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Risk Return Abstract rr_RiskReturnAbstract  
Registrant Name dei_EntityRegistrantName JOHN HANCOCK VARIABLE INSURANCE TRUST
Prospectus Date rr_ProspectusDate Apr. 28, 2025
Managed Volatility Balanced Portfolio  
Risk Return Abstract rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading <span style="color:#000000;font-family:Arial Narrow;font-size:24pt;">Managed Volatility Balanced Portfolio</span>
Objective [Heading] rr_ObjectiveHeading <span style="color:#000000;font-family:Arial Narrow;font-size:10pt;font-weight:bold;">Investment objective</span>
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock To seek growth of capital and current income while seeking to both manage the volatility of return and limit the magnitude of portfolio losses.
Expense [Heading] rr_ExpenseHeading <span style="color:#000000;font-family:Arial Narrow;font-size:10pt;font-weight:bold;">Fees and expenses</span>
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the fund. The fees and expenses do not reflect fees and expenses of any variable insurance or variable annuities contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption <span style="font-family:Arial Narrow;font-size:8pt;font-weight:bold;margin-left:0.0pt;">Annual fund operating expenses (%) </span><span style="font-family:Arial Narrow;font-size:8pt;margin-left:0.0pt;">(expenses that you pay each year as a percentage of the value of your investment)</span>
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading <span style="color:#000000;font-family:Arial Narrow;font-size:10pt;font-weight:bold;">Portfolio turnover</span>
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock The fund, which operates as a fund of funds and invests in underlying funds, does not pay transaction costs, such as commissions, when it buys and sells shares of underlying funds (or “turns over” its portfolio). An underlying fund does pay transaction costs when it turns over its portfolio, and a higher portfolio turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or in the example, affect the performance of the underlying funds and of the fund. During its most recent fiscal year, the fund’s portfolio turnover rate was 6% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 6.00%
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees <span style="color:#000000;font-family:Arial Narrow;font-size:8pt;">The “Total annual fund operating expenses” shown may not correlate to the fund’s ratios of expenses to average daily net assets shown in the “Financial highlights” section of the fund’s prospectus, which does not include “Acquired fund fees and expenses.”</span>
Expense Example [Heading] rr_ExpenseExampleHeading <span style="color:#000000;font-family:Arial Narrow;font-size:10pt;font-weight:bold;">Expense example</span>
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock The examples are intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The examples assume that $10,000 is invested in the fund for the periods indicated and then all shares are redeemed at the end of those periods. The examples also assume that the investment has a 5% return each year and that the fund’s operating expenses remain the same. The expense example does not reflect fees and expenses of any variable insurance contract that may use the fund as its underlying investment option and would be higher if they did. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading <span style="color:#000000;font-family:Arial Narrow;font-size:10pt;font-weight:bold;">Principal investment strategies</span>
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock The Managed Volatility Balanced Portfolio, except as otherwise described below, normally invests primarily in underlying funds that invest primarily in equity securities (“Equity Funds”) and underlying funds that invest primarily in fixed-income securities (“Fixed-Income Funds”). The fund may also use certain risk management techniques to seek to manage the volatility of returns (i.e. standard deviation) and limit the magnitude of portfolio losses. As described below, the fund may directly hold derivative instruments and collateral for these derivative instruments. The fund’s economic exposure to equities and fixed-income securities may fluctuate due to its risk management strategy as noted below. The fund may employ a risk management strategy to attempt to manage the volatility of returns and limit the magnitude of portfolio losses. The risk management strategy may cause the fund’s economic exposure to equity securities, fixed-income securities and cash and cash equivalents (either directly or through investment in underlying funds or derivatives) to fluctuate, and during extreme market volatility, the fund’s economic exposure to either equity or fixed-income securities could be reduced to 0% and its economic exposure to cash and cash equivalents could increase to 100%. The subadvisor normally will seek to limit the fund’s exposure to equity securities (either directly or through investment in underlying funds or derivatives) to no more than 55% and normally will seek to reduce any equity exposure in excess of this amount as soon as practicable. However, the subadvisor may determine in light of market or economic conditions that the limit should be exceeded to achieve the fund’s investment objective. The fund seeks long term growth of capital while attempting to manage the volatility of returns and limit the magnitude of portfolio losses. The fund seeks to limit the volatility of returns to a range of 8.25% to 10.25% (as measured by annualized standard deviation of the fund’s returns). However, during periods of prolonged low market volatility the actual volatility experienced by the fund may fall below the range due to maximum limits on equity and fixed-income exposures. Volatility is a measure of the magnitude of up and down fluctuations in the fund’s NAV over time as measured by the annualized standard deviation of its returns. Higher volatility generally indicates higher risk. The more a fund’s returns vary from the fund’s average return, the more volatile the fund and the higher the standard deviation. The purpose of managing the volatility of returns is to attempt to limit exposure to more volatile asset classes, including both equities and fixed-income asset classes, during periods of high volatility and protect the fund from losses during market declines. The fund also seeks to limit the magnitude of portfolio losses in order to limit exposure during market declines. There can be no assurance that the risk management strategy will be successful in managing the volatility of returns and limiting the magnitude of portfolio losses. In seeking to