Collaboration Agreements (Ang2 Antibody) (Details) - Ang2 Antibody [Member] $ in Millions	Mar. 31, 2016 USD ($)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Deferred Revenue, Additions	$ 50.0
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%

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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Period Type:	duration

- 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

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.

+ References

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=65893310&loc=d3e214044-122780

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.3)
-URI http://asc.fasb.org/extlink&oid=65893310&loc=d3e214044-122780

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

- Details

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