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Label Element Value
(John Hancock Variable Insurance Trust) | (500 Index Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To approximate the aggregate total return of a broad-based U.S. domestic equity market index.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 2% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 2.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund seeks to approximate the aggregate total return of a broad-based U.S. domestic equity market index. To pursue this goal, the fund invests at least 80% of its net assets (plus any borrowings for investment purposes) at the time of investment in (a) the common stocks that are included in the S&P 500 Index and (b) securities (which may or may not be included in the S&P 500 Index) that the subadvisor believes as a group will behave in a manner similar to the index. (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.) The subadvisor may determine that the fund’s investments in certain instruments, such as index futures, total return swaps and exchanged-traded funds (“ETFs”) have similar economic characteristics as securities that are in the S&P 500 Index. As of February 28, 2022, the market capitalizations of companies included in the S&P 500 Index ranged from $3.4 billion to $2.7 trillion.
An index is an unmanaged group of securities whose overall performance is used as an investment benchmark. Indexes may track broad investment markets, such as the global equity market, or more narrow investment markets, such as the U.S. small cap equity market. In contrast to actively managed funds, which seek to outperform their respective benchmark indexes through research and analysis, index funds are passively managed funds that seek to mirror the performance of their target indexes, minimizing performance differences over time. The fund attempts to match the performance of the S&P 500 Index by: (a) holding all, or a representative sample, of the securities that comprise that index and/or (b) by holding securities (which may or may not be included in the index) that the subadvisor believes as a group will behave in a manner similar to the index.
However, an index fund has operating expenses and transaction costs, while a market index does not. Therefore, the fund, while it attempts to track its target index closely, typically will be unable to match the performance of the index exactly. The composition of an index changes from time to time, and the subadvisor will reflect those changes in the composition of the fund’s portfolio as soon as practicable.
Use of Hedging and Other Strategic Transactions. The fund may invest in futures contracts, swaps, and depositary receipts. The fund may invest in derivatives (investments whose value is based on securities, indexes or currencies).
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance.
Credit and counterparty risk. 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.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions.
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.
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 the fund intends to utilize include: futures contracts, depositary receipts, total return swaps, and swaps. Futures contracts 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.
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 transaction expenses, 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.
Information technology companies risk. Information technology companies can be significantly affected by rapid obsolescence, short product cycles, competition from new market entrants, and heightened cybersecurity risk, among other factors.
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.
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.
Quantitative modeling risk. Quantitative models may not accurately predict future market movements or characteristics, which may negatively impact performance. Models also may perform differently than expected due to implementation problems, technological malfunction, or programming or data inaccuracies, among other possible issues.
S&P 500 Index risk An investment in the fund involves risks similar to the risks of investing directly in the equity securities included in the S&P 500 Index.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. Performance shown for periods prior to the inception date of a class is the performance of the fund’s oldest share class. This pre-inception performance, with respect to any other share class of the fund, has not been adjusted to reflect the Rule 12b-1 fees of that class. As a result, the pre-inception performance shown for a share class other than the oldest share class may be higher or lower than it would be if adjusted to reflect the Rule 12b-1 fees of the class. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series NAV 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 20.49%
Worst quarter: 2020, Q1, -19.64%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (500 Index Trust) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 28.71%
5 Years rr_AverageAnnualReturnYear05 18.47%
10 Years rr_AverageAnnualReturnYear10 16.55%
(John Hancock Variable Insurance Trust) | (500 Index Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.46%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.03%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.54%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.24%) [1]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.30%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 31
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 149
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 278
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 654
1 Year rr_AverageAnnualReturnYear01 28.29%
5 Years rr_AverageAnnualReturnYear05 18.13%
10 Years rr_AverageAnnualReturnYear10 16.22%
Date of inception rr_AverageAnnualReturnInceptionDate Nov. 05, 2012
(John Hancock Variable Insurance Trust) | (500 Index Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.46%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.03%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.74%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.24%) [1]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.50%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 51
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 212
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 388
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 896
1 Year rr_AverageAnnualReturnYear01 28.04%
5 Years rr_AverageAnnualReturnYear05 17.89%
10 Years rr_AverageAnnualReturnYear10 16.00%
Date of inception rr_AverageAnnualReturnInceptionDate Nov. 05, 2012
(John Hancock Variable Insurance Trust) | (500 Index Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.46%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.03%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.49%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.24%) [1]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.25%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 26
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 133
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 250
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 593
Annual Return 2012 rr_AnnualReturn2012 15.80%
Annual Return 2013 rr_AnnualReturn2013 32.03%
Annual Return 2014 rr_AnnualReturn2014 13.43%
Annual Return 2015 rr_AnnualReturn2015 1.15%
Annual Return 2016 rr_AnnualReturn2016 11.64%
Annual Return 2017 rr_AnnualReturn2017 21.54%
Annual Return 2018 rr_AnnualReturn2018 (4.65%)
Annual Return 2019 rr_AnnualReturn2019 31.16%
Annual Return 2020 rr_AnnualReturn2020 18.14%
Annual Return 2021 rr_AnnualReturn2021 28.36%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 20.49%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 20.49%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -19.64%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (19.64%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 28.36%
5 Years rr_AverageAnnualReturnYear05 18.18%
10 Years rr_AverageAnnualReturnYear10 16.27%
Date of inception rr_AverageAnnualReturnInceptionDate May 01, 1996
(John Hancock Variable Insurance Trust) | (Active Bond Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek income and capital appreciation.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees 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.”
