants. Right of Use Assets/Lease Liabilities Deferred Tax Assets Right Of Use Assets Or Lease Liabilities Deferred tax assets right of use assets/ lease liabilities. Total Lease, Cost Collaboration And License Agreements [Abstract] Collaboration And License Agreements [Abstract] Collaboration and license agreements. NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect Amount insured in FDIC per account Cash, FDIC Insured Amount Common Stock Common Stock [Member] Schedule of Lease Assets and Liabilities and Lease Cost Lease, Cost [Table Text Block] Common stock reserved for issuance (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant Income Taxes Income Tax, Policy [Policy Text Block] Statement [Table] Statement [Table] Vested (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Operating lease renewal term Lessee, Operating Lease, Renewal Term Schedule Of Held To Maturity Securities And Marketable Securities [Line Items] Schedule Of Held To Maturity Securities And Marketable Securities [Line Items] Schedule of held to maturity securities and marketable securities. Current assets: Assets, Current [Abstract] Payments for leasehold improvements, net of tenant improvement allowances Payments Of Leasehold Improvements Net Of Tenant Improvement Allowances Payments of leasehold improvements net of tenant improvement allowances. Lease liabilities, net of current portion Operating Lease, Liability, Noncurrent Organization And Significant Accounting Policies [Table] Organization And Significant Accounting Policies [Table] Organization and significant accounting policies. Employee benefits costs Defined Contribution Plan, Cost Statistical Measurement [Axis] Statistical Measurement [Axis] Asset Acquisition Asset Acquisition [Domain] Accumulated deficit Retained Earnings (Accumulated Deficit) Accounts receivable Accounts Receivable, after Allowance for Credit Loss, Current Schedule Of Finite Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Common Stock Equity Components [Axis] Fair Value, Measurements, Recurring Fair Value, Recurring [Member] Weighted-Average Exercise Price Per Share, Exercisable (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Weighted Average Exercise Price Cancelled (in dollars per share) Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Expirations in Period, Weighted Average Exercise Price Interest income, net Interest Income (Expense), Nonoperating, Net Document Fiscal Year Focus Document Fiscal Year Focus Number of options to renew Number Of Options To Renew Number of options to renew. Takeda License Agreement Takeda Pharmaceuticals United States Of America Incorporated [Member] Takeda Pharmaceuticals United States of America Incorporated. CASH FLOWS FROM OPERATING ACTIVITIES: Net Cash Provided by (Used in) Operating Activities [Abstract] Statement [Line Items] Statement [Line Items] Share-based payment award (in shares) Beginning of period (in shares) End of period (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number Short-term investments, Held to maturity, Fair Value Debt Securities, Held-to-Maturity, Fair Value, Current Total other income Nonoperating Income (Expense) Fair Value Hierarchy and NAV Fair Value Hierarchy and NAV [Axis] Gross Carrying Amount Finite-Lived Intangible Assets, Gross Unrecognized tax benefits, penalties related to uncertain tax positions Unrecognized Tax Benefits, Income Tax Penalties Expense California CALIFORNIA Current Current Income Tax Expense (Benefit) Marketable debt securities, Gross Unrealized Losses Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax Right-of-use assets Operating Lease, Right-of-Use Asset Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Horizon Therapeutics Ireland DAC Horizon Therapeutics Ireland D A C [Member] Horizon Therapeutics Ireland DAC. Auditor Firm ID Auditor Firm ID Document Transition Report Document Transition Report Local Phone Number Local Phone Number Summarized Information about Stock Options Share-Based Payment Arrangement, Option, Activity [Table Text Block] Operating loss Operating Income (Loss) Summary of Awards Outstanding Share-Based Payment Arrangement, Activity [Table Text Block] Upfront milestone payment received Upfront Milestone Payment Received Upfront milestone payment received. Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Stock Compensation Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-Based Compensation Cost Milestone payments Milestone Payments Milestone payments. Prepaid expenses and other current assets Increase (Decrease) in Prepaid Expense and Other Assets Weighted-average shares used in calculating Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Long-Lived Tangible Asset Long-Lived Tangible Asset [Axis] Interest in joint venture Noncontrolling Interest, Increase from Subsidiary Equity Issuance Adjustments to reconcile net loss to net cash flow from operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Income tax expense Income tax provision Income Tax Expense (Benefit) Geographical Geographical [Domain] Valuation allowance Deferred Tax Assets, Valuation Allowance Schedule Of Collaborative Arrangements And Noncollaborative Arrangement Transactions [Table] Collaborative Arrangement and Arrangement Other than Collaborative [Table] Property and Equipment Property, Plant and Equipment, Policy [Policy Text Block] Preferred stock, par value (in dollars per share) Preferred Stock, Par or Stated Value Per Share 2026 Lessee, Operating Lease, Liability, to be Paid, Year Four Income Statement [Abstract] Income Statement [Abstract] Granted (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross Entity Public Float Entity Public Float Deferred Deferred Federal Income Tax Expense (Benefit) Additional Paid-In Capital Additional Paid-in Capital [Member] License Licensing Agreements [Member] Balance Sheet Location Balance Sheet Location [Domain] Document Fiscal Period Focus Document Fiscal Period Focus Intrinsic value of options exercised Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period, Intrinsic Value Diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Volatility, minimum Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum Less: Accumulated depreciation and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Expected term (in years) Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Term Collaborative Arrangement and Arrangement Other than Collaborative [Domain] Collaborative Arrangement and Arrangement Other than Collaborative [Domain] Novartis Novartis [Member] Novartis. ICFR Auditor Attestation Flag ICFR Auditor Attestation Flag Short-term investments, Held to maturity, Gross Unrealized Losses Debt Securities, Held-to-Maturity, Accumulated Unrecognized Loss, Current Debt Securities, Held-to-Maturity, Accumulated Unrecognized Loss, Current Common stock, $0.001 par value: Authorized 145,000 shares; issued and outstanding 105,960 and 104,327 shares Common Stock, Value, Issued Outside Of Equity Compensation Plans Outside Of Equity Compensation Plans [Member] Outside of equity compensation plans. Net increase (decrease) in cash and investments Increase Decrease In Cash And Investments Increase decrease in cash and investments. License and Co-Funding Agreement License And Co Funding Agreement [Member] License and co-funding agreement. Granted (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Common stock - restricted stock units vesting (in shares) Stock Issued During Period, Shares, Restricted Stock Award, Gross Fair Value Measurements for Assets and Liabilities Measured at Fair Value on Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Aggregate Intrinsic Value, Exercisable Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Intrinsic Value Short-term lease cost Short-Term Lease, Cost Preferred stock, shares authorized (in shares) Preferred Stock, Shares Authorized Intangible assets subject to amortization, impairment Impairment of Intangible Assets, Finite-Lived Cash, cash equivalents and restricted cash CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD CASH AND CASH EQUIVALENTS AT END OF PERIOD Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents Foreign currency translation adjustments Foreign currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Organization And Significant Accounting Policies [Line Items] Organization And Significant Accounting Policies [Line Items] Organization and significant accounting policies. ATM Agreement At The Market Agreement [Member] At-the-market agreement. Corporate Headquarters In Pasadena Corporate Headquarters In Pasadena [Member] Corporate Headquarters in Pasadena Net loss attributable to noncontrolling interest, net of tax Net Income (Loss) Attributable to Noncontrolling Interest Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Current liabilities: Liabilities, Current [Abstract] Proceeds from the exercises of stock options Proceeds from Stock Options Exercised Common stock, shares issued (in shares) Common Stock, Shares, Issued Deferred revenue Contract liabilities Contract with Customer, Liability, Current Percentage of compensation Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay Collaboration Agreement