<?xml version="1.0" encoding="utf-8"?>
<xbrl
  xmlns="http://www.xbrl.org/2003/instance"
  xmlns:dei="http://xbrl.sec.gov/dei/2025"
  xmlns:fnd="http://xbrl.sec.gov/fnd/2025"
  xmlns:iso4217="http://www.xbrl.org/2003/iso4217"
  xmlns:link="http://www.xbrl.org/2003/linkbase"
  xmlns:oef="http://xbrl.sec.gov/oef/2025"
  xmlns:pvt="http://www.franklintempleton.com/20261001"
  xmlns:xbrldi="http://xbrl.org/2006/xbrldi"
  xmlns:xlink="http://www.w3.org/1999/xlink">
    <link:schemaRef xlink:href="cik0000822671-20261001.xsd" xlink:type="simple"/>
    <context id="D20260630_20260630_S000003884Member_CommonStockRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">pvt:S000003884Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">pvt:CommonStockRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-06-30</startDate>
            <endDate>2026-06-30</endDate>
        </period>
    </context>
    <context id="D20260630_20260630_S000003884Member_CybersecurityRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">pvt:S000003884Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">pvt:CybersecurityRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-06-30</startDate>
            <endDate>2026-06-30</endDate>
        </period>
    </context>
    <context id="D20260630_20260630_S000003884Member_IndustryOrSectorFocusRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">pvt:S000003884Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">pvt:IndustryOrSectorFocusRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-06-30</startDate>
            <endDate>2026-06-30</endDate>
        </period>
    </context>
    <context id="D20260630_20260630_S000003884Member_LargeShareholderTransactionRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">pvt:S000003884Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">pvt:LargeShareholderTransactionRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-06-30</startDate>
            <endDate>2026-06-30</endDate>
        </period>
    </context>
    <context id="D20260630_20260630_S000003884Member_ManagementAndOperationalRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">pvt:S000003884Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">pvt:ManagementAndOperationalRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-06-30</startDate>
            <endDate>2026-06-30</endDate>
        </period>
    </context>
    <context id="D20260630_20260630_S000003884Member_MarketRisksMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">pvt:S000003884Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">pvt:MarketRisksMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-06-30</startDate>
            <endDate>2026-06-30</endDate>
        </period>
    </context>
    <context id="D20260630_20260630_S000003884Member_RiskLoseMoneyMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">pvt:S000003884Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskLoseMoneyMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-06-30</startDate>
            <endDate>2026-06-30</endDate>
        </period>
    </context>
    <context id="D20260630_20260630_S000003884Member_RiskNondiversifiedStatusMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">pvt:S000003884Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskNondiversifiedStatusMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-06-30</startDate>
            <endDate>2026-06-30</endDate>
        </period>
    </context>
    <context id="D20260630_20260630_S000003884Member_RiskNotInsuredMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">pvt:S000003884Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskNotInsuredMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-06-30</startDate>
            <endDate>2026-06-30</endDate>
        </period>
    </context>
    <context id="DefaultContext">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
        </entity>
        <period>
            <startDate>2026-06-30</startDate>
            <endDate>2026-06-30</endDate>
        </period>
    </context>
    <context id="FiveY2025_C000010863Member">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="oef:ClassAxis">pvt:C000010863Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-01-01</startDate>
            <endDate>2025-12-31</endDate>
        </period>
    </context>
    <context id="FiveY2025_C000010864Member">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="oef:ClassAxis">pvt:C000010864Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-01-01</startDate>
            <endDate>2025-12-31</endDate>
        </period>
    </context>
    <context id="FiveY2025_LinkedSP500IndexMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">pvt:LinkedSP500IndexMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-01-01</startDate>
            <endDate>2025-12-31</endDate>
        </period>
    </context>
    <context id="FiveY2025_Russell3000IndexMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">pvt:Russell3000IndexMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-01-01</startDate>
            <endDate>2025-12-31</endDate>
        </period>
    </context>
    <context id="FiveY2025_SP500IndexMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">pvt:SP500IndexMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-01-01</startDate>
            <endDate>2025-12-31</endDate>
        </period>
    </context>
    <context id="FY2016_S000003884Member_C000010863Member">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">pvt:S000003884Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">pvt:C000010863Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2016-01-01</startDate>
            <endDate>2016-12-31</endDate>
        </period>
    </context>
    <context id="FY2017_S000003884Member_C000010863Member">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">pvt:S000003884Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">pvt:C000010863Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2017-01-01</startDate>
            <endDate>2017-12-31</endDate>
        </period>
    </context>
    <context id="FY2018_S000003884Member_C000010863Member">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">pvt:S000003884Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">pvt:C000010863Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2018-01-01</startDate>
