<?xml version="1.0" encoding="utf-8"?>
<xbrl
  xml:lang="en-US"
  xmlns="http://www.xbrl.org/2003/instance"
  xmlns:dei="http://xbrl.sec.gov/dei/2021q4"
  xmlns:link="http://www.xbrl.org/2003/linkbase"
  xmlns:xlink="http://www.w3.org/1999/xlink">
    <link:schemaRef xlink:href="regn-20220204.xsd" xlink:type="simple"/>
    <context id="i2f5eb5837e004184a19cb2bd448a0b33_D20220204-20220204">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000872589</identifier>
        </entity>
        <period>
            <startDate>2022-02-04</startDate>
            <endDate>2022-02-04</endDate>
        </period>
    </context>
    <dei:EntityCentralIndexKey
      contextRef="i2f5eb5837e004184a19cb2bd448a0b33_D20220204-20220204"
      id="id3VybDovL2RvY3MudjEvZG9jOjhmNDA5M2Y1YTZjZjRkNWU4NTFjYWNlMjJmMWMwMTU2L3NlYzo4ZjQwOTNmNWE2Y2Y0ZDVlODUxY2FjZTIyZjFjMDE1Nl80L2ZyYWc6OGIxZTEwMmFmNTUwNDkwOTk4ZDUxY2FiNTQwMjU2ZGIvdGFibGU6ZjI2NzA0ZjJlNjAwNGQ2Y2I4OTRiYjliMDkzMzQ4NjAvdGFibGVyYW5nZTpmMjY3MDRmMmU2MDA0ZDZjYjg5NGJiOWIwOTMzNDg2MF8yLTEtMS0xLTQ4MDA1_046380ab-4291-4c98-b8d7-db8a4d7a857a">0000872589</dei:EntityCentralIndexKey>
    <dei:AmendmentFlag
      contextRef="i2f5eb5837e004184a19cb2bd448a0b33_D20220204-20220204"
      id="id3VybDovL2RvY3MudjEvZG9jOjhmNDA5M2Y1YTZjZjRkNWU4NTFjYWNlMjJmMWMwMTU2L3NlYzo4ZjQwOTNmNWE2Y2Y0ZDVlODUxY2FjZTIyZjFjMDE1Nl80L2ZyYWc6OGIxZTEwMmFmNTUwNDkwOTk4ZDUxY2FiNTQwMjU2ZGIvdGFibGU6ZjI2NzA0ZjJlNjAwNGQ2Y2I4OTRiYjliMDkzMzQ4NjAvdGFibGVyYW5nZTpmMjY3MDRmMmU2MDA0ZDZjYjg5NGJiOWIwOTMzNDg2MF8zLTEtMS0xLTQ4MDA1_079704af-ede7-4cff-981e-66019e3c5b24">false</dei:AmendmentFlag>
    <dei:DocumentType
      contextRef="i2f5eb5837e004184a19cb2bd448a0b33_D20220204-20220204"
      id="id3VybDovL2RvY3MudjEvZG9jOjhmNDA5M2Y1YTZjZjRkNWU4NTFjYWNlMjJmMWMwMTU2L3NlYzo4ZjQwOTNmNWE2Y2Y0ZDVlODUxY2FjZTIyZjFjMDE1Nl8xL2ZyYWc6N2JmMGUxMjEwZmIxNDQ5ZmI4MGNmZjM3NDlkYzU2ZWQvdGV4dHJlZ2lvbjo3YmYwZTEyMTBmYjE0NDlmYjgwY2ZmMzc0OWRjNTZlZF8xNTk1_7322a44c-ef35-4837-b5c9-c3d9b0fa90f9">8-K</dei:DocumentType>
