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Maximum shares the collaborator could sell through September 30, 2020.

No definition available.

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Data Type:	xbrli:sharesItemType
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Number of demand rights to require the Company to use all reasonable efforts to conduct registered underwritten public offering with respect to shares of the Company's Common Stock held by Sanofi from time to time.

No definition available.

Name:	regn_NumberOfDemandRightsToRequireTheCompanyToConductRegisteredUnderwrittenPublicOffering
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Number Of Votes Per Share

No definition available.

Name:	regn_NumberOfVotesPerShare
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The number of newly issued shares of the Company's Common Stock purchased in connection with the Sanofi collaboration agreement.

No definition available.

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The percentage of the then outstanding shares or voting rights of the Company's Class A Stock and Common Stock, which if a stock issuance equals or exceeds such amount, the collaborator has not contractually agreed to vote, and cause its affiliates to vote, either as recommended by the Company's board of directors or proportionally with the votes cast by the Company's other shareholders.

No definition available.

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The percentage outstanding shares that the Company is required to appoint an individual agreed upon by the Company and the collaborator to the Company's board of directors.

No definition available.

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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.

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Face amount or stated value per share of common stock.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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