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Label Element Value
Prospectus [Line Items] rr_ProspectusLineItems  
Document Type dei_DocumentType 485BPOS
Document Period End Date dei_DocumentPeriodEndDate Dec. 21, 2022
Entity Registrant Name dei_EntityRegistrantName Putnam Variable Trust
Entity Central Index Key dei_EntityCentralIndexKey 0000822671
Entity Inv Company Type dei_EntityInvCompanyType N-1A
Amendment Flag dei_AmendmentFlag false
Putnam VT Core Equity Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading Fund summary
Objective [Heading] rr_ObjectiveHeading Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

Putnam VT Core Equity Fund seeks capital appreciation.
Expense [Heading] rr_ExpenseHeading Fees and expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses you may pay if you buy, hold and sell shares of the fund. 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. 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.

Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (expenses you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock

The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or the above example, affect fund performance. The fund’s turnover rate in the most recent fiscal year was 17%.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 17.00%
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

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’s operating expenses remain the same. Your actual costs may be higher or lower.

Strategy [Heading] rr_StrategyHeading Investments, risks, and performance
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Investments

We invest mainly in common stocks (growth or value stocks or both) of U.S. companies of any size that we believe have favorable investment potential. For example, we may purchase stocks of companies with stock prices that reflect a value lower than that which we place on the company. We may also consider other factors we believe will cause the stock price to rise. We may consider, among other factors, a company’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, we invest at least 80% of the fund’s net assets (plus the amount of any borrowings for investment purposes) in equity investments, including common stocks, preferred stocks, convertible securities, warrants, American Depositary Receipts (ADRs) and Global Depositary Receipts (GDRs). This policy may be changed only after 60 days’ notice to shareholders.
Risk [Heading] rr_RiskHeading Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. Before June 30, 2018, the fund was managed with a materially different investment strategy and may have achieved materially different performance results under its current investment strategy from that shown for periods before this date. The performance information does not reflect insurance-related charges or expenses. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results.



 
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Please remember that past performance is not necessarily an indication of future results.
Bar Chart [Heading] rr_BarChartHeading Annual total returns for class IA shares
Year to Date Return, Label rr_YearToDateReturnLabel Year-to-date performance through
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Mar. 31, 2023
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 6.64%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best calendar quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 21.34%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst calendar quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (22.84%)
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (for periods ended 12/31/22)
Putnam VT Core Equity Fund | Russell 3000 Index (no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (19.21%) [1]
5 Years rr_AverageAnnualReturnYear05 8.79% [1]
10 Years rr_AverageAnnualReturnYear10 12.13% [1]
Putnam VT Core Equity Fund | Class IA C000010855  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.55%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.14% [2]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.69%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 70
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 221
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 384
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 859
Annual Return 2013 rr_AnnualReturn2013 35.52%
Annual Return 2014 rr_AnnualReturn2014 14.25%
Annual Return 2015 rr_AnnualReturn2015 (1.96%)
Annual Return 2016 rr_AnnualReturn2016 12.34%
Annual Return 2017 rr_AnnualReturn2017 23.14%
Annual Return 2018 rr_AnnualReturn2018 (7.44%)
Annual Return 2019 rr_AnnualReturn2019 32.00%
Annual Return 2020 rr_AnnualReturn2020 17.64%
Annual Return 2021 rr_AnnualReturn2021 31.32%
Annual Return 2022 rr_AnnualReturn2022 (15.54%)
1 Year rr_AverageAnnualReturnYear01 (15.54%)
5 Years rr_AverageAnnualReturnYear05 9.77%
10 Years rr_AverageAnnualReturnYear10 12.84%
Putnam VT Core Equity Fund | Class IB C000010856  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.55%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.14% [2]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.94%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 96
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 300
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 520
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,155
1 Year rr_AverageAnnualReturnYear01 (15.77%)
5 Years rr_AverageAnnualReturnYear05 9.50%
10 Years rr_AverageAnnualReturnYear10 12.55%
Putnam VT Diversified Income Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading Fund summary
Objective [Heading] rr_ObjectiveHeading Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

Putnam VT Diversified Income Fund seeks as high a level of current income as Putnam Investment Management, LLC believes is consistent with preservation of capital.

Expense [Heading] rr_ExpenseHeading Fees and expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses you may pay if you buy, hold and sell shares of the fund. 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. 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.

Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (expenses you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination 4/30/24
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock

The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or the above example, affect fund performance. The fund’s turnover rate in the most recent fiscal year was 1,417%.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 1417.00%
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

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’s operating expenses remain the same. Your actual costs may be higher or lower.

Strategy [Heading] rr_StrategyHeading Investments, risks, and performance
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Investments

We invest mainly in bonds that are securitized debt instruments (such as mortgage-backed investments) and related derivative instruments, and other obligations of companies and governments worldwide, including bank loans, that are either investment-grade or below-investment-grade in quality (sometimes referred to as “junk bonds”) and have intermediate- to long-term maturities (three years or longer). The fund currently has significant investment exposure to residential and commercial mortgage-backed securities.

We may consider, among other factors, credit, interest rate and prepayment risks, as well as general market conditions, when deciding whether to buy or sell investments. We typically use to a significant extent derivatives, including credit default swaps, interest rate swaps, total return swaps, to-be-announced (TBA) commitments, futures, options and swaptions on mortgage-backed securities and indices, and certain foreign currency transactions and credit default, total return and interest rate swap contracts for both hedging and non-hedging purposes, including to obtain or adjust exposure to mortgage-backed investments.
Risk [Heading] rr_RiskHeading Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. The performance information does not reflect insurance-related charges or expenses. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results.

Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Please remember that past performance is not necessarily an indication of future results.
Bar Chart [Heading] rr_BarChartHeading Annual total returns for class IA shares
Year to Date Return, Label rr_YearToDateReturnLabel Year-to-date performance through
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Mar. 31, 2023
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 0.01%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best calendar quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 6.80%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst calendar quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (12.79%)
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (for periods ended 12/31/22)
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
ICE BofA Indexes: ICE Data Indices, LLC (“ICE BofA”), used with permission. ICE BofA permits use of the ICE BofA indices and related data on an “as is” basis; makes no warranties regarding same; does not guarantee the suitability, quality, accuracy, timeliness, and/or completeness of the ICE BofA indices or any data included in, related to, or derived therefrom; assumes no liability in connection with the use of the foregoing; and does not sponsor, endorse, or recommend Putnam Investments, or any of its products or services.
All Bloomberg indices are provided by Bloomberg Index Services Limited.
BLOOMBERG® is a trademark and service mark of Bloomberg Finance L.P. and its affiliates (collectively “Bloomberg”). Bloomberg or Bloomberg’s licensors, own all proprietary rights in the Bloomberg Indices. Neither Bloomberg nor Bloomberg’s licensors approve or endorse this material, or guarantee the accuracy or completeness of any information herein, or make any warranty, express or implied, as to the results to be obtained therefrom, and to the maximum extent allowed by law, neither shall have any liability or responsibility for injury or damages arising in connection therewith.
Putnam VT Diversified Income Fund | ICE BofA U.S. Treasury Bill Index (no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 1.33%
5 Years rr_AverageAnnualReturnYear05 1.27%
10 Years rr_AverageAnnualReturnYear10 0.77%
Putnam VT Diversified Income Fund | Bloomberg U.S. Aggregate Bond Index (no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (13.01%)
5 Years rr_AverageAnnualReturnYear05 0.02%
10 Years rr_AverageAnnualReturnYear10 1.06%
Putnam VT Diversified Income Fund | Class IA C000010881  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.54%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.30% [3]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.84%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [4]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.82%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 84
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 266
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 464
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,035
Annual Return 2013 rr_AnnualReturn2013 8.08%
Annual Return 2014 rr_AnnualReturn2014 0.68%
Annual Return 2015 rr_AnnualReturn2015 (2.32%)
Annual Return 2016 rr_AnnualReturn2016 5.76%
Annual Return 2017 rr_AnnualReturn2017 7.42%
Annual Return 2018 rr_AnnualReturn2018 (0.74%)
Annual Return 2019 rr_AnnualReturn2019 11.56%
Annual Return 2020 rr_AnnualReturn2020 (0.76%)
Annual Return 2021 rr_AnnualReturn2021 (6.73%)
Annual Return 2022 rr_AnnualReturn2022 (2.06%)
1 Year rr_AverageAnnualReturnYear01 (2.06%)
5 Years rr_AverageAnnualReturnYear05 0.08%
10 Years rr_AverageAnnualReturnYear10 1.94%
Putnam VT Diversified Income Fund | Class IB C000010882  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.54%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.30% [3]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.09%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [4]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.07%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 109
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 345
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 599
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,327
1 Year rr_AverageAnnualReturnYear01 (2.35%)
5 Years rr_AverageAnnualReturnYear05 (0.17%)
10 Years rr_AverageAnnualReturnYear10 1.70%
Putnam VT Emerging Markets Equity Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading Fund summary
Objective [Heading] rr_ObjectiveHeading Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

Putnam VT Emerging Markets Equity Fund seeks long-term capital appreciation.

Expense [Heading] rr_ExpenseHeading Fees and expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses you may pay if you buy, hold and sell shares of the fund. 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. 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.

Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (expenses you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination 4/30/24
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock

The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or the above example, affect fund performance. The fund’s turnover rate in the most recent fiscal year was 118%.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 118.00%
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

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’s operating expenses remain the same. Only the first year of each period in the example takes into account the expense reimbursement described above. Your actual costs may be higher or lower.

Strategy [Heading] rr_StrategyHeading Investments, risks, and performance
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Investments

We invest mainly in common stocks (growth or value stocks or both) of emerging market companies of any size that we believe have favorable investment potential. For example, we may purchase stocks of companies with stock prices that reflect a value lower than that which we place on the company. We may also consider other factors that we believe will cause the stock price to rise. Under normal circumstances, we invest at least 80% of the fund’s net assets in equity securities of emerging market companies. This policy may be changed only after 60 days’ notice to shareholders.

Emerging markets include countries in the MSCI Emerging Market Index or that we consider to be emerging markets based on our evaluation of their level of economic development or the size and nature of their securities markets. We may consider, among other factors, a company’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. We may also use derivatives, such as futures, options, certain foreign currency transactions, warrants and swap contracts, for both hedging and non-hedging purposes.

The fund is “non-diversified,” which means it may invest a greater percentage of its assets in fewer issuers than a “diversified” fund.
Risk [Heading] rr_RiskHeading Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. Before April 30, 2020, the fund was managed with a different investment strategy and may have achieved different performance results under its current strategy from that shown for periods before this date. The performance information does not reflect insurance-related charges or expenses. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results.

Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Please remember that past performance is not necessarily an indication of future results.
Bar Chart [Heading] rr_BarChartHeading Annual total returns for class IA shares
Year to Date Return, Label rr_YearToDateReturnLabel Year-to-date performance through
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Mar. 31, 2023
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 6.06%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best calendar quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 21.39%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst calendar quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (21.47%)
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (for periods ended 12/31/22)
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
The Putnam VT Emerging Markets Equity Linked Benchmark represents the performance of the MSCI EAFE Growth Index (ND) through April 29, 2020, and the performance of the MSCI Emerging Markets Index (ND) thereafter.
Putnam VT Emerging Markets Equity Fund | MSCI Emerging Markets Index (ND) (no deduction for fees, expenses or taxes, other than withholding taxes on reinvested dividends)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (20.09%)
5 Years rr_AverageAnnualReturnYear05 (1.40%)
10 Years rr_AverageAnnualReturnYear10 1.44%
Putnam VT Emerging Markets Equity Fund | Putnam VT Emerging Markets Equity Linked Benchmark (no deduction for fees, expenses or taxes, other than withholding taxes on reinvested dividends)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (20.09%)
5 Years rr_AverageAnnualReturnYear05 1.87%
10 Years rr_AverageAnnualReturnYear10 5.27%
Putnam VT Emerging Markets Equity Fund | Class IA C000010853  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.92%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.60% [5]
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.54%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.43%) [6]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.11%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 113
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 444
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 799
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,798
Annual Return 2013 rr_AnnualReturn2013 22.70%
Annual Return 2014 rr_AnnualReturn2014 (5.90%)
Annual Return 2015 rr_AnnualReturn2015 1.33%
Annual Return 2016 rr_AnnualReturn2016 (6.46%)
Annual Return 2017 rr_AnnualReturn2017 35.37%
Annual Return 2018 rr_AnnualReturn2018 (18.40%)
Annual Return 2019 rr_AnnualReturn2019 25.21%
Annual Return 2020 rr_AnnualReturn2020 28.25%
Annual Return 2021 rr_AnnualReturn2021 (3.98%)
Annual Return 2022 rr_AnnualReturn2022 (27.24%)
1 Year rr_AverageAnnualReturnYear01 (27.24%)
5 Years rr_AverageAnnualReturnYear05 (1.75%)
10 Years rr_AverageAnnualReturnYear10 3.09%
Putnam VT Emerging Markets Equity Fund | Class IB C000010854  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.92%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.60% [5]
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.79%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.43%) [6]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.36%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 138
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 522
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 930
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,070
1 Year rr_AverageAnnualReturnYear01 (27.44%)
5 Years rr_AverageAnnualReturnYear05 (2.01%)
10 Years rr_AverageAnnualReturnYear10 2.83%
Putnam VT Focused International Equity Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Objective [Heading] rr_ObjectiveHeading Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

Putnam VT Focused International Equity Fund seeks capital appreciation.

Expense [Heading] rr_ExpenseHeading Fees and expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses you may pay if you buy, hold and sell shares of the fund. 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. 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.

Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (expenses you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination 4/30/24
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock

The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or the above example, affect fund performance. The fund’s turnover rate in the most recent fiscal year was 30%.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 30.00%
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

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’s operating expenses remain the same. Only the first year of each period in the example takes into account the expense reimbursement described above. Your actual costs may be higher or lower.

Strategy [Heading] rr_StrategyHeading Investments, risks, and performance
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Investments

We invest mainly in common stocks (growth or value stocks or both) of companies of any size outside the United States that we believe have favorable investment potential. Under normal circumstances, we invest at least 80% of the fund’s net assets in equity investments. This policy may be changed only after 60 days’ notice to shareholders. The fund’s equity investments may include common stocks, preferred stocks, convertible securities, warrants, American Depositary Receipts (ADRs) and Global Depositary Receipts (GDRs). We invest in both developed countries and in emerging markets.

We may consider, among other factors, a company’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. We may also consider other factors that we believe will cause the stock price to rise. We may also use derivatives, such as futures, options, warrants and swap contracts, for both hedging and non-hedging purposes.

The fund is “non-diversified,” which means it may invest a greater percentage of its assets in fewer issuers than a “diversified” fund. The fund expects to invest in a limited number of issuers.

Risk [Heading] rr_RiskHeading Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. Before April 30, 2021, the fund was managed with a materially different investment strategy and may have achieved materially different performance results under its current investment strategy from that shown for periods before this date. The performance information does not reflect insurance-related charges or expenses. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results.

Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Please remember that past performance is not necessarily an indication of future results.
Bar Chart [Heading] rr_BarChartHeading Annual total returns for class IA shares
Year to Date Return, Label rr_YearToDateReturnLabel Year-to-date performance through
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Mar. 31, 2023
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 10.00%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best calendar quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 22.73%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst calendar quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (24.51%)
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (for periods ended 12/31/22)
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
The Putnam VT Focused International Equity Linked Benchmark represents the performance of the MSCI World Index (ND) through April 29, 2021, and the performance of the MSCI ACWI ex USA Index (ND) thereafter.
Putnam VT Focused International Equity Fund | MSCI ACWI ex USA Index (ND) (no deduction for fees, expenses or taxes, other than withholding taxes on reinvested dividends)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (16.00%)
5 Years rr_AverageAnnualReturnYear05 0.88%
10 Years rr_AverageAnnualReturnYear10 3.80%
Putnam VT Focused International Equity Fund | Putnam VT Focused International Equity Linked Benchmark (no deduction for fees, expenses or taxes, other than withholding taxes on reinvested dividends)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (16.00%)
5 Years rr_AverageAnnualReturnYear05 4.69%
10 Years rr_AverageAnnualReturnYear10 8.11%
Putnam VT Focused International Equity Fund | Class IA C000010889  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.69%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.17% [7]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.86%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.05%) [8]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.81%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 83
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 269
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 472
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,056
Annual Return 2013 rr_AnnualReturn2013 32.27%
Annual Return 2014 rr_AnnualReturn2014 1.77%
Annual Return 2015 rr_AnnualReturn2015 (1.49%)
Annual Return 2016 rr_AnnualReturn2016 1.37%
Annual Return 2017 rr_AnnualReturn2017 28.71%
Annual Return 2018 rr_AnnualReturn2018 (12.21%)
Annual Return 2019 rr_AnnualReturn2019 26.92%
Annual Return 2020 rr_AnnualReturn2020 10.32%
Annual Return 2021 rr_AnnualReturn2021 12.84%
Annual Return 2022 rr_AnnualReturn2022 (17.99%)
1 Year rr_AverageAnnualReturnYear01 (17.99%)
5 Years rr_AverageAnnualReturnYear05 2.61%
10 Years rr_AverageAnnualReturnYear10 7.00%
Putnam VT Focused International Equity Fund | Class IB C000010890  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.69%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.17% [7]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.11%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.05%) [8]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.06%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 108
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 348
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 607
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,347
1 Year rr_AverageAnnualReturnYear01 (18.19%)
5 Years rr_AverageAnnualReturnYear05 2.36%
10 Years rr_AverageAnnualReturnYear10 6.74%
Putnam VT George Putnam Balanced Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading Fund summary
Objective [Heading] rr_ObjectiveHeading Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

Putnam VT George Putnam Balanced Fund seeks to provide a balanced investment composed of a well-diversified portfolio of stocks and bonds which produce both capital growth and current income.

Expense [Heading] rr_ExpenseHeading Fees and expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses you may pay if you buy, hold and sell shares of the fund. 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. 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.

Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (expenses you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock

The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or the above example, affect fund performance. The fund’s turnover rate in the most recent fiscal year was 69%.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 69.00%
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

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’s operating expenses remain the same. Your actual costs may be higher or lower.

Strategy [Heading] rr_StrategyHeading Investments, risks, and performance
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Investments

We invest mainly in a combination of bonds and common stocks (growth or value stocks or both) of large U.S. companies, with a greater focus on common stocks. For example, we may purchase stocks of companies with stock prices that reflect a value lower than that which we place on the company. We may also consider other factors that we believe will cause the stock price to rise. We buy bonds of governments and private companies that are mostly investment-grade in quality with intermediate- to long-term maturities (three years or longer). We may consider, among other factors, a company'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 equity investments, and, among other factors, credit, interest rate and prepayment risks, as well as general market conditions, when deciding whether to buy or sell fixed-income investments. We may also use derivatives, such as futures, options, warrants and swap contracts, for both hedging and non-hedging purposes.

Risk [Heading] rr_RiskHeading Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. The performance information does not reflect insurance-related charges or expenses. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results.

Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Please remember that past performance is not necessarily an indication of future results.
Bar Chart [Heading] rr_BarChartHeading Annual total returns for class IA shares
Year to Date Return, Label rr_YearToDateReturnLabel Year-to-date performance through
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Mar. 31, 2023
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 5.75%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best calendar quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 14.44%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst calendar quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (11.64%)
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (for periods ended 12/31/22)
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
The fund's performance is compared to the George Putnam Blended Index, an unmanaged index administered by Putnam Management, 60% of which is the S&P 500 Index and 40% of which is the Bloomberg U.S. Aggregate Bond Index. The fund's performance is also compared to the S&P 500 Index, an unmanaged index of large U.S. company stocks. In addition, the fund's performance is compared to the Bloomberg U.S. Aggregate Bond Index, an unmanaged index of U.S. investment-grade fixed income securities.
All Bloomberg indices are provided by Bloomberg Index Services Limited.
BLOOMBERG® is a trademark and service mark of Bloomberg Finance L.P. and its affiliates (collectively “Bloomberg”). Bloomberg or Bloomberg’s licensors, own all proprietary rights in the Bloomberg Indices. Neither Bloomberg nor Bloomberg’s licensors approve or endorse this material, or guarantee the accuracy or completeness of any information herein, or make any warranty, express or implied, as to the results to be obtained therefrom, and to the maximum extent allowed by law, neither shall have any liability or responsibility for injury or damages arising in connection therewith.
Putnam VT George Putnam Balanced Fund | George Putnam Blended Index (no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (15.56%)
5 Years rr_AverageAnnualReturnYear05 6.21%
10 Years rr_AverageAnnualReturnYear10 8.25%
Putnam VT George Putnam Balanced Fund | S&P 500 Index (no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (18.11%)
5 Years rr_AverageAnnualReturnYear05 9.42%
10 Years rr_AverageAnnualReturnYear10 12.56%
Putnam VT George Putnam Balanced Fund | Bloomberg U.S. Aggregate Bond Index (no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (13.01%)
5 Years rr_AverageAnnualReturnYear05 0.02%
10 Years rr_AverageAnnualReturnYear10 1.06%
Putnam VT George Putnam Balanced Fund | Class IA C000010885  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.52%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.15% [9]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.67%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 68
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 214
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 373
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 835
Annual Return 2013 rr_AnnualReturn2013 18.46%
Annual Return 2014 rr_AnnualReturn2014 10.93%
Annual Return 2015 rr_AnnualReturn2015 (0.96%)
Annual Return 2016 rr_AnnualReturn2016 8.40%
Annual Return 2017 rr_AnnualReturn2017 15.29%
Annual Return 2018 rr_AnnualReturn2018 (2.82%)
Annual Return 2019 rr_AnnualReturn2019 24.35%
Annual Return 2020 rr_AnnualReturn2020 15.61%
Annual Return 2021 rr_AnnualReturn2021 14.28%
Annual Return 2022 rr_AnnualReturn2022 (15.82%)
1 Year rr_AverageAnnualReturnYear01 (15.82%)
5 Years rr_AverageAnnualReturnYear05 6.09%
10 Years rr_AverageAnnualReturnYear10 8.14%
Putnam VT George Putnam Balanced Fund | Class IB C000010886  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.52%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.15% [9]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.92%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 94
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 293
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 509
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,131
1 Year rr_AverageAnnualReturnYear01 (15.99%)
5 Years rr_AverageAnnualReturnYear05 5.82%
10 Years rr_AverageAnnualReturnYear10 7.86%
Putnam VT Global Asset Allocation Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading Fund summary
Objective [Heading] rr_ObjectiveHeading Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

Putnam VT Global Asset Allocation Fund seeks long-term return consistent with preservation of capital.

