Stock repurchase program, authorized amount Stock Repurchase Program, Authorized Amount Supplemental disclosure of cash flow information Supplemental Cash Flow Information [Abstract] Customer [Domain] Customer [Domain] Legal Matters Legal Matters and Contingencies [Text Block] U.S. federal statutory tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Class of treasury stock Class of Treasury Stock [Table Text Block] Letters of credit Letter of Credit [Member] Per Share Data Earnings Per Share, Policy [Policy Text Block] Intellia Collaboration Agreement Intellia Collaboration Agreement [Member] Intellia Collaboration Agreement State Current State and Local Tax Expense (Benefit) Awards vested (in shares) Vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Leasehold improvements Leasehold Improvements [Member] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Net income Net income Net income - basic and diluted Net Income (Loss) Attributable to Parent Up-front and development milestone revenue recognized Up-Front And Development Milestone Revenue Recognized Up-Front And Development Milestone Revenue Recognized Preferred Stock, shares outstanding (in shares) Preferred Stock, Shares Outstanding Accrued payroll and related costs Employee-related Liabilities, Current November 2021 Share Repurchase Program Share Repurchase Program, November 2021 [Member] Share Repurchase Program, November 2021 Income Statement Location [Axis] Income Statement Location [Axis] Receivable Type [Axis] Receivable Type [Axis] Statistical Measurement [Domain] Statistical Measurement [Domain] Number of IPR filed Number of Inter Parties Review (IPR) Petitions Filed Number of Inter Parties Review (IPR) Petitions Filed Finance lease, option to extend Lessee, Finance Lease, Option to Extend Other collaboration Collaboration Agreements, Excluding Sanofi Agreements [Member] Collaboration Agreements, Excluding Sanofi Agreements Security Exchange Name Security Exchange Name Equity securities Equity Securities, FV-NI, Current Royalty percentage to be received on net product sales outside of the United States Royalty Percentage To Be Received On Net Product Sales Outside Of United States Royalty Percentage To Be Received On Net Product Sales Outside Of United States Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Increase Limit Line Of Credit Facility, Increase Limit Line Of Credit Facility, Increase Limit Forfeited (in dollars of shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Schedule of accounts receivable and deferred revenue information Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block] Forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period '226 Patent and '992 Patent '226 Patent And '992 Patent [Member] '226 Patent And '992 Patent Starting share of profits outside the United States, based on sales, for collaborating party Starting share of profits outside the United States, based on sales, for collaborating party On a sliding scale, this element represents the starting share of profits outside the United States, based on sales, for the collaborating party. Other noncurrent assets Other Assets, Noncurrent IO Discovery Agreement IO Discovery Agreement [Member] In July 2015, the Company entered into a collaboration agreement (Immuno-Oncology agreement) with Sanofi, to jointly develop and commercialize Immuno-Oncology programs. Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Investment, Name [Axis] Investment, Name [Axis] Expected dividend yield Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Number of shares available for future grants (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Research and Development Arrangement Contract to Perform for Others by Product [Domain] Research and Development Arrangement Contract to Perform for Others by Product [Domain] [Domain] for Research and Development Arrangement Contract to Perform for Others by Product [Axis] Retirement Benefits [Abstract] Retirement Benefits [Abstract] Net increase in cash, cash equivalents, and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Entity File Number Entity File Number Redemption price, percentage Debt Instrument, Redemption Price, Percentage Expected volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Stock-based compensation charges APIC, Share-based Payment Arrangement, Increase for Cost Recognition Total intrinsic value - of stock options exercised Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value Certificates of deposit Certificates of Deposit [Member] Available-for-sale debt securities Debt Securities, Available-for-sale [Table Text Block] '487 Patent '487 Patent [Member] '487 Patent [Member] SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] January 1, 2024 Through December 31, 2026 January 1, 2024 Through December 31, 2026 [Member] January 1, 2024 Through December 31, 2026 [Member] Lessee, Lease, Description [Line Items] Lessee, Lease, Description [Line Items] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Agreements with Royalty Provisions Royalty Agreement Terms [Member] Remaining authorized repurchase amount Stock Repurchase Program, Remaining Authorized Repurchase Amount Gross increases related to prior year tax positions Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions Percentage of royalties to be paid Payments For Royalties, Percentage Payments For Royalties, Percentage Net deferred tax assets Deferred Tax Assets, Net Weighted average number of shares (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Schedule of inventory Schedule of Inventory, Current [Table Text Block] Research and development expense Research and Development Expense [Member] Granted (in dollars of shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Amounts due to collaborators (see Note 3) Collaborative Agreements, Obligations, Current Collaborative Agreements, Obligations, Current Share of losses outside the United States, for company Share of losses outside the United States, for Company This element represents the share of losses outside the United States for the Company. Property, plant, and equipment, gross Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, before Accumulated Depreciation and Amortization Sales-based milestones earned Sales-Based Milestone Earned [Member] Sales-Based Milestone Earned Unrealized (loss) gain on debt securities OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax Expenditure costs cap Expenditure Costs Cap Expenditure Costs Cap Award Type [Domain] Award Type [Domain] Share Repurchase Program [Domain] Share Repurchase Program [Domain] McKesson Corporation McKesson Corporation [Member] McKesson Corporation [Member] Local Phone Number Local Phone Number Credit Facility [Domain] Credit Facility [Domain] Evkeeza Evkeeza [Member] Evkeeza ASSETS Assets [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract] Exercisable (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Land Land [Member] Vested and expected to vest (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price IO Agreement IO Agreement [Member] IO Agreement Through December 31, 2023 Through December 31, 2023 [Member] Through December 31, 2023 [Member] Marketable securities, based on contractual maturity dates Investments Classified by Contractual Maturity Date [Table Text Block] Awards granted (in shares) Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] PD-1 PD-1 [Member] Programed Cell Death protein 1, or PD-1 ("REGN2810") Concentration risk, percentage Concentration Risk, Percentage Preferred Stock, $.01 par value; 30,000,000 shares authorized; issued and outstanding - none