manage the volatility of returns and limit the magnitude of portfolio losses, the fund may employ certain risk management techniques using derivative instruments and may reallocate assets between the underlying Equity and Fixed-Income Funds. These derivatives may be used to increase or decrease the fund’s net equity exposure and will typically consist of stock index futures, but may also include stock index options, options on stock index futures, and stock index swaps. The fund may also employ risk management techniques using derivatives that may increase or decrease the fund’s exposure to certain types of fixed-income securities. These instruments may include government bond futures, swaps, and credit default swaps. For more information about these derivative instruments in which the fund may invest, please see the “Hedging And Other Strategic Transactions” risk section in the Statement of Additional Information. Fund assets employed for its risk management strategy include not only derivative instruments but also fixed-income instruments. Because equity and fixed-income derivative instruments may be purchased with a fraction of the assets that would be needed to purchase the securities directly, the remainder of the assets used for the risk management strategy will be invested in a variety of fixed-income instruments. The fund may be required to hold cash or other liquid assets and post these assets with a broker as collateral to cover its obligation under the futures contracts. The fund’s risk management strategy could limit the upside participation of the fund in strong, rising markets with high volatility and could underperform funds that do not use a risk management strategy. The use of derivatives may be combined with asset allocation techniques. The timing and extent of these techniques will depend on several factors, including market movements. In general, when equity markets are more volatile or are declining, assets may be reallocated to Fixed-Income Funds, cash and/or cash equivalents, and short positions in equity derivative instruments. When equity markets rise, or if volatility is lower, assets may be reallocated to Equity Funds and stock index futures, options, and swaps. Similarly, if fixed-income markets are volatile or are declining, assets may be reallocated to Equity Funds, cash and cash equivalents, and short positions in fixed-income derivative instruments. Even in periods of low volatility, the subadvisor may continue to use risk management techniques to protect against sudden market movements, preserve gains after favorable market conditions, and reduce losses in adverse market conditions. Due to the leverage provided by derivatives, the notional value of the fund’s derivative positions could exceed 100% of the fund’s assets. In determining when to employ risk management techniques and/or reallocate assets between Equity Funds and Fixed-Income Funds, the subadvisor may use quantitative models that use historical factors such as market movements, and historical changes in the NAV of the fund to make this determination. The subadvisor selects the percentage level to be maintained in specific underlying Equity Funds and Fixed-Income Funds, and cash and cash equivalents and may from time to time change the allocation in specific underlying funds or rebalance the underlying funds. From time to time, a significant portion of the fund’s underlying fixed income assets may be managed by an affiliated subadvisor. To maintain a target allocation in the underlying funds, daily cash flows for the fund may be directed to its underlying funds that most deviate from target. The fund may invest in various Equity Funds that as a group hold a wide range of equity type securities. These include small-, mid- and large-capitalization stocks, domestic and foreign securities (including emerging market securities), and sector holdings such as utilities, science, and technology stocks. Each of these Equity Funds has its own investment strategy which, for example, may focus on growth stocks or value stocks or may employ a strategy combining growth and income stocks and/or may invest in derivatives such as options on securities and futures contracts. The fund may also invest in Fixed-Income Funds that as a group hold a wide range of fixed-income securities including investment grade and below-investment-grade debt securities with maturities that range from short to longer term. The Fixed-Income Funds collectively hold various types of debt instruments, such as corporate bonds and mortgage backed, government issued, domestic and international securities. Equity Funds and Fixed-Income Funds may include funds that employ a passive investment style (i.e., index funds and exchange-traded funds (ETFs)) and at times most of the fund’s assets may be invested in index funds. The fund may also invest in the securities of other investment companies including ETFs and may invest directly in other types of investments, such as equity and fixed-income securities including U.S. government securities, closed-end funds, exchange-traded notes, and partnerships. See “Other Permitted Investments by the Funds of Funds.” The fund may also engage in short selling. The fund may engage in active and frequent trading of portfolio securities and other instruments to achieve its primary investment strategies. The fund bears its own expenses and, in addition, indirectly bears its proportionate share of the expenses of the underlying funds in which it invests. Use of Risk Management and Other Strategic Transactions. In addition to the risk management techniques described above, the fund is authorized to use other investment strategies referred to under “Hedging And Other Strategic Transactions” risk section including, without limitation, investing in foreign currency forward contracts, futures contracts including stock index and foreign currency futures, swaps including interest rate swaps, stock index swaps and credit default swaps and options including stock index options and options on stock index futures, among others. The manager considers environmental, social, and/or governance (ESG) factors, alongside other relevant factors, as part of its investment process. ESG factors may include, but are not limited to, matters regarding board diversity, climate change policies, and supply chain and human rights policies. The ESG characteristics utilized in the fund’s investment process may change over time and one or more characteristics may not be relevant with respect to all issuers that are eligible fund investments. Because ESG factors are considered alongside other relevant factors, the manager may determine that an investment is appropriate notwithstanding its relative ESG characteristics.