Expense [Heading] rr_ExpenseHeading Fees and expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses you may pay if you buy, hold and sell shares of the fund. 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. 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.

Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (expenses you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination 4/30/24.
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock

The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or the above example, affect fund performance. The fund’s turnover rate in the most recent fiscal year was 262%.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 262.00%
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

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’s operating expenses remain the same. Only the first year of each period in the example takes into account the expense reimbursement described above. Your actual costs may be higher or lower.

Strategy [Heading] rr_StrategyHeading Investments, risks, and performance
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Investments

We invest a majority of the fund’s assets in a diversified portfolio of equity securities (growth or value stocks or both) of both U.S. and foreign companies of any size.

We may consider, among other factors, a company’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 equity investments. We also invest in a diversified portfolio of fixed-income investments, including both U.S. and foreign government obligations, corporate obligations and securitized debt instruments (such as mortgage-backed investments). We may consider, among other factors, credit, interest rate and prepayment risks, as well as general market conditions, when deciding whether to buy or sell fixed income investments. We may also select other investments that do not fall within these asset classes. We may also use to a significant extent derivatives, such as futures, options, certain foreign currency transactions, warrants and swap contracts, for both hedging and non-hedging purposes.

Risk [Heading] rr_RiskHeading Risks
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. The performance information does not reflect insurance-related charges or expenses. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results.

Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Please remember that past performance is not necessarily an indication of future results.
Bar Chart [Heading] rr_BarChartHeading Annual total returns for class IA shares
Year to Date Return, Label rr_YearToDateReturnLabel Year-to-date performance through
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Mar. 31, 2023
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 5.17%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best calendar quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 12.90%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst calendar quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (12.77%)
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (for periods ended 12/31/22)
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
Putnam Balanced Blended Benchmark is an unmanaged index administered by Putnam Investment Management, LLC, 50% of which is the Russell 3000 Index, 35% of which is the Bloomberg U.S. Aggregate Bond Index, 10% of which is the MSCI EAFE Index (ND) and 5% of which is the JPMorgan Developed High Yield Index.
Frank Russell Company is the source and owner of the trademarks, service marks and copyrights related to the Russell Indexes. Russell ® is a trademark of Frank Russell Company.
All Bloomberg indices are provided by Bloomberg Index Services Limited.
BLOOMBERG® is a trademark and service mark of Bloomberg Finance L.P. and its affiliates (collectively “Bloomberg”). Bloomberg or Bloomberg’s licensors, own all proprietary rights in the Bloomberg Indices. Neither Bloomberg nor Bloomberg’s licensors approve or endorse this material, or guarantee the accuracy or completeness of any information herein, or make any warranty, express or implied, as to the results to be obtained therefrom, and to the maximum extent allowed by law, neither shall have any liability or responsibility for injury or damages arising in connection therewith.



 
Putnam VT Global Asset Allocation Fund | Russell 3000 Index (no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (19.21%)
5 Years rr_AverageAnnualReturnYear05 8.79%
10 Years rr_AverageAnnualReturnYear10 12.13%
Putnam VT Global Asset Allocation Fund | Putnam Balanced Blended Benchmark (no deduction for fees, expenses or taxes, other than withholding taxes on reinvested dividends in the case of the MSCI EAFE Index (ND))  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (15.86%)
5 Years rr_AverageAnnualReturnYear05 4.99%
10 Years rr_AverageAnnualReturnYear10 7.27%
Putnam VT Global Asset Allocation Fund | Class IA C000010887  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.59%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.31% [10]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.90%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.04%) [11]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.86%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 88
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 283
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 495
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,104
Annual Return 2013 rr_AnnualReturn2013 19.78%
Annual Return 2014 rr_AnnualReturn2014 9.66%
Annual Return 2015 rr_AnnualReturn2015 0.42%
Annual Return 2016 rr_AnnualReturn2016 6.98%
Annual Return 2017 rr_AnnualReturn2017 15.67%
Annual Return 2018 rr_AnnualReturn2018 (7.02%)
Annual Return 2019 rr_AnnualReturn2019 17.42%
Annual Return 2020 rr_AnnualReturn2020 12.58%
Annual Return 2021 rr_AnnualReturn2021 14.25%
Annual Return 2022 rr_AnnualReturn2022 (15.82%)
1 Year rr_AverageAnnualReturnYear01 (15.82%)
5 Years rr_AverageAnnualReturnYear05 3.40%
10 Years rr_AverageAnnualReturnYear10 6.79%
Putnam VT Global Asset Allocation Fund | Class IB C000010888  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.59%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.31% [10]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.15%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.04%) [11]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.11%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 113
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 361
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 629
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,394
1 Year rr_AverageAnnualReturnYear01 (16.03%)
5 Years rr_AverageAnnualReturnYear05 3.14%
10 Years rr_AverageAnnualReturnYear10 6.53%
Putnam VT Global Health Care Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading Fund summary
Objective [Heading] rr_ObjectiveHeading Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

Putnam VT Global Health Care Fund seeks capital appreciation.

Expense [Heading] rr_ExpenseHeading Fees and expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses you may pay if you buy, hold and sell shares of the fund. 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. 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.

Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (expenses you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock

The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or the above example, affect fund performance. The fund’s turnover rate in the most recent fiscal year was 72%.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 72.00%
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

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’s operating expenses remain the same. Your actual costs may be higher or lower.

Strategy [Heading] rr_StrategyHeading Investments, risks, and performance
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Investments

For this non-diversified fund concentrating in the health care industries, we invest mainly in common stocks (growth or value stocks or both) of large and midsize companies worldwide that we believe have favorable investment potential. Under normal circumstances, we invest at least 80% of the fund’s net assets in securities of companies in the health care industries. This policy may be changed only after 60 days’ notice to shareholders. Potential investments include companies that manufacture health care supplies or provide health care-related services, and companies in the research, development, production and marketing of pharmaceuticals and biotechnology products. We may purchase stocks of companies with stock prices that reflect a value lower than that which we place on the company. We may consider, among other factors, a company’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. We may also consider other factors that we believe will cause the stock price to rise. We may also use derivatives, such as futures, options, certain foreign currency transactions, warrants and swap contracts, for both hedging and non-hedging purposes, and may engage in short sales of securities. For example, we typically use foreign currency forward contracts in connection with the fund’s investments in foreign securities in order to hedge the fund’s currency exposure relative to the fund’s benchmark index.

The use of the term “global” in the fund’s name is meant to emphasize that we look for investment opportunities on a worldwide basis and that our investment strategies are not constrained by the countries or regions in which companies are located. Under normal market conditions, the fund intends to invest in at least five different countries and at least 40% of its net assets in securities of foreign companies (or, if less, at least the percentage of net assets that is ten percentage points less than the percentage of the fund’s benchmark represented by foreign companies, as determined by the providers of the benchmark).

Risk [Heading] rr_RiskHeading Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. The performance information does not reflect insurance-related charges or expenses. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results.

Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Please remember that past performance is not necessarily an indication of future results.
Bar Chart [Heading] rr_BarChartHeading Annual total returns for class IA shares
Year to Date Return, Label rr_YearToDateReturnLabel Year-to-date performance through
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Mar. 31, 2023
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn (2.06%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best calendar quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2019
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 17.58%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst calendar quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2015
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (11.72%)
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (for periods ended 12/31/22)
Putnam VT Global Health Care Fund | MSCI World Health Care Index (ND) (no deduction for fees, expenses or taxes, other than withholding taxes on reinvested dividends)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (5.41%)
5 Years rr_AverageAnnualReturnYear05 10.20%
10 Years rr_AverageAnnualReturnYear10 12.02%
Putnam VT Global Health Care Fund | Class IA C000010843  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.62%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.14% [12]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.76%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 78
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 243
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 422
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 942
Annual Return 2013 rr_AnnualReturn2013 41.98%
Annual Return 2014 rr_AnnualReturn2014 27.96%
Annual Return 2015 rr_AnnualReturn2015 8.06%
Annual Return 2016 rr_AnnualReturn2016 (11.14%)
Annual Return 2017 rr_AnnualReturn2017 15.60%
Annual Return 2018 rr_AnnualReturn2018 (0.29%)
Annual Return 2019 rr_AnnualReturn2019 30.58%
Annual Return 2020 rr_AnnualReturn2020 16.47%
Annual Return 2021 rr_AnnualReturn2021 19.77%
Annual Return 2022 rr_AnnualReturn2022 (4.44%)
1 Year rr_AverageAnnualReturnYear01 (4.44%)
5 Years rr_AverageAnnualReturnYear05 11.66%
10 Years rr_AverageAnnualReturnYear10 13.35%
Putnam VT Global Health Care Fund | Class IB C000010844  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.62%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.14% [12]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.01%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 103
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 322
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 558
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,236
1 Year rr_AverageAnnualReturnYear01 (4.67%)
5 Years rr_AverageAnnualReturnYear05 11.38%
10 Years rr_AverageAnnualReturnYear10 13.07%
Putnam VT Government Money Market Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading Fund summary
Objective [Heading] rr_ObjectiveHeading Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

Putnam VT Government Money Market Fund seeks as high a rate of current income as Putnam Investment Management, LLC believes is consistent with preservation of capital and maintenance of liquidity.

Expense [Heading] rr_ExpenseHeading Fees and expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses you may pay if you buy, hold and sell shares of the fund. 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. 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.

Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (expenses you pay each year as a percentage of the value of your investment)
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

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’s operating expenses remain the same. Your actual costs may be higher or lower.

Strategy [Heading] rr_StrategyHeading Investments, risks, and performance
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Investments

We invest at least 99.5 percent of the fund’s total assets in cash, U.S. government securities and repurchase agreements that are fully collateralized by U.S. government securities or cash. We invest mainly in debt securities that are obligations of the U.S. government, its agencies and instrumentalities and accordingly are backed by the full faith and credit of the United States (e.g., U.S. Treasury bills) or by the credit of a federal agency or government-sponsored entity (e.g.,securities issued by Fannie Mae and Freddie Mac). The U.S. government securities in which we invest may also include variable and floating rate instruments and when-issued and delayed delivery securities (i.e., payment or delivery of the securities occurs at a future date for a predetermined price). Under normal circumstances, we invest at least 80% of the fund’s net assets in U.S. government securities and repurchase agreements that are fully collateralized by U.S. government securities. This policy may be changed only after 60 days’ notice to shareholders. The securities purchased by the fund are subject to quality, maturity, diversification and other requirements pursuant to rules promulgated by the Securities and Exchange Commission. We may consider, among other factors, credit and interest rate risks and characteristics of the issuer or counterparty, as well as general market conditions, when deciding whether to buy or sell investments.
Risk [Heading] rr_RiskHeading Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. Please remember that past performance is not necessarily an indication of future results.

Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Please remember that past performance is not necessarily an indication of future results.
Bar Chart [Heading] rr_BarChartHeading Annual total returns for class IA shares
Year to Date Return, Label rr_YearToDateReturnLabel Year-to-date performance through
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Mar. 31, 2023
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 1.02%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best calendar quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2022
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 0.79%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst calendar quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn none
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (for periods ended 12/31/22)
Putnam VT Government Money Market Fund | Class IA C000010859  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.28%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.18% [13]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.46%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 47
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 148
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 258
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 579
Annual Return 2013 rr_AnnualReturn2013 0.01%
Annual Return 2014 rr_AnnualReturn2014 0.01%
Annual Return 2015 rr_AnnualReturn2015 0.01%
Annual Return 2016 rr_AnnualReturn2016 0.01%
Annual Return 2017 rr_AnnualReturn2017 0.47%
Annual Return 2018 rr_AnnualReturn2018 1.43%
Annual Return 2019 rr_AnnualReturn2019 1.81%
Annual Return 2020 rr_AnnualReturn2020 0.24%
Annual Return 2021 rr_AnnualReturn2021 0.01%
Annual Return 2022 rr_AnnualReturn2022 1.29%
1 Year rr_AverageAnnualReturnYear01 1.29%
5 Years rr_AverageAnnualReturnYear05 0.95%
10 Years rr_AverageAnnualReturnYear10 0.53%
Putnam VT Government Money Market Fund | Class IB C000010860  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.28%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.18% [13]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.71%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 73
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 227
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 395
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 883
1 Year rr_AverageAnnualReturnYear01 1.12%
5 Years rr_AverageAnnualReturnYear05 0.81%
10 Years rr_AverageAnnualReturnYear10 0.43%
Putnam VT High Yield Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading Fund summary
Objective [Heading] rr_ObjectiveHeading Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

Putnam VT High Yield Fund seeks high current income. Capital growth is a secondary goal when consistent with achieving high current income.

Objective, Secondary [Text Block] rr_ObjectiveSecondaryTextBlock Capital growth is a secondary goal when consistent with achieving high current income.
Expense [Heading] rr_ExpenseHeading Fees and expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses you may pay if you buy, hold and sell shares of the fund. 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. 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.

Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (expenses you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock

The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or the above example, affect fund performance. The fund’s turnover rate in the most recent fiscal year was 28%.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 28.00%
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

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’s operating expenses remain the same. Your actual costs may be higher or lower.

Strategy [Heading] rr_StrategyHeading Investments, risks, and performance
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Investments

We invest mainly in bonds that are obligations of U.S. companies, are below-investment-grade in quality (sometimes referred to as “junk bonds”), and have intermediate- to long-term maturities (three years or longer). Under normal circumstances, we invest at least 80% of the fund’s net assets in securities rated below-investment-grade. This policy may be changed only after 60 days’ notice to shareholders. We may also invest in other debt instruments, including loans.

We may consider, among other factors, credit, interest rate and prepayment risks, as well as general market conditions, when deciding whether to buy or sell investments. We may also use derivatives, such as futures, options, certain foreign currency transactions, and credit default swap contracts for both hedging and non-hedging purposes.
Risk [Heading] rr_RiskHeading Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. The performance information does not reflect insurance-related charges or expenses. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results.

Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Please remember that past performance is not necessarily an indication of future results.
Bar Chart [Heading] rr_BarChartHeading Annual total returns for class IA shares
Year to Date Return, Label rr_YearToDateReturnLabel Year-to-date performance through
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Mar. 31, 2023
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 3.48%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best calendar quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 9.63%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst calendar quarte
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (13.09%)
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (for periods ended 12/31/22)
Putnam VT High Yield Fund | JPMorgan Developed High Yield Index (no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (10.47%)
5 Years rr_AverageAnnualReturnYear05 2.25%
10 Years rr_AverageAnnualReturnYear10 4.18%
Putnam VT High Yield Fund | Class IA C000010845  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.56%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.18% [14]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.74%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 76
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 237
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 411
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 918
Annual Return 2013 rr_AnnualReturn2013 8.10%
Annual Return 2014 rr_AnnualReturn2014 1.91%
Annual Return 2015 rr_AnnualReturn2015 (5.14%)
Annual Return 2016 rr_AnnualReturn2016 15.66%
Annual Return 2017 rr_AnnualReturn2017 7.22%
Annual Return 2018 rr_AnnualReturn2018 (3.59%)
Annual Return 2019 rr_AnnualReturn2019 14.55%
Annual Return 2020 rr_AnnualReturn2020 5.50%
Annual Return 2021 rr_AnnualReturn2021 5.20%
Annual Return 2022 rr_AnnualReturn2022 (11.37%)
1 Year rr_AverageAnnualReturnYear01 (11.37%)
5 Years rr_AverageAnnualReturnYear05 1.67%
10 Years rr_AverageAnnualReturnYear10 3.48%
Putnam VT High Yield Fund | Class IB C000010846  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.56%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.18% [14]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.99%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 101
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 315
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 547
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,213
1 Year rr_AverageAnnualReturnYear01 (11.60%)
5 Years rr_AverageAnnualReturnYear05 1.39%
10 Years rr_AverageAnnualReturnYear10 3.22%
Putnam VT Income Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading Fund summary
Objective [Heading] rr_ObjectiveHeading Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

Putnam VT Income Fund seeks high current income consistent with what Putnam Investment Management, LLC believes to be prudent risk.

Expense [Heading] rr_ExpenseHeading Fees and expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses you may pay if you buy, hold and sell shares of the fund. 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. 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.

Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (expenses you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock

The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or the above example, affect fund performance. The fund’s turnover rate in the most recent fiscal year was 793%.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 793.00%
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

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’s operating expenses remain the same. Your actual costs may be higher or lower.

Strategy [Heading] rr_StrategyHeading Investments, risks, and performance
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Investments

We invest mainly in bonds that are securitized debt instruments (such as mortgage-backed investments) and related derivative instruments, and other obligations of companies and governments worldwide denominated in U.S. dollars or (to a lesser extent) foreign currencies, are either investment-grade or below-investment-grade in quality (sometimes referred to as “junk bonds”) and have intermediate- to long-term maturities (three years or longer). The fund currently has significant investment exposure to residential and commercial mortgage-backed securities. We may consider, among other factors, credit, interest rate and prepayment risks, as well as general market conditions, when deciding whether to buy or sell investments. We typically use to a significant extent derivatives, including credit default swaps, interest rate swaps, total return swaps, to-be-announced (TBA) commitments, futures, options and swaptions, including on mortgage-backed securities and indices, and certain foreign currency transactions, for both hedging and non-hedging purposes, including to obtain or adjust exposure to mortgage-backed investments.
Risk [Heading] rr_RiskHeading Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. The performance information does not reflect insurance-related charges or expenses. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results.

Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Please remember that past performance is not necessarily an indication of future results.
Bar Chart [Heading] rr_BarChartHeading Annual total returns for class IA shares
Year to Date Return, Label rr_YearToDateReturnLabel Year-to-date performance through
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Mar. 31, 2023
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 1.96%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best calendar quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2019
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 4.18%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst calendar quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (5.77%)
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (for periods ended 12/31/22)
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
All Bloomberg indices are provided by Bloomberg Index Services Limited.
BLOOMBERG® is a trademark and service mark of Bloomberg Finance L.P. and its affiliates (collectively “Bloomberg”). Bloomberg or Bloomberg’s licensors, own all proprietary rights in the Bloomberg Indices. Neither Bloomberg nor Bloomberg’s licensors approve or endorse this material, or guarantees the accuracy or completeness of any information herein, or makes any warranty, express or implied, as to the results to be obtained therefrom, and to the maximum extent allowed by law, neither shall have any liability or responsibility for injury or damages arising in connection therewith.
Putnam VT Income Fund | Bloomberg U.S. Aggregate Bond Index (no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (13.01%)
5 Years rr_AverageAnnualReturnYear05 0.02%
10 Years rr_AverageAnnualReturnYear10 1.06%
Putnam VT Income Fund | Class IA C000010847  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.39%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.22% [15]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.61%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 62
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 195
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 340
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 762
Annual Return 2013 rr_AnnualReturn2013 2.13%
Annual Return 2014 rr_AnnualReturn2014 6.68%
Annual Return 2015 rr_AnnualReturn2015 (1.19%)
Annual Return 2016 rr_AnnualReturn2016 2.27%
Annual Return 2017 rr_AnnualReturn2017 5.90%
Annual Return 2018 rr_AnnualReturn2018 0.37%
Annual Return 2019 rr_AnnualReturn2019 12.24%
Annual Return 2020 rr_AnnualReturn2020 6.00%
Annual Return 2021 rr_AnnualReturn2021 (4.44%)
Annual Return 2022 rr_AnnualReturn2022 (13.48%)
1 Year rr_AverageAnnualReturnYear01 (13.48%)
5 Years rr_AverageAnnualReturnYear05 (0.25%)
10 Years rr_AverageAnnualReturnYear10 1.42%
Putnam VT Income Fund | Class IB C000010848  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.39%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.22% [15]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.86%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 88
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 274
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 477
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,061
1 Year rr_AverageAnnualReturnYear01 (13.81%)
5 Years rr_AverageAnnualReturnYear05 (0.51%)
10 Years rr_AverageAnnualReturnYear10 1.16%
Putnam VT International Equity Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading Fund summary
Objective [Heading] rr_ObjectiveHeading Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

Putnam VT International Equity Fund seeks capital appreciation.

Expense [Heading] rr_ExpenseHeading Fees and expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses you may pay if you buy, hold and sell shares of the fund. 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. 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.

Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (expenses you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock

The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or the above example, affect fund performance. The fund’s turnover rate in the most recent fiscal year was 82%.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 82.00%
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

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’s operating expenses remain the same. Your actual costs may be higher or lower.

Strategy [Heading] rr_StrategyHeading Investments, risks, and performance
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Investments

We invest mainly in common stocks (growth or value stocks or both) of large and midsize companies outside the United States that we believe have favorable investment potential. For example, we may purchase stocks of companies with stock prices that reflect a value lower than that which we place on the company. Under normal circumstances, we invest at least 80% of the fund’s net assets in equity investments. This policy may be changed only after 60 days’ notice to shareholders. We may consider, among other factors, a company’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. We may also consider other factors that we believe will cause the stock price to rise. We invest mainly in developed countries but may invest in emerging markets. We may also use derivatives, such as certain foreign currency transactions, futures, options, warrants and swap contracts, for both hedging and non-hedging purposes. For example, we typically use foreign currency forward contracts in connection with the fund’s investments in foreign securities in order to hedge the fund’s currency exposure relative to the fund’s benchmark index.
Risk [Heading] rr_RiskHeading Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. The performance information does not reflect insurance-related charges or expenses. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results.

Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Please remember that past performance is not necessarily an indication of future results.
Bar Chart [Heading] rr_BarChartHeading Annual total returns for class IA shares
Year to Date Return, Label rr_YearToDateReturnLabel Year-to-date performance through
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Mar. 31, 2023
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 9.41%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best calendar quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2022
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 17.24%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst calendar quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (20.40%)
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (for periods ended 12/31/22)
Putnam VT International Equity Fund | MSCI EAFE Index (ND) (no deduction for fees, expenses or taxes, other than withholding taxes on reinvested dividends)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (14.45%)
5 Years rr_AverageAnnualReturnYear05 1.54%
10 Years rr_AverageAnnualReturnYear10 4.67%
Putnam VT International Equity Fund | Class IA C000010849  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.69%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.17% [16]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.86%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 88
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 274
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 477
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,061
Annual Return 2013 rr_AnnualReturn2013 28.44%
Annual Return 2014 rr_AnnualReturn2014 (6.58%)
Annual Return 2015 rr_AnnualReturn2015 0.41%
Annual Return 2016 rr_AnnualReturn2016 (2.21%)
Annual Return 2017 rr_AnnualReturn2017 26.93%
Annual Return 2018 rr_AnnualReturn2018 (18.95%)
Annual Return 2019 rr_AnnualReturn2019 25.55%
Annual Return 2020 rr_AnnualReturn2020 12.35%
Annual Return 2021 rr_AnnualReturn2021 9.09%
Annual Return 2022 rr_AnnualReturn2022 (14.58%)
1 Year rr_AverageAnnualReturnYear01 (14.58%)
5 Years rr_AverageAnnualReturnYear05 1.27%
10 Years rr_AverageAnnualReturnYear10 4.77%
Putnam VT International Equity Fund | Class IB C000010850  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.69%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.17% [16]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.11%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 113
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 353
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 612
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,352
1 Year rr_AverageAnnualReturnYear01 (14.77%)
5 Years rr_AverageAnnualReturnYear05 1.03%
10 Years rr_AverageAnnualReturnYear10 4.51%
Putnam VT International Value Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading Fund summary
Objective [Heading] rr_ObjectiveHeading Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

Putnam VT International Value Fund seeks capital growth. Current income is a secondary objective.

Objective, Secondary [Text Block] rr_ObjectiveSecondaryTextBlock Current income is a secondary objective
Expense [Heading] rr_ExpenseHeading Fees and expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses you may pay if you buy, hold and sell shares of the fund. 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. 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.

Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (expenses you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock

The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or the above example, affect fund performance. The fund’s turnover rate in the most recent fiscal year was 11%.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 11.00%
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

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’s operating expenses remain the same. Your actual costs may be higher or lower.

Strategy [Heading] rr_StrategyHeading Investments, risks, and performance
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Investments

We invest mainly in common stocks of large and midsize companies outside the United States, with a focus on value stocks. Value stocks are those that we believe are currently undervalued by the market. If we are correct and other investors ultimately recognize the value of the company, the price of its stock may rise. We invest mainly in developed countries, but may invest in emerging markets. We may consider, among other factors, a company’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. We may also use derivatives, such as certain foreign currency transactions, warrants, futures, options, and swap contracts, for both hedging and non-hedging purposes. For example, we typically use foreign currency forward contracts in connection with the fund’s investments in foreign securities in order to hedge the fund’s currency exposure relative to the fund’s benchmark index.
Risk [Heading] rr_RiskHeading Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. The performance information does not reflect insurance-related charges or expenses. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results.

Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Please remember that past performance is not necessarily an indication of future results.
Bar Chart [Heading] rr_BarChartHeading Annual total returns for class IA shares
Year to Date Return, Label rr_YearToDateReturnLabel Year-to-date performance through
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Mar. 31, 2023
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 7.60%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best calendar quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2022
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 21.60%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst calendar quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (25.58%)
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (for periods ended 12/31/22)
Putnam VT International Value Fund | MSCI EAFE Value Index (ND) (no deduction for fees, expenses or taxes, other than withholding taxes on reinvested dividends)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (5.58%)
5 Years rr_AverageAnnualReturnYear05 0.17%
10 Years rr_AverageAnnualReturnYear10 3.51%
Putnam VT International Value Fund | Class IA C000010851  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.69%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.21% [17]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.90%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 92
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 287
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 498
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,108
Annual Return 2013 rr_AnnualReturn2013 22.63%
Annual Return 2014 rr_AnnualReturn2014 (9.29%)
Annual Return 2015 rr_AnnualReturn2015 (1.71%)
Annual Return 2016 rr_AnnualReturn2016 1.28%
Annual Return 2017 rr_AnnualReturn2017 24.95%
Annual Return 2018 rr_AnnualReturn2018 (17.31%)
Annual Return 2019 rr_AnnualReturn2019 20.44%
Annual Return 2020 rr_AnnualReturn2020 4.23%
Annual Return 2021 rr_AnnualReturn2021 15.28%
Annual Return 2022 rr_AnnualReturn2022 (6.70%)
1 Year rr_AverageAnnualReturnYear01 (6.70%)
5 Years rr_AverageAnnualReturnYear05 2.23%
10 Years rr_AverageAnnualReturnYear10 4.45%
Putnam VT International Value Fund | Class IB C000010852  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.69%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.21% [17]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.15%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 117
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 365
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 633
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,398
1 Year rr_AverageAnnualReturnYear01 (6.81%)
5 Years rr_AverageAnnualReturnYear05 1.97%
10 Years rr_AverageAnnualReturnYear10 4.19%
Putnam VT Large Cap Growth Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading Fund summary
Objective [Heading] rr_ObjectiveHeading Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

Putnam VT Large Cap Growth Fund seeks capital appreciation.
Expense [Heading] rr_ExpenseHeading Fees and expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses you may pay if you buy, hold and sell shares of the fund. 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. 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.

Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (expenses you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock

The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or the above example, affect fund performance. The fund’s turnover rate in the most recent fiscal year was 33%.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 33.00%
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

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’s operating expenses remain the same. Your actual costs may be higher or lower.
Strategy [Heading] rr_StrategyHeading Investments, risks, and performance
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Investments

We invest mainly in common stocks of large U.S. companies, with a focus on growth stocks. Growth stocks are stocks of companies whose earnings are expected to grow faster than those of similar firms, and whose business growth and other characteristics may lead to an increase in stock price. We may consider, among other factors, a company’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, we invest at least 80% of the fund’s net assets (plus the amount of any borrowings for investment purposes) in companies of a size similar to those in the Russell 1000 Growth Index. This policy may be changed only after 60 days’ notice to shareholders.

The fund is “non-diversified,” which means it may invest in a greater percentage of its assets in fewer issuers than a “diversified” fund.
Risk [Heading] rr_RiskHeading Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. The performance information does not reflect insurance-related charges or expenses. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results.

Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Please remember that past performance is not necessarily an indication of future results.
Bar Chart [Heading] rr_BarChartHeading Annual total returns for class IA shares
Year to Date Return, Label rr_YearToDateReturnLabel Year-to-date performance through
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Mar. 31, 2023
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 14.24%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best calendar quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 28.83%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst calendar quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (22.06%)
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (for periods ended 12/31/22)
Putnam VT Large Cap Growth Fund | Russell 1000 Growth Index (no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (29.14%) [18]
5 Years rr_AverageAnnualReturnYear05 10.96% [18]
10 Years rr_AverageAnnualReturnYear10 14.10% [18]
Putnam VT Large Cap Growth Fund | Class IA C000010841  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.55%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.11%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.66%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 67
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 211
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 368
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 822
Annual Return 2013 rr_AnnualReturn2013 36.55%
Annual Return 2014 rr_AnnualReturn2014 14.16%
Annual Return 2015 rr_AnnualReturn2015 1.28%
Annual Return 2016 rr_AnnualReturn2016 6.72%
Annual Return 2017 rr_AnnualReturn2017 31.30%
Annual Return 2018 rr_AnnualReturn2018 2.60%
Annual Return 2019 rr_AnnualReturn2019 37.11%
Annual Return 2020 rr_AnnualReturn2020 39.09%
Annual Return 2021 rr_AnnualReturn2021 23.00%
Annual Return 2022 rr_AnnualReturn2022 (30.36%)
1 Year rr_AverageAnnualReturnYear01 (30.36%)
5 Years rr_AverageAnnualReturnYear05 10.88%
10 Years rr_AverageAnnualReturnYear10 14.00%
Putnam VT Large Cap Growth Fund | Class IB C000010842  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.55%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.11%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.91%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 93
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 290
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 504
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,120
1 Year rr_AverageAnnualReturnYear01 (30.50%)
5 Years rr_AverageAnnualReturnYear05 10.60%
10 Years rr_AverageAnnualReturnYear10 13.72%
Putnam VT Large Cap Value Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading Fund summary
Objective [Heading] rr_ObjectiveHeading Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

Putnam VT Large Cap Value Fund seeks capital growth and current income.

Expense [Heading] rr_ExpenseHeading Fees and expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses you may pay if you buy, hold and sell shares of the fund. 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. 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.

Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (expenses you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock

The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or the above example, affect fund performance. The fund’s turnover rate in the most recent fiscal year was 14%.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 14.00%
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

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’s operating expenses remain the same. Your actual costs may be higher or lower.

Strategy [Heading] rr_StrategyHeading Investments, risks, and performance
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Investments

We invest mainly in common stocks of U.S. companies, with a focus on value stocks that offer the potential for capital growth, current income, or both. Under normal circumstances, we invest at least 80% of the fund’s net assets in large-cap companies, which, for purposes of this policy, are of a size similar to those in the Russell 1000 Value Index. This policy may be changed only after 60 days’ notice to shareholders. As of March 31, 2023, the index was composed of companies having market capitalizations of between approximately $542.8 million to $1.3 trillion. We may also invest in midsize companies. Value stocks are issued by companies that we believe are currently undervalued by the market. If we are correct and other investors ultimately recognize the value of the company, the price of its stock may rise. We may consider, among other factors, a company’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.
Risk [Heading] rr_RiskHeading Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. The performance information does not reflect insurance-related charges or expenses. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results.



