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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

On a sliding scale, this element represents the ending share of profits outside the United States, based on sales, for the collaborating party.

No definition available.

Name:	regn_EndingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCollaboratingParty
Namespace Prefix:	regn_
Data Type:	num:percentItemType
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Period Type:	duration

On a sliding scale, this element represents the ending share of profits outside the United States, based on sales, for the Company.

No definition available.

Name:	regn_EndingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCompany
Namespace Prefix:	regn_
Data Type:	num:percentItemType
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Period Type:	duration

Aggregate amount of twelve month sales upon which sales milestone would be received.

No definition available.

Name:	regn_Levelsoftwelvemonthsalesatwhichsalesmilestonepaymentswouldbereceived
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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Loss Contingency, Percentage Of Damages Responsible For

No definition available.

Name:	regn_LossContingencyPercentageOfDamagesResponsibleFor
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Percentage Of Quarterly Profits Required To Be Paid For Reimbursement Of Development Costs

No definition available.

Name:	regn_PercentageOfQuarterlyProfitsRequiredToBePaidForReimbursementOfDevelopmentCosts
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Data Type:	num:percentItemType
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Period Type:	duration

Percentage of repayment of development balance out of profits under the collaboration agreement.

No definition available.

Name:	regn_PercentageOfRepaymentOfDevelopmentBalanceOutOfProfits
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Data Type:	num:percentItemType
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Period Type:	duration

Percentage of Royalty Payment That Can Be Offset

No definition available.

Name:	regn_PercentageOfRoyaltyPaymentThatCanBeOffset
Namespace Prefix:	regn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Percentage of Trial Costs Required To Be Funded By Collaborating Party

No definition available.

Name:	regn_PercentageOfTrialCostsRequiredToBeFundedByCollaboratingParty
Namespace Prefix:	regn_
Data Type:	num:percentItemType
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Period Type:	duration

Period for Achieving Sales Target for Milestone Payment, Rolling Basis

No definition available.

Name:	regn_PeriodForAchievingSalesTargetForMilestonePaymentRollingBasis
Namespace Prefix:	regn_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Remaining Amount Of Sales Milestone Payments If Total Sales Achieve Specific Levels

No definition available.

Name:	regn_RemainingAmountOfSalesMilestonePaymentsIfTotalSalesAchieveSpecificLevels
Namespace Prefix:	regn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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Royalty Percentage To Be Received On Net Product Sales Outside Of United States

No definition available.

Name:	regn_RoyaltyPercentageToBeReceivedOnNetProductSalesOutsideOfUnitedStates
Namespace Prefix:	regn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Sales Milestone Payment If Total Sales Achieve Specific Levels

No definition available.

Name:	regn_SalesMilestonePaymentIfTotalSalesAchieveSpecificLevels
Namespace Prefix:	regn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

This element represents the share of losses outside the United States for the collaborating party.

No definition available.

Name:	regn_ShareOfLossesOutsideUnitedStatesForCollaboratingParty
Namespace Prefix:	regn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

This element represents the share of losses outside the United States for the Company.

No definition available.

Name:	regn_ShareOfLossesOutsideUnitedStatesForCompany
Namespace Prefix:	regn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

On a sliding scale, this element represents the starting share of profits outside the United States, based on sales, for the collaborating party.

No definition available.

Name:	regn_StartingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCollaboratingParty
Namespace Prefix:	regn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

On a sliding scale, this element represents the starting share of profits outside the United States, based on sales, for the Company.

No definition available.

Name:	regn_StartingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCompany
Namespace Prefix:	regn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

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.

No definition available.

Name:	us-gaap_DisaggregationOfRevenueLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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Namespace Prefix:
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Balance Type:
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Namespace Prefix:
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Namespace Prefix:
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