Risk [Heading] rr_RiskHeading <span style="color:#000000;font-family:Arial Narrow;font-size:10pt;font-weight:bold;">Principal risks</span>
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading <span style="color:#000000;font-family:Arial Narrow;font-size:10pt;font-weight:bold;">Past performance</span>
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock The following information illustrates the variability of the fund’s returns and provides some indication of the risks of investing in the fund by showing changes in the fund’s performance from year to year and by showing how the fund’s average annual returns compared with a broad-based securities market index.Past performance does not indicate future results. The Morningstar U.S. Moderate Target Allocation Index and 35% Russell 3000 Index/15% MSCI EAFE Index/50% Bloomberg U.S. Aggregate Bond Index show how the fund’s performance compares against the returns of similar investments. All figures assume dividend reinvestment. The performance information below does not reflect fees and expenses of any variable insurance contract which may use JHVIT as its underlying investment option. If such fees and expenses had been reflected, performance would be lower.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns <span style="font-family:Arial Narrow;font-size:9pt;">The following information illustrates the variability of the fund’s returns and provides some indication of the risks of investing in the fund by showing changes in the fund’s performance from year to year and by showing how the fund’s average annual returns compared with a broad-based securities market index.</span>
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture <span style="font-family:Arial Narrow;font-size:9pt;">Past performance does not indicate future results.</span>
Bar Chart [Heading] rr_BarChartHeading <span style="font-family:Arial Narrow;font-size:9pt;font-weight:bold;">Calendar year total returns (%)—Series I</span>
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock Best quarter:Q4 20239.47%Worst quarter:Q1 2020-13.22%
Performance Table Heading rr_PerformanceTableHeading <span style="font-family:Arial Narrow;font-size:8pt;font-weight:bold;margin-left:0.0pt;">Average annual total returns (%)—as of 12/31/2024</span>
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged <span style="font-family:Arial Narrow;font-size:8pt;">The fund has designated the S&P 500 Index as its new broad-based securities market index in accordance with the revised definition for such an index.</span>
Managed Volatility Balanced Portfolio | Risk Lose Money [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Many factors affect performance, and fund shares will fluctuate in price, meaning you could lose money.
Managed Volatility Balanced Portfolio | Risk Not Insured Depository Institution [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Managed Volatility Balanced Portfolio | Affiliated Insurance Companies [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Affiliated insurance companies risk. The advisor may be influenced by the benefits to its affiliated life insurance companies in managing the fund and overseeing its subadvisors. The John Hancock insurance companies issuing guaranteed benefits on variable annuity and insurance contracts investing in the fund have a financial interest in preserving the value of the funds and reducing their volatility due to their obligations for these guaranteed benefits (the cost of providing these guaranteed benefits is related to several factors including the performance and volatility of the fund). To the extent the fund is successful in managing the volatility of returns and downside risk, the John Hancock insurance companies issuing guaranteed benefits on variable annuity and insurance contracts investing in the fund will also benefit from a reduction in their potential investment risk which will reduce their costs of hedging this risk and may reduce their reserve and capital requirements. These financial benefits to the John Hancock insurance companies may be material. The fund and the fund’s investment advisor have adopted procedures that are intended to address these conflicts and ensure that the fund is managed in accordance with its disclosed investment objectives and strategies.
Managed Volatility Balanced Portfolio | Asset Allocation Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Asset allocation risk. Although allocation among asset categories generally limits exposure to any one category, the management team may favor a category that performs poorly relative to the others.
Managed Volatility Balanced Portfolio | Cash And Cash Equivalents Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Cash and cash equivalents risk. Under certain market conditions, such as during a rising stock market, rising interest rate or rising credit spread markets, the use of cash and/or cash equivalents, including money market instruments, could have a negative effect on the fund’s ability to achieve its investment objective and may negatively impact the fund’s performance.