            <endDate>2018-12-31</endDate>
        </period>
    </context>
    <context id="FY2019_S000003884Member_C000010863Member">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">pvt:S000003884Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">pvt:C000010863Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2019-01-01</startDate>
            <endDate>2019-12-31</endDate>
        </period>
    </context>
    <context id="FY2020_S000003884Member_C000010863Member">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">pvt:S000003884Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">pvt:C000010863Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-01-01</startDate>
            <endDate>2020-12-31</endDate>
        </period>
    </context>
    <context id="FY2021_S000003884Member_C000010863Member">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">pvt:S000003884Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">pvt:C000010863Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-01-01</startDate>
            <endDate>2021-12-31</endDate>
        </period>
    </context>
    <context id="FY2022_S000003884Member_C000010863Member">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">pvt:S000003884Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">pvt:C000010863Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2022-01-01</startDate>
            <endDate>2022-12-31</endDate>
        </period>
    </context>
    <context id="FY2023_S000003884Member_C000010863Member">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">pvt:S000003884Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">pvt:C000010863Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2023-01-01</startDate>
            <endDate>2023-12-31</endDate>
        </period>
    </context>
    <context id="FY2024_S000003884Member_C000010863Member">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">pvt:S000003884Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">pvt:C000010863Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-01-01</startDate>
            <endDate>2024-12-31</endDate>
        </period>
    </context>
    <context id="FY2025_C000010863Member">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="oef:ClassAxis">pvt:C000010863Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-01-01</startDate>
            <endDate>2025-12-31</endDate>
        </period>
    </context>
    <context id="FY2025_C000010864Member">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="oef:ClassAxis">pvt:C000010864Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-01-01</startDate>
            <endDate>2025-12-31</endDate>
        </period>
    </context>
    <context id="FY2025_LinkedSP500IndexMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">pvt:LinkedSP500IndexMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-01-01</startDate>
            <endDate>2025-12-31</endDate>
        </period>
    </context>
    <context id="FY2025_Russell3000IndexMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">pvt:Russell3000IndexMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-01-01</startDate>
            <endDate>2025-12-31</endDate>
        </period>
    </context>
    <context id="FY2025_S000003884Member_C000010863Member">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">pvt:S000003884Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">pvt:C000010863Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-01-01</startDate>
            <endDate>2025-12-31</endDate>
        </period>
    </context>
    <context id="FY2025_SP500IndexMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">pvt:SP500IndexMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-01-01</startDate>
            <endDate>2025-12-31</endDate>
        </period>
    </context>
    <context id="S000003884Member">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">pvt:S000003884Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-06-30</startDate>
            <endDate>2026-06-30</endDate>
        </period>
    </context>
    <context id="S000003884Member_C000010863Member">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">pvt:S000003884Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">pvt:C000010863Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-06-30</startDate>
            <endDate>2026-06-30</endDate>
        </period>
    </context>
    <context id="S000003884Member_C000010864Member">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">pvt:S000003884Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">pvt:C000010864Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-06-30</startDate>
            <endDate>2026-06-30</endDate>
        </period>
    </context>
    <context id="TenY2025_C000010863Member">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="oef:ClassAxis">pvt:C000010863Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2016-01-01</startDate>
            <endDate>2025-12-31</endDate>
        </period>
    </context>
    <context id="TenY2025_C000010864Member">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="oef:ClassAxis">pvt:C000010864Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2016-01-01</startDate>
            <endDate>2025-12-31</endDate>
        </period>
    </context>
    <context id="TenY2025_LinkedSP500IndexMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">pvt:LinkedSP500IndexMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2016-01-01</startDate>
            <endDate>2025-12-31</endDate>
        </period>
    </context>
    <context id="TenY2025_Russell3000IndexMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">pvt:Russell3000IndexMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2016-01-01</startDate>
            <endDate>2025-12-31</endDate>
        </period>
    </context>
    <context id="TenY2025_SP500IndexMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000822671</identifier>
            <segment>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">pvt:SP500IndexMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2016-01-01</startDate>
            <endDate>2025-12-31</endDate>
        </period>
    </context>
    <unit id="USD">
        <measure>iso4217:USD</measure>
    </unit>
    <unit id="pure">
        <measure>pure</measure>
    </unit>
    <dei:EntityCentralIndexKey
