Collaboration Agreements (PDGFR-beta Antibody) (Details) - PDGF - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Jun. 30, 2015	Sep. 30, 2016
Collaboration Agreement [Line Items]
Percentage of global development cost to be paid by the collaboration partner under the collaboration		25.00%
Percentage of development cost for the territory outside the United States to be paid for under the collaboration		50.00%
Revenue Recognition, Milestone Method, Revenue Recognized	$ 5.0

Percentage of development cost for the territory outside the United States previously required to be paid for under the collaboration.

No definition available.

+ Details

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- Definition

Percentage of global development cost to be paid by the collaboration partner under the collaboration

+ References

No definition available.

+ Details

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Namespace Prefix:	regn_
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Period Type:	duration

- Definition

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.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of consideration recognized during the period for the milestone or milestones.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 28
-Section 50
-Paragraph 2
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=51671726&loc=SL6892177-166501

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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