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

The percentage of net sales of the product the Company will supply the product to MTPC (subject to adjustment in certain circumstances).

No definition available.

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

The amount of contingent payments the Company is entitled to receive related to development and other milestones achieved by MTPC.

No definition available.

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

Future development milestone payment the Company is eligible to receive.

No definition available.

Name:	regn_FuturedevelopmentmilestonepaymenttheCompanyiseligibletoreceive
Namespace Prefix:	regn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The starting specified levels of total annual sales within the MTPC Territories at which the Company is eligible to receive additional payments.

No definition available.

Name:	regn_Startingspecifiedlevelsofannualsalesatwhichsalesmilestonepaymentsmaybereceived
Namespace Prefix:	regn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Amount of deferred revenue recognized for transactions arising during the current reporting period. Deferred revenue is a liability as of the balance sheet date related to a revenue producing activity for which revenue has not yet been recognized. Generally, an Entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 13.A.4(a).Q1)
-URI http://asc.fasb.org/extlink&oid=27012821&loc=d3e214044-122780

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 13
-Section A

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Name:	us-gaap_CounterpartyNameAxis=regn_MitsubishiTanabePharmaCorporationMTPCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_TypeOfArrangementAxis=us-gaap_CollaborativeArrangementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
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