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 95% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 95.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in a diversified mix of debt securities and instruments. (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.) The fund seeks to invest its assets in debt securities and instruments with an average duration of plus or minus one year of its benchmark, Bloomberg US Aggregate Bond Index, however, there is no limit on the fund’s average maturity. As part of its investment strategy, the fund may invest in mortgage-backed securities to a significant extent.
Eligible investments include, but are not limited to:
■
U.S. Treasury and agency securities;
■
Asset-backed securities and mortgage-backed securities, both investment grade and below-investment grade, including mortgage pass-through securities, interest-only securities, commercial mortgage-backed securities (“CMBS”) and collateralized mortgage obligations (“CMOs”);
■
Corporate bonds, both U.S. and foreign, and without any limit on credit quality; and
■
Foreign government and agency securities.
The fund may invest in asset-backed securities rated, at the time of purchase, less than A (but not rated lower than B by S&P Global Ratings (“S&P”) or Moody’s Investors Service (“Moody’s”), or a comparable rating by another Nationally Recognized Statistical Ratings Organization). The subadvisor uses proprietary research and economic and industry analysis to identify specific bonds, bond sectors and industries that are attractively priced. Because the fund is actively managed, it may have a higher than average portfolio turnover ratio, which may increase expenses and affect performance results.
The foreign securities in which the fund invests may be denominated in U.S. dollars or foreign currency.
Manulife Investment Management (US) LLC manages the fund with two investment teams, each of which employs its own investment approach and independently manages its portion of the fund. The fund will be rebalanced periodically so that each team manages the following portions of the fund:
50%* Securitized Asset Team 50%* Core / Core Plus Team
*Percentages are approximate. Since the fund is only rebalanced periodically, the actual portion of the fund managed by each team will vary.
This allocation methodology may change in the future.
Securitized Asset Team
The Securitized Asset Team uses a combination of proprietary research and quantitative tools and seeks to identify bonds and bond sectors that are attractively priced based upon market fundamentals and technical factors. The Securitized Asset Team opportunistically emphasizes bonds with yields in excess of U.S. Treasury securities.
This portion of the fund normally has no more than 10% of its total assets in high yield bonds (“junk bonds”) and normally invests in foreign securities only if U.S. dollar-denominated. This portion of the fund normally has an average credit rating of “A” or “AA.”
The Core / Core Plus Team
The Core / Core Plus Team uses proprietary research to identify specific bond sectors, industries and bonds that are attractively priced. The team seeks to anticipate shifts in the business cycle, using economic and industry analysis to determine which sectors and industries might benefit over the next 12 months.
This portion of the fund normally has no more than 25% of its total assets in high yield bonds (sometimes referred to as “junk bonds”) and may invest in both U.S. dollar-denominated and foreign currency-denominated foreign securities. This portion of the fund normally has an average credit rating of “A” or “AA.”
Under normal circumstances, no more than 15% of the total assets of the portion of the fund managed by the Core / Core Plus Team will be invested in asset-backed securities rated lower than A by both rating agencies. The fund’s investment policies are based on credit ratings at the time of purchase.
Use of Hedging and Other Strategic Transactions. The fund is authorized to use all of the various investment strategies referred to under “Additional Information About the Funds’ Principal Risks — Hedging, derivatives and other strategic transactions risk” including, but not limited to, U.S. Treasury futures and options, index derivatives, credit default swaps and forwards.

The manager considers environmental, social, and/or governance (ESG) factors, alongside other relevant factors, as part of its investment process. 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.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
Changing distribution levels risk. The fund may cease or reduce the level of its distribution if income or dividends paid from its investments declines.
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.
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.
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. 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.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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 the fund intends to utilize include: foreign currency forward contracts, futures contracts, options, and credit default 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.
High portfolio turnover risk. Trading securities actively and frequently can increase transaction costs (thus lowering performance) and taxable distributions.
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.
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.
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.