Managed Volatility Balanced Portfolio | Cash Collateral Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Cash collateral risk. Subject to the requirements of Rule 18f-4, to the extent a fund maintains cash collateral required to cover its obligations, such collateral holdings may have the effect of reducing overall portfolio returns. In addition, because such collateral positions cannot be eliminated or reduced unless the corresponding derivative obligation is eliminated or reduced, a large derivative position may materially limit the subadvisor’s flexibility in managing the fund.
Managed Volatility Balanced Portfolio | Commodity Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Commodity risk. Commodity prices may be volatile due to fluctuating demand, supply disruption, speculation, and other factors. Certain commodity investments may have no active trading market at times.
Managed Volatility Balanced Portfolio | Credit And Counterparty Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Credit and counterparty risk. The issuer or guarantor of a fixed-income security, the counterparty to an over-the-counter derivatives contract, or a borrower of fund securities may not make timely payments or otherwise honor its obligations. U.S. government securities are subject to varying degrees of credit risk depending upon the nature of their support. A downgrade or default affecting any of the fund’s securities could affect the fund’s performance.Credit and counterparty risk. The issuer or guarantor of a fixed-income security, the counterparty to an over-the-counter derivatives contract, or a borrower of fund securities may not make timely payments or otherwise honor its obligations. U.S. government securities are subject to varying degrees of credit risk depending upon the nature of their support. A downgrade or default affecting any of the fund’s securities could affect the fund’s performance.
Managed Volatility Balanced Portfolio | Economic And Market Events Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Economic and market events risk. Events in the U.S. and global financial markets, including actions taken by the U.S. Federal Reserve or foreign central banks to stimulate or stabilize economic growth, may at times result in unusually high market volatility, which could negatively impact performance. Reduced liquidity in credit and fixed-income markets could adversely affect issuers worldwide. Banks and financial services companies could suffer losses if interest rates rise or economic conditions deteriorate.Economic and market events risk. Events in the U.S. and global financial markets, including actions taken by the U.S. Federal Reserve or foreign central banks to stimulate or stabilize economic growth, may at times result in unusually high market volatility, which could negatively impact performance. Reduced liquidity in credit and fixed-income markets could adversely affect issuers worldwide. Banks and financial services companies could suffer losses if interest rates rise or economic conditions deteriorate.
Managed Volatility Balanced Portfolio | Equity Securities Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions.Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions. Growth company securities may fluctuate more in price than other securities because of the greater emphasis on earnings expectations. Securities the manager believes are undervalued may never realize their full potential value, and in certain markets value stocks may underperform the market as a whole.
Managed Volatility Balanced Portfolio | ESG Integration Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock ESG integration risk. The manager considers ESG factors that it deems relevant or additive, along with other material factors and analysis, when managing the fund. ESG factors may include, but are not limited to, matters regarding board diversity, climate change policies, and supply chain and human rights policies. The manager may consider these ESG factors on all or a meaningful portion of the fund’s investments. Incorporating ESG criteria and making investment decisions based on certain ESG characteristics, as determined by the manager, carries the risk that the fund may perform differently, including underperforming, funds that do not utilize ESG criteria, or funds that utilize different ESG criteria.
Managed Volatility Balanced Portfolio | Exchange Traded Funds Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Exchange-traded funds (ETFs) risk. The risks of owning shares of an ETF include the risks of owning the underlying securities the ETF holds. Lack of liquidity in an ETF could result in the ETF being more volatile than its underlying securities. An ETF’s shares could trade at a significant premium or discount to its net asset value (NAV). A fund bears ETF fees and expenses indirectly.Exchange-traded funds (ETFs) risk. The risks of owning shares of an ETF include the risks of owning the underlying securities the ETF holds. Lack of liquidity in an ETF could result in the ETF being more volatile than its underlying securities. An ETF’s shares could trade at a significant premium or discount to its net asset value (NAV). A fund bears ETF fees and expenses indirectly.
Managed Volatility Balanced Portfolio | Exchange Traded Notes ETNs Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Exchange-traded notes (ETNs) risk. An ETN generally reflects the risks associated with the assets composing the underlying market benchmark or strategy it is designed to track. ETNs also are subject to issuer and fixed-income risks.
Managed Volatility Balanced Portfolio | Fixed Income Securities Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Fixed-income securities risk. A rise in interest rates typically causes bond prices to fall. The longer the average maturity or duration of the bonds held by a fund, the more sensitive it will likely be to interest-rate fluctuations. An issuer may not make all interest payments or repay all or any of the principal borrowed. Changes in a security’s credit quality may adversely affect fund performance.Fixed-income securities risk. A rise in interest rates typically causes bond prices to fall. The longer the average maturity or duration of the bonds held by a fund, the more sensitive it will likely be to interest-rate fluctuations. An issuer may not make all interest payments or repay all or any of the principal borrowed. Changes in a security’s credit quality may adversely affect fund performance.