    <dei:DocumentPeriodEndDate
      contextRef="i2f5eb5837e004184a19cb2bd448a0b33_D20220204-20220204"
      id="id3VybDovL2RvY3MudjEvZG9jOjhmNDA5M2Y1YTZjZjRkNWU4NTFjYWNlMjJmMWMwMTU2L3NlYzo4ZjQwOTNmNWE2Y2Y0ZDVlODUxY2FjZTIyZjFjMDE1Nl8xL2ZyYWc6N2JmMGUxMjEwZmIxNDQ5ZmI4MGNmZjM3NDlkYzU2ZWQvdGV4dHJlZ2lvbjo3YmYwZTEyMTBmYjE0NDlmYjgwY2ZmMzc0OWRjNTZlZF8yMTk5MDIzMjU3MTUy_394efa08-8db3-4c28-9e1e-2de1722e9bc6">2022-02-04</dei:DocumentPeriodEndDate>
    <dei:DocumentPeriodEndDate
      contextRef="i2f5eb5837e004184a19cb2bd448a0b33_D20220204-20220204"
      id="id3VybDovL2RvY3MudjEvZG9jOjhmNDA5M2Y1YTZjZjRkNWU4NTFjYWNlMjJmMWMwMTU2L3NlYzo4ZjQwOTNmNWE2Y2Y0ZDVlODUxY2FjZTIyZjFjMDE1Nl8xL2ZyYWc6N2JmMGUxMjEwZmIxNDQ5ZmI4MGNmZjM3NDlkYzU2ZWQvdGV4dHJlZ2lvbjo3YmYwZTEyMTBmYjE0NDlmYjgwY2ZmMzc0OWRjNTZlZF8yMTk5MDIzMjU3MTU2_394efa08-8db3-4c28-9e1e-2de1722e9bc6">2022-02-04</dei:DocumentPeriodEndDate>
    <dei:EntityRegistrantName
      contextRef="i2f5eb5837e004184a19cb2bd448a0b33_D20220204-20220204"
      id="id3VybDovL2RvY3MudjEvZG9jOjhmNDA5M2Y1YTZjZjRkNWU4NTFjYWNlMjJmMWMwMTU2L3NlYzo4ZjQwOTNmNWE2Y2Y0ZDVlODUxY2FjZTIyZjFjMDE1Nl8xL2ZyYWc6N2JmMGUxMjEwZmIxNDQ5ZmI4MGNmZjM3NDlkYzU2ZWQvdGV4dHJlZ2lvbjo3YmYwZTEyMTBmYjE0NDlmYjgwY2ZmMzc0OWRjNTZlZF8xNTg5_4d401df9-b3d6-47f4-86cc-efee2caca8df">REGENERON PHARMACEUTICALS, INC.</dei:EntityRegistrantName>
    <dei:EntityIncorporationStateCountryCode
      contextRef="i2f5eb5837e004184a19cb2bd448a0b33_D20220204-20220204"
      id="id3VybDovL2RvY3MudjEvZG9jOjhmNDA5M2Y1YTZjZjRkNWU4NTFjYWNlMjJmMWMwMTU2L3NlYzo4ZjQwOTNmNWE2Y2Y0ZDVlODUxY2FjZTIyZjFjMDE1Nl8xL2ZyYWc6N2JmMGUxMjEwZmIxNDQ5ZmI4MGNmZjM3NDlkYzU2ZWQvdGFibGU6ZDNjMDJjMzg0MzkwNDk3MWJiMmVlNzRjMzI1ZTMxZmMvdGFibGVyYW5nZTpkM2MwMmMzODQzOTA0OTcxYmIyZWU3NGMzMjVlMzFmY18wLTAtMS0xLTQ4MDA1_b124ecfe-9335-40a1-b6d1-6d368c973f81">NY</dei:EntityIncorporationStateCountryCode>