      contextRef="DefaultContext"
      id="h1_59d38b1d_3830_4c50_b537_d029bc38d659">0000822671</dei:EntityCentralIndexKey>
    <dei:AmendmentFlag
      contextRef="DefaultContext"
      id="h3_a220b114_f115_4cfe_85c3_93430d043c50">false</dei:AmendmentFlag>
    <dei:DocumentType
      contextRef="DefaultContext"
      id="h7_6b72407d_9c47_432f_9116_63ebc05f34b2">485BPOS</dei:DocumentType>
    <dei:DocumentPeriodEndDate
      contextRef="DefaultContext"
      id="h8_b9a19593_506b_407a_b02e_456983b33585">2026-06-30</dei:DocumentPeriodEndDate>
    <oef:AnnlRtrPct
      contextRef="FY2016_S000003884Member_C000010863Member"
      decimals="4"
      id="h_1_19c46502-e327-4c5e-9ae1-d8e4112af739"
      unitRef="pure">0.0806</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="FY2025_S000003884Member_C000010863Member"
      decimals="4"
      id="h_10_5cff8196-8ba6-0684-2ee7-d9c43be91c42"
      unitRef="pure">0.1099</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="FY2017_S000003884Member_C000010863Member"
      decimals="4"
      id="h_2_2615bbcc-af1c-758d-3ce6-73feac1bd2ee"
      unitRef="pure">0.2955</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="FY2018_S000003884Member_C000010863Member"
      decimals="4"
      id="h_3_d4121f6f-9a2b-a9fc-bcc4-da79a70151f6"
      unitRef="pure">-0.0128</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="FY2019_S000003884Member_C000010863Member"
      decimals="4"
      id="h_4_87f4efee-36e6-0a56-cce6-16a021e91b19"
      unitRef="pure">0.3672</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="FY2020_S000003884Member_C000010863Member"
      decimals="4"
      id="h_5_2ff7d0f7-ed0d-ca15-90ad-d1516e2065d6"
      unitRef="pure">0.2904</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="FY2021_S000003884Member_C000010863Member"
      decimals="4"
      id="h_6_f7d402f3-f75e-419e-e340-586a1d0da7bf"
      unitRef="pure">0.2387</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="FY2022_S000003884Member_C000010863Member"
      decimals="4"
      id="h_7_adaeed3a-b46a-0dbb-400a-13f9710efe38"
      unitRef="pure">-0.2272</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="FY2023_S000003884Member_C000010863Member"
      decimals="4"
      id="h_8_14150713-a527-299f-fc59-f79154c4065f"
      unitRef="pure">0.2642</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="FY2024_S000003884Member_C000010863Member"
      decimals="4"
      id="h_9_0c1d560b-befe-de46-115a-6e560675184f"
      unitRef="pure">0.2333</oef:AnnlRtrPct>
    <dei:EntityInvCompanyType
      contextRef="DefaultContext"
      id="h_01_f2c4ed95_658e_41f5_a8bd_e4f72e26fd44">N-1A</dei:EntityInvCompanyType>
    <dei:EntityRegistrantName
      contextRef="DefaultContext"
      id="h_02_57ffa31d_e906_48ac_abef_70045387ebe2">PUTNAM VARIABLE TRUST</dei:EntityRegistrantName>
    <oef:ProspectusDate
      contextRef="DefaultContext"
      id="h_03_c1025b5c_5eb3_4cc8_940b_1807a98f6787">2026-10-05</oef:ProspectusDate>
    <oef:RiskReturnHeading
      contextRef="S000003884Member"
      id="t_24_7be5fd45_4a6a_b066_a937_58dd7cc47b22">Fund summary Prior to October 5, 2026, Putnam VT Focused U.S. Research Fund was named Putnam VT Sustainable Leaders Fund. </oef:RiskReturnHeading>
    <oef:ObjectiveHeading
      contextRef="S000003884Member"
      id="t_25_8f4069b1_785b_7dcc_af3d_791fa692b144">Goal </oef:ObjectiveHeading>
    <oef:ObjectivePrimaryTextBlock
      contextRef="S000003884Member"
      id="t_26_41f272f6_89ee_8ceb_a6f9_9afe971168b1">&lt;div style="margin-top:6pt;margin-bottom:0pt;margin-left:2%;font-size:9pt;font-family:arial;"&gt;The fund seeks long-term capital appreciation. &lt;/div&gt;</oef:ObjectivePrimaryTextBlock>
    <oef:ExpenseHeading
      contextRef="S000003884Member"
      id="t_1_300aacc1_5495_48df_82cc_27c4af2102c7">Fees and expenses </oef:ExpenseHeading>
    <oef:ExpenseNarrativeTextBlock
      contextRef="S000003884Member"
      id="t_2_dff655a7_6d8b_4ee0_b8b2_203bef82bcc6">&lt;div style="margin-top:6pt;margin-bottom:0pt;margin-left:2%;font-size:9pt;font-family:arial;"&gt;The following table describes the fees and expenses you may pay if you buy, hold and sell shares of the fund. &lt;span style="font-weight:bold"&gt;You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.&lt;/span&gt; The fees and expenses information does not reflect insurance-related charges or expenses borne by contract holders indirectly investing in the fund. If it did, expenses would be higher. &lt;/div&gt;</oef:ExpenseNarrativeTextBlock>
    <oef:OperatingExpensesCaption
      contextRef="S000003884Member"
      id="t_27_0dd66879_06b1_fddc_8d43_d7e198ba8bbf">Annual Fund Operating Expenses (expenses you pay each year as a percentage of the value of your investment) </oef:OperatingExpensesCaption>
    <oef:ManagementFeesOverAssets
      contextRef="S000003884Member_C000010863Member"
      decimals="4"
      id="h_1_ad3372cc_8478_45e5_a80a_8bc6caed64fb"
      unitRef="pure">0.0053</oef:ManagementFeesOverAssets>
    <oef:DistributionAndService12b1FeesOverAssets
      contextRef="S000003884Member_C000010863Member"
      decimals="4"
      id="h_2_6a0eb50d_f2de_4e7b_b02b_1075c391cca1"
      unitRef="pure">0</oef:DistributionAndService12b1FeesOverAssets>
    <oef:OtherExpensesOverAssets
      contextRef="S000003884Member_C000010863Member"
      decimals="4"
      id="h_3_809fb1fb_cbca_479f_b5dc_f6ab81cf96fc"
      unitRef="pure">0.0010</oef:OtherExpensesOverAssets>
    <oef:ExpensesOverAssets
      contextRef="S000003884Member_C000010863Member"
      decimals="4"
      id="h_4_74d257a8_2f30_4d04_8c99_0cd57c569926"
      unitRef="pure">0.0063</oef:ExpensesOverAssets>
    <oef:ManagementFeesOverAssets
      contextRef="S000003884Member_C000010864Member"
      decimals="4"
      id="h_5_24e92104_e68f_4819_91f4_4e712986e24d"
      unitRef="pure">0.0053</oef:ManagementFeesOverAssets>
    <oef:DistributionAndService12b1FeesOverAssets
      contextRef="S000003884Member_C000010864Member"
      decimals="4"
      id="h_6_727b7986_1ff7_4145_8cab_e6768b2127d5"
      unitRef="pure">0.0025</oef:DistributionAndService12b1FeesOverAssets>
    <oef:OtherExpensesOverAssets
      contextRef="S000003884Member_C000010864Member"
      decimals="4"
      id="h_7_1a45178f_84c9_44ea_91e1_f6747dd6ebd9"
      unitRef="pure">0.0010</oef:OtherExpensesOverAssets>
    <oef:ExpensesOverAssets