Managed Volatility Balanced Portfolio | Fund Of Funds Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Fund of funds risk. The fund’s ability to achieve its investment objective will depend largely, in part, on: (i) the underlying funds’ performance, expenses and ability to meet their investment objectives; and (ii) properly rebalancing assets among underlying funds and different asset classes. The fund is also subject to risks related to: (i) layering of fees of the underlying funds; and (ii) conflicts of interest associated with the subadvisor’s ability to allocate fund assets without limit to other funds it advises and/or other funds advised by affiliated subadvisors. There is no assurance that either the fund or the underlying funds will achieve their investment objectives. A fund bears underlying fund fees and expenses indirectly.
Managed Volatility Balanced Portfolio | Hedging Derivatives And Other Strategic Transactions Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Hedging, derivatives, and other strategic transactions risk. Hedging, derivatives, and other strategic transactions may increase a fund’s volatility and could produce disproportionate losses, potentially more than the fund’s principal investment. Risks of these transactions are different from and possibly greater than risks of investing directly in securities and other traditional instruments. Under certain market conditions, derivatives could become harder to value or sell and may become subject to liquidity risk (i.e., the inability to enter into closing transactions). Derivatives and other strategic transactions that a fund intends to utilize include: credit default swaps, foreign currency forward contracts, futures contracts, interest-rate swaps, options, and swaps. Foreign currency forward contracts, futures contracts, options, and swaps generally are subject to counterparty risk. In addition, swaps may be subject to interest-rate and settlement risk, and the risk of default of the underlying reference obligation. Derivatives associated with foreign currency transactions are subject to currency risk.Hedging, derivatives, and other strategic transactions risk. Hedging, derivatives, and other strategic transactions may increase a fund’s volatility and could produce disproportionate losses, potentially more than the fund’s principal investment. Risks of these transactions are different from and possibly greater than risks of investing directly in securities and other traditional instruments. Under certain market conditions, derivatives could become harder to value or sell and may become subject to liquidity risk (i.e., the inability to enter into closing transactions). Derivatives and other strategic transactions that a fund intends to utilize include: credit default swaps, foreign currency forward contracts, futures contracts, interest-rate swaps, and options. Foreign currency forward contracts, futures contracts, options, and swaps generally are subject to counterparty risk. In addition, swaps may be subject to interest-rate and settlement risk, and the risk of default of the underlying reference obligation. Derivatives associated with foreign currency transactions are subject to currency risk.
Managed Volatility Balanced Portfolio | Hedging Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Hedging risk. There may be imperfect or even negative correlation between the price of the futures contracts and the price of the underlying securities. For example, futures contracts may not provide an effective hedge because changes in futures contract prices may not track those of the underlying securities or indexes they are intended to hedge. In addition, there are significant differences between the securities and futures markets that could result in an imperfect correlation between the markets, causing a given hedge not to achieve its objectives. The degree of imperfection of correlation depends on circumstances such as variations in speculative market demand for futures, including technical influences in futures trading, and differences between the financial instruments being hedged and the instruments underlying the standard contracts available for trading. A decision as to whether, when and how to hedge involves the exercise of skill and judgment, and even a well-conceived hedge may be unsuccessful to some degree because of market behavior or unexpected interest rate trends. In addition, the fund’s investment in exchange-traded futures as a result of the risk management strategy could limit the upside participation of the fund in strong, rising markets with high volatility and could cause the fund to underperform funds that do not use a risk management strategy.
Managed Volatility Balanced Portfolio | High Portfolio Turnover Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock High portfolio turnover risk. Trading securities actively and frequently can increase transaction costs (thus lowering performance) and taxable distributions.
Managed Volatility Balanced Portfolio | Investment Company Securities Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Investment company securities risk. Fund shareholders indirectly bear their proportionate share of the expenses of any investment company in which the fund invests. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
Managed Volatility Balanced Portfolio | Leveraging Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Leveraging risk. Using derivatives may result in a leveraged portfolio. Leveraging long exposures increases a fund’s losses when the value of its investments declines. Some derivatives have the potential for unlimited loss, regardless of the size of the initial investment.
Managed Volatility Balanced Portfolio | Liquidity Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Liquidity risk. The extent (if at all) to which a security may be sold or a derivative position closed without negatively impacting its market value may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments. Liquidity risk may be magnified in rising interest rate environments due to higher than normal redemption rates. Widespread selling of fixed-income securities to satisfy redemptions during periods of reduced demand may adversely impact the price or salability of such securities. Periods of heavy redemption could cause the fund to sell assets at a loss or depressed value, which could negatively affect performance. Redemption risk is heightened during periods of declining or illiquid markets.Liquidity risk. The extent (if at all) to which a security may be sold or a derivative position closed without negatively impacting its market value may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments. Liquidity risk may be magnified in rising interest rate environments due to higher than normal redemption rates. Widespread selling of fixed-income securities to satisfy redemptions during periods of reduced demand may adversely impact the price or salability of such securities. Periods of heavy redemption could cause the fund to sell assets at a loss or depressed value, which could negatively affect performance. Redemption risk is heightened during periods of declining or illiquid markets.