Collaboration Agreement [Member] Collaboration agreement. Number of distinct bundle Number Of Distinct Bundle Number of distinct bundle. Retirement Plan Type [Domain] Retirement Plan Type [Domain] Income Statement Location [Domain] Income Statement Location [Domain] Royalty payment threshold Royalty Payment Threshold Royalty Payment Threshold 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] Amendment Flag Amendment Flag Facilities Facilities [Member] Facilities. Useful Lives Finite-Lived Intangible Asset, Useful Life Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Operating lease cost Operating Lease, Cost Gross federal net operating loss carry forwards Federal Net Operating Loss Carry Forward Federal net operating loss carry forward. ARO-XDH A R O X D H Agreement [Member] ARO-XDH Agreement. Investments Investment, Policy [Policy Text Block] Stock compensation Effective Income Tax Rate Reconciliation Deductions Stock Compensation Percent Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to stock compensation. Marketable debt securities, Gross Unrealized Gains Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax Basis of Presentation and Use of Estimates Basis Of Presentation And Use Of Estimates Policy [Policy Text Block] Basis of presentation and use of estimates. Entity Current Reporting Status Entity Current Reporting Status Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Disclosure [Abstract] Other assets Other Assets, Noncurrent Intangible Assets subject to amortization Goodwill and Intangible Assets, Policy [Policy Text Block] Number of Options Outstanding, Exercisable (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Number Depreciation and amortization expense for property and equipment Depreciation, Depletion and Amortization Royalty Pharma Agreement Royalty Pharma Agreement [Member] Royalty Pharma Agreement Chief Executive Officer Chief Executive Officer [Member] At U.S. federal statutory rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Thereafter Finite-Lived Intangible Asset, Expected Amortization, after Year Five Common Stock Purchase Agreement Common Stock Purchase Agreement [Member] Common stock purchase agreement. Lease term Lessee, Operating Lease, Term of Contract Counterparty Name Counterparty Name [Axis] Options (in shares) Beginning balance (in shares) Ending balance (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number Cash and Cash Equivalents [Axis] Cash and Cash Equivalents [Axis] Janssen Janssen Pharmaceuticals And Johnson And Johnson Innovation J J D C Incorporation [Member] Janssen Pharmaceuticals and Johnson And Johnson Innovation JJDC Incorporation. Capital Loss Deferred Tax Assets, Capital Loss Carryforwards Schedule Of Stock By Class [Table] Schedule of Stock by Class [Table] Entity Incorporation State Country Code Entity Incorporation, State or Country Code State taxes, net of federal effect Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items] Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] EFFECT OF EXCHANGE RATE ON CASH AND CASH EQUIVALENTS Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Continuing Operations Property and equipment, net Property and equipment, net Property, Plant and Equipment, Net Verona Technology Park Verona Technology Park [Member] Verona technology park. Operating cash flows from operating leases Operating Lease, Payments Schedule of Intangible Assets Future Amortization Expense Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Lease Assets and Liabilities Assets and Liabilities, Lessee [Abstract] Employee Stock Option Share-Based Payment Arrangement, Option [Member] Amgen Amgen Incorporated [Member] Amgen Incorporated. Title of Individual [Domain] Title of Individual [Domain] Exercise of stock options Stock Issued During Period, Value, Stock Options Exercised Forfeited (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeited in Period Other income (expense), net Other Nonoperating Income (Expense) Balance Sheet Location Balance Sheet Location [Axis] Fair value of contingent consideration obligation due to discontinuation of clinical trials Business Combination, Contingent Consideration, Liability, Noncurrent Common stock, shares authorized (in shares) Common Stock, Shares Authorized Total operating expenses Operating Expenses Maximum Maximum [Member] Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Cash and Cash Equivalents and Restricted Cash Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Deferred revenue Increase (Decrease) in Contract with Customer, Liability Total current assets Assets, Current