Preferred Stock, Value, Issued Property, Plant and Equipment Property, Plant and Equipment, Policy [Policy Text Block] Accrued sales-related costs Accrual For Sales-Related Costs, Current Accrual For Sales-Related Costs, Current New Accounting Pronouncements or Change in Accounting Principle [Table] Accounting Standards Update and Change in Accounting Principle [Table] Outstanding at beginning of period (in shares) Outstanding at end of period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Libtayo LIBTAYO Net Product Sales [Member] LIBTAYO Net Product Sales [Member] Retained Earnings Retained Earnings [Member] Debt Instrument [Axis] Debt Instrument [Axis] (Increase) decrease in prepaid expenses and other assets Increase (Decrease) in Prepaid Expense and Other Assets Available-for-sale debt securities: Debt Securities, Available-for-sale [Abstract] Trade Accounts Receivable Trade Accounts Receivable [Member] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Rebates, Chargebacks, and Discounts Rebates and Chargebacks [Member] A valuation allowance for rebates and chargebacks under governmental programs (including Medicaid), which are netted against revenue from product sales. Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Number of votes per share Number Of Votes Per Share Number Of Votes Per Share Royalty rate minimum Royalty rate minimum The minimum royalty rate to be paid to the Company under the agreements. Project [Domain] Project [Domain] EYLEA EYLEA Net Product Sales [Member] Revenue during the period derived from a specified product line (EYLEA), after deducting applicable provisions for discounts, returns, rebates, chargebacks, distribution fees, and other sales-related deductions. Regeneron's net profit in connection with commercialization of EYLEA outside the United States Net Profit In Connection With Commercialization [Member] Net Profit In Connection With Commercialization [Member] Fair value and unrealized losses of marketable securities Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value [Table Text Block] Gains on marketable and other securities, net Marketable Securities, Gain (Loss) Inventory, Current [Table] Inventory, Current [Table] Increase in accounts receivable Increase (Decrease) in Accounts Receivable Accrued capital expenditures Capital Expenditures Incurred but Not yet Paid Issuance/distribution of Common Stock for 401(k) Savings Plan Stock Issued/Distributed During Period, Value, Employee Benefit Plan Stock Issued/Distributed During Period, Value, Employee Benefit Plan Schedule of deferred tax assets and liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations (in shares) Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Number of products approved by the U.S. FDA Number of Products Approved By The Unites States Food And Drug Administration Number of Products Approved By The Unites States Food And Drug Administration Debt financing costs Lessee, Finance Lease, Liability, Debt Financing Costs Lessee, Finance Lease, Liability, Debt Financing Costs Repayment of bridge loan facility Repayments of Short-term Debt Net income per share - basic (in dollars per share) Earnings Per Share, Basic First Milestone Sales Milestone One [Member] Sales Milestone One Pending claims Loss Contingency, Pending Claims, Number U.S. government and government agency obligations US Treasury and Government [Member] IO License and Collaboration Agreement IO License and Collaboration Agreement [Member] In July 2015, the Company entered into a Immuno-oncology License and Collaboration Agreement (the "IO License and Collaboration Agreement") with Sanofi, to jointly develop and commercialize Immuno-oncology products. Product Sales Revenue from Contract with Customer [Text Block] BCMAxCD3 Program Amended IO Discovery Agreement, BCMAxCD3 Program [Member] Amended IO Discovery Agreement, BCMAxCD3 Program [Member] Awards outstanding (in shares) Beginning balance (in shares) Ending balance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Distribution- Related Fees Distribution Related Fees [Member] A valuation allowance for distribution-related fees which are netted against revenue from product sales. SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis] SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis] Interest expense Interest Expense, Debt Schedule of product sales Schedule of collaboration revenue Disaggregation of Revenue [Table Text Block] Number of Shares/Units (In millions) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Research and Development Arrangement Contract to Perform for Others by Product [Axis] Research and Development Arrangement Contract to Perform for Others by Product [Axis] Research and Development Arrangement Contract to Perform for Others by Product [Axis] Percentage of trial costs required to be funded by collaborating party Percentage of Trial Costs Required To Be Funded By Collaborating Party Percentage of Trial Costs Required To Be Funded By Collaborating Party Research Collaboration and Licensing Arrangements [Line Items] Research Collaboration and Licensing Arrangements [Line Items] Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Shares purchase price Investment Owned, at Cost Issuance/distribution of Common Stock for 401(k) Savings Plan (in shares) Stock Issued/Distributed During Period, Shares, Employee Benefit Plan Stock Issued/Distributed During Period, Shares, Employee Benefit Plan Regeneron's obligation for Sanofi's share of Libtayo U.S. gross profits Sanofi's Share of Libtayo U.S. Gross Profits [Member] Sanofi's Share of Libtayo U.S. Gross Profits Adjustment upon adoption of new accounting standard Cumulative Effect, Period of Adoption, Adjustment [Member] Commercial paper Commercial Paper [Member] Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations Share-based Payment Arrangement, Decrease for Tax Withholding Obligation Number of shares authorized for issuance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Other non-cash items, net Other Noncash Income (Expense) Research and Development Expenses Research and Development Expense, Policy [Policy Text Block] Classification of Investment [Axis] Classification of Investment [Axis] This element represents the general categories of investments, which may be classified as Unrestricted or Restricted. Other operating income Other Operating Income (Expense) [Member] Provision for doubtful accounts Accounts Receivable, Credit Loss Expense (Reversal) Amended IO Discovery Agreement Amended IO Discovery Agreement [Member] Amended IO Discovery Agreement [Member] Entity Voluntary Filers Entity Voluntary Filers Contingent reimbursement obligation Contingent Reimbursement Obligation The Company's total contingent reimbursement obligation to its collaboration partner for development expenses previously funded by its collaboration partner. Besse Medical, a subsidiary of AmerisourceBergen Corporation Besse Medical [Member] Besse Medical [Member] Plan Name [Axis] Plan Name [Axis] Finance lease right-of-use assets Finance Lease, Right-of-Use Asset, after Accumulated Amortization Long-term Debt Long-term Debt Level 1 Fair Value, Inputs, Level 1 [Member] Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] 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] Other liabilities Other Liabilities Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Entity Small Business Entity Small Business '165 Patent '165 Patent [Member] '165 Patent [Member] Gross increases related to current year tax positions Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions Remaining lease term (in years) Finance