      contextRef="S000003884Member_C000010864Member"
      decimals="4"
      id="h_8_17f53604_574a_418e_a03e_5e0b26ac9c65"
      unitRef="pure">0.0088</oef:ExpensesOverAssets>
    <oef:ExpenseExampleHeading
      contextRef="S000003884Member"
      id="t_4_931b848b_d0a9_4945_bd02_4a675b3792d2">Example </oef:ExpenseExampleHeading>
    <oef:ExpenseExampleNarrativeTextBlock
      contextRef="S000003884Member"
      id="t_5_19f2a612_ca3a_4224_bf11_92a0a41e43f4">&lt;div style="margin-top:6pt;margin-bottom:0pt;margin-left:2%;font-size:9pt;font-family:arial;"&gt;The following hypothetical example is intended to help you compare the cost of investing in the fund with the cost of investing in other funds. The example does not reflect insurance-related charges or expenses. If it did, expenses would be higher. It assumes that you invest $10,000 in the fund for the time periods indicated and then redeem or hold all your shares at the end of those periods. It assumes a 5% return on your investment each year and that the fund&#x2019;s operating expenses remain the same (except that any applicable fee waiver or expense reimbursement is reflected only through its expiration date). Your actual costs may be higher or lower. &lt;/div&gt;</oef:ExpenseExampleNarrativeTextBlock>
    <oef:ExpenseExampleYear01
      contextRef="S000003884Member_C000010863Member"
      decimals="INF"
      id="h_9_6bef8b9b_736e_473a_8396_246d5d4b315b"
      unitRef="USD">64</oef:ExpenseExampleYear01>
    <oef:ExpenseExampleNoRedemptionYear01
      contextRef="S000003884Member_C000010863Member"
      decimals="INF"
      id="h_39_2e4320e5_898a_1cad_b8f6_204de785acc5"
      unitRef="USD">64</oef:ExpenseExampleNoRedemptionYear01>
    <oef:ExpenseExampleYear03
      contextRef="S000003884Member_C000010863Member"
      decimals="INF"
      id="h_10_1186a07a_5429_4c43_bcd2_d0c2c191efa3"
      unitRef="USD">201</oef:ExpenseExampleYear03>
    <oef:ExpenseExampleNoRedemptionYear03
      contextRef="S000003884Member_C000010863Member"
      decimals="INF"
      id="h_40_49114e86_9916_f678_0441_e60dd5eb84e9"
      unitRef="USD">201</oef:ExpenseExampleNoRedemptionYear03>
    <oef:ExpenseExampleYear05
      contextRef="S000003884Member_C000010863Member"
      decimals="INF"
      id="h_11_5d0f1587_9e81_4a5e_ab6e_a618797386af"
      unitRef="USD">350</oef:ExpenseExampleYear05>
    <oef:ExpenseExampleNoRedemptionYear05
      contextRef="S000003884Member_C000010863Member"
      decimals="INF"
      id="h_41_38afa343_540c_7793_7031_e8eca10676f1"
      unitRef="USD">350</oef:ExpenseExampleNoRedemptionYear05>
    <oef:ExpenseExampleYear10
      contextRef="S000003884Member_C000010863Member"
      decimals="INF"
      id="h_12_dbc86176_3f31_451e_9062_a242e10a3ddb"
      unitRef="USD">786</oef:ExpenseExampleYear10>
    <oef:ExpenseExampleNoRedemptionYear10
      contextRef="S000003884Member_C000010863Member"
      decimals="INF"
      id="h_42_bede2957_252b_3e74_38b1_a24ab796436b"
      unitRef="USD">786</oef:ExpenseExampleNoRedemptionYear10>
    <oef:ExpenseExampleYear01
      contextRef="S000003884Member_C000010864Member"
      decimals="INF"
      id="h_13_c484ac20_f38b_4f93_ab12_e55e1163585f"
      unitRef="USD">90</oef:ExpenseExampleYear01>
    <oef:ExpenseExampleNoRedemptionYear01
      contextRef="S000003884Member_C000010864Member"
      decimals="INF"
      id="h_43_6bb1993d_4a99_9c80_545a_41326eb4f445"
      unitRef="USD">90</oef:ExpenseExampleNoRedemptionYear01>
    <oef:ExpenseExampleYear03
      contextRef="S000003884Member_C000010864Member"
      decimals="INF"
      id="h_14_9c888b1b_83a3_4120_a929_5a5bed5af507"
      unitRef="USD">281</oef:ExpenseExampleYear03>
    <oef:ExpenseExampleNoRedemptionYear03
      contextRef="S000003884Member_C000010864Member"
      decimals="INF"
      id="h_44_673ed9f6_b370_a063_5136_6aee4111c456"
      unitRef="USD">281</oef:ExpenseExampleNoRedemptionYear03>
    <oef:ExpenseExampleYear05
      contextRef="S000003884Member_C000010864Member"
      decimals="INF"
      id="h_15_cf76e2f4_ad22_46f5_9f90_bc489d4c0829"
      unitRef="USD">488</oef:ExpenseExampleYear05>
    <oef:ExpenseExampleNoRedemptionYear05
      contextRef="S000003884Member_C000010864Member"
      decimals="INF"
      id="h_45_6a117e73_3f08_2e70_cb55_5f4626db26da"
      unitRef="USD">488</oef:ExpenseExampleNoRedemptionYear05>
    <oef:ExpenseExampleYear10
      contextRef="S000003884Member_C000010864Member"
      decimals="INF"
      id="h_16_accc909b_fd78_453f_b3e0_ff77ca37d257"
      unitRef="USD">1084</oef:ExpenseExampleYear10>
    <oef:ExpenseExampleNoRedemptionYear10
      contextRef="S000003884Member_C000010864Member"
      decimals="INF"
      id="h_46_286205dd_cecc_d0b6_ec04_7865c19ff98b"
      unitRef="USD">1084</oef:ExpenseExampleNoRedemptionYear10>
    <oef:PortfolioTurnoverHeading
      contextRef="S000003884Member"
      id="t_6_34c07784_77ef_408c_ad1b_4b158446f1ee">Portfolio turnover </oef:PortfolioTurnoverHeading>
    <oef:PortfolioTurnoverTextBlock
      contextRef="S000003884Member"
      id="t_28_fc555c35_640a_230a_052d_42e4a79b8ded">&lt;div style="margin-top:6pt;margin-bottom:0pt;margin-left:2%;font-size:9pt;font-family:arial;"&gt;The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or &#x201c;turns over&#x201d; its portfolio). A higher turnover rate may indicate higher transaction costs. These costs, which are not reflected in &lt;/div&gt;&lt;div style="margin-top:0pt;margin-bottom:0pt;margin-left:2%;font-size:9pt;font-family:arial;"&gt; annual fund operating expenses or the above example, affect fund performance. The fund&#x2019;s turnover rate in the most recent fiscal year was 43%. &lt;/div&gt;</oef:PortfolioTurnoverTextBlock>
    <oef:PortfolioTurnoverRate
      contextRef="S000003884Member"
      decimals="4"
      id="h_48_1c72fb8c_b92c_bde3_8ca5_4a65d00b69bc"
      unitRef="pure">0.43</oef:PortfolioTurnoverRate>
    <oef:StrategyHeading
      contextRef="S000003884Member"
      id="t_29_f20afa9e_0c02_a337_31b0_ecfdbdf23692">Investments, risks, and performance Investments </oef:StrategyHeading>
    <oef:StrategyNarrativeTextBlock
      contextRef="S000003884Member"