Managed Volatility Balanced Portfolio | Master Limited Partnership Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Master limited partnership (MLP) risk. MLPs generally reflect the risks associated with their underlying assets and with pooled investment vehicles. MLPs with credit-related holdings are subject to interest-rate risk and risk of default.
Managed Volatility Balanced Portfolio | Operational And Cybersecurity Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Operational and cybersecurity risk. Cybersecurity breaches may allow an unauthorized party to gain access to fund assets, customer data, or proprietary information, or cause a fund or its service providers to suffer data corruption or lose operational functionality. Similar incidents affecting issuers of a fund’s securities may negatively impact performance. Operational risk may arise from human error, error by third parties, communication errors, or technology failures, among other causes.Operational and cybersecurity risk. Cybersecurity breaches may allow an unauthorized party to gain access to fund assets, customer data, or proprietary information, or cause a fund or its service providers to suffer data corruption or lose operational functionality. Similar incidents affecting issuers of a fund’s securities may negatively impact performance. Operational risk may arise from human error, error by third parties, communication errors, or technology failures, among other causes.
Managed Volatility Balanced Portfolio | Quantitative Models May Not Produce The Desired Results [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Quantitative models may not produce the desired results. In determining when to employ risk management techniques and/or reallocate exposure among equity, fixed-income and cash, the subadvisor uses quantitative models that use historical market data. However, future market conditions may not be consistent with historical periods, and the historical data may not, therefore, prove to be an accurate predictor of future volatility or losses. The model also may not measure or analyze such data effectively. Thus, the quantitative model may not produce the desired results and may not accurately forecast either future volatility or future large market declines, and this would affect the ability of a fund to be successful in managing the volatility of returns and limiting the magnitude of portfolio losses.
Managed Volatility Balanced Portfolio | Risk Management Strategies May Not Be Successful [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Risk management strategies risk. The purposes of the risk management strategies are to attempt to limit the fund’s total risk exposure during periods of high market volatility and reduce the fund’s losses during market declines; however, there is no assurance that these strategies will be successful. These risk management strategies could limit the upside participation of the fund in rising equity markets during periods of high volatility. In instances of equity market declines followed by rising equity markets and significant levels of market volatility, these risk management strategies may detract from fund performance and at times prevent the fund from fully recovering losses by limiting the levels of exposure to equity markets. Due to the use of historical data in the models used in the risk management strategy, there can be delays, especially during volatile markets, in fully implementing the strategy when markets are declining causing the fund to experience greater losses than if the strategy had been fully implemented. There can also be delays, especially during volatile markets, in removing hedges designed to limit losses during declining markets when markets are rising strongly causing the fund to not fully participate in the rising market. The application of risk management techniques can be complex, and misjudgments in implementation may result in under- or over-allocations to equity, fixed-income and/or cash and cash equivalent exposure causing the fund to underperform or experience losses. Also, futures contracts may be subject to exchange-imposed daily price fluctuation limits, and trading may be halted if a contract’s price moves above or below the limit on a given day. As a result, the fund may not be able to promptly liquidate unfavorable futures positions and could be required to hold such positions until the delivery date, regardless of changes in its value. Since the characteristics of many securities change as markets change or time passes, the success of risk management techniques will be subject to the portfolio managers’ ability to execute the strategy. Moreover, risk management strategies may increase portfolio transaction costs, which could cause or increase losses or reduce gains. Any one or more of these factors may prevent the fund from achieving the intended risk management goals or could cause the fund to underperform or experience losses (some of which may be sudden) or volatility for any particular period.
Managed Volatility Balanced Portfolio | Short Positions Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Short positions risk. In taking a short position, a fund seeks to profit from an anticipated decline in the value of a security or index of securities. If the security or index instead appreciates in value, the fund will incur losses by having to pay to close out its position at a higher price than the price it received to open that position. Unlike losses from declines in long positions in stocks or other securities (which may not exceed the original amount invested), the losses a fund may incur to close out a short position if the underlying security or index increases in value are potentially unlimited.
Managed Volatility Balanced Portfolio | Short Sales Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Short sales risk. Short sales involve costs and risk. A fund must pay the lender interest on a security it borrows, and the fund will lose money if the price of the borrowed security increases between the time of the short sale and the date when the fund replaces the borrowed security.
