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Milestone Type [Domain] Milestone Type [Domain] Milestone Type [Domain] Total current assets Assets, Current Joseph L. Goldstein, M.D. [Member] Joseph L. 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Fenimore [Member] Christopher R. 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Decibel Therapeutics, Inc. [Member] Decibel Therapeutics, Inc. Document Fiscal Year Focus Document Fiscal Year Focus Geographical [Domain] Geographical [Domain] Upfront payment made Upfront Payment Made Upfront payment made under a collaboration agreement Minimum Minimum [Member] Share Repurchase Program [Domain] Share Repurchase Program [Domain] Alnylam Pharmaceuticals, Inc. Collaboration Agreement Alnylam Pharmaceuticals, Inc. Collaboration Agreement [Member] Alnylam Pharmaceuticals, Inc. 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Stock Purchase Agreement Alnylam Pharmaceuticals, Inc. Stock Purchase Agreement [Member] Alnylam Pharmaceuticals, Inc. 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Checkmate Pharmaceuticals, Inc. [Member] Checkmate Pharmaceuticals, Inc. 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] All Trading Arrangements All Trading Arrangements [Member] All Adjustments to Compensation All Adjustments to Compensation [Member] Award Timing Disclosures [Line Items] Regeneron's obligation for its share of Bayer R&D expenses, net of reimbursement of R&D expenses Regeneron's Obligation Of Research And Development Expenses, Net of Reimbursement Of Research And Development Expenses [Member] Regeneron's Obligation Of Research And Development Expenses, Net of Reimbursement Of Research And Development Expenses Up-front payment to collaborating party Up-Front Payment to Collaborating Party Up-Front Payment to Collaborating Party Compensation Amount Outstanding Recovery Compensation Amount Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Additional paid-in capital Additional Paid in Capital Other comprehensive income (loss), net of tax: Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Document Information [Line Items] Document Information [Line Items] Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Reimbursement for manufacturing of commercial supplies Reimbursement for manufacturing of ex-U.S. commercial supplies Reimbursement For Manufacturing Of Commercial Supplies [Member] Reimbursement For Manufacturing Of Commercial Supplies [Member] Statement of Cash Flows Cash Flow, Supplemental Disclosures [Text Block] Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Percentage of share of profits used to reimburse collaborating party for trial costs Percentage of Share of Profits Used to Reimburse Collaborating Party for Trial Costs Percentage of Share of Profits Used to Reimburse Collaborating Party for Trial Costs Insider Trading Arrangements [Line Items] Losses on marketable and other securities, net Marketable and Other Securities, Gain (Loss) Marketable and Other Securities, Gain (Loss) Issuance of Common Stock for equity awards granted under long-term incentive plans (in shares) Shares Issued, Shares, Share-Based Payment Arrangement, after Forfeiture Entity Registrant Name Entity Registrant Name Arthur F. Ryan [Member] Arthur F. Ryan Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Award Timing Method Award Timing Method [Text Block] Effect of dilutive securities (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements BARDA, Other Transaction Agreement BARDA, Other Transaction Agreement [Member] BARDA, Other Transaction Agreement Net unrealized gains (losses) Equity Securities, FV-NI, Unrealized Gain (Loss) Collaboration revenue Collaboration Revenue [Member] Collaboration Revenue Adjustment to Compensation, Amount Adjustment to Compensation Amount 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 Document Period End Date Document Period End Date Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Adoption Date Trading Arrangement Adoption Date Schedule of assets measured at fair value on a recurring basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Finance lease liabilities Finance Lease, Liability, Noncurrent Treasury Stock Treasury Stock, Common [Member] Entity Central Index Key Entity Central Index Key Liabilities, Fair Value Disclosure [Abstract] Liabilities, Fair Value Disclosure [Abstract] Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Loss Contingency Nature [Axis] Loss Contingency Nature [Axis] Income tax expense Income Tax Expense (Benefit) Finished goods Inventory, Finished Goods, Net of Reserves Outside United States Non-US [Member] Fair Value Measurements Fair Value Disclosures [Text Block] Name Trading Arrangement, Individual Name Cash and Cash Equivalents [Abstract] Bayer Bayer Collaboration Agreement [Member] Bayer Collaboration Agreement [Member] Schedule of Product Sales Schedule of Collaborative Revenue Disaggregation of Revenue [Table Text Block] Unrealized Loss - 12 Months or Greater Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Sonoma Biotherapeutics, Inc. Collaboration Agreement Sonoma Biotherapeutics, Inc. Collaboration Agreement [Member] Sonoma Biotherapeutics, Inc. 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basic (in shares) Weighted average shares - basic (in shares) Weighted Average Number of Shares Outstanding, Basic Entity Current Reporting Status Entity Current Reporting Status Concentration Risk Type [Domain] Concentration Risk Type [Domain] Income from operations Operating Income (Loss) Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Sanofi Collaboration Agreement, Immuno-oncology Sanofi Collaboration Agreement, Immuno-oncology Sanofi Collaboration Agreement, Immuno-oncology [Member] Sanofi Collaboration Agreement, Immuno-oncology [Member] 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 [Member] Revenues: Revenues [Abstract] Statements of Comprehensive Income Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Statement [Line Items] Statement [Line Items] Concentration Risk [Table] Concentration Risk [Table] Acquired in-process research and development Acquired In-Process Research and Development Acquired In-Process Research and Development Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Available-for-sale Debt Securities Debt Securities, Available-for-Sale [Table Text Block] Regeneron's obligation for its share of Sanofi R&D expenses, net of reimbursement of R&D expenses Reimbursement Of Research And Development Expenses, Net Of Obligation For Share Of R&D Expenses [Member] Reimbursement Of Research And Development Expenses, Net Of Obligation For Share Of R&D Expenses