      id="t_31_dd3300c9_df6e_2b4b_833b_f6ae687f3fb7">&lt;div style="margin-top:6pt;margin-bottom:0pt;margin-left:2%;font-size:9pt;font-family:arial;"&gt;The fund invests mainly in equity securities (growth or value stocks or both) of large and midsize companies that the Investment Manager, as defined below, believes have favorable investment potential, although the Investment Manager anticipates that the fund will invest to a greater extent in large companies than in midsize companies. The Investment Manager may consider, among other factors, a company&#x2019;s valuation, financial strength, growth potential, competitive position in its industry, projected future earnings, cash flows and dividends when deciding whether to buy or sell investments. Under normal circumstances, the fund invests at least 80% of its net assets (plus the amount of borrowings for investment purposes, if any) in equity securities of companies located in the United States. This policy may be changed only after 60 days&#x2019; notice to shareholders. The Investment Manager considers a company to be located in the United States if the company&#x2019;s securities trade in the United States, the company is headquartered or organized in the United States or the company derives a majority of its revenues or profits in the United States. Equity securities include common stocks, preferred stocks, convertible securities, warrants, American Depositary Receipts (&#x201c;ADRs&#x201d;) and Global Depositary Receipts (&#x201c;GDRs&#x201d;). &lt;/div&gt;&lt;div style="margin-top:6pt;margin-bottom:0pt;margin-left:2%;font-size:9pt;font-family:arial;"&gt;From time to time, the fund may invest a significant portion of its assets in companies in one or more related industries or sectors. &lt;/div&gt;&lt;div style="margin-top:6pt;margin-bottom:0pt;margin-left:2%;font-size:9pt;font-family:arial;"&gt;The fund is &#x201c;non-diversified,&#x201d; which means it may invest a greater percentage of its assets in fewer issuers than a &#x201c;diversified&#x201d; fund. The fund expects to invest in a limited number of issuers. &lt;/div&gt;</oef:StrategyNarrativeTextBlock>
    <fnd:NmRule35d1EightyPctInvstmntPlcyTextBlock
      contextRef="S000003884Member"
      id="t_30_347b8b91_aa5c_fbbe_d408_21ae4f4421e0">Under normal circumstances, the fund invests at least 80% of its net assets (plus the amount of borrowings for investment purposes, if any) in equity securities of companies located in the United States.</fnd:NmRule35d1EightyPctInvstmntPlcyTextBlock>
    <oef:RiskTextBlock
      contextRef="D20260630_20260630_S000003884Member_RiskLoseMoneyMember"
      id="t_42_a0c15a96_5caf_3c57_1aa2_3c40272a6393">&lt;div style="margin-top:6pt;margin-bottom:0pt;margin-left:2%;font-size:9pt;font-family:arial;"&gt;It is important to understand that you can lose money by investing in the fund. &lt;/div&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="D20260630_20260630_S000003884Member_MarketRisksMember"
      id="t_43_db67ad27_82ee_19b6_707b_bf19b01ce70f">&lt;div style="margin-top:6pt;margin-bottom:0pt;margin-left:2%;font-size:9pt;font-family:arial;"&gt;&lt;span style="font-weight:bold"&gt;Market risk:&lt;/span&gt; The value of investments in the fund&#x2019;s portfolio may fall or fail to rise over extended periods of time for a variety of reasons, including general economic, political or financial market conditions, investor sentiment and market perceptions, government actions, geopolitical events or changes, outbreaks of infectious illnesses or other widespread public health issues, and factors related to a specific issuer, asset class, geography, industry or sector. These and other factors may lead to increased volatility and reduced liquidity in the fund&#x2019;s portfolio holdings, may negatively impact the fund&#x2019;s performance, and may exacerbate other risks to which the fund is subject. &lt;/div&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="D20260630_20260630_S000003884Member_CommonStockRiskMember"
      id="t_44_82c3d712_7882_ccf6_119e_d39d65e9f49a">&lt;div style="margin-top:6pt;margin-bottom:0pt;margin-left:2%;font-size:9pt;font-family:arial;"&gt;&lt;span style="font-weight:bold"&gt;Common stock risk:&lt;/span&gt; Common stock represents an ownership interest in a company. The value of a company&#x2019;s stock may fall or fail to rise as a result of factors directly relating to that company, such as decisions made by its management or lower demand for the company&#x2019;s products or services. A &lt;/div&gt;&lt;div style="margin-top:0pt;margin-bottom:0pt;margin-left:2%;font-size:9pt;font-family:arial;"&gt; stock&#x2019;s value may also fall because of factors affecting not just the company, but also other companies in the same industry or in a number of different industries, such as increases in production costs. Companies whose stocks the Investment Manager believes are undervalued by the market may have experienced adverse business developments or may be subject to special risks that have caused their stocks to be out of favor. Growth stocks may be more susceptible to earnings disappointments, and value stocks may fail to rebound. The fund will be more susceptible to these risks than other funds because it concentrates its investments in a limited number of issuers or sectors, and the fund may perform poorly as a result of adverse developments affecting those issuers or sectors. These risks are generally greater for small and midsize companies. &lt;/div&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="D20260630_20260630_S000003884Member_IndustryOrSectorFocusRiskMember"
      id="t_45_e12fccdf_8ada_9b58_e2a8_8e9d13e40fd7">&lt;div style="margin-top:6pt;margin-bottom:0pt;margin-left:2%;font-size:9pt;font-family:arial;"&gt;&lt;span style="font-weight:bold"&gt;Industry or sector focus risk:&lt;/span&gt; From time to time, the fund may invest a significant portion of its assets in companies in one or more related industries or sectors, which would make the fund more vulnerable to adverse developments affecting those industries or sectors. For example, the fund may invest a significant portion of its assets in companies in the information technology sector that may be significantly affected by technological obsolescence or innovation, short product cycles, falling prices and profits, competitive pressures and general market conditions. &lt;/div&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="D20260630_20260630_S000003884Member_RiskNondiversifiedStatusMember"