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.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series NAV 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 5.41%
Worst quarter: 2021, Q1, -2.71%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Active Bond Trust) | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.54%)
5 Years rr_AverageAnnualReturnYear05 3.57%
10 Years rr_AverageAnnualReturnYear10 2.90%
(John Hancock Variable Insurance Trust) | (Active Bond Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.60%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.05%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02% [2]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.72% [3]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [4]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.71%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 73
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 229
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 400
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 894
1 Year rr_AverageAnnualReturnYear01 (0.57%)
5 Years rr_AverageAnnualReturnYear05 4.25%
10 Years rr_AverageAnnualReturnYear10 4.22%
Date of inception rr_AverageAnnualReturnInceptionDate May 02, 2005
(John Hancock Variable Insurance Trust) | (Active Bond Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.60%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.05%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02% [2]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.92% [3]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [4]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.91%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 93
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 292
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 508
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,130
1 Year rr_AverageAnnualReturnYear01 (0.77%)
5 Years rr_AverageAnnualReturnYear05 4.04%
10 Years rr_AverageAnnualReturnYear10 4.01%
Date of inception rr_AverageAnnualReturnInceptionDate May 02, 2005
(John Hancock Variable Insurance Trust) | (Active Bond Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.60%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.05%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02% [2]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.67% [3]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [4]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.66%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 67
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 213
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 372
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 834
Annual Return 2012 rr_AnnualReturn2012 9.76%
Annual Return 2013 rr_AnnualReturn2013 0.19%
Annual Return 2014 rr_AnnualReturn2014 6.97%
Annual Return 2015 rr_AnnualReturn2015 0.12%
Annual Return 2016 rr_AnnualReturn2016 4.50%
Annual Return 2017 rr_AnnualReturn2017 4.89%
Annual Return 2018 rr_AnnualReturn2018 (0.55%)
Annual Return 2019 rr_AnnualReturn2019 9.30%
Annual Return 2020 rr_AnnualReturn2020 8.73%
Annual Return 2021 rr_AnnualReturn2021 (0.42%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 5.41%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 5.41%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2021, Q1, -2.71%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (2.71%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2021
1 Year rr_AverageAnnualReturnYear01 (0.42%)
5 Years rr_AverageAnnualReturnYear05 4.30%
10 Years rr_AverageAnnualReturnYear10 4.27%
Date of inception rr_AverageAnnualReturnInceptionDate Mar. 29, 1986
(John Hancock Variable Insurance Trust) | (American Asset Allocation Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek to provide high total return (including income and capital gains) consistent with preservation of capital over the long term.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund, which operates as a feeder fund, does not pay transaction costs, such as commissions, when it buys and sells shares of the master fund (or “turns over” its portfolio). A master 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 master fund and of the fund. During its most recent fiscal year, the master fund’s portfolio turnover rate was 5% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 5.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The fund invests all of its assets in Class 1 shares of its master fund, the Asset Allocation Fund, a series of American Funds Insurance Series. The master fund invests in a diversified portfolio of common stocks and other equity securities, bonds and other intermediate and long-term debt securities, and money market instruments (debt securities maturing in one year or less). The master fund may invest up to 25% of its debt assets in lower quality debt securities (rated Ba1 or below and BB+ or below by a nationally recognized statistical rating organization (“NRSRO”) designated by the master fund’s investment advisor or unrated but determined to be of equivalent quality by the master fund’s investment advisor). Such securities are sometimes referred to as “junk bonds.”
In seeking to pursue its investment objective, the fund varies its mix of equity securities, debt securities and money market instruments. Under normal market conditions, the master fund’s investment advisor expects (but is not required) to maintain an investment mix falling within the following ranges: 40% – 80% in equity securities, 20% – 50% in debt securities and 0% – 40% in money market instruments and cash. The proportion of equities, debt and money market securities held by the master fund will vary with market conditions and the investment advisor’s assessment of their relative attractiveness as investment opportunities. The master fund may invest up to 15% of its assets in common stocks and other equity securities of issuers domiciled outside the U.S. and up to 5% of its assets in debt securities of issuers domiciled outside the U.S.
The master fund may invest in other funds managed by the investment adviser or its affiliates to more effectively invest in a diversified set of securities in a specific asset class such as money market instruments, bonds and other securities (“Central Funds”). Shares of Central Funds are only offered for
purchase to the master fund’s investment advisor and its affiliates and other funds, investment vehicles and accounts managed by the master fund’s investment advisor and its affiliates. When investing in Central Funds, the master fund bears its proportionate share of the expenses of the Central Funds in which it invests but does not bear additional management fees through its investment in such Central Funds. The investment results of the portion of the master fund’s assets invested in the Central Funds will be based upon the investment results of the Central Funds.

The manager considers environmental, social, and/or governance (ESG) factors, alongside other relevant factors, as part of its investment process. 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.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
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.