    <dei:EntityFileNumber
      contextRef="i2f5eb5837e004184a19cb2bd448a0b33_D20220204-20220204"
      id="id3VybDovL2RvY3MudjEvZG9jOjhmNDA5M2Y1YTZjZjRkNWU4NTFjYWNlMjJmMWMwMTU2L3NlYzo4ZjQwOTNmNWE2Y2Y0ZDVlODUxY2FjZTIyZjFjMDE1Nl8xL2ZyYWc6N2JmMGUxMjEwZmIxNDQ5ZmI4MGNmZjM3NDlkYzU2ZWQvdGFibGU6ZDNjMDJjMzg0MzkwNDk3MWJiMmVlNzRjMzI1ZTMxZmMvdGFibGVyYW5nZTpkM2MwMmMzODQzOTA0OTcxYmIyZWU3NGMzMjVlMzFmY18wLTEtMS0xLTQ4MDA1_f0eb8eab-991c-4f35-b13d-36d527368f7b">000-19034</dei:EntityFileNumber>
    <dei:EntityTaxIdentificationNumber
      contextRef="i2f5eb5837e004184a19cb2bd448a0b33_D20220204-20220204"
      id="id3VybDovL2RvY3MudjEvZG9jOjhmNDA5M2Y1YTZjZjRkNWU4NTFjYWNlMjJmMWMwMTU2L3NlYzo4ZjQwOTNmNWE2Y2Y0ZDVlODUxY2FjZTIyZjFjMDE1Nl8xL2ZyYWc6N2JmMGUxMjEwZmIxNDQ5ZmI4MGNmZjM3NDlkYzU2ZWQvdGFibGU6ZDNjMDJjMzg0MzkwNDk3MWJiMmVlNzRjMzI1ZTMxZmMvdGFibGVyYW5nZTpkM2MwMmMzODQzOTA0OTcxYmIyZWU3NGMzMjVlMzFmY18wLTMtMS0xLTQ4MDA1_86e2d9b7-a7e8-4284-aa4c-91a554876b2e">13-3444607</dei:EntityTaxIdentificationNumber>
    <dei:EntityAddressAddressLine1
      contextRef="i2f5eb5837e004184a19cb2bd448a0b33_D20220204-20220204"
      id="id3VybDovL2RvY3MudjEvZG9jOjhmNDA5M2Y1YTZjZjRkNWU4NTFjYWNlMjJmMWMwMTU2L3NlYzo4ZjQwOTNmNWE2Y2Y0ZDVlODUxY2FjZTIyZjFjMDE1Nl8xL2ZyYWc6N2JmMGUxMjEwZmIxNDQ5ZmI4MGNmZjM3NDlkYzU2ZWQvdGFibGU6MTI3Nzk5OGE4MmRkNDZjNTgwY2M1YWViMjBiYzU4NjEvdGFibGVyYW5nZToxMjc3OTk4YTgyZGQ0NmM1ODBjYzVhZWIyMGJjNTg2MV8wLTAtMS0xLTQ4MDA1L3RleHRyZWdpb246M2QwY2U5OWNiYzUxNGJiMjgzYzVhZTcyZmVhMDE2NDdfNA_87058efc-2377-4a4c-8da6-b44e65e16f7a">777 Old Saw Mill River Road</dei:EntityAddressAddressLine1>
    <dei:EntityAddressCityOrTown
      contextRef="i2f5eb5837e004184a19cb2bd448a0b33_D20220204-20220204"
      id="id3VybDovL2RvY3MudjEvZG9jOjhmNDA5M2Y1YTZjZjRkNWU4NTFjYWNlMjJmMWMwMTU2L3NlYzo4ZjQwOTNmNWE2Y2Y0ZDVlODUxY2FjZTIyZjFjMDE1Nl8xL2ZyYWc6N2JmMGUxMjEwZmIxNDQ5ZmI4MGNmZjM3NDlkYzU2ZWQvdGFibGU6MTI3Nzk5OGE4MmRkNDZjNTgwY2M1YWViMjBiYzU4NjEvdGFibGVyYW5nZToxMjc3OTk4YTgyZGQ0NmM1ODBjYzVhZWIyMGJjNTg2MV8wLTAtMS0xLTQ4MDA1L3RleHRyZWdpb246M2QwY2U5OWNiYzUxNGJiMjgzYzVhZTcyZmVhMDE2NDdfOQ_477e1a66-fbc3-4647-b44c-1c623dc0a81b">Tarrytown</dei:EntityAddressCityOrTown>