      id="t_46_36ad1256_8117_0803_e30f_3a386639ae3e">&lt;div style="margin-top:6pt;margin-bottom:0pt;margin-left:2%;font-size:9pt;font-family:arial;"&gt;&lt;span style="font-weight:bold"&gt;Non-diversified risk:&lt;/span&gt; As a non-diversified fund, the fund invests in fewer issuers and is more vulnerable than a more broadly diversified fund to fluctuations in the values of the securities it holds. Moreover, the gains and losses on a single investment may have a greater impact on the fund&#x2019;s net asset value and may make the fund more volatile than more diversified funds. &lt;/div&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="D20260630_20260630_S000003884Member_LargeShareholderTransactionRiskMember"
      id="t_47_5c1569db_78fe_75fd_ee09_5f3a9739fe79">&lt;div style="margin-top:6pt;margin-bottom:0pt;margin-left:2%;font-size:9pt;font-family:arial;"&gt;&lt;span style="font-weight:bold"&gt;Large shareholder transaction risk:&lt;/span&gt; The fund is subject to the risk that shareholders will purchase or redeem large quantities of shares of the fund. The fund may be an investment option for mutual funds that are managed by the Investment Manager and its affiliates as &#x201c;funds of funds.&#x201d; Additionally, other investors from time to time may make substantial investments in the fund. Such shareholders may at times be considered to control the fund. In addition, a large number of shareholders may collectively purchase or redeem fund shares in large amounts rapidly or unexpectedly. Large shareholder transactions may adversely affect the fund&#x2019;s liquidity and net assets. These redemptions may also adversely affect the fund&#x2019;s performance if the fund is forced to sell securities, which may also increase the fund&#x2019;s brokerage costs. &lt;/div&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="D20260630_20260630_S000003884Member_ManagementAndOperationalRiskMember"
      id="t_48_76793fe1_6a91_087f_d5d3_5f530b1ffa30">&lt;div style="margin-top:6pt;margin-bottom:0pt;margin-left:2%;font-size:9pt;font-family:arial;"&gt;&lt;span style="font-weight:bold"&gt;Management and operational risk:&lt;/span&gt; There is no guarantee that the investment techniques, analyses, or judgments that the Investment Manager applies in making investment decisions for the fund will produce the intended outcome or that the investments selected for the fund will perform as well as other securities that were not selected for the fund. The Investment Manager, or the fund&#x2019;s other service providers, may experience disruptions or operating errors that could negatively impact the fund. &lt;/div&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="D20260630_20260630_S000003884Member_RiskNotInsuredMember"
      id="t_49_47767601_d7a3_fb4a_5226_f63833fcf2ac">An investment in the fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="D20260630_20260630_S000003884Member_CybersecurityRiskMember"
      id="t_50_dfc93b3a_14a6_1b38_0a2d_c50614c99f4d">&lt;div style="margin-top:6pt;margin-bottom:0pt;margin-left:2%;font-size:9pt;font-family:arial;"&gt;&lt;span style="font-weight:bold"&gt;Cybersecurity risk:&lt;/span&gt; Cybersecurity incidents, both intentional and unintentional, may allow an unauthorized party to gain access to fund assets, fund or customer data (including private shareholder information), or proprietary information, cause the fund, the Investment Manager and/or their service providers (including, but not limited to, fund accountants, custodians, sub-custodians, transfer agents and financial intermediaries) to suffer data breaches, data corruption or loss of operational functionality or prevent fund investors from purchasing, redeeming, or exchanging shares, or receiving distributions. The fund and the Investment Manager have limited ability to prevent or mitigate cybersecurity incidents affecting third party service providers, and such third party service providers may have limited indemnification obligations to the fund and/or the Investment Manager. Cybersecurity incidents may result in financial losses to the fund and its shareholders, and substantial costs may be incurred in an effort to prevent or mitigate future cybersecurity incidents. Issuers of securities in which the fund invests are also subject to cybersecurity risks, and the value of these securities could decline if the issuers experience cybersecurity incidents. &lt;/div&gt;&lt;div style="margin-top:6pt;margin-bottom:0pt;margin-left:2%;font-size:9pt;font-family:arial;"&gt;Because technology continues to evolve rapidly, including through developments in artificial intelligence and machine learning, new methods of carrying out cyber-attacks continue to emerge. As a result, certain cybersecurity risks may not yet be identified and some cyber-attacks may not be detected promptly, which may limit the fund&#x2019;s ability to anticipate, prepare for or respond effectively to a cybersecurity incident. Like other funds and business enterprises, the fund, the Investment Manager and their service providers are subject to the risk of cybersecurity incidents from time to time. The rapid development and increasingly widespread use of artificial intelligence technologies may increase the sophistication and effectiveness of cyber attacks, which may exacerbate these risks. &lt;/div&gt;</oef:RiskTextBlock>
    <oef:BarChartAndPerformanceTableHeading
      contextRef="S000003884Member"
      id="t_9_2a281742_2830_4df4_8e6c_5d1c22de62da">Performance </oef:BarChartAndPerformanceTableHeading>
    <oef:PerformanceNarrativeTextBlock
      contextRef="S000003884Member"