Credit and counterparty risk. The issuer or guarantor of a fixed-income security 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.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions.
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. 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.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity risk.
Income stock risk. Income provided by the fund may be affected by changes in the dividend polices of the companies in which the fund invests and the capital resources available for such payments at such companies.
Investment company securities risk. The fund may invest in securities of other investment companies. Fund shareholders indirectly bear their proportionate share of the expenses of each such investment company. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
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.
Liquidity risk. The extent (if at all) to which a security may be sold 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.
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.
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.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index and the Combined Index (described below) show how the fund’s performance compares against the returns of similar investments. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
The Combined Index represents 60% of the S&P 500 Index and 40% of the Bloomberg U.S. Aggregate Bond Index.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series II 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 13.62%
Worst quarter: 2020, Q1, -13.59%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (American Asset Allocation Trust) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 28.71%
5 Years rr_AverageAnnualReturnYear05 18.47%
10 Years rr_AverageAnnualReturnYear10 16.55%
(John Hancock Variable Insurance Trust) | (American Asset Allocation Trust) | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.54%)
5 Years rr_AverageAnnualReturnYear05 3.57%
10 Years rr_AverageAnnualReturnYear10 2.90%
(John Hancock Variable Insurance Trust) | (American Asset Allocation Trust) | Combined Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 15.86%
5 Years rr_AverageAnnualReturnYear05 12.62%
10 Years rr_AverageAnnualReturnYear10 11.14%
(John Hancock Variable Insurance Trust) | (American Asset Allocation Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.26% [5]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.60%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.07%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.93%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [6]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.92%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 94
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 295
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 514
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,142
1 Year rr_AverageAnnualReturnYear01 14.71%
5 Years rr_AverageAnnualReturnYear05 11.31%
10 Years rr_AverageAnnualReturnYear10 10.93%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 28, 2008
(John Hancock Variable Insurance Trust) | (American Asset Allocation Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.26% [5]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.75%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.07%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.08%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [6]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.07%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 109
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 342
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 595
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,316
Annual Return 2012 rr_AnnualReturn2012 15.49%
Annual Return 2013 rr_AnnualReturn2013 23.13%
Annual Return 2014 rr_AnnualReturn2014 4.89%
Annual Return 2015 rr_AnnualReturn2015 0.91%
Annual Return 2016 rr_AnnualReturn2016 8.92%
Annual Return 2017 rr_AnnualReturn2017 15.69%
Annual Return 2018 rr_AnnualReturn2018 (5.06%)
Annual Return 2019 rr_AnnualReturn2019 20.67%
Annual Return 2020 rr_AnnualReturn2020 11.92%
Annual Return 2021 rr_AnnualReturn2021 14.61%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 13.62%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 13.62%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -13.59%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (13.59%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 14.61%
5 Years rr_AverageAnnualReturnYear05 11.20%
10 Years rr_AverageAnnualReturnYear10 10.79%
Date of inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (American Asset Allocation Trust) | Series III  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.26% [5]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.07%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.58%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [6]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.57%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 58
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 185
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 323
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 725
1 Year rr_AverageAnnualReturnYear01 15.07%
5 Years rr_AverageAnnualReturnYear05 11.69%
10 Years rr_AverageAnnualReturnYear10 11.32%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 03, 2008
(John Hancock Variable Insurance Trust) | (American Global Growth Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek to provide long-term growth of capital.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund, which operates as a feeder fund, does not pay transaction costs, such as commissions, when it buys and sells shares of the master fund (or “turns over” its portfolio). A master 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 master fund and of the fund. During its most recent fiscal year, the master fund’s portfolio turnover rate was 8% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 8.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The fund invests all of its assets in Class 1 shares of its master fund, the Global Growth Fund, a series of American Funds Insurance Series. The Global Growth Fund invests primarily in common stocks of companies around the world that the advisor believes have potential for growth. As a fund that seeks to invest globally, the Global Growth Fund will allocate its assets among securities of companies domiciled in various countries, including the United States and countries with emerging markets (but in no fewer than three countries). Under normal market conditions, the Global Growth Fund will invest significantly in issuers domiciled outside the United States (i.e., at least 40% of its net assets, unless market conditions are not deemed favorable by the fund’s investment advisor, in which case the fund would invest at least 30% of its net assets in issuers outside the United States.
Use of Hedging and Other Strategic Transactions. The fund is authorized to use all of the various investment strategies referred to under “Additional Information About the Funds’ Principal Risks — Hedging, derivatives and other strategic transactions risk.”