Lease, Remaining Lease Term Finance Lease, Remaining Lease Term Total liabilities and stockholders' equity Liabilities and Equity Other accrued expenses and liabilities Other Accrued Liabilities, Current Pending Litigation Pending Litigation [Member] Investments, Debt and Equity Securities [Abstract] Investments, Debt and Equity Securities [Abstract] Unrealized gain (loss) on cash flow hedges Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax Deferred revenue Contract with Customer, Liability, Current Restricted cash included in Other noncurrent assets Restricted Cash Exercised (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Additional paid-in capital Additional Paid in Capital Lessee, Lease, Description [Table] Lessee, Lease, Description [Table] Invalid claims Loss Contingency, Claims Invalid, Number Loss Contingency, Claims Invalid, Number Concentration Risk [Line Items] Concentration Risk [Line Items] LIABILITIES AND STOCKHOLDERS' EQUITY Liabilities and Equity [Abstract] Unrecognized tax benefits that would impact effective tax rate Unrecognized Tax Benefits that Would Impact Effective Tax Rate Accrued expenses and other current liabilities Accounts Payable and Accrued Liabilities, Current MUC16xCD3 Program Amended IO Discovery Agreement, MUC16xCD3 Program [Member] Amended IO Discovery Agreement, MUC16xCD3 Program [Member] Short-term Debt, Type [Domain] Short-term Debt, Type [Domain] SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Table] SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Table] Net Income Per Share Earnings Per Share [Text Block] Cost of stock repurchased Total cost of shares received Treasury Stock, Value, Acquired, Cost Method Research Collaboration and Licensing Agreements [Domain] Research Collaboration and Licensing Agreements [Domain] Research collaboration and licensing agreements, by name. Entity Interactive Data Current Entity Interactive Data Current Sanofi Sanofi [Member] Sanofi 2019 Share Repurchase Program Share Repurchase Program, 2019 [Member] Share Repurchase Program, 2019 Minimum Minimum [Member] Marketable securities Marketable Securities, Current Roche Collaboration Agreement Roche Collaboration Agreement [Member] Roche Collaboration Agreement Borrowings outstanding Long-term Line of Credit Schedule of assets measured at fair value on a recurring basis Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Table Text Block] Selling, general, and administrative Selling, General and Administrative Expense Other comprehensive income (loss), net of tax: Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Preferred Stock, shares authorized (in shares) Preferred Stock, Shares Authorized Balance as of January 1 Balance as of December 31 Unrecognized Tax Benefits Total deferred tax assets Deferred Tax Assets, Gross Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Unrealized Gains Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax Entity Address, State or Province Entity Address, State or Province Cumulative Effect, Period of Adoption [Axis] Cumulative Effect, Period of Adoption [Axis] Fair Value - 12 Months or Greater Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer Amounts recognized in connection with up-front and development milestone payments received Amounts Recognized In Connection With Up-Front Payments [Member] Amounts Recognized In Connection With Up-Front Payments [Member] Deferred tax assets Deferred Income Tax Assets, Net Current liabilities: Liabilities, Current [Abstract] Receivable [Domain] Receivable [Domain] Statement of Cash Flows Cash Flow, Supplemental Disclosures [Text Block] Debt Debt Disclosure [Text Block] Beginning Balance (in shares) Ending Balance (in shares) Shares, Outstanding Schedule of components of income tax expense Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Exercisable (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Line of credit Line of Credit [Member] Long-Term Incentive Plans Share-based Payment Arrangement [Text Block] Senior unsecured notes Senior Notes [Member] Reimbursement of research and development expenses Reimbursement of development expenses Reimbursement Of Research And Development Expenses [Member] Reimbursement Of Research And Development Expenses [Member] Inventories Inventory Disclosure [Text Block] Leases Lessee, Leases [Policy Text Block] Less, accumulated depreciation and amortization Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, Accumulated Depreciation and Amortization Accounting Policies [Abstract] Accounting Policies [Abstract] Weighted average remaining contractual term (in years) - outstanding Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Number of business segments Number of Reportable Segments Federal Current Federal Tax Expense (Benefit) Reimbursement of commercialization-related expenses Reimbursement Of Commercialization-Related Expenses [Member] Reimbursement Of Commercialization-Related Expenses [Member] Document Transition Report Document Transition Report Common stock Common Stock, Value, Issued Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Total other income (expense) Nonoperating Income (Expense) Weighted average period for recognition of total unrecognized compensation expense (in years) Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Weighted-average grant date fair value of awards outstanding (in USD per share) Beginning balance (in dollars of shares) Ending balance (in dollars of shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Customer concentration risk Customer Concentration Risk [Member] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Performance-based stock options Performance Shares [Member] Commitments and contingencies (Note 10) Commitments and Contingencies Second Milestone Sales Milestone Two [Member] Sales Milestone Two Other Sales- Related Deductions Other Sales Related Deductions [Member] A valuation allowance for other sales-related deductions which are netted against revenue from product sales. Accumulated other comprehensive (loss) income Accumulated Other Comprehensive Income (Loss), Net of Tax Entity Emerging Growth Company Entity Emerging Growth Company Amortization of right-of-use assets Finance Lease, Right-of-Use Asset, Amortization Class of Treasury Stock [Table] Class of Treasury Stock [Table] Allowance for doubtful accounts receivable, current Accounts Receivable, Allowance for Credit Loss, Current Inventory write-downs and reserves Inventory Write-down January 2021 Share Repurchase Program Share Repurchase Program, January 2021 [Member] Share Repurchase Program, January 2021 Restricted stock awards and restricted stock units Restricted Stock [Member] Teva Teva Pharmaceuticals Collaboration Agreement [Member] Teva Pharmaceuticals Collaboration Agreement [Member] Levels of twelve month sales at which sales milestone payments would be received Levels of twelve month sales at which sales milestone payments would be received Aggregate amount of twelve month sales upon which sales milestone would be received. ICFR Auditor Attestation Flag ICFR Auditor Attestation Flag Audit Information [Abstract] Audit Information [Abstract] Schedule of weighted-average values of assumptions used in computing fair value of option grants Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Foreign Deferred Foreign Income Tax Expense (Benefit) Marketable Securities Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Legal Entity [Axis] Legal Entity [Axis] Auditor Name Auditor Name Cover [Abstract] Cover [Abstract] Effect of dilutive securities (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Cash