      id="t_35_1f62d27c_38af_7b0c_79ee_f5ad68fcdb3c">&lt;div style="margin-top:6pt;margin-bottom:0pt;margin-left:2%;font-size:9pt;font-family:arial;"&gt;The accompanying bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund&#x2019;s performance from year to year for Class IA shares.&#160;The table shows the average annual total returns of each class of the fund that has been in operation for at least one full calendar year and also compares the fund&#x2019;s performance with the average annual total returns of a broad measure of market performance, an additional index with characteristics relevant to the fund and the Linked S&amp;amp;P 500 Index, which represents the performance of the Russell 3000&#xae; Growth Index through August&#160;31, 2019, and the performance of the S&amp;amp;P 500&#xae; Index thereafter. On April&#160;30, 2018 and again on October 5, 2026, the fund materially changed its investment strategy and may have achieved materially different performance results under its current investment strategy than it achieved under the investment strategies in effect before those dates. Performance for &lt;/div&gt;&lt;div style="margin-top:0pt;margin-bottom:0pt;margin-left:2%;font-size:9pt;font-family:arial;"&gt;classes other than those shown may vary from the performance shown to the extent the expenses for those classes differ. The fund makes updated performance information, including its current net asset value per share, available at www.franklintempleton.com. &lt;/div&gt;&lt;div style="margin-top:6pt;margin-bottom:0pt;margin-left:0%;text-indent:2%;font-size:9pt;font-family:arial;"&gt;&lt;span style="font-style:italic"&gt;The fund&#x2019;s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future. &lt;/span&gt;&lt;/div&gt;&lt;div style="margin-top:6pt;margin-bottom:0pt;margin-left:2%;font-size:9pt;font-family:arial;"&gt;Insurance-related charges or expenses are not reflected in the performance information below, and if those charges were included, returns would be less than those shown. &lt;/div&gt;</oef:PerformanceNarrativeTextBlock>
    <oef:PerformanceInformationIllustratesVariabilityOfReturns
      contextRef="S000003884Member"
      id="t_32_0b8675ed_4945_5c19_450b_dc198e811ee7">The bar chart shows changes in the fund&#x2019;s performance from year to year for Class IA shares.&#160;The table shows the average annual total returns of each class of the fund that has been in operation for at least one full calendar year and also compares the fund&#x2019;s performance with the average annual total returns of a broad measure of market performance, an additional index with characteristics relevant to the fund and the Linked S&amp;P 500 Index, which represents the performance of the Russell 3000&#xae; Growth Index through August&#160;31, 2019, and the performance of the S&amp;P 500&#xae; Index thereafter.</oef:PerformanceInformationIllustratesVariabilityOfReturns>
    <oef:PerformanceAdditionalMarketIndex
      contextRef="S000003884Member"
      id="t_51_2493be9d_ec41_c786_1502_3fa03b178fd2">The table shows the average annual total returns of each class of the fund that has been in operation for at least one full calendar year and also compares the fund&#x2019;s performance with the average annual total returns of a broad measure of market performance, an additional index with characteristics relevant to the fund and the Linked S&amp;P 500 Index, which represents the performance of the Russell 3000&#xae; Growth Index through August&#160;31, 2019, and the performance of the S&amp;P 500&#xae; Index thereafter.</oef:PerformanceAdditionalMarketIndex>
    <oef:PerformanceAvailabilityWebSiteAddress
      contextRef="S000003884Member"
      id="t_33_36a1b786_15c3_748c_eea0_abfc94eccb99">www.franklintempleton.com</oef:PerformanceAvailabilityWebSiteAddress>
    <oef:PerformancePastDoesNotIndicateFuture
      contextRef="S000003884Member"
      id="t_34_02cf9eda_6913_80d2_f6ea_3605514901f2">The fund&#x2019;s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future. </oef:PerformancePastDoesNotIndicateFuture>
    <oef:BarChartHeading
      contextRef="S000003884Member"
      id="t_36_0c8eda9a_36b4_6ea1_653e_71bfb04f09a4">Annual total returns for class IA shares </oef:BarChartHeading>
    <oef:BarChartClosingTextBlock
      contextRef="S000003884Member"
      id="t_37_5c6dee5d_5a42_e634_e5bc_1b456eba57cf">
&lt;table cellpadding="0" cellspacing="0" style="border-collapse:collapse;font-family:arial;font-size:1pt;width:98%;border-spacing:0px;margin-left:auto"&gt; 
&lt;tr&gt; 
&lt;td style="width:58%;"&gt;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&lt;/td&gt; 
&lt;td style="width:19%;"&gt;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;width:1%;"&gt;&lt;/td&gt; 
&lt;td style="width:19%;"&gt;&lt;/td&gt; &lt;/tr&gt; 
&lt;tr style="page-break-inside:avoid;font-family:arial;font-size:1pt;background-color:#cccccc"&gt; 
&lt;td style="vertical-align:top;"&gt;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&#160;&#160;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&#160;&#160;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&lt;/td&gt; &lt;/tr&gt; 
&lt;tr style="page-break-inside:avoid;font-family:arial;font-size:10pt"&gt; 
&lt;td style="vertical-align:top;"&gt; &lt;div style="margin-top:0pt;margin-bottom:0pt;margin-left:1.00em;text-indent:-1.00em;font-size:10pt;font-family:arial;"&gt;Best Quarter:&lt;/div&gt; &lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&#160;&#160;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;white-space:nowrap;text-align:right;"&gt;Q2 2020&lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&#160;&#160;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;white-space:nowrap;text-align:right;"&gt;24.12%&lt;/td&gt; &lt;/tr&gt; 
&lt;tr style="page-break-inside:avoid;font-family:arial;font-size:1pt;background-color:#cccccc"&gt; 
&lt;td style="vertical-align:top;"&gt;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&#160;&#160;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&#160;&#160;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&lt;/td&gt; &lt;/tr&gt; 
&lt;tr style="page-break-inside:avoid;font-family:arial;font-size:10pt"&gt; 
&lt;td style="vertical-align:top;"&gt; &lt;div style="margin-top:0pt;margin-bottom:0pt;margin-left:1.00em;text-indent:-1.00em;font-size:10pt;font-family:arial;"&gt;Worst Quarter:&lt;/div&gt; &lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&#160;&#160;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;white-space:nowrap;text-align:right;"&gt;Q2 2022&lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&#160;&#160;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;white-space:nowrap;text-align:right;"&gt;-17.79%&lt;/td&gt; &lt;/tr&gt; 
&lt;tr style="page-break-inside:avoid;font-family:arial;font-size:1pt;background-color:#cccccc"&gt; 
&lt;td style="vertical-align:top;"&gt;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&#160;&#160;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&#160;&#160;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&lt;/td&gt; &lt;/tr&gt; 