The master fund may invest in other funds managed by the investment adviser or its affiliates to more effectively invest in a diversified set of securities in a specific asset class such as money market instruments, bonds and other securities (“Central Funds”). Shares of Central Funds are only offered for purchase to the master fund’s investment advisor and its affiliates and other funds, investment vehicles and accounts managed by the master fund’s investment advisor and its affiliates. When investing in Central Funds, the master fund bears its proportionate share of the expenses of the Central Funds in which it invests but does not bear additional management fees through its investment in such Central Funds. The investment results of the
portion of the master fund’s assets invested in the Central Funds will be based upon the investment results of the Central Funds.

The manager considers environmental, social, and/or governance (ESG) factors, alongside other relevant factors, as part of its investment process. 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.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
Credit and counterparty risk. 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.
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.
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.
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. 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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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 the fund intends to utilize include: credit default swaps, foreign currency forward contracts, foreign currency swaps, futures contracts, options on futures, swaptions, 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 instrument.
Information technology companies risk. Information technology companies can be significantly affected by rapid obsolescence, short product cycles, competition from new market entrants, and heightened cybersecurity risk, among other factors.
Investment company securities risk. The fund may invest in securities of other investment companies. Fund shareholders indirectly bear their proportionate share of the expenses of each such investment company. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
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.
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.
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.
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.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. The Lipper Global Fund Index shows how the fund’s performance compares against the returns of similar investments. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series II 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 24.15%
Worst quarter: 2020, Q1, -16.36%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (American Global Growth Trust) | MSCI ACWI (reflects no deduction for fees, expenses, or taxes, except foreign withholding taxes on dividends)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 18.54%
5 Years rr_AverageAnnualReturnYear05 14.40%
10 Years rr_AverageAnnualReturnYear10 11.85%
(John Hancock Variable Insurance Trust) | (American Global Growth Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.48% [7]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.60%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.09%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.17%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.12%) [8],[9]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.05%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 107
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 360
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 632
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,410
1 Year rr_AverageAnnualReturnYear01 16.00%
5 Years rr_AverageAnnualReturnYear05 19.23%
10 Years rr_AverageAnnualReturnYear10 15.23%
Date of inception rr_AverageAnnualReturnInceptionDate Nov. 05, 2010
(John Hancock Variable Insurance Trust) | (American Global Growth Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.48% [7]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.75%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.09%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.32%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.12%) [8],[9]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.20%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 122
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 406
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 712
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,580
Annual Return 2012 rr_AnnualReturn2012 22.00%
Annual Return 2013 rr_AnnualReturn2013 28.43%
Annual Return 2014 rr_AnnualReturn2014 1.82%
Annual Return 2015 rr_AnnualReturn2015 6.50%
Annual Return 2016 rr_AnnualReturn2016 0.10%
Annual Return 2017 rr_AnnualReturn2017 30.92%
Annual Return 2018 rr_AnnualReturn2018 (9.46%)
Annual Return 2019 rr_AnnualReturn2019 34.66%
Annual Return 2020 rr_AnnualReturn2020 29.80%
Annual Return 2021 rr_AnnualReturn2021 15.92%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 24.15%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 24.15%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -16.36%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (16.36%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 15.92%
5 Years rr_AverageAnnualReturnYear05 19.15%
10 Years rr_AverageAnnualReturnYear10 15.11%
Date of inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (American Global Growth Trust) | Series III  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.48% [7]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.09%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.82%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.12%) [8],[9]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.70%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 72
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 250
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 443
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,002
1 Year rr_AverageAnnualReturnYear01 16.41%
5 Years rr_AverageAnnualReturnYear05 19.65%
10 Years rr_AverageAnnualReturnYear10 15.63%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 03, 2008
(John Hancock Variable Insurance Trust) | (American Growth Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek to provide growth of capital.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund, which operates as a feeder fund, does not pay transaction costs, such as commissions, when it buys and sells shares of the master fund (or “turns over” its portfolio). A master 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 master fund and of the fund. During its most recent fiscal year, the master fund’s portfolio turnover rate was 14% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 14.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The fund invests all of its assets in Class 1 shares of its master fund, the Growth Fund, a series of American Funds Insurance Series. The Growth Fund invests primarily in common stocks and seeks to invest in companies that appear to offer superior opportunities for growth of capital. The Growth Fund may also invest up to 25% of its assets in common stocks and other securities of issuers domiciled outside the U.S.

The master fund may invest in other funds managed by the investment adviser or its affiliates to more effectively invest in a diversified set of securities in a specific asset class such as money market instruments, bonds and other securities (“Central Funds”). Shares of Central Funds are only offered for purchase to the master fund’s investment advisor and its affiliates and other funds, investment vehicles and accounts managed by the master fund’s investment advisor and its affiliates. When investing in Central Funds, the master fund bears its proportionate share of the expenses of the Central Funds in which it invests but does not bear additional management fees through its investment in such Central Funds. The investment results of the portion of the master fund’s assets invested in the Central Funds will be based upon the investment results of the Central Funds.