consideration for Stock Purchase Agreement Payments Made To Acquire Equity Within A Collaboration Agreement Payments Made To Acquire Equity Within A Collaboration Agreement Collaborative Arrangement, Number Of Doses Counterparty To Purchase Collaborative Arrangement, Number Of Doses Counterparty To Purchase Collaborative Arrangement, Number Of Doses Counterparty To Purchase Total expenses Costs and Expenses Debt and Equity Securities Marketable Securities, Policy [Policy Text Block] Class of Stock [Axis] Class of Stock [Axis] U.S. government US Government [Member] US Government Accrued expenses Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Accrued Liabilities Royalty expense, net of reimbursements from collaborators Royalty Expense Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Treasury Stock (in shares) Treasury Stock, Shares Furniture, office equipment, and other Furniture, Office Equipment And Other [Member] Furniture, Office Equipment And Other [Member] Work-in-process Inventory, Work in Process, Net of Reserves Discount rate Lessee, Finance Lease, Discount Rate Capital expenditures Payments to Acquire Productive Assets Performance threshold, target number of awards granted, percent Share-Based Compensation Arrangement, Performance Threshold, Target Number Of Awards Granted, Percent Share-Based Compensation Arrangement, Performance Threshold, Target Number Of Awards Granted, Percent Thereafter Finance Lease, Liability, to be Paid, after Year Five Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Statements of Comprehensive Income Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Financial Instrument [Axis] Financial Instrument [Axis] Accrued expenses and other current liabilities Accrued Liabilities, Current Entity [Domain] Entity [Domain] Selling, general, and administrative expense Selling, General and Administrative Expenses [Member] Revenue from contract with customer Revenues Revenue from Contract with Customer, Excluding Assessed Tax Imputed interest Finance Lease, Liability, Undiscounted Excess Amount Finished goods Inventory, Finished Goods, Net of Reserves Apotex Inc. Apotex Inc. [Member] Apotex Inc. Current: Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Stock options Share-based Payment Arrangement, Option [Member] Deferred costs Other Inventory, Net of Reserves Foreign-derived intangible income deduction Effective Income Tax Rate Reconciliation, Deduction, Foreign Intangible Income, Percent Effective Income Tax Rate Reconciliation, Deduction, Foreign Intangible Income, Percent Equity [Abstract] Equity [Abstract] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fixed assets and intangible assets Deferred Tax Assets, Property, Plant and Equipment Income tax credits Effective Income Tax Rate Reconciliation, Tax Credit, Percent Bridge Facility Bridge Facility [Member] Bridge Facility 2026 Finance Lease, Liability, to be Paid, Year Five Fair Value - Less than 12 Months Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months Common Stock Common Stock [Member] Income before income taxes, Foreign Income (Loss) from Continuing Operations before Income Taxes, Foreign Income from operations Operating Income (Loss) Property, Plant and Equipment [Table] Schedule of Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Cost of goods sold Cost Of Goods Sold [Member] Cost Of Goods Sold Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-sale [Line Items] Maturities after one year through five years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five Unrealized Losses Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax Collaboration, License, and Other Agreements Collaborative Arrangement Disclosure [Text Block] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Document Fiscal Year Focus Document Fiscal Year Focus Regeneron's obligation for its share of Sanofi commercial expenses Regeneron's Share Of Commercial Expenses [Member] Regeneron's Share Of Commercial Expenses Property, Plant and Equipment [Abstract] Property, Plant and Equipment [Abstract] Non-cash compensation expense Share-based Payment Arrangement, Noncash Expense Sanofi Collaboration Agreement, Antibody Sanofi Collaboration Agreement, Antibody [Member] Sanofi Collaboration Agreement, Antibody [Member] Additional Paid-in Capital Additional Paid-in Capital [Member] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Cash and Cash Equivalents [Abstract] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Deferred taxes Increase (Decrease) in Deferred Income Taxes Laboratory and Office Facilities Laboratory And Office Facilities [Member] Laboratory And Office Facilities Treasury Stock Treasury Stock [Member] Conversion of Class A Stock to Common Stock (in shares) Stock Issued During Period, Shares, Conversion of Units Entity Information [Line Items] Entity Information [Line Items] Sales related deductions activity Schedule of Sales Related Deductions Activity [Table Text Block] Tabular disclosure of the activity of sales-related deductions during the period, which includes rebates, chargebacks, discounts, and distributor-related fees. Other income (expense), net Other Nonoperating Income (Expense) Long-term debt fair value Long-term Debt, Fair Value Deferred revenue Deferred Tax Assets, Deferred Income Collaborative Arrangement, Upfront Payment Made Collaborative Arrangement, Upfront Payment Made Collaborative Arrangement, Upfront Payment Made Maximum Maximum [Member] Share-based Payment Arrangement [Abstract] Share-based Payment Arrangement [Abstract] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Summary of presentation in statement of operations of payments to and from collaborators Collaborative Arrangement and Arrangement Other than Collaborative [Table Text Block] Total liabilities Liabilities Raw materials Inventory, Raw Materials, Net of Reserves EYLEA Aflibercept Injection EYLEA Aflibercept Injection [Member] EYLEA Aflibercept Injection Award Type [Axis] Award Type [Axis] Granted (in dollars per share) Weighted-Average Exercise Price (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Intrinsic value - outstanding Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Sales Milestones [Axis] Sales Milestones [Axis] Sales Milestones Total stockholders' equity Beginning Balance Ending Balance Stockholders' Equity Attributable to Parent Common Stock, shares issued (in shares) Common Stock, Shares, Issued Preferred Stock, shares issued (in shares) Preferred Stock, Shares Issued City Area Code City Area Code Increase in accounts payable, accrued expenses, and other liabilities Increase (Decrease) in Accounts Payable and Accrued Liabilities Amgen v.s. Regeneron Amgen v.s. Regeneron [Member] Amgen v.s. Regeneron [Member] Intrinsic value - exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Entity Address, City or Town Entity Address, City or Town Number of ex parte reexamination requests Loss Contingency, Ex Parte Reexamination, Filed, Number Loss Contingency, Ex Parte Reexamination, Filed, Number Repurchases of Common Stock Payments for Repurchase of Common Stock Estimated useful life Property, Plant and Equipment, Useful Life Percentage of repayment of development balance out of profits Percentage Of Repayment Of Development Balance Out Of Profits Percentage of repayment of development balance out of profits under the collaboration agreement. Stockholders' equity: Stockholders' Equity Attributable to Parent [Abstract] Schedule of unrecognized tax benefits Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block] Equity, Class of Treasury Stock [Line Items] Equity, Class of Treasury Stock [Line