    <dei:EntityAddressStateOrProvince
      contextRef="i2f5eb5837e004184a19cb2bd448a0b33_D20220204-20220204"
      id="id3VybDovL2RvY3MudjEvZG9jOjhmNDA5M2Y1YTZjZjRkNWU4NTFjYWNlMjJmMWMwMTU2L3NlYzo4ZjQwOTNmNWE2Y2Y0ZDVlODUxY2FjZTIyZjFjMDE1Nl8xL2ZyYWc6N2JmMGUxMjEwZmIxNDQ5ZmI4MGNmZjM3NDlkYzU2ZWQvdGFibGU6MTI3Nzk5OGE4MmRkNDZjNTgwY2M1YWViMjBiYzU4NjEvdGFibGVyYW5nZToxMjc3OTk4YTgyZGQ0NmM1ODBjYzVhZWIyMGJjNTg2MV8wLTAtMS0xLTQ4MDA1L3RleHRyZWdpb246M2QwY2U5OWNiYzUxNGJiMjgzYzVhZTcyZmVhMDE2NDdfMTQ_668b6f9e-5667-4a7e-83d6-32998f5cf54a">NY</dei:EntityAddressStateOrProvince>
    <dei:EntityAddressPostalZipCode
      contextRef="i2f5eb5837e004184a19cb2bd448a0b33_D20220204-20220204"
      id="id3VybDovL2RvY3MudjEvZG9jOjhmNDA5M2Y1YTZjZjRkNWU4NTFjYWNlMjJmMWMwMTU2L3NlYzo4ZjQwOTNmNWE2Y2Y0ZDVlODUxY2FjZTIyZjFjMDE1Nl8xL2ZyYWc6N2JmMGUxMjEwZmIxNDQ5ZmI4MGNmZjM3NDlkYzU2ZWQvdGFibGU6MTI3Nzk5OGE4MmRkNDZjNTgwY2M1YWViMjBiYzU4NjEvdGFibGVyYW5nZToxMjc3OTk4YTgyZGQ0NmM1ODBjYzVhZWIyMGJjNTg2MV8wLTAtMS0xLTQ4MDA1L3RleHRyZWdpb246M2QwY2U5OWNiYzUxNGJiMjgzYzVhZTcyZmVhMDE2NDdfMTg_f828ab7a-4c08-41d2-8e39-af9e948dfdd8">10591-6707</dei:EntityAddressPostalZipCode>
    <dei:CityAreaCode
      contextRef="i2f5eb5837e004184a19cb2bd448a0b33_D20220204-20220204"
      id="id3VybDovL2RvY3MudjEvZG9jOjhmNDA5M2Y1YTZjZjRkNWU4NTFjYWNlMjJmMWMwMTU2L3NlYzo4ZjQwOTNmNWE2Y2Y0ZDVlODUxY2FjZTIyZjFjMDE1Nl8xL2ZyYWc6N2JmMGUxMjEwZmIxNDQ5ZmI4MGNmZjM3NDlkYzU2ZWQvdGV4dHJlZ2lvbjo3YmYwZTEyMTBmYjE0NDlmYjgwY2ZmMzc0OWRjNTZlZF8xNTk2_024085fe-601f-4bc2-8957-76e04e4a887e">914</dei:CityAreaCode>
    <dei:LocalPhoneNumber
      contextRef="i2f5eb5837e004184a19cb2bd448a0b33_D20220204-20220204"