Income Taxes (Paid) Refunded Income Taxes Paid, Net Entity Small Business Entity Small Business State: State and Local Income Tax Expense (Benefit), Continuing Operations [Abstract] Other Commitments [Table] Other Commitments [Table] Beginning balance (in shares) Ending balance (in shares) Shares, Outstanding Measurement Frequency Measurement Frequency [Domain] Stockholders' Equity Stockholders' Equity Note Disclosure [Text Block] Deferred Revenue Deferred Revenue [Member] Deferred revenue. Intangible assets, net Net Carrying Amount Finite-Lived Intangible Assets, Net Shares Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding [Roll Forward] Property and Equipment Property, Plant and Equipment Disclosure [Text Block] Milestone payment receivable upon FDA approval Milestone Payment Receivable Upon FDA Approval Milestone Payment Receivable Upon FDA Approval Variable Interest Entity Consolidation, Variable Interest Entity, Policy [Policy Text Block] Aggregate Intrinsic Value, Outstanding Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Intrinsic Value Long-Lived Tangible Asset Long-Lived Tangible Asset [Domain] Milestone payment receivable upon achievement of enrollment in phase 3 clinical trial Milestone Payment Receivable Upon Achievement of Enrollment in Phase 3 Clinical Trial Milestone Payment Receivable Upon Achievement of Enrollment in Phase 3 Clinical Trial Accounts receivable Increase (Decrease) in Accounts Receivable Security12b Title Title of 12(b) Security Schedule Of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Proceeds from sale of investments Proceeds from Sale, Maturity and Collection of Investments Consolidated Entities [Axis] Consolidated Entities [Axis] Total Federal Federal Income Tax Expense (Benefit), Continuing Operations Schedule of Gross Unrecognized Tax Benefits Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block] Impairment Finite-Lived Intangible Assets, Impairment Finite-Lived Intangible Assets, Impairment Subsequent Event [Line Items] Subsequent Event [Line Items] Class Of Stock [Line Items] Class of Stock [Line Items] Total operating lease liabilities Operating Lease, Liability Land Land Milestone payments Milestone Payment Received Milestone payment received. Stock-Based Compensation Share-Based Payment Arrangement [Policy Text Block] 2004 Plan Two Thousands Four Equity Incentive Plan [Member] Two thousands four equity incentive plan. 2024 Finite-Lived Intangible Asset, Expected Amortization, Year Two Research equipment Research Equipment Gross Research equipment gross. ARO-XDH Supply Agreement A R O X D H Supply Agreement [Member] ARO-XDH supply agreement. LIABILITIES, NONCONTROLLING INTEREST AND STOCKHOLDERS’ EQUITY Liabilities and Equity [Abstract] Granted (in dollars per share) Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Percentage of eligible to receive tiered royalties on net sales Percentage Of Eligible To Receive Tiered Royalties On Net Sales Percentage of eligible to receive tiered royalties on net sales. Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table] Fair Value, Recurring and Nonrecurring [Table] Marketable debt securities, Adjusted Basis Debt Securities, Available-for-Sale, Amortized Cost Employee Contributions up to 3% Employee Contributions Up To Three Percent [Member] Employee contributions up to three percent. Land purchased (in acres) Number Of Acres Of Land Purchased Number of acres of land purchased. Deferred tax assets: Deferred Tax Assets, Net [Abstract] Accounts payable Accounts Payable, Current Other comprehensive loss, net of tax: Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Employee Contributions Next 2% Employee Contribution Next Two Percent [Member] Employee contribution next two percent. Auditor Location Auditor Location Entity Filer Category Entity Filer Category Proceeds from the issuance of common stock Proceeds from Issuance of Common Stock Basic (in shares) Weighted Average Number of Shares Outstanding, Basic Noncontrolling interest and stockholders' equity: Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Total (in shares) Share-Based Compensation Arrangement By Share-Based Payment Award, Options And Equity Instruments Other Than Options, Outstanding Share-Based Compensation Arrangement By Share-Based Payment Award, Options And Equity Instruments Other Than Options, Outstanding Current Current Federal Tax Expense (Benefit) Contingent liabilities Loss Contingency Accrual Stock-based compensation expense Share-Based Payment Arrangement, Expense Long-term investments, Held to maturity, Gross Unrealized Losses Debt Securities, Held-to-Maturity, Accumulated Unrecognized Loss, Noncurrent Debt Securities, Held-to-Maturity, Accumulated Unrecognized Loss, Noncurrent Commitments and contingencies (Note 7) Commitments and Contingencies Security Exchange Name Security Exchange Name Beginning balance (in dollars per share) Ending balance (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price General and administrative expense General and Administrative Expense [Member] Revenue Revenues Revenue from Contract with Customer, Excluding Assessed Tax GSK Glaxosmithkline Intellectual Property Limited [Member] Glaxosmithkline Intellectual Property Limited. Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Schedule of Operating Leased Assets [Table] Schedule of Operating Leased Assets [Table] Discretionary match percentage Defined Contribution Plan, Employer Matching Contribution, Percent of Match Colorado Owner, LLC Colorado Owner L L C [Member] Colorado Owner, LLC. Shares reserve for issuance (in shares) Common Stock, Capital Shares Reserved for Future Issuance Long-term liabilities: Liabilities, Noncurrent [Abstract] Cover [Abstract] Cover [Abstract] Leases Lessee, Leases [Policy Text Block] Level 3 Fair Value, Inputs, Level 3 [Member] Number of agreements Number Of Agreements Number of agreements. Entity Voluntary Filers Entity Voluntary Filers Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Stock-Based Compensation Share-Based Payment Arrangement [Text Block] Held to maturity securities Debt Securities, Held-to-Maturity, Fair Value Short-term investments, Held to maturity, Gross Unrealized Gains Debt Securities, Held-to-Maturity, Accumulated Unrecognized Gain, Current Debt Securities, Held-to-Maturity, Accumulated Unrecognized Gain, Current J N J3989 A R O H B V Agreement J N J3989 A R O H B V Agreement [Member] JNJ-3989 (ARO-HBV) Agreement. Deferred Revenue Deferred Tax Assets, Deferred Income Long-term investments Long-term investments, Held to maturity, Adjusted Basis Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss, Noncurrent U.S. government bonds US Government Debt Securities [Member] Non- controlling Interest Noncontrolling Interest [Member] Documents Incorporated by Reference Documents Incorporated by Reference [Text Block] Total Liabilities, Noncontrolling Interest and Stockholders' Equity Liabilities and Equity Components of the Net Deferred Tax Assets and Liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Collaborative Arrangement and Arrangement Other than Collaborative [Axis] Collaborative Arrangement and Arrangement Other than Collaborative [Axis] State income tax credits Effective Income Tax Rate Reconciliation, Tax Credit, Amount Intangible Assets Deferred Tax Assets, Goodwill and Intangible Assets ARO-ENaC and ARO-HIF2 Candidates A R O E Nac And A R O H I F2 Candidates [Member] ARO-ENac and ARO-HIF2 Candidates. Total gross deferred tax assets Deferred Tax Assets, Gross Level 2 Fair Value, Inputs, Level 2 [Member] Purchases of investments Payments to Acquire Investments Current Fiscal Year End Date Current Fiscal Year End Date Amount intends to invest for buildout of facilities Amount Intends To Invest For Buildout Of Facilities Amount intends to invest for buildout of facilities. Less imputed interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Marketable securities Marketable Securities, Current Finite Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Diluted (in dollars per share) Earnings Per Share, Diluted Sale of Stock Sale of Stock [Domain] Unrecognized tax benefits, interest related to uncertain tax positions Unrecognized Tax Benefits, Interest on Income Taxes Expense Schedule of Shares of Common Stock and Preferred Stock Schedule of Stock by Class [Table Text Block] Stock-based compensation APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Milestone payment receivable upon receipt of royalty payments Milestone Payment Receivable, Upon Receipt Of Royalty Payments Milestone Payment Receivable, Upon Receipt Of Royalty Payments Total current liabilities Liabilities, Current Risk-free interest rate, minimum Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum 2024 Lessee, Operating Lease, Liability, to be Paid, Year Two Other current assets Other Assets, Current Unrecognized tax benefits Beginning balance of unrecognized tax benefits Ending balance of unrecognized tax benefits Unrecognized Tax Benefits Total: Income Tax Expense (Benefit), Continuing Operations [Abstract] Summary of Share Activity Related to RSUs Share-Based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block] Collaboration