Name:	regn_AdvancePaymentReceivedDueToAmendedLicensingAgreement
Namespace Prefix:	regn_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration

The amount of non-refundable payment made annually to the Company under the terms of the licensing agreement.

No definition available.

Name:	regn_AnnualNonRefundableLicensingPaymentReceived
Namespace Prefix:	regn_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration

The amount of future payment to be made to the Company in June 2018 under the terms of the amended licensing agreement, unless the license agreement is terminated prior to that date.

No definition available.

Name:	regn_FuturePaymentToBeMadeUnderTermsOfAmendedLicensingAgreement
Namespace Prefix:	regn_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

The term (in years) of the non-exclusive license agreement.

No definition available.

Name:	regn_NonExclusiveLicenseAgreementTerm
Namespace Prefix:	regn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The number of annual payments not paid to the Company due to the termination of the licensing agreement.

No definition available.

Name:	regn_NumberOfAnnualPaymentsNotReceivedDueToCancellationOfObligation
Namespace Prefix:	regn_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

The number of days the licensee must provide advance written notice in order to terminate the licensing agreement.

No definition available.

Name:	regn_NumberOfDaysOfAdvanceWrittenNoticeToTerminateAgreement
Namespace Prefix:	regn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The ensuing period (in months) over which each annual payment is ratably recognized as revenue.

No definition available.

Name:	regn_PeriodOverWhichAnnualPaymentIsRecognizedAsRevenue
Namespace Prefix:	regn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The revenue recognition period (in years) of the up-front payment the Company received under the terms of the amended licensing agreement. This payment was deferred upon receipt and will be recognized as revenue ratably, beginning in mid-2011.

No definition available.

Name:	regn_RecognitionPeriodForAdvancePayment
Namespace Prefix:	regn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Amount of deferred revenue as of balance sheet date. Deferred revenue represents collections of cash or other assets 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 SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 13

-Section A

Reference 2: 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 Response)

-URI http://asc.fasb.org/extlink&oid=6600647&loc=d3e214044-122780

Name:	us-gaap_DeferredRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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

Revenue earned during the period relating to consideration received from another party for the right to use, but not own, certain of the entity's intangible assets. Licensing arrangements include, but are not limited to, rights to use a patent, copyright, technology, manufacturing process, software or trademark. Licensing fees are generally, but not always, fixed as to amount and not dependent upon the revenue generated by the licensing party. An entity may receive licensing fees for licenses that also generate royalty payments to the entity.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1(e))

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688