      id="id3VybDovL2RvY3MudjEvZG9jOjhmNDA5M2Y1YTZjZjRkNWU4NTFjYWNlMjJmMWMwMTU2L3NlYzo4ZjQwOTNmNWE2Y2Y0ZDVlODUxY2FjZTIyZjFjMDE1Nl8xL2ZyYWc6N2JmMGUxMjEwZmIxNDQ5ZmI4MGNmZjM3NDlkYzU2ZWQvdGV4dHJlZ2lvbjo3YmYwZTEyMTBmYjE0NDlmYjgwY2ZmMzc0OWRjNTZlZF8xNTk3_577f397e-161f-4205-b83b-55cd738b7e22">847-7000</dei:LocalPhoneNumber>
    <dei:WrittenCommunications
      contextRef="i2f5eb5837e004184a19cb2bd448a0b33_D20220204-20220204"
      id="id3VybDovL2RvY3MudjEvZG9jOjhmNDA5M2Y1YTZjZjRkNWU4NTFjYWNlMjJmMWMwMTU2L3NlYzo4ZjQwOTNmNWE2Y2Y0ZDVlODUxY2FjZTIyZjFjMDE1Nl8xL2ZyYWc6N2JmMGUxMjEwZmIxNDQ5ZmI4MGNmZjM3NDlkYzU2ZWQvdGV4dHJlZ2lvbjo3YmYwZTEyMTBmYjE0NDlmYjgwY2ZmMzc0OWRjNTZlZF8xNTky_06564ee8-c0a6-49ef-aaf7-b667f80168a5">false</dei:WrittenCommunications>
    <dei:SolicitingMaterial
      contextRef="i2f5eb5837e004184a19cb2bd448a0b33_D20220204-20220204"
      id="id3VybDovL2RvY3MudjEvZG9jOjhmNDA5M2Y1YTZjZjRkNWU4NTFjYWNlMjJmMWMwMTU2L3NlYzo4ZjQwOTNmNWE2Y2Y0ZDVlODUxY2FjZTIyZjFjMDE1Nl8xL2ZyYWc6N2JmMGUxMjEwZmIxNDQ5ZmI4MGNmZjM3NDlkYzU2ZWQvdGV4dHJlZ2lvbjo3YmYwZTEyMTBmYjE0NDlmYjgwY2ZmMzc0OWRjNTZlZF8xNTkw_fe6a0a4b-ee18-4cdf-9f13-581f1040a64f">false</dei:SolicitingMaterial>
    <dei:PreCommencementTenderOffer
      contextRef="i2f5eb5837e004184a19cb2bd448a0b33_D20220204-20220204"
      id="id3VybDovL2RvY3MudjEvZG9jOjhmNDA5M2Y1YTZjZjRkNWU4NTFjYWNlMjJmMWMwMTU2L3NlYzo4ZjQwOTNmNWE2Y2Y0ZDVlODUxY2FjZTIyZjFjMDE1Nl8xL2ZyYWc6N2JmMGUxMjEwZmIxNDQ5ZmI4MGNmZjM3NDlkYzU2ZWQvdGV4dHJlZ2lvbjo3YmYwZTEyMTBmYjE0NDlmYjgwY2ZmMzc0OWRjNTZlZF8xNTkz_8b0b11c4-f5b9-40a1-93b2-586a3508e29e">false</dei:PreCommencementTenderOffer>
    <dei:PreCommencementIssuerTenderOffer
      contextRef="i2f5eb5837e004184a19cb2bd448a0b33_D20220204-20220204"
      id="id3VybDovL2RvY3MudjEvZG9jOjhmNDA5M2Y1YTZjZjRkNWU4NTFjYWNlMjJmMWMwMTU2L3NlYzo4ZjQwOTNmNWE2Y2Y0ZDVlODUxY2FjZTIyZjFjMDE1Nl8xL2ZyYWc6N2JmMGUxMjEwZmIxNDQ5ZmI4MGNmZjM3NDlkYzU2ZWQvdGV4dHJlZ2lvbjo3YmYwZTEyMTBmYjE0NDlmYjgwY2ZmMzc0OWRjNTZlZF8xNTkx_2dd07d69-bbd2-4c5f-a22b-c07968878999">false</dei:PreCommencementIssuerTenderOffer>