and License agreements Collaboration And License Agreement [Member] Collaboration and license agreements. Corporate debt securities Corporate Debt Securities [Member] Other income (expense): Nonoperating Income (Expense) [Abstract] Risk-free interest rate, maximum Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Maximum Summary of Maturities of Operating Lease Liabilities on an Undiscounted Basis Lessee, Operating Lease, Liability, Maturity [Table Text Block] Entity Address, Address Line Two Entity Address, Address Line Two Entity Address, Address Line One Entity Address, Address Line One JNJ-75220795 (ARO-JNJ1) J N J75220795 A R O J N J1 [Member] JNJ 75220795 ARO JNJ1. Gross state net operating loss carry forwards State Net Operating Loss Carry Forwards State net operating loss carry forwards. Deferred tax liabilities: Deferred Tax Liabilities, Net [Abstract] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Retirement Plan Type [Axis] Retirement Plan Type [Axis] Cash and Cash Equivalents [Domain] Cash and Cash Equivalents [Domain] Equity [Abstract] Equity [Abstract] Subsequent Event [Table] Subsequent Event [Table] Vested (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period Entity Tax Identification Number Entity Tax Identification Number Number of shares authorized (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized Milestone payment receivable Milestone Payment Receivable Milestone Payment Receivable Wisconsin WISCONSIN JJDC Johnson And Johnson Innovation J J D C Incorporation [Member] Johnson and Johnson Innovation-JJDC, Incorporation. Equity award value Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Granted in Period, Fair Value Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Granted in Period, Fair Value Accrued Compensation Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits Total gross deferred tax liability Deferred Tax Liabilities, Gross Contract assets Contract with Customer, Asset, after Allowance for Credit Loss, Current Consolidated Entities [Domain] Consolidated Entities [Domain] Research and development Research and Development Expense (Excluding Acquired in Process Cost) Summary of Effective Income Tax Rate Reconciliation Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Accrued Expenses Accrued Liabilities [Member] 2027 Finite-Lived Intangible Asset, Expected Amortization, Year Five Entity Central Index Key Entity Central Index Key Estimated payments for operating expenses year one Estimated Payments For Operating Expenses Year One Estimated payments for operating expenses year one. Measurement Frequency Measurement Frequency [Axis] Research and Development Research and Development Expense, Policy [Policy Text Block] Weighted- Average Grant Date Fair Value Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Finite-Lived Intangible Assets by Major Class Finite-Lived Intangible Assets by Major Class [Axis] Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table] Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Collaboration and License Agreements Collaborative Arrangement Disclosure [Text Block] Concentration of Credit Risk Concentration Risk, Credit Risk, Policy [Policy Text Block] Entity [Domain] Entity [Domain] City Area Code City Area Code General and administrative General and Administrative Expense ASSETS Assets [Abstract] Retirement Benefits [Abstract] Retirement Benefits [Abstract] Other Commitments [Line Items] Other Commitments [Line Items] Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Sale of Stock Sale of Stock [Axis] Laboratory And Office Facility Laboratory And Office Facility [Member] Laboratory and office facility. CASH FLOWS FROM FINANCING ACTIVITIES: Net Cash Provided by (Used in) Financing Activities [Abstract] Earnings per Share Earnings Per Share, Policy [Policy Text Block] Stock-based compensation Share-Based Payment Arrangement, Noncash Expense Weighted-average grant date fair value per share Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Research Facility in Madison Research Facility In Madison [Member] Research facility in Madison. Long-term investments, Held to maturity, Gross Unrealized Gains Debt Securities, Held-to-Maturity, Accumulated Unrecognized Gain, Noncurrent Debt Securities, Held-to-Maturity, Accumulated Unrecognized Gain, Noncurrent Other Increase (Decrease) in Other Operating Liabilities Purchases of property and equipment Payments to Acquire Property, Plant, and Equipment Research and development Research and Development Expense [Member] 2023 Finite-Lived Intangible Asset, Expected Amortization, Year One