 
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Please remember that past performance is not necessarily an indication of future results.
Bar Chart [Heading] rr_BarChartHeading Annual total returns for class IA shares
Year to Date Return, Label rr_YearToDateReturnLabel Year-to-date performance through
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Mar. 31, 2023
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 1.77%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best calendar quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 17.78%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst calendar quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (25.53%)
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (for periods ended 12/31/22)
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
Frank Russell Company is the source and owner of the trademarks, service marks and copyrights related to the Russell Indexes. Russell ® is a trademark of Frank Russell Company.
Putnam VT Large Cap Value Fund | Russell 1000 Value Index (no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (7.54%)
5 Years rr_AverageAnnualReturnYear05 6.67%
10 Years rr_AverageAnnualReturnYear10 10.29%
Putnam VT Large Cap Value Fund | Class IA C000010883  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.47%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.10%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.57%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 58
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 183
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 318
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 714
Annual Return 2013 rr_AnnualReturn2013 32.72%
Annual Return 2014 rr_AnnualReturn2014 12.97%
Annual Return 2015 rr_AnnualReturn2015 (2.79%)
Annual Return 2016 rr_AnnualReturn2016 13.96%
Annual Return 2017 rr_AnnualReturn2017 19.06%
Annual Return 2018 rr_AnnualReturn2018 (8.27%)
Annual Return 2019 rr_AnnualReturn2019 30.73%
Annual Return 2020 rr_AnnualReturn2020 6.06%
Annual Return 2021 rr_AnnualReturn2021 27.62%
Annual Return 2022 rr_AnnualReturn2022 (2.87%)
1 Year rr_AverageAnnualReturnYear01 (2.87%)
5 Years rr_AverageAnnualReturnYear05 9.53%
10 Years rr_AverageAnnualReturnYear10 12.04%
Putnam VT Large Cap Value Fund | Class IB C000010884  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.47%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.10%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.82%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 84
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 262
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 455
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,014
1 Year rr_AverageAnnualReturnYear01 (3.13%)
5 Years rr_AverageAnnualReturnYear05 9.26%
10 Years rr_AverageAnnualReturnYear10 11.76%
Putnam VT Mortgage Securities Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading Fund summary
Objective [Heading] rr_ObjectiveHeading Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

Putnam VT Mortgage Securities Fund seeks as high a level of current income as Putnam Investment Management, LLC believes is consistent with preservation of capital.

Expense [Heading] rr_ExpenseHeading Fees and expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses you may pay if you buy, hold and sell shares of the fund. 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. 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.

Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (expenses you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination 4/30/24
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock

The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or the above example, affect fund performance. The fund’s turnover rate in the most recent fiscal year was 1,110%.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 1110.00%
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

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’s operating expenses remain the same. Only the first year of each period in the example takes into account the expense reimbursement described above. Your actual costs may be higher or lower.

Strategy [Heading] rr_StrategyHeading Investments, risks, and performance
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Investments

We invest mainly in mortgages, mortgage-related fixed income securities and related derivatives that are either investment-grade or below-investment-grade in quality (sometimes referred to as “junk bonds”). Under normal circumstances, we invest at least 80% of the fund’s net assets (plus any borrowings for investment purposes) in mortgages, mortgage-related fixed income securities and related derivatives (i.e., derivatives used to acquire exposure to, or whose underlying securities are, mortgages or mortgage-related securities). The fund generally uses the net unrealized gain or loss, or market value, of mortgage-related derivatives for purposes of this policy, but may use the notional value of a derivative if that is determined to be a more appropriate measure of the fund’s investment exposure. This policy may be changed only after 60 days’ notice to shareholders.

We expect to invest in mortgage-backed investments that are obligations of U.S. government agencies and instrumentalities and accordingly are backed by the full faith and credit of the United States (e.g., Ginnie Mae mortgage-backed bonds) as well as in mortgage-backed investments that are backed by only the credit of a federal agency or government-sponsored entity (e.g., Fannie Mae and Freddie Mac mortgage-backed bonds), and that have short- to long-term maturities.

We also expect to invest in lower-rated, higher-yielding mortgage-backed securities, including non-agency residential mortgage-backed securities (which may be backed by non-qualified or “sub-prime” mortgages), commercial mortgage-backed securities, and collateralized mortgage obligations (including interest only, principal only, and other prepayment derivatives). Non-agency (i.e., privately issued) securities typically are lower-rated and higher yielding than securities issued or backed by agencies such as Ginnie Mae, Fannie Mae or Freddie Mac. The fund currently has significant investment exposure to commercial mortgage-backed securities. While our emphasis will be on mortgage-backed securities, we may also invest to a lesser extent in other types of asset-backed securities.

We may consider, among other factors, credit, interest rate, prepayment and liquidity risks, as well as general market conditions, when deciding whether to buy or sell investments. We typically use to a significant extent derivatives, including credit default swaps, interest rate swaps, total return swaps, to-be-announced (TBA) commitments, futures, options and swaptions, including on mortgage-backed securities and indices, for both hedging and non-hedging purposes, including to obtain or adjust exposure to mortgage-backed investments.



 
Risk [Heading] rr_RiskHeading Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. Before April 30, 2018, the fund was managed with a materially different investment strategy and may have achieved materially different performance results under its current investment strategy from that shown for periods before this date. The performance information does not reflect insurance-related charges or expenses. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results.



 
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Please remember that past performance is not necessarily an indication of future results.
Bar Chart [Heading] rr_BarChartHeading Annual total returns for class IA shares
Year to Date Return, Label rr_YearToDateReturnLabel Year-to-date performance through
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Mar. 31, 2023
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 0.61%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best calendar quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 4.99%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst calendar quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (9.91%)
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (for periods ended 12/31/22)
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
The Putnam VT Mortgage Securities Linked Benchmark represents the performance of the Bloomberg Government Bond Index through April 29, 2018, and the performance of the Bloomberg U.S. MBS Index thereafter.
All Bloomberg indices are provided by Bloomberg Index Services Limited.
BLOOMBERG® is a trademark and service mark of Bloomberg Finance L.P. and its affiliates (collectively “Bloomberg”). Bloomberg or Bloomberg’s licensors, own all proprietary rights in the Bloomberg Indices. Neither Bloomberg nor Bloomberg’s licensors approve or endorse this material, or guarantee the accuracy or completeness of any information herein, or make any warranty, express or implied, as to the results to be obtained therefrom, and to the maximum extent allowed by law, neither shall have any liability or responsibility for injury or damages arising in connection therewith.
Putnam VT Mortgage Securities Fund | Bloomberg U.S. MBS Index (no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (11.81%)
5 Years rr_AverageAnnualReturnYear05 (0.53%)
10 Years rr_AverageAnnualReturnYear10 0.74%
Putnam VT Mortgage Securities Fund | Putnam VT Mortgage Securities Linked Benchmark (no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (11.81%)
5 Years rr_AverageAnnualReturnYear05 (0.60%)
10 Years rr_AverageAnnualReturnYear10 0.33%
Putnam VT Mortgage Securities Fund | Class IA C000010837  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.39%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.53% [19]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.92%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.42%) [20]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.50%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 51
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 251
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 468
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,093
Annual Return 2013 rr_AnnualReturn2013 (0.19%)
Annual Return 2014 rr_AnnualReturn2014 4.49%
Annual Return 2015 rr_AnnualReturn2015 (0.33%)
Annual Return 2016 rr_AnnualReturn2016 0.36%
Annual Return 2017 rr_AnnualReturn2017 2.27%
Annual Return 2018 rr_AnnualReturn2018 (0.62%)
Annual Return 2019 rr_AnnualReturn2019 13.36%
Annual Return 2020 rr_AnnualReturn2020 (1.29%)
Annual Return 2021 rr_AnnualReturn2021 (3.43%)
Annual Return 2022 rr_AnnualReturn2022 (9.95%)
1 Year rr_AverageAnnualReturnYear01 (9.95%)
5 Years rr_AverageAnnualReturnYear05 (0.67%)
10 Years rr_AverageAnnualReturnYear10 0.31%
Putnam VT Mortgage Securities Fund | Class IB C000010838  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.39%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.53% [19]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.17%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.42%) [20]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.75%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 77
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 330
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 603
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,383
1 Year rr_AverageAnnualReturnYear01 (10.07%)
5 Years rr_AverageAnnualReturnYear05 (0.91%)
10 Years rr_AverageAnnualReturnYear10 0.07%
Putnam VT Research Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading Fund summary
Objective [Heading] rr_ObjectiveHeading Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

Putnam VT Research Fund seeks capital appreciation.

Expense [Heading] rr_ExpenseHeading Fees and expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses you may pay if you buy, hold and sell shares of the fund. 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. 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.

Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (expenses you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock

The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or the above example, affect fund performance. The fund’s turnover rate in the most recent fiscal year was 40%.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 40.00%
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

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’s operating expenses remain the same. Your actual costs may be higher or lower.

Strategy [Heading] rr_StrategyHeading Investments, risks, and performance
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Investments

We invest mainly in common stocks (growth or value stocks or both) of large U.S. companies that we believe have favorable investment potential. For example, we may purchase stocks of companies with stock prices that reflect a value lower than that which we place on the company. We may also consider other factors we believe will cause the stock price to rise. We may consider, among other factors, a company’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.

Risk [Heading] rr_RiskHeading Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. The performance information does not reflect insurance-related charges or expenses. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results.



 
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time.
Bar Chart [Heading] rr_BarChartHeading Annual total returns for class IA shares
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads Please remember that past performance is not necessarily an indication of future results.
Year to Date Return, Label rr_YearToDateReturnLabel Year-to-date performance through
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Mar. 31, 2023
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 7.29%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best calendar quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 21.49%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst calendar quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (19.00%)
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (for periods ended 12/31/22)
Putnam VT Research Fund | S&P 500 Index (no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (18.11%)
5 Years rr_AverageAnnualReturnYear05 9.42%
10 Years rr_AverageAnnualReturnYear10 12.56%
Putnam VT Research Fund | Class IA C000010869  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.55%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.20% [21]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.75%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 77
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 240
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 417
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 930
Annual Return 2013 rr_AnnualReturn2013 33.60%
Annual Return 2014 rr_AnnualReturn2014 15.17%
Annual Return 2015 rr_AnnualReturn2015 (1.29%)
Annual Return 2016 rr_AnnualReturn2016 10.32%
Annual Return 2017 rr_AnnualReturn2017 23.70%
Annual Return 2018 rr_AnnualReturn2018 (4.51%)
Annual Return 2019 rr_AnnualReturn2019 33.59%
Annual Return 2020 rr_AnnualReturn2020 20.23%
Annual Return 2021 rr_AnnualReturn2021 24.44%
Annual Return 2022 rr_AnnualReturn2022 (17.07%)
1 Year rr_AverageAnnualReturnYear01 (17.07%)
5 Years rr_AverageAnnualReturnYear05 9.62%
10 Years rr_AverageAnnualReturnYear10 12.62%
Putnam VT Research Fund | Class IB C000010870  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.55%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.20% [21]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.00%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 102
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 318
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 552
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,225
1 Year rr_AverageAnnualReturnYear01 (17.28%)
5 Years rr_AverageAnnualReturnYear05 9.35%
10 Years rr_AverageAnnualReturnYear10 12.34%
Putnam VT Small Cap Growth Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading Fund summary
Objective [Heading] rr_ObjectiveHeading Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

Putnam VT Small Cap Growth Fund seeks capital appreciation.

Expense [Heading] rr_ExpenseHeading Fees and expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses you may pay if you buy, hold and sell shares of the fund. 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. 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.

Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (expenses you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination 4/30/24
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock

The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or the above example, affect fund performance. The fund’s turnover rate in the most recent fiscal year was 58%.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 58.00%
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

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’s operating expenses remain the same. Only the first year of each period in the example takes into account the expense reimbursement described above. Your actual costs may be higher or lower.

Strategy [Heading] rr_StrategyHeading Investments, risks, and performance
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Investments

We invest mainly in common stocks of small U.S. companies, with a focus on growth stocks. Growth stocks are issued by companies whose earnings are expected to grow faster than those of similar firms, and whose business growth and other characteristics may lead to an increase in stock price. Under normal circumstances, we invest at least 80% of the fund’s net assets in companies of a size similar to those in the Russell 2000 Growth Index. This policy may be changed only after 60 days’ notice to shareholders. As of March 31, 2023, the index was composed of companies having market capitalizations of between approximately $6.3 million and $7.9 billion.

We may consider, among other factors, a company’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.

Risk [Heading] rr_RiskHeading Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. Before September 17, 2018, the fund was managed with a materially different investment strategy and may have achieved materially different performance results under its current investment strategy from that shown for periods before this date. The performance information does not reflect insurance-related charges or expenses. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results.

Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Please remember that past performance is not necessarily an indication of future results.
Bar Chart [Heading] rr_BarChartHeading Annual total returns for class IA shares
Year to Date Return, Label rr_YearToDateReturnLabel Year-to-date performance through
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Mar. 31, 2023
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 7.13%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best calendar quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 32.68%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst calendar quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2018
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (20.45%)
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (for periods ended 12/31/22)
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
Frank Russell Company is the source and owner of the trademarks, service marks and copyrights related to the Russell Indexes. Russell ® is a trademark of Frank Russell Company.
Putnam VT Small Cap Growth Fund | Russell 2000 Growth Index (no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (26.36%)
5 Years rr_AverageAnnualReturnYear05 3.51%
10 Years rr_AverageAnnualReturnYear10 9.20%
Putnam VT Small Cap Growth Fund | Class IA C000010861  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.62%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.36% [22]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.98%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.09%) [23]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.89%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 91
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 303
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 533
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,193
Annual Return 2013 rr_AnnualReturn2013 34.33%
Annual Return 2014 rr_AnnualReturn2014 7.36%
Annual Return 2015 rr_AnnualReturn2015 (7.37%)
Annual Return 2016 rr_AnnualReturn2016 15.77%
Annual Return 2017 rr_AnnualReturn2017 8.26%
Annual Return 2018 rr_AnnualReturn2018 (13.64%)
Annual Return 2019 rr_AnnualReturn2019 37.73%
Annual Return 2020 rr_AnnualReturn2020 48.71%
Annual Return 2021 rr_AnnualReturn2021 14.18%
Annual Return 2022 rr_AnnualReturn2022 (28.11%)
1 Year rr_AverageAnnualReturnYear01 (28.11%)
5 Years rr_AverageAnnualReturnYear05 7.74%
10 Years rr_AverageAnnualReturnYear10 9.29%
Putnam VT Small Cap Growth Fund | Class IB C000010862  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.62%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.36% [22]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.23%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.09%) [23]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.14%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 116
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 381
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 667
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,481
1 Year rr_AverageAnnualReturnYear01 (28.30%)
5 Years rr_AverageAnnualReturnYear05 7.48%
10 Years rr_AverageAnnualReturnYear10 9.02%
Putnam VT Small Cap Value Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading Fund summary
Objective [Heading] rr_ObjectiveHeading Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

Putnam VT Small Cap Value Fund seeks capital appreciation.

Expense [Heading] rr_ExpenseHeading Fees and expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses you may pay if you buy, hold and sell shares of the fund. 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. 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.

Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (expenses you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock

The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or the above example, affect fund performance. The fund’s turnover rate in the most recent fiscal year was 79%.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 79.00%
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

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’s operating expenses remain the same. Your actual costs may be higher or lower.

Strategy [Heading] rr_StrategyHeading Investments, risks, and performance
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Investments

We invest mainly in common stocks of small U.S. companies, with a focus on value stocks. Value stocks are issued by companies that we believe are currently undervalued by the market. If we are correct and other investors ultimately recognize the value of the company, the price of its stock may rise. Under normal circumstances, we invest at least 80% of the fund’s net assets in companies of a size similar to those in the Russell 2000 Value Index. This policy may be changed only after 60 days’ notice to shareholders. As of March 31, 2023, the index was composed of companies having market capitalizations of between approximately $6.3 million and $6.8 billion. We may consider, among other factors, a company’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.
Risk [Heading] rr_RiskHeading Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. The performance information does not reflect insurance-related charges or expenses. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results.



 
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Please remember that past performance is not necessarily an indication of future results.
Bar Chart [Heading] rr_BarChartHeading Annual total returns for class IA shares
Year to Date Return, Label rr_YearToDateReturnLabel Year-to-date performance through
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Mar. 31, 2023
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn (1.12%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best calendar quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 34.30%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst calendar quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (40.27%)
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (for periods ended 12/31/22)
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
Frank Russell Company is the source and owner of the trademarks, service marks and copyrights related to the Russell Indexes. Russell ® is a trademark of Frank Russell Company.
Putnam VT Small Cap Value Fund | Russell 2000 Value Index (no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (14.48%)
5 Years rr_AverageAnnualReturnYear05 4.13%
10 Years rr_AverageAnnualReturnYear10 8.48%
Putnam VT Small Cap Value Fund | Class IA C000010871  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.62%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.16% [24]
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets none [24]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.78%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 80
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 249
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 433
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 966
Annual Return 2013 rr_AnnualReturn2013 39.93%
Annual Return 2014 rr_AnnualReturn2014 3.69%
Annual Return 2015 rr_AnnualReturn2015 (3.90%)
Annual Return 2016 rr_AnnualReturn2016 27.70%
Annual Return 2017 rr_AnnualReturn2017 8.15%
Annual Return 2018 rr_AnnualReturn2018 (19.42%)
Annual Return 2019 rr_AnnualReturn2019 24.12%
Annual Return 2020 rr_AnnualReturn2020 4.12%
Annual Return 2021 rr_AnnualReturn2021 40.37%
Annual Return 2022 rr_AnnualReturn2022 (12.80%)
1 Year rr_AverageAnnualReturnYear01 (12.80%)
5 Years rr_AverageAnnualReturnYear05 4.97%
10 Years rr_AverageAnnualReturnYear10 9.39%
Putnam VT Small Cap Value Fund | Class IB C000010872  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.62%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.16% [24]
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets none [24]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.03%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 105
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 328
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 569
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,259
1 Year rr_AverageAnnualReturnYear01 (12.98%)
5 Years rr_AverageAnnualReturnYear05 4.72%
10 Years rr_AverageAnnualReturnYear10 9.12%
Putnam VT Sustainable Future Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading Fund summary
Objective [Heading] rr_ObjectiveHeading Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

Putnam VT Sustainable Future Fund seeks long-term capital appreciation.

Expense [Heading] rr_ExpenseHeading Fees and expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses you may pay if you buy, hold and sell shares of the fund. 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. 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.

Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (expenses you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination 4/30/24
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock

The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or the above example, affect fund performance. The fund’s turnover rate in the most recent fiscal year was 64%.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 64.00%
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

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’s operating expenses remain the same. Your actual costs may be higher or lower.

Strategy [Heading] rr_StrategyHeading Investments, risks, and performance
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Investments

We invest mainly in common stocks of U.S. companies of any size, with a focus on companies whose products and services we believe provide solutions that directly contribute to sustainable social, environmental and economic development (Solutions Companies). Stocks of this type of company are typically, but not always, considered to be growth stocks. Growth stocks are stocks of companies whose revenues, earnings, or cash flows are expected to grow faster than those of similar firms, and whose business growth and other characteristics may lead to an increase in stock price. We may consider, among other factors, a company’s impact on sustainable environmental, social and economic development (as described below), 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. We may also invest in non-U.S. companies.

Our approach to sustainable investing incorporates fundamental research together with consideration of sustainable environmental, social and economic development impact. We believe that companies whose products and services produce positive environmental, social and economic development impact also often demonstrate potential for strong financial growth. Under normal circumstances, the fund invests at least 80% of the value of its net assets in securities that meet our sustainability criteria. These criteria are based on a proprietary sustainability solutions map that links to the United Nations Sustainable Development Goals (SDGs). In applying these criteria, we will assign each company a proprietary environmental, social and/or corporate governance (ESG) rating ranging from 1 to 4 (1 indicating the highest (best) ESG rating and 4 indicating the lowest (worst) ESG rating). In order to meet our sustainability criteria for purposes of this investment policy, a company must be rated 2 or 1 by us. This policy is non-fundamental and may be changed only after 60 days’ notice to shareholders. We may not apply sustainability criteria to investments that are not subject to the fund’s 80% policy, and such investments may not meet Putnam Management’s sustainability criteria. In selecting each investment, we consider the extent to which a company’s products or services may provide solutions to forward-looking sustainability needs, creating positive impact in environmental, social and economic development areas. Environmental impacts may include, for example, reduction of carbon emissions and improved water quality. Social impacts may include, for example, improvements in employee well-being, supplier standards, or access to products, information, or security. Economic development impacts may include, for example, stakeholder analysis and shared value approaches to business practices, access to economic opportunity, or improvements in operational effectiveness or efficiency.



 
Risk [Heading] rr_RiskHeading Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. Before April 30, 2018, the fund was managed with a materially different investment strategy and may have achieved materially different performance results under its current investment strategy from that shown for periods before this date. The performance information does not reflect insurance-related charges or expenses. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results.

Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Please remember that past performance is not necessarily an indication of future results.
Bar Chart [Heading] rr_BarChartHeading Annual total returns for class IA shares
Year to Date Return, Label rr_YearToDateReturnLabel Year-to-date performance through
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Mar. 31, 2023
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 8.69%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best calendar quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 33.72%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst calendar quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (21.47%)
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (for periods ended 12/31/22)
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
Frank Russell Company is the source and owner of the trademarks, service marks and copyrights related to the Russell Indexes. Russell® is a trademark of Frank Russell Company.
The Putnam VT Sustainable Future Linked Benchmark represents the performance of the Russell 3000® Value Index through April 29, 2018, and the performance of the Russell Midcap® Growth Index thereafter.
Putnam VT Sustainable Future Fund | Russell MidCap Growth Index (no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (26.72%)
5 Years rr_AverageAnnualReturnYear05 7.64%
10 Years rr_AverageAnnualReturnYear10 11.41%
Putnam VT Sustainable Future Fund | Putnam VT Sustainable Future Linked Benchmark (no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (26.72%)
5 Years rr_AverageAnnualReturnYear05 6.91%
10 Years rr_AverageAnnualReturnYear10 10.37%
Putnam VT Sustainable Future Fund | Class IA C000010857  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.55%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.35% [25]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.90%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.08%) [26]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.82%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 84
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 279
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 491
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,100
Annual Return 2013 rr_AnnualReturn2013 42.43%
Annual Return 2014 rr_AnnualReturn2014 11.08%
Annual Return 2015 rr_AnnualReturn2015 (4.06%)
Annual Return 2016 rr_AnnualReturn2016 13.23%
Annual Return 2017 rr_AnnualReturn2017 10.94%
Annual Return 2018 rr_AnnualReturn2018 (4.64%)
Annual Return 2019 rr_AnnualReturn2019 30.32%
Annual Return 2020 rr_AnnualReturn2020 52.99%
Annual Return 2021 rr_AnnualReturn2021 6.33%
Annual Return 2022 rr_AnnualReturn2022 (33.85%)
1 Year rr_AverageAnnualReturnYear01 (33.85%)
5 Years rr_AverageAnnualReturnYear05 5.98%
10 Years rr_AverageAnnualReturnYear10 9.81%
Putnam VT Sustainable Future Fund | Class IB C000010858  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.55%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.35% [25]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.15%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.08%) [26]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.07%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 109
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 357
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 625
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,390
1 Year rr_AverageAnnualReturnYear01 (34.03%)
5 Years rr_AverageAnnualReturnYear05 5.71%
10 Years rr_AverageAnnualReturnYear10 9.53%
Putnam VT Sustainable Leaders Fund  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading Fund summary
Objective [Heading] rr_ObjectiveHeading Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

Putnam VT Sustainable Leaders Fund seeks long-term capital appreciation.

Expense [Heading] rr_ExpenseHeading Fees and expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses you may pay if you buy, hold and sell shares of the fund. 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. 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.

Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (expenses you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock

The fund pays transaction-related costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or the above example, affect fund performance. The fund’s turnover rate in the most recent fiscal year was 35%.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 35.00%
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

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’s operating expenses remain the same. Your actual costs may be higher or lower.

Strategy [Heading] rr_StrategyHeading Investments, risks, and performance
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Investments

We invest mainly in common stocks of U.S. companies of any size, with a focus on companies that we believe exhibit a commitment to financially material sustainable business practices. In evaluating investments for the fund, we view “financially material sustainable business practices” as business practices that we believe are reasonably likely to impact the financial condition or operating performance of a company and that relate to environmental, social, or corporate governance issues. We identify relevant environmental, social, or corporate governance issues on a sector-specific basis using an internally developed materiality map, which is informed by the sustainability issues identified by the Sustainability Accounting Standards Board as material to companies within a particular industry. A materiality map provides a guide to understanding which ESG criteria are more or less important for a given sector or subsector; it includes those ESG criteria that may be reasonably likely to influence investment decision-making. We construct the materiality map by evaluating the significance of specified ESG criteria (i.e., board structure and composition, diversity, equity and inclusion, or climate change risk, among others) in specific industries (i.e., consumer, healthcare, financials, etc.), subsectors, or countries. We then categorize the relevance of these ESG criteria for each industry , subsector, or country. As part of this analysis, we may utilize metrics and information such as emissions data, carbon intensity, sources of energy used for operations, water use and re-use, water generation, waste diversion from landfill, employee safety and diversity data, supplier audits, product safety, board composition, and incentive compensation structures. Stocks of companies that exhibit a commitment to financially material sustainable business practices are typically, but not always, considered to be growth stocks. Growth stocks are stocks of companies whose revenues, earnings, or cash flows are expected to grow faster than those of similar firms, and whose business growth and other characteristics may lead to an increase in stock price. We may consider, among other factors, a company’s sustainable business practices (as described above), 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. We may also invest in non-U.S. companies.

Under normal circumstances, the fund invests at least 80% of the value of its net assets in securities that meet our sustainability criteria. These criteria are based on the proprietary materiality map described above. In applying these criteria, we will assign each company a proprietary environmental, social and/or corporate governance (ESG) rating ranging from 1 to 4 (1 indicating the highest (best) ESG rating and 4 indicating the lowest (worst) ESG rating). In order to meet our sustainability criteria for purposes of this investment policy, a company must be rated 2 or 1 by us. This policy is non-fundamental and may be changed only after 60 days’ notice to shareholders. We may not apply sustainability criteria to investments that are not subject to the fund’s 80% policy, and such investments may not meet Putnam Management’s sustainability criteria. In selecting each investment, we focus on companies that have a demonstrated commitment to sustainable business practices in areas that are relevant and material to their long-term financial returns and risk profiles. We believe that companies that have exhibited such a commitment



 



also often demonstrate potential for strong financial growth. This commitment may be reflected through ESG policies, practices, or outcomes. The fund’s approach to sustainable investing incorporates fundamental research together with consideration of ESG factors. Environmental factors include, for example, a company’s carbon intensity and use of resources like water or minerals. Sustainability measures in this area might include plans to reduce waste, increase recycling, raise the proportion of energy supply from renewable sources, or improve product design to be less resource intensive. Social factors include, for example, labor practices and supply chain management. Sustainability measures in this area might include programs to improve employee well-being, commitment to workplace equality and diversity, or improved stewardship of supplier relationships and working conditions. Corporate governance factors include, for example, board composition and executive compensation. Sustainability measures in this area might include improvements in board independence or diversity, or alignment of management incentives with the company’s strategic sustainability objectives. Our integrated approach combines analysis of the growing body of ESG data and deep fundamental analysis and looks for companies that demonstrate leadership, beyond compliance, on relevant sustainability issues. The characteristics that we may use when considering sustainability leadership include:

(1) Materiality. The company is focused on sustainability issues that are relevant to long term business success.

(2) Creativity and proactiveness. The company’s sustainability characteristics go beyond compliance to demonstrate heightened commitment.

(3) Transparency. The company’s goals are specific, with candid and consistent progress reporting.

(4) Impact. The sustainability characteristics create benefits that are meaningful both at the company and more broadly.

Risk [Heading] rr_RiskHeading Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time. Before April 30, 2018, the fund was managed with a materially different investment strategy and may have achieved materially different performance results under its current investment strategy from that shown for periods before this date. The performance information does not reflect insurance-related charges or expenses. If it did, performance would be lower. Please remember that past performance is not necessarily an indication of future results.

Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information below gives some indication of the risks associated with an investment in the fund by showing the fund’s performance year to year and over time.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Please remember that past performance is not necessarily an indication of future results.
Bar Chart [Heading] rr_BarChartHeading Annual total returns for class IA shares
Year to Date Return, Label rr_YearToDateReturnLabel Year-to-date performance through
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Mar. 31, 2023
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 6.40%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best calendar quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 24.12%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst calendar quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (17.79%)
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (for periods ended 12/31/22)
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
The Putnam VT Sustainable Leaders Linked Benchmark represents the performance of the Russell 3000® Growth Index through August 31, 2019, and the performance of the S&P 500® Index thereafter.
Frank Russell Company is the source and owner of the trademarks, service marks and copyrights related to the Russell Indexes. Russell® is a trademark of Frank Russell Company.
Putnam VT Sustainable Leaders Fund | S&P 500 Index (no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (18.11%)
5 Years rr_AverageAnnualReturnYear05 9.42%
10 Years rr_AverageAnnualReturnYear10 12.56%
Putnam VT Sustainable Leaders Fund | Putnam VT Sustainable Leaders Linked Benchmark  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 (18.11%)
5 Years rr_AverageAnnualReturnYear05 10.76%
10 Years rr_AverageAnnualReturnYear10 13.91%
Putnam VT Sustainable Leaders Fund | Class IA C000010863  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.55%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.11%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.66%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 67
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 211
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 368
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 822
Annual Return 2013 rr_AnnualReturn2013 36.74%
Annual Return 2014 rr_AnnualReturn2014 13.80%
Annual Return 2015 rr_AnnualReturn2015 (0.07%)
Annual Return 2016 rr_AnnualReturn2016 8.06%
Annual Return 2017 rr_AnnualReturn2017 29.55%
Annual Return 2018 rr_AnnualReturn2018 (1.28%)
Annual Return 2019 rr_AnnualReturn2019 36.72%
Annual Return 2020 rr_AnnualReturn2020 29.04%
Annual Return 2021 rr_AnnualReturn2021 23.87%
Annual Return 2022 rr_AnnualReturn2022 (22.72%)
1 Year rr_AverageAnnualReturnYear01 (22.72%)
5 Years rr_AverageAnnualReturnYear05 10.76%
10 Years rr_AverageAnnualReturnYear10 13.76%
Putnam VT Sustainable Leaders Fund | Class IB C000010864  
Prospectus [Line Items] rr_ProspectusLineItems  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.55%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.11%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.91%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 93
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 290
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 504
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,120
1 Year rr_AverageAnnualReturnYear01 (22.91%)
5 Years rr_AverageAnnualReturnYear05 10.48%
10 Years rr_AverageAnnualReturnYear10 13.48%
[1] Frank Russell Company is the source and owner of the trademarks, service marks and copyrights related to the Russell Indexes. Russell ® is a trademark of Frank Russell Company.
[2] Restated to reflect current fees.
[3] Restated to reflect current fees.
[4] Reflects Putnam Investment Management, LLC’s contractual obligation to limit certain fund expenses through 4/30/24. This obligation may be modified or discontinued only with approval of the fund’s Board of Trustees.
[5] Restated to reflect current fees.
[6] Reflects Putnam Investment Management, LLC’s contractual obligation to limit certain fund expenses through 4/30/24. This obligation may be modified or discontinued only with approval of the fund’s Board of Trustees.
[7] Restated to reflect current fees.
[8] Reflects Putnam Investment Management, LLC’s contractual obligation to limit certain fund expenses through 4/30/24. This obligation may be modified or discontinued only with approval of the fund’s Board of Trustees.
[9] Restated to reflect current fees.
[10] Restated to reflect current fees.
[11] Reflects Putnam Investment Management, LLC’s contractual obligation to limit certain fund expenses through 4/30/24. This obligation may be modified or discontinued only with approval of the fund’s Board of Trustees.
[12] Restated to reflect current fees.
[13] Restated to reflect current fees.
[14] Restated to reflect current fees.
[15] Restated to reflect current fees.
[16] Restated to reflect current fees.
[17] Restated to reflect current fees.
[18] Frank Russell Company is the source and owner of the trademarks, service marks and copyrights related to the Russell Indexes. Russell® is a trademark of Frank Russell Company.
[19] Restated to reflect current fees.
[20] Reflects Putnam Investment Management, LLC’s contractual obligation to limit certain fund expenses through 4/30/24. This obligation may be modified or discontinued only with approval of the fund’s Board of Trustees.
[21] Restated to reflect current fees.
[22] Restated to reflect current fees.
[23] Reflects Putnam Investment Management, LLC’s contractual obligation to limit certain fund expenses through 4/30/24. This obligation may be modified or discontinued only with approval of the fund’s Board of Trustees.
[24] Restated to reflect current fees.
[25] Restated to reflect current fees.
[26] Reflects Putnam Investment Management, LLC’s contractual obligation to limit certain fund expenses through 4/30/24. This obligation may be modified or discontinued only with approval of the fund’s Board of Trustees.