The manager considers environmental, social, and/or governance (ESG) factors, alongside other relevant factors, as part of its investment process. 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.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
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.
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.
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. 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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity risk.
Information technology companies risk. Information technology companies can be significantly affected by rapid obsolescence, short product cycles, competition from new market entrants, and heightened cybersecurity risk, among other factors.
Investment company securities risk. The fund may invest in securities of other investment companies. Fund shareholders indirectly bear their proportionate share of the expenses of each such investment company. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
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.
Liquidity risk. The extent (if at all) to which a security may be sold without negatively impacting its market value may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.
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.
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.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series II 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 28.53%
Worst quarter: 2018, Q4, -14.16%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (American Growth Trust) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 28.71%
5 Years rr_AverageAnnualReturnYear05 18.47%
10 Years rr_AverageAnnualReturnYear10 16.55%
(John Hancock Variable Insurance Trust) | (American Growth Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.31% [10]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.60%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.07%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.98%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [11]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.97%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 99
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 311
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 541
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,200
1 Year rr_AverageAnnualReturnYear01 21.55%
5 Years rr_AverageAnnualReturnYear05 24.97%
10 Years rr_AverageAnnualReturnYear10 19.27%
Date of inception rr_AverageAnnualReturnInceptionDate Jul. 10, 2003
(John Hancock Variable Insurance Trust) | (American Growth Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.31% [10]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.75%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.07%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.13%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [11]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.12%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 114
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 358
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 621
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,374
Annual Return 2012 rr_AnnualReturn2012 17.23%
Annual Return 2013 rr_AnnualReturn2013 29.48%
Annual Return 2014 rr_AnnualReturn2014 7.96%
Annual Return 2015 rr_AnnualReturn2015 6.35%
Annual Return 2016 rr_AnnualReturn2016 9.03%
Annual Return 2017 rr_AnnualReturn2017 27.74%
Annual Return 2018 rr_AnnualReturn2018 (0.71%)
Annual Return 2019 rr_AnnualReturn2019 30.20%
Annual Return 2020 rr_AnnualReturn2020 51.46%
Annual Return 2021 rr_AnnualReturn2021 21.49%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 28.53%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 28.53%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2018, Q4, -14.16%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (14.16%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2018
1 Year rr_AverageAnnualReturnYear01 21.49%
5 Years rr_AverageAnnualReturnYear05 24.89%
10 Years rr_AverageAnnualReturnYear10 19.16%
Date of inception rr_AverageAnnualReturnInceptionDate May 06, 2003
(John Hancock Variable Insurance Trust) | (American Growth Trust) | Series III  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.31% [10]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.07%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.63%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [11]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.62%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 63
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 201
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 350
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 785
1 Year rr_AverageAnnualReturnYear01 22.00%
5 Years rr_AverageAnnualReturnYear05 25.40%
10 Years rr_AverageAnnualReturnYear10 19.69%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 03, 2008
(John Hancock Variable Insurance Trust) | (American Growth-Income Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek to provide long-term growth of capital and income.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund, which operates as a feeder fund, does not pay transaction costs, such as commissions, when it buys and sells shares of the master fund (or “turns over” its portfolio). A master 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 master fund and of the fund. During its most recent fiscal year, the master fund’s portfolio turnover rate was 3% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 3.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The fund invests all of its assets in Class 1 shares of its master fund, the Growth-Income Fund, a series of American Funds Insurance Series. The Growth-Income Fund invests primarily in common stocks or other securities that the Growth-Income Fund’s investment advisor believes demonstrate the potential for appreciation and/or dividends. The Growth-Income Fund may invest up to 15% of its assets, at the time of purchase, in securities of issuers domiciled outside the U.S. The Growth-Income Fund is designed for investors seeking both capital appreciation and income.

The master fund may invest in other funds managed by the investment adviser or its affiliates to more effectively invest in a diversified set of securities in a specific asset class such as money market instruments, bonds and other securities (“Central Funds”). Shares of Central Funds are only offered for purchase to the master fund’s investment advisor and its affiliates and other funds, investment vehicles and accounts managed by the master fund’s investment advisor and its affiliates. When investing in Central Funds, the master fund bears its proportionate share of the expenses of the Central Funds in which it invests but does not bear additional management fees through its investment in such Central Funds. The investment results of the portion of the master fund’s assets invested in the Central Funds will be based upon the investment results of the Central Funds.

The manager considers environmental, social, and/or governance (ESG) factors, alongside other relevant factors, as part of its investment process. 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.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
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.
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.
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. 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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity risk.
Income stock risk. Income provided by the fund may be affected by changes in the dividend polices of the companies in which the fund invests and the capital resources available for such payments at such companies.