Managed Volatility Balanced Portfolio | Swaps Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Swaps risk. Counterparty risk, liquidity risk (i.e., the inability to enter into closing transactions), interest-rate risk, settlement risk, risk of default of the underlying reference obligation and risk of disproportionate loss are the principal risks of engaging in transactions involving swaps.
Managed Volatility Balanced Portfolio | Target Allocation Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Target allocation risk. The fund's risk profile will change due to reallocation or rebalancing of portfolio assets.
Managed Volatility Balanced Portfolio | Use Of Index Futures Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Use of index futures risk. While the use of index futures may involve a small investment of cash, the losses to a fund could exceed the amount invested, and in certain cases even the total value of the fund’s assets, due to the embedded leverage provided by the derivative. Index futures may also result in a loss to the fund if the counterparty to the transaction does not perform.
Managed Volatility Balanced Portfolio | US Government Agency Obligations Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock U.S. government agency obligations risk. The fund invests in obligations issued by agencies and instrumentalities of the U.S. government. Government-sponsored entities such as Federal National Mortgage Association (Fannie Mae), Federal Home Loan Mortgage Corporation (Freddie Mac) and the Federal Home Loan Banks, although chartered or sponsored by Congress, are not funded by congressional appropriations and the debt securities that they issue are neither guaranteed nor issued by the U.S. government. Such debt securities are subject to the risk of default on the payment of interest and/or principal, similar to the debt securities of private issuers. The maximum potential liability of the issuers of some U.S. government obligations may greatly exceed their current resources, including any legal right to support from the U.S. government. Although the U.S. government has provided financial support to Fannie Mae and Freddie Mac in the past, there can be no assurance that it will support these or other government-sponsored entities in the future.U.S. government agency obligations risk. The fund invests in obligations issued by agencies and instrumentalities of the U.S. government. Government-sponsored entities such as Federal National Mortgage Association (Fannie Mae), Federal Home Loan Mortgage Corporation (Freddie Mac) and the Federal Home Loan Banks, although chartered or sponsored by Congress, are not funded by congressional appropriations and the debt securities that they issue are neither guaranteed nor issued by the U.S. government. Such debt securities are subject to the risk of default on the payment of interest and/or principal, similar to the debt securities of private issuers. The maximum potential liability of the issuers of some U.S. government obligations may greatly exceed their current resources, including any legal right to support from the U.S. government. Although the U.S. government has provided financial support to Fannie Mae and Freddie Mac in the past, there can be no assurance that it will support these or other government-sponsored entities in the future.
Managed Volatility Balanced Portfolio | Convertible Securities Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Convertible securities risk. Convertible securities are subject to certain risks of both equity and debt securities. The market values of convertible securities tend to fall as interest rates rise and rise as interest rates fall. As the market price of underlying common stock declines below the conversion price, the market value of the convertible security tends to be increasingly influenced by its yield.
Managed Volatility Balanced Portfolio | Foreign Securities Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Foreign securities risk. Less information may be publicly available regarding foreign issuers, including foreign government issuers. Foreign securities may be subject to foreign taxes and may be more volatile than U.S. securities. Currency fluctuations and political and economic developments may adversely impact the value of foreign securities. The risks of investing in foreign securities are magnified in emerging markets.
Managed Volatility Balanced Portfolio | Index Management Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Index management risk. Certain factors may cause a fund that is an index fund to track its target index less closely. For example, a subadvisor may select securities that are not fully representative of the index, and the fund’s operating expenses and transaction costs, and the size and timing of its cash flows, may result in the fund’s performance being different than that of its index. Moreover, the fund will generally reflect the performance of its target index even when the index does not perform well.
Managed Volatility Balanced Portfolio | Initial Public Offerings Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Initial public offerings (IPOs) risk. IPO share prices are frequently volatile and may significantly impact fund performance.
Managed Volatility Balanced Portfolio | Large Company Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Large company risk. Larger companies may grow more slowly than smaller companies or be slower to respond to business developments. Large-capitalization securities may underperform the market as a whole.
Managed Volatility Balanced Portfolio | Lower Rated And High Yield Fixed Income Securities Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Lower-rated and high-yield fixed-income securities risk. Lower-rated and high-yield fixed-income securities (junk bonds) are subject to greater credit quality risk, risk of default, and price volatility than higher-rated fixed-income securities, may be considered speculative, and can be difficult to resell.
Managed Volatility Balanced Portfolio | Mortgage Backed And Asset Backed Securities Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Mortgage-backed and asset-backed securities risk. Mortgage-backed and asset-backed securities are subject to different combinations of prepayment, extension, interest-rate, and other market risks. Factors that impact the value of these securities include interest rate changes, the reliability of available information, credit quality or enhancement, and market perception.