&lt;tr style="page-break-inside:avoid;font-family:arial;font-size:10pt"&gt; 
&lt;td style="vertical-align:top;"&gt; &lt;div style="margin-top:0pt;margin-bottom:0pt;margin-left:1.00em;text-indent:-1.00em;font-size:10pt;font-family:arial;"&gt;As of June&#160;30, 2026, the fund&#x2019;s year-to-date return was 4.21%.&lt;/div&gt; &lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&#160;&#160;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&#160;&#160;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&lt;/td&gt; &lt;/tr&gt; 
&lt;tr style="page-break-inside:avoid;font-family:arial;font-size:1pt;background-color:#cccccc"&gt; 
&lt;td style="vertical-align:top;"&gt;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&#160;&#160;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&#160;&#160;&lt;/td&gt; 
&lt;td style="vertical-align:bottom;"&gt;&lt;/td&gt; &lt;/tr&gt; &lt;/table&gt;</oef:BarChartClosingTextBlock>
    <oef:HighestQuarterlyReturnLabel
      contextRef="S000003884Member_C000010863Member"
      id="h_17_dbbacd60_ef31_45c3_ac23_19526f578ad8">Best Quarter:</oef:HighestQuarterlyReturnLabel>
    <oef:BarChartHighestQuarterlyReturnDate
      contextRef="S000003884Member_C000010863Member"
      id="h_18_e2305d37_93da_4d71_9957_38281ccb9fab">2020-06-30</oef:BarChartHighestQuarterlyReturnDate>
    <oef:BarChartHighestQuarterlyReturn
      contextRef="S000003884Member_C000010863Member"
      decimals="4"
      id="h_19_a6436342_7194_4a7f_baa3_9c84ede18901"
      unitRef="pure">0.2412</oef:BarChartHighestQuarterlyReturn>
    <oef:LowestQuarterlyReturnLabel
      contextRef="S000003884Member_C000010863Member"
      id="h_20_6fa03fa3_6933_4af9_a3dc_40df1ab27801">Worst Quarter:</oef:LowestQuarterlyReturnLabel>
    <oef:BarChartLowestQuarterlyReturnDate
      contextRef="S000003884Member_C000010863Member"
      id="h_21_ec22980e_0fe4_475d_998b_149081b01bd2">2022-06-30</oef:BarChartLowestQuarterlyReturnDate>
    <oef:BarChartLowestQuarterlyReturn
      contextRef="S000003884Member_C000010863Member"
      decimals="4"
      id="h_22_6d765a42_dcd7_4588_bbf2_5d2471e8799c"
      unitRef="pure">-0.1779</oef:BarChartLowestQuarterlyReturn>
    <oef:BarChartYearToDateReturnDate
      contextRef="S000003884Member_C000010863Member"
      id="t_40_87854263_08f0_72e7_3acf_081b1cb2820b">2026-06-30</oef:BarChartYearToDateReturnDate>
    <oef:YearToDateReturnLabel
      contextRef="S000003884Member_C000010863Member"
      id="t_41_88906266_2a9d_8957_91cd_4d40d4ed375a">year-to-date return</oef:YearToDateReturnLabel>
    <oef:BarChartYearToDateReturn
      contextRef="S000003884Member_C000010863Member"
      decimals="4"
      id="h_47_6e138cb0_a52e_2095_634a_d4cc35e20892"
      unitRef="pure">0.0421</oef:BarChartYearToDateReturn>
    <oef:PerformanceTableHeading
      contextRef="S000003884Member"
      id="t_38_c7ebf384_503c_20f3_6395_28b713bd7260">Average annual total returns (for periods ended 12/31/25) </oef:PerformanceTableHeading>
    <oef:AvgAnnlRtrPct
      contextRef="FY2025_C000010863Member"
      decimals="4"
      id="h_24_6939b806_01c8_40b6_80f5_54fbe0961234"
      unitRef="pure">0.1099</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="FiveY2025_C000010863Member"
      decimals="4"
      id="h_25_eba09a6c_a2f0_4527_8ef5_4276a8c67db6"
      unitRef="pure">0.1062</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="TenY2025_C000010863Member"
      decimals="4"
      id="h_26_684bc137_6076_4ca7_b7e3_ffe5f33bcc7b"
      unitRef="pure">0.1498</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="FY2025_C000010864Member"
      decimals="4"
      id="h_27_cd4c384c_7490_48aa_bf30_8122ccf5f606"
      unitRef="pure">0.1069</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="FiveY2025_C000010864Member"
      decimals="4"
      id="h_28_e5a39774_39fa_4227_8831_ff36c52ebb7d"
      unitRef="pure">0.1034</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="TenY2025_C000010864Member"
      decimals="4"
      id="h_29_0cb09075_e02d_4474_948d_24d3273e9f95"
      unitRef="pure">0.1469</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="FY2025_Russell3000IndexMember"
      decimals="4"
      id="h_30_22309dea_32a6_4fde_a0de_de0168112c11"
      unitRef="pure">0.1715</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="FiveY2025_Russell3000IndexMember"
      decimals="4"
      id="h_31_0fc904b7_db75_4a44_afb3_6c4bb1bad91f"
      unitRef="pure">0.1315</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="TenY2025_Russell3000IndexMember"
      decimals="4"
      id="h_32_02de89be_7621_42a6_8654_d5c95f1d153d"
      unitRef="pure">0.1429</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="FY2025_SP500IndexMember"
      decimals="4"
      id="h_33_a04b301f_23f4_4cbd_ba51_e9c7a45acd45"
      unitRef="pure">0.1788</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="FiveY2025_SP500IndexMember"
      decimals="4"
      id="h_34_ad9b38c0_b67b_4ba6_9a4c_7c31f346b7c0"
      unitRef="pure">0.1442</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="TenY2025_SP500IndexMember"
      decimals="4"
      id="h_35_fbfb8829_6380_4101_95d4_b6e4b6bc89e0"
      unitRef="pure">0.1482</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="FY2025_LinkedSP500IndexMember"
      decimals="4"
      id="h_36_dd4ae139_87d9_44d4_9208_5c01469655a7"
      unitRef="pure">0.1788</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="FiveY2025_LinkedSP500IndexMember"
      decimals="4"
      id="h_37_5510e619_a4af_4e47_af36_08a80603633b"
      unitRef="pure">0.1442</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="TenY2025_LinkedSP500IndexMember"
      decimals="4"
      id="h_38_37338ff3_a0d4_4b25_8f8e_1f524c8eade1"
      unitRef="pure">0.1575</oef:AvgAnnlRtrPct>
    <oef:PerformanceTableClosingTextBlock
      contextRef="S000003884Member"
      id="t_39_1afe7c61_7c93_369c_aa4c_ec01e4841710">&lt;div style="margin-top:6pt;margin-bottom:0pt;margin-left:2%;font-size:9pt;font-family:arial;"&gt;Important data provider notices and terms are available at &lt;span style="font-family:arial;font-size:9pt;color:#467886"&gt;&lt;span style="text-decoration:underline"&gt;www.franklintempletondatasources.com&lt;/span&gt;&lt;/span&gt;&lt;span style="font-family:arial"&gt;. Such information is subject to change. &lt;/span&gt;&lt;/div&gt;</oef:PerformanceTableClosingTextBlock>
</xbrl>