Items] Concentration of Credit Risk Concentration Risk, Credit Risk, Policy [Policy Text Block] Total undiscounted lease payments Finance Lease, Liability, Payment, Due Measurement Frequency [Domain] Measurement Frequency [Domain] Total current tax expense Current Income Tax Expense (Benefit) Debt, principle amount Debt Instrument, Face Amount Unrestricted Unrestricted [Member] Investments whose use is not restricted in whole or in part, by contractual agreements or regulatory requirements. Interest expense Interest Expense 2022 Finance Lease, Liability, to be Paid, Year One Deferred: Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Proceeds from bridge loan facility Proceeds from Short-term Debt Loss Contingency Nature [Axis] Loss Contingency Nature [Axis] Retained earnings Retained Earnings (Accumulated Deficit) Litigation Case [Domain] Litigation Case [Domain] Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Entity Filer Category Entity Filer Category Finance Lease, Liability Total lease liabilities Finance Lease, Liability Regeneron's share of profits in connection with commercialization of antibodies Share Of Profits (Losses) In Connection With Commercialization [Member] Share Of Profits (Losses) In Connection With Commercialization [Member] Provisions SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Other Account Libtayo Development and Dupilumab/Itepekimab Eligible Investments Libtayo Development And Dupilumab/Itepekimab Eligible Investments [Member] Libtayo Development And Dupilumab/Itepekimab Eligible Investments Risk-free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Share Repurchase Program [Axis] Share Repurchase Program [Axis] Schedule of restrictions on cash and cash equivalents Restrictions on Cash and Cash Equivalents [Table Text Block] Statements of Operations Income Statement [Abstract] Concentration Risk [Table] Concentration Risk [Table] Entity Registrant Name Entity Registrant Name Inventory Disclosure [Abstract] Inventory Disclosure [Abstract] 2024 Finance Lease, Liability, to be Paid, Year Three 2025 Finance Lease, Liability, to be Paid, Year Four Regeneron's obligation for its share of Sanofi research and development expenses Regeneron's obligation for its share of Bayer research and development expenses Regeneron's Share Of Research And Development Expenses [Member] Regeneron's Share Of Research And Development Expenses Credits/payments SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction Restricted Restricted [Member] Restricted [Member] Amended & Restated Long-Term Incentive Plan 2014 Amended & Restated Long-Term Incentive Plan 2014 [Member] Amended & Restated Long-Term Incentive Plan 2014 2023 Finance Lease, Liability, to be Paid, Year Two Finance lease costs Finance Lease, Cost Finance Lease, Cost Forfeited (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price Up-front payment received Up-Front Payment Received Up-front payment received upon the execution of a collaboration agreement. Income tax expense Total income tax expense (benefit) Income Tax Expense (Benefit) Accounts receivable, net Accounts receivable, net Accounts receivable, net Accounts Receivable, after Allowance for Credit Loss, Current Amendment Flag Amendment Flag Proceeds from issuance of long-term debt Proceeds from Issuance of Long-term Debt Equity Components [Axis] Equity Components [Axis] Entity Tax Identification Number Entity Tax Identification Number SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Investment Type [Axis] Investment Type [Axis] Document Fiscal Period Focus Document Fiscal Period Focus Sanofi Sanofi Collaboration Agreement [Member] Sanofi Collaboration Agreement [Member] Total current assets Assets, Current Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Accounts receivable Accounts Receivable [Member] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Awards forfeited (in shares) Forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Inventories Total Inventories Inventory, Net Granted (in shares) Number of Options Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Depreciation and amortization expense Depreciation, Depletion And Amortization, Excluding Intangible Assets Depreciation, Depletion And Amortization, Excluding Intangible Assets Stock-based Compensation Share-based Payment Arrangement [Policy Text Block] Repurchases of Common Stock Stock Repurchased During Period, Value Federal Deferred Federal Income Tax Expense (Benefit) 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] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Aggregate payment received with regards to amendment Aggregate Payment Received With Regards To Amendment Aggregate Payment Received With Regards To Amendment '741 Patent '741 Patent [Member] '741 Patent [Member] Total adjustments Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities Product and Service [Axis] Product and Service [Axis] Property, Plant and Equipment, Type [Domain] Long-Lived Tangible Asset [Domain] Schedule of cash and cash equivalents Schedule of Cash and Cash Equivalents [Table Text Block] Securities without readily determinable fair value Equity Securities without Readily Determinable Fair Value, Amount Preferred Stock, par value (in dollars per share) Preferred Stock, Par or Stated Value Per Share Entity Public Float Entity Public Float Stock-based compensation Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Payment Arrangement, Percent Documents Incorporated by Reference Documents Incorporated by Reference [Text Block] Maximum transaction agreement payments Maximum Transaction Agreement Payments Maximum Transaction Agreement Payments Weighted-Average Fair Value (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Equity Component [Domain] Equity Component [Domain] Issuance of Common Stock for equity awards granted under long-term incentive plans (in shares) Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture Revenue, remaining performance obligation, variable consideration amount Revenue, Remaining Performance Obligation, Variable Consideration Amount Revenue, Remaining Performance Obligation, Variable Consideration Amount Repurchases of Common Stock (in shares) Stock Repurchased During Period, Shares Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Cost of collaboration and contract manufacturing Collaboration and Contract Manufacturing [Member] Collaboration and Contract Manufacturing [Member] Deferred tax assets: Components of Deferred Tax Assets [Abstract] Marketable securities Marketable Securities, Noncurrent Statement [Line Items] Statement [Line Items] Litigation Case [Axis] Litigation Case [Axis] SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain] SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain] Property, plant, and equipment, net Property, plant, and equipment, net Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization (Decrease) increase in deferred revenue Increase (Decrease) in Contract with Customer, Liability Weighted-Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Remaining performance obligation Revenue, Remaining Performance Obligation, Amount Issuance of Common Stock for equity awards granted under long-term incentive plans Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture Short-term Debt, Type [Axis] Short-term Debt, Type [Axis] Fair Value Total Available-for-sale debt securities Debt Securities, Available-for-sale Counterparty Name [Domain] Counterparty Name [Domain] Debt Disclosure [Abstract] Debt Disclosure [Abstract] Potential optional extension of research term Option to Extend Research Term, Period Option to Extend Research Term, Period Purchases of marketable and other securities Payments to Acquire Marketable Securities Finance lease liabilities Finance Lease, Liability, Current ARCALYST Arcalyst Net Product Sales [Member] Revenue during the period derived from a specified product line (ARCALYST), after deducting applicable provisions for discounts, returns, rebates, chargebacks, distribution fees, and other sales-related deductions. Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Level 2 Fair Value, Inputs, Level 2 [Member] Gross Product Revenue Gross Product Revenue [Member] Gross Product Revenue Cumulative catch-up adjustment to revenue, modification of contract Contract with Customer, Asset, Cumulative Catch-up Adjustment to Revenue, Modification of Contract Property, Plant and Equipment, Type [Axis] Long-Lived Tangible Asset [Axis] Deferred revenue Contract with Customer, Liability, Noncurrent Auditor Location Auditor Location Fair Value - Total Debt Securities, Available-for-sale, Unrealized Loss Position Finance lease, term of contract Lessee, Finance Lease, Term of Contract Computer equipment and software Computer Equipment And Software [Member] Computer Equipment And Software [Member] Amortized Cost Basis Debt Securities, Available-for-sale, Amortized Cost Deferred compensation Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits Customer [Axis] Customer [Axis] Interest on lease liabilities Finance Lease, Interest Expense Employee Savings Plans Retirement Benefits [Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Basic and diluted net income (loss) per share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Number of claims invalidated Gain Contingency, Claims Invalidated, Number Gain Contingency, Claims Invalidated, Number Document Annual Report Document Annual Report Finance Leases Finance Lease, Liability, Payment, Due [Abstract] Title of 12(b) Security Title of 12(b) Security Upfront payment made Upfront Payment Made Upfront payment made under a collaboration agreement Proceeds from issuance of Common Stock Proceeds from Issuance of Common Stock Total assets Assets Accrued clinical expenses Accrued Clinical Trial Expense Current Carrying value as of the balance sheet date of obligations incurred (and for which invoices have not been received) in connection with clinical trials. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Investment, Name [Domain] Investment, Name [Domain] Deferred tax liabilities: Components of Deferred Tax Liabilities [Abstract] Plan Name [Domain] Plan Name [Domain] Common Stock, shares authorized (in shares) Common Stock, Shares Authorized Extension of research term fee Extension Of Research Term Fee Extension Of Research Term Fee Alnylam Pharmaceuticals, Inc. Collaboration Agreement Alnylam Pharmaceuticals, Inc. Collaboration Agreement [Member] Alnylam Pharmaceuticals, Inc. Collaboration Agreement [Member] Percentage of damages company is responsible for Loss Contingency, Percentage Of Damages Responsible For Loss Contingency, Percentage Of Damages Responsible For Percentage of quarterly profits require to be paid for reimbursement of development costs Percentage Of Quarterly Profits Required To Be Paid For Reimbursement Of Development Costs Percentage Of Quarterly Profits Required To Be Paid For Reimbursement Of Development Costs Cash paid for interest (net of amounts capitalized) Interest Paid, Excluding Capitalized Interest, Operating Activities Share of losses outside the United States, for collaborating party Share of losses outside the United States, for collaborating party This element represents the share of losses outside the United States for the collaborating party. Geographical [Domain] Geographical [Domain] Document Type Document Type Accrued Expenses and Other Current Liabilities Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block] Research and development Research and Development Expense Product and Service [Domain] Product and Service [Domain] Interest rate Debt Instrument, Interest Rate, Stated Percentage Praluent Agreement Praluent Cross License and Commercialization Agreement [Member] Praluent Cross License and Commercialization Agreement Research Collaboration and Licensing Arrangements [Table] Research Collaboration and Licensing Arrangements [Table] -- None. No documentation exists for this element. -- Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Long-Term Incentive Plan 2014 Long-Term Incentive Plan 2014 [Member] Long-Term Incentive Plan 2014 Senior unsecured revolving credit facility Revolving Credit Facility [Member] Business Overview and Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Cumulative Effect, Period of Adoption [Domain] Cumulative Effect, Period of Adoption [Domain] Measurement Frequency [Axis] Measurement Frequency [Axis] Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Litigation Status [Axis] Litigation Status [Axis] Summary of issued senior unsecured notes Schedule of Debt [Table Text Block] United States Government United States Government [Member] United States Government Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Period for achieving sales target for milestone payment, rolling basis Period for Achieving Sales Target for Milestone Payment, Rolling Basis Period for Achieving Sales Target for Milestone Payment, Rolling Basis Furniture and fixtures Furniture and Fixtures [Member] Schedule of lease cost and other information Lease, Cost [Table Text Block] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Share Repurchase Programs Share Repurchase Programs [Member] Share Repurchase Programs Corporate bonds Corporate Bond Securities [Member] Alnylam Pharmaceuticals, Inc. Stock Purchase Agreement Alnylam Pharmaceuticals, Inc. Stock Purchase Agreement [Member] Alnylam Pharmaceuticals, Inc. Stock Purchase Agreement [Member] Geographical [Axis] Geographical [Axis] Accrued expenses and other current liabilities Accrued Liabilities and Other Liabilities Weighted average shares outstanding - basic (in shares) Weighted Average Number of Shares Outstanding, Basic Net income per share - diluted (in dollars per share) Earnings Per Share, Diluted Effect of dilutive securities: Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract] Collaborative arrangement, additional eligible aggregate payments Collaborative Arrangement, Additional Eligible Aggregate Payments The aggregate amount of additional payments the Company is entitled to receive upon the achievement of specified annual net sales amounts. Contract with Customer, Duration [Axis] Contract with Customer, Duration [Axis] Net product sales Product [Member] Cash paid for income taxes Income Taxes Paid, Net Line of credit facility, expiration period Line of Credit Facility, Expiration Period Project [Axis] Project [Axis] Outside United States Non-US [Member] Third Milestone Sales Milestone Three [Member] Sales Milestone Three Comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Deferred revenue Contract with Customer, Liability Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities Treasury Stock, at cost; 19,392,961 shares in 2021 and 16,431,520 shares in 2020 Treasury Stock, Value Percentage of royalty payment that can be used to offset litigation proceedings Percentage of Royalty Payment That Can Be Offset Percentage of Royalty Payment That Can Be Offset Award vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period '631 Patent '631 Patent [Member] '631 Patent Schedule of activity related to restricted stock awards Share-based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block] Schedule of effective income tax rate