Investment company securities risk. The fund may invest in securities of other investment companies. Fund shareholders indirectly bear their proportionate share of the expenses of each such investment company. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
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.
Liquidity risk. The extent (if at all) to which a security may be sold without negatively impacting its market value may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.
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.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series II 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 19.82%
Worst quarter: 2020, Q1, -19.87%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (American Growth-Income Trust) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 28.71%
5 Years rr_AverageAnnualReturnYear05 18.47%
10 Years rr_AverageAnnualReturnYear10 16.55%
(John Hancock Variable Insurance Trust) | (American Growth-Income Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.25% [12]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.60%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.07%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.92%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [13]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.91%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 93
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 292
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 508
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,130
1 Year rr_AverageAnnualReturnYear01 23.61%
5 Years rr_AverageAnnualReturnYear05 15.97%
10 Years rr_AverageAnnualReturnYear10 15.01%
Date of inception rr_AverageAnnualReturnInceptionDate Jul. 10, 2003
(John Hancock Variable Insurance Trust) | (American Growth-Income Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.25% [12]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.75%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.07%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.07%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [13]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.06%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 108
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 339
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 589
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,305
Annual Return 2012 rr_AnnualReturn2012 16.94%
Annual Return 2013 rr_AnnualReturn2013 32.84%
Annual Return 2014 rr_AnnualReturn2014 10.12%
Annual Return 2015 rr_AnnualReturn2015 0.96%
Annual Return 2016 rr_AnnualReturn2016 11.06%
Annual Return 2017 rr_AnnualReturn2017 21.89%
Annual Return 2018 rr_AnnualReturn2018 (2.27%)
Annual Return 2019 rr_AnnualReturn2019 25.64%
Annual Return 2020 rr_AnnualReturn2020 13.02%
Annual Return 2021 rr_AnnualReturn2021 23.51%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 19.82%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 19.82%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -19.87%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (19.87%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 23.51%
5 Years rr_AverageAnnualReturnYear05 15.88%
10 Years rr_AverageAnnualReturnYear10 14.89%
Date of inception rr_AverageAnnualReturnInceptionDate May 06, 2003
(John Hancock Variable Insurance Trust) | (American Growth-Income Trust) | Series III  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.25% [12]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.07%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.57%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [13]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.56%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 57
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 182
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 317
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 713
1 Year rr_AverageAnnualReturnYear01 24.13%
5 Years rr_AverageAnnualReturnYear05 16.38%
10 Years rr_AverageAnnualReturnYear10 15.42%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 03, 2008
(John Hancock Variable Insurance Trust) | (American International Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek to provide long-term growth of capital.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund, which operates as a feeder fund, does not pay transaction costs, such as commissions, when it buys and sells shares of the master fund (or “turns over” its portfolio). A master 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 master fund and of the fund. During its most recent fiscal year, the master fund’s portfolio turnover rate was 9% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 9.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The fund invests all of its assets in Class 1 shares of its master fund, the International Fund, a series of American Funds Insurance Series. The International Fund invests primarily in common stocks of companies domiciled outside the United States, including companies domiciled in emerging markets, that the advisor believes have the potential for growth.

The master fund may invest in other funds managed by the investment adviser or its affiliates to more effectively invest in a diversified set of securities in a specific asset class such as money market instruments, bonds and other securities (“Central Funds”). Shares of Central Funds are only offered for purchase to the master fund’s investment advisor and its affiliates and other funds, investment vehicles and accounts managed by the master fund’s investment advisor and its affiliates. When investing in Central Funds, the master fund bears its proportionate share of the expenses of the Central Funds in which it invests but does not bear additional management fees through its investment in such Central Funds. The investment results of the portion of the master fund’s assets invested in the Central Funds will be based upon the investment results of the Central Funds.

The manager considers environmental, social, and/or governance (ESG) factors, alongside other relevant factors, as part of its investment process. 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.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
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.
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.
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. 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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity risk.
Investment company securities risk. The fund may invest in securities of other investment companies. Fund shareholders indirectly bear their proportionate share of the expenses of each such investment company. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
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.
Liquidity risk. The extent (if at all) to which a security may be sold without negatively impacting its market value may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.