    <dei:Security12bTitle
      contextRef="i2f5eb5837e004184a19cb2bd448a0b33_D20220204-20220204"
      id="id3VybDovL2RvY3MudjEvZG9jOjhmNDA5M2Y1YTZjZjRkNWU4NTFjYWNlMjJmMWMwMTU2L3NlYzo4ZjQwOTNmNWE2Y2Y0ZDVlODUxY2FjZTIyZjFjMDE1Nl8xL2ZyYWc6N2JmMGUxMjEwZmIxNDQ5ZmI4MGNmZjM3NDlkYzU2ZWQvdGFibGU6OGVkNmQ2YjZkNmIzNDJjZmFhN2IzYjk5MGVkYTFiMzgvdGFibGVyYW5nZTo4ZWQ2ZDZiNmQ2YjM0MmNmYWE3YjNiOTkwZWRhMWIzOF8xLTAtMS0xLTQ4MDA1_e5d0ee27-4cad-4be9-ac1d-916cbe41359d">Common Stock - par value $.001 per share</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="i2f5eb5837e004184a19cb2bd448a0b33_D20220204-20220204"
      id="id3VybDovL2RvY3MudjEvZG9jOjhmNDA5M2Y1YTZjZjRkNWU4NTFjYWNlMjJmMWMwMTU2L3NlYzo4ZjQwOTNmNWE2Y2Y0ZDVlODUxY2FjZTIyZjFjMDE1Nl8xL2ZyYWc6N2JmMGUxMjEwZmIxNDQ5ZmI4MGNmZjM3NDlkYzU2ZWQvdGFibGU6OGVkNmQ2YjZkNmIzNDJjZmFhN2IzYjk5MGVkYTFiMzgvdGFibGVyYW5nZTo4ZWQ2ZDZiNmQ2YjM0MmNmYWE3YjNiOTkwZWRhMWIzOF8xLTEtMS0xLTQ4MDA1_80066f60-96f9-411b-92f5-499418377bf0">REGN</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="i2f5eb5837e004184a19cb2bd448a0b33_D20220204-20220204"
      id="id3VybDovL2RvY3MudjEvZG9jOjhmNDA5M2Y1YTZjZjRkNWU4NTFjYWNlMjJmMWMwMTU2L3NlYzo4ZjQwOTNmNWE2Y2Y0ZDVlODUxY2FjZTIyZjFjMDE1Nl8xL2ZyYWc6N2JmMGUxMjEwZmIxNDQ5ZmI4MGNmZjM3NDlkYzU2ZWQvdGFibGU6OGVkNmQ2YjZkNmIzNDJjZmFhN2IzYjk5MGVkYTFiMzgvdGFibGVyYW5nZTo4ZWQ2ZDZiNmQ2YjM0MmNmYWE3YjNiOTkwZWRhMWIzOF8xLTItMS0xLTQ4MDA1_b5790ade-69b3-47df-ad40-9ce6e4f01d18">NASDAQ</dei:SecurityExchangeName>
    <dei:EntityEmergingGrowthCompany
      contextRef="i2f5eb5837e004184a19cb2bd448a0b33_D20220204-20220204"
      id="id3VybDovL2RvY3MudjEvZG9jOjhmNDA5M2Y1YTZjZjRkNWU4NTFjYWNlMjJmMWMwMTU2L3NlYzo4ZjQwOTNmNWE2Y2Y0ZDVlODUxY2FjZTIyZjFjMDE1Nl8xL2ZyYWc6N2JmMGUxMjEwZmIxNDQ5ZmI4MGNmZjM3NDlkYzU2ZWQvdGV4dHJlZ2lvbjo3YmYwZTEyMTBmYjE0NDlmYjgwY2ZmMzc0OWRjNTZlZF8xNTg4_b88ca087-9349-472a-bcbb-e72ade9d2df3">false</dei:EntityEmergingGrowthCompany>
</xbrl>