reconciliation Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Schedule of maturities of finance lease liabilities Finance Lease, Liability, Fiscal Year Maturity [Table Text Block] Fair Value Measurements Fair Value Disclosures [Text Block] Accounts payable Accounts Payable, Current Concentration Risk Type [Axis] Concentration Risk Type [Axis] Depreciation and amortization Depreciation, Depletion and Amortization 2.800% Senior Notes due September 2050 Senior Unsecured Notes Due 2050 [Member] Senior Unsecured Notes Due 2050 Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Increase in inventories Increase (Decrease) in Inventories Common Stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Other operating (income) expense, net Other Operating Income (Expense), Net Financial Instruments [Domain] Financial Instruments [Domain] Casirivimab and imdevimab Casirivimab and imdevimab [Member] Casirivimab and imdevimab Cost of goods sold and of collaboration and contract manufacturing Cost of Goods and Services Sold Revenues: Revenues [Abstract] Document Period End Date Document Period End Date REGEN-COV REGEN-COV [Member] REGEN-COV Long-Term Incentive Plan 2000 Long-Term Incentive Plan 2000 [Member] Long-Term Incentive Plan 2000 [Member] Entity Central Index Key Entity Central Index Key Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Other revenue Product and Service, Other [Member] Research Collaboration and Licensing Agreements [Axis] Research Collaboration and Licensing Agreements [Axis] The research collaboration and licensing agreements entered into. Number of Shares (In millions) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Starting share of profits outside the United States, based on sales, for company Starting share of profits outside the United States, based on sales, for Company On a sliding scale, this element represents the starting share of profits outside the United States, based on sales, for the Company. State Deferred State and Local Income Tax Expense (Benefit) Maximum term of awards Share Based Compensation Arrangement By Share Based Payment Award Expiration The term (in years) when the equity-based award expires as specified in the award agreement. Schedule of estimated useful lives of property, plant, and equipment Schedule of property, plant and equipment Property, Plant and Equipment [Table Text Block] Income Statement Location [Domain] Income Statement Location [Domain] Gross decreases related to prior year tax positions Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions Bridge Loan Bridge Loan [Member] Debt Securities, Available-for-sale [Table] Debt Securities, Available-for-sale [Table] Reimbursement for manufacturing of commercial supplies Reimbursement For Manufacturing Of Commercial Supplies [Member] Reimbursement For Manufacturing Of Commercial Supplies [Member] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Other permanent differences Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Percent Property, Plant and Equipment Property, Plant and Equipment Disclosure [Text Block] Other noncurrent liabilities Other Liabilities, Noncurrent Aggregate future development milestone payments the Company is eligible to receive Aggregate Future Development Milestone Payments The Company Is Eligible To Receive Aggregate future development milestone payments the Company is eligible to receive. Treasury stock, shares acquired (in shares) Treasury Stock, Shares, Acquired Debt Instrument [Line Items] Debt Instrument [Line Items] Total marketable securities Marketable Securities Trading Symbol Trading Symbol Earnings Per Share [Abstract] Earnings Per Share [Abstract] Gross decreases due to settlements and lapse of statutes of limitations Unrecognized Tax Benefits, Decrease Resulting From Settlements With Taxing Authorities And Reduction Resulting From Lapse Of Applicable Statute Of Limitations Unrecognized Tax Benefits, Decrease Resulting From Settlements With Taxing Authorities And Reduction Resulting From Lapse Of Applicable Statute Of Limitations Ending share of profits outside the United States, based on sales, for collaborating party Ending share of profits outside the United States, based on sales, for collaborating party On a sliding scale, this element represents the ending share of profits outside the United States, based on sales, for the collaborating party. Net unrealized gains (losses) on equity securities in other income (expense) Equity Securities, FV-NI, Unrealized Gain (Loss) 1.750% Senior Notes due September 2030 Senior Unsecured Notes Due 2030 [Member] Senior Unsecured Notes Due 2030 Other Transaction Agreement BARDA, Other Transaction Agreement [Member] BARDA, Other Transaction Agreement Unrealized Loss - Total Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss Collaboration revenue Collaboration Revenue [Member] Collaboration Revenue Laboratory equipment Equipment [Member] Classification of Investment [Domain] Classification of Investment [Domain] Provides general categories of investments for which information is required or determined to be disclosed. Praluent Praluent Net Product Sales [Member] Praluent Net Product Sales Vested and expected to vest (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number Maximum amount of sales milestone payments if total sales achieve specific levels Maximum amount of sales milestone payments if total sales achieve specific levels The maximum amount of sales milestone payments the Company is eligible to receive when and if total annual sales achieve certain specified levels. Ending share of profits outside the United States, based on sales, for company Ending share of profits outside the United States, based on sales, for Company On a sliding scale, this element represents the ending share of profits outside the United States, based on sales, for the Company. Schedule of weighted-average exercise prices and weighted-average grant-date fair values of options issued Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value [Table Text Block] Revenue based on percentage of annual sales in Japan Revenue Based On Percentage Of Annual Sales In Japan The percentage on annual sales in Japan that the Company is entitled to receive, subject to certain potential adjustments. Outstanding at beginning of period (in dollars per share) Outstanding at end of period (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Expenses: Costs and Expenses [Abstract] Long-term debt Long-term Debt, Excluding Current Maturities Non-cash stock-based compensation expense Share-based Payment Arrangement, Expense Weighted average remaining contractual term - exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Accumulated amortization of right-of-use assets Finance Lease, Right-of-Use Asset, Accumulated Amortization Europe Europe [Member] Entity Current Reporting Status Entity Current Reporting Status Common Stock Held By Sanofi Common Stock Held By Sanofi [Member] Common Stock Held By Sanofi 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] Contract with Customer, Duration [Domain] Contract with Customer, Duration [Domain] Legal Matters Legal Costs, Policy [Policy Text Block] Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Three individual customers Three Individual Customers [Member] Three Individual Customers [Member] Entities [Table] Entities [Table] Sales Milestones [Domain] Sales Milestones [Domain] Sales Milestones Investments [Domain] Investments [Domain] Bayer Bayer Collaboration Agreement [Member] Bayer Collaboration Agreement [Member] Sale of non-inventory related assets between foreign subsidiaries