Managed Volatility Balanced Portfolio | Sector Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Sector risk. When a fund focuses its investments in certain sectors of the economy, its performance may be driven largely by sector performance and could fluctuate more widely than if the fund were invested more evenly across sectors.
Managed Volatility Balanced Portfolio | Small And Mid Sized Company Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small and/or mid-capitalization securities may underperform the market as a whole.
Managed Volatility Balanced Portfolio | Series I  
Risk Return Abstract rr_RiskReturnAbstract  
Management fee rr_ManagementFeesOverAssets 0.17%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.03%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.55% [1]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.80% [2]
1 year rr_ExpenseExampleYear01 $ 82
3 years rr_ExpenseExampleYear03 255
5 years rr_ExpenseExampleYear05 444
10 years rr_ExpenseExampleYear10 $ 990
2015 rr_AnnualReturn2015 (2.25%)
2016 rr_AnnualReturn2016 4.79%
2017 rr_AnnualReturn2017 14.13%
2018 rr_AnnualReturn2018 (4.89%)
2019 rr_AnnualReturn2019 17.92%
2020 rr_AnnualReturn2020 1.81%
2021 rr_AnnualReturn2021 9.76%
2022 rr_AnnualReturn2022 (15.08%)
2023 rr_AnnualReturn2023 11.99%
2024 rr_AnnualReturn2024 9.36%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel <span style="color:#000000;font-family:Arial Narrow;font-size:8pt;font-weight:bold;margin-left:0.0pt;">Best quarter:</span>
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2023
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 9.47%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel <span style="color:#000000;font-family:Arial Narrow;font-size:8pt;font-weight:bold;margin-left:0.0pt;">Worst quarter:</span>
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (13.22%)
1 year rr_AverageAnnualReturnYear01 9.36%
5 year rr_AverageAnnualReturnYear05 3.05%
10 year rr_AverageAnnualReturnYear10 4.30%
Managed Volatility Balanced Portfolio | Series II  
Risk Return Abstract rr_RiskReturnAbstract  
Management fee rr_ManagementFeesOverAssets 0.17%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.03%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.55% [1]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 1.00% [2]
1 year rr_ExpenseExampleYear01 $ 102
3 years rr_ExpenseExampleYear03 318
5 years rr_ExpenseExampleYear05 552
10 years rr_ExpenseExampleYear10 $ 1,225
1 year rr_AverageAnnualReturnYear01 9.13%
5 year rr_AverageAnnualReturnYear05 2.85%
10 year rr_AverageAnnualReturnYear10 4.10%
Managed Volatility Balanced Portfolio | NAV  
Risk Return Abstract rr_RiskReturnAbstract  
Management fee rr_ManagementFeesOverAssets 0.17%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.03%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.55% [1]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.75% [2]
1 year rr_ExpenseExampleYear01 $ 77
3 years rr_ExpenseExampleYear03 240
5 years rr_ExpenseExampleYear05 417
10 years rr_ExpenseExampleYear10 $ 930
1 year rr_AverageAnnualReturnYear01 9.37%
5 year rr_AverageAnnualReturnYear05 3.09%
10 year rr_AverageAnnualReturnYear10 4.36%
Managed Volatility Balanced Portfolio | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Risk Return Abstract rr_RiskReturnAbstract  
1 year rr_AverageAnnualReturnYear01 25.02% [3]
5 year rr_AverageAnnualReturnYear05 14.53% [3]
10 year rr_AverageAnnualReturnYear10 13.10% [3]
Managed Volatility Balanced Portfolio | Morningstar U.S. Moderate Target Allocation Index (reflects no deduction for fees, expenses, or taxes)  
Risk Return Abstract rr_RiskReturnAbstract  
1 year rr_AverageAnnualReturnYear01 12.96%
5 year rr_AverageAnnualReturnYear05 7.47%
10 year rr_AverageAnnualReturnYear10 7.45%
Managed Volatility Balanced Portfolio | 35% Russell 3000 Index/15% MSCI EAFE Index/50% Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes, except foreign withholding taxes on dividends)  
Risk Return Abstract rr_RiskReturnAbstract  
1 year rr_AverageAnnualReturnYear01 9.20%
5 year rr_AverageAnnualReturnYear05 5.57%
10 year rr_AverageAnnualReturnYear10 6.03%
[1] “Acquired fund fees and expenses” are based on indirect net expenses associated with the fund’s investments in underlying investment companies.
[2] The “Total annual fund operating expenses” shown may not correlate to the fund’s ratios of expenses to average daily net assets shown in the “Financial highlights” section of the fund’s prospectus, which does not include “Acquired fund fees and expenses.”
[3] The fund has designated the S&P 500 Index as its new broad-based securities market index in accordance with the revised definition for such an index.