Effective Income Tax Rate Reconciliation, Sale Of Non-Inventory Related Assets Between Foreign Subsidiaries, Percent Effective Income Tax Rate Reconciliation, Sale Of Non-Inventory Related Assets Between Foreign Subsidiaries, Percent Marketable securities, realized gain Marketable Securities, Realized Gain Marketable Securities, Realized Gain Counterparty Name [Axis] Counterparty Name [Axis] Sales or maturities of marketable and other securities Proceeds from Sale and Maturity of Marketable Securities Celltrion, Inc. Celltrion, Inc. [Member] Celltrion, Inc. Payables and Accruals [Abstract] Payables and Accruals [Abstract] Inventory reserves Inventory Valuation Reserves Schedule of income before income tax Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block] Construction in progress Construction in Progress [Member] Class A Stock Common Class A [Member] Cash, cash equivalents, and restricted cash at beginning of period Cash, cash equivalents, and restricted cash at end of period Total cash, cash equivalents, and restricted cash shown in the Consolidated Statement of Cash Flows Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Sovereign bonds Sovereign Debt Securities [Member] Number of shares sold (in shares) Sale of Stock, Number of Shares Issued in Transaction United States UNITED STATES Common Stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Income taxes payable Taxes Payable, Current Schedules of concentration of risk, by risk factor Schedules of Concentration of Risk, by Risk Factor [Table Text Block] Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Current assets: Assets, Current [Abstract] Income Taxes Income Tax, Policy [Policy Text Block] Schedule of amounts recognized in the Condensed Consolidated Balance Sheet Assets And Liabilities, Lessee [Table Text Block] Assets And Liabilities, Lessee [Table Text Block] Maximum percentage of outstanding shares that may be acquired, under 'standstill' provisions Maximum Percentage Of Outstanding Shares That May Be Acquired, Under 'Standstill' Provisions The maximum percentage of outstanding shares of the Company's Class A Stock and Common Stock that may be acquired under the 'standstill' provisions, in effect after the specified date. Entity Address, Postal Zip Code Entity Address, Postal Zip Code Schedule of accrued expenses and other current liabilities Schedule of Accounts Payable and Accrued Liabilities [Table Text Block] Exercised (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Revenue Recognition Revenue from Contract with Customer [Policy Text Block] Weighted average shares outstanding - diluted (in shares) Weighted average shares - diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Income before income taxes, United States Income (Loss) from Continuing Operations before Income Taxes, Domestic Marketable securities, realized loss Marketable Securities, Realized Loss Marketable Securities, Realized Loss Other comprehensive income, net of tax Other Comprehensive Income (Loss), Net of Tax Measured on a recurring basis Fair Value, Recurring [Member] Income Taxes Income Tax Disclosure [Text Block] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Schedule of transactions involving stock option awards Share-based Payment Arrangement, Option, Activity [Table Text Block] Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration] Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration] Stockholders' Equity Stockholders' Equity Note Disclosure [Text Block] Antidilutive securities Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Potential automatic extension of research term Potential Extension Of Research Term Potential Extension Of Research Term Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Other income (expense): Nonoperating Income (Expense) [Abstract] Auditor Firm ID Auditor Firm ID Realized gain (loss) on sales of marketable securities Marketable Securities, Realized Gain (Loss) Class of Stock [Line Items] Class of Stock [Line Items] Credit Facility [Axis] Credit Facility [Axis] Entity Address, Address Line One Entity Address, Address Line One Royalty rate maximum Royalty rate maximum The maximum royalty rate to be paid to the Company under the agreements. Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Building and improvements Building and Building Improvements [Member] Changes in assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Initial research term Initial Research Term Initial Research Term Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Vested (in dollars of shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Entity Shell Company Entity Shell Company Collaborative arrangement additional payment eligible Collaborative Arrangement, Additional Payment Eligible, Milestone Collaborative Arrangement, Additional Payment Eligible, Milestone Expected lives from grant date Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Total current liabilities Liabilities, Current Payments in connection with Common Stock tendered for employee tax obligations Payment, Tax Withholding, Share-based Payment Arrangement Class of Stock [Domain] Class of Stock [Domain] Litigation Status [Domain] Litigation Status [Domain] '338 Patent and '069 Patent '338 Patent And '069 Patent [Member] '338 Patent And '069 Patent Non-performance based stock options Non-Performance Based Stock Options [Member] A stock option whose vesting is not contingent upon performance achievements. Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Loss Contingencies [Table] Loss Contingencies [Table] Intrinsic value - vested and expected to vest Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value Current Fiscal Year End Date Current Fiscal Year End Date Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Statement [Table] Statement [Table] Asset-backed securities Asset-backed Securities [Member] Other Deferred Tax Assets, Other Finance lease, renewal term Lessee, Finance Lease, Renewal Term Unrecognized stock-based compensation cost, net of estimated forfeitures Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Statistical Measurement [Axis] Statistical Measurement [Axis] Accounts Receivable Accounts Receivable [Policy Text Block] Subsequent Event Subsequent Event [Member] Finance lease liabilities Finance Lease, Liability, Noncurrent Sanofi Collaboration Agreement, Immuno-oncology Sanofi Collaboration Agreement, Immuno-oncology [Member] Sanofi Collaboration Agreement, Immuno-oncology [Member] Unrealized gains on investments Deferred Tax Liabilities, Unrealized Gains on Trading Securities Taxation of non-U.S. operations Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Percent Beginning Balance Ending Balance SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount Unrealized Loss - Less than 12 months Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Inventories Inventory, Policy [Policy Text Block] Foreign Current Foreign Tax Expense (Benefit) Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Maturities within one year Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Inventory [Line Items] Inventory [Line Items] Unrealized Loss - 12 Months or Greater Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Total deferred tax (benefit) expense Deferred Income Tax Expense (Benefit) Weighted average remaining contractual term - vested and expected to vest Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term Redemption price with change-in-control provision, percentage Debt Instrument, Redemption Price With Change-In-Control Provision, Percentage Debt Instrument, Redemption Price With Change-In-Control Provision, Percentage