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.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series II 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q4, 21.55%
Worst quarter: 2020, Q1, -24.67%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (American International Trust) | MSCI ACWI ex USA Index (reflects no deduction for fees, expenses, or taxes, except foreign withholding taxes on dividends)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 7.82%
5 Years rr_AverageAnnualReturnYear05 9.61%
10 Years rr_AverageAnnualReturnYear10 7.28%
(John Hancock Variable Insurance Trust) | (American International Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.48% [14]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.60%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.09%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.17%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [15]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.16%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 118
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 371
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 643
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,419
1 Year rr_AverageAnnualReturnYear01 (1.81%)
5 Years rr_AverageAnnualReturnYear05 9.23%
10 Years rr_AverageAnnualReturnYear10 7.74%
Date of inception rr_AverageAnnualReturnInceptionDate Jul. 10, 2003
(John Hancock Variable Insurance Trust) | (American International Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.48% [14]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.75%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.09%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.32%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [15]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.31%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 133
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 417
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 723
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,589
Annual Return 2012 rr_AnnualReturn2012 17.26%
Annual Return 2013 rr_AnnualReturn2013 20.98%
Annual Return 2014 rr_AnnualReturn2014 (3.15%)
Annual Return 2015 rr_AnnualReturn2015 (4.98%)
Annual Return 2016 rr_AnnualReturn2016 2.97%
Annual Return 2017 rr_AnnualReturn2017 31.49%
Annual Return 2018 rr_AnnualReturn2018 (13.59%)
Annual Return 2019 rr_AnnualReturn2019 22.27%
Annual Return 2020 rr_AnnualReturn2020 13.40%
Annual Return 2021 rr_AnnualReturn2021 (1.96%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q4, 21.55%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 21.55%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -24.67%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (24.67%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 (1.96%)
5 Years rr_AverageAnnualReturnYear05 9.08%
10 Years rr_AverageAnnualReturnYear10 7.58%
Date of inception rr_AverageAnnualReturnInceptionDate May 06, 2003
(John Hancock Variable Insurance Trust) | (American International Trust) | Series III  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.48% [14]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.09%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.82%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [15]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.81%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 83
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 261
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 454
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,013
1 Year rr_AverageAnnualReturnYear01 (1.50%)
5 Years rr_AverageAnnualReturnYear05 9.61%
10 Years rr_AverageAnnualReturnYear10 8.11%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 03, 2008
(John Hancock Variable Insurance Trust) | (Blue Chip Growth Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To provide long-term growth of capital. Current income is a secondary objective.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 36% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 36.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in the common stocks of large and medium-sized blue chip growth companies. (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.) These are firms that, in the subadvisor’s view, are well established in their industries and have the potential for above-average earnings growth.
In identifying blue chip companies, the subadvisor generally considers the following characteristics:
Leading market positions. Blue chip companies often have leading market positions that are expected to be maintained or enhanced over time. Strong positions, particularly in growing industries, can give a company pricing flexibility as well as the potential for good unit sales. These factors, in turn, can lead to higher earnings growth and greater share price appreciation.
Seasoned management teams. Seasoned management teams with a track record of providing superior financial results are important for a company’s long-term growth prospects. The subadvisor’s analysts will evaluate the depth and breadth of a company’s management experience.
Strong financial fundamentals. Companies should demonstrate faster earnings growth than their competitors and the market in general; high profit margins relative to competitors; strong cash flow; a healthy balance sheet with relatively low debt; and a high return on equity with a comparatively low dividend payout ratio.
This investment approach reflects the subadvisor’s belief that the combination of solid company fundamentals (with emphasis on the potential for above-average growth in earnings or operating cash flow) along with a positive industry outlook will ultimately reward investors with strong
investment performance. Some of the companies the subadvisor targets will have good prospects for dividend growth. The fund may at times invest significantly in stocks of information technology companies.
While most of the assets of the fund are invested in U.S. common stocks, the fund may also purchase or invest in other types of securities, including (i) U.S. and foreign currency-denominated foreign securities (up to 20% of its net assets) including American Depositary Receipts (ADRs), (ii) convertible stocks, warrants and bonds, and (iii) futures and options. Investments in convertible securities, warrants, preferred stocks and debt securities are limited to 25% of total assets.
The fund may invest in debt securities of any type, including municipal securities, without restrictions on quality or rating. Such securities would be issued by companies which meet the investment criteria for the fund but may include below-investment-grade debt securities (“junk bonds”). The fund will not purchase a below-investment-grade debt security if, immediately after such purchase, the fund would have more than 5% of its total assets invested in such securities.
The fund’s debt securities may include privately negotiated notes or loans, including loan participations and assignments (“bank loans”). These investments will only be made in companies, municipalities or entities that meet the fund’s investment criteria. Direct investments in loans may be illiquid and holding a loan could expose the fund to the risks of being a direct lender. Since the fund invests primarily in equity securities, the risks associated with fixed-income securities will not affect the fund as much as they would a fund that invests more of its assets in fixed-income securities.
The fund holds a certain portion of its assets in money market reserves, which can consist of shares of certain internal T. Rowe Price money market funds as well as U.S. dollar and foreign currency-denominated money market securities, including repurchase agreements, in the two highest rating categories, maturing in one year or less.
The fund may invest up to 10% of its total assets in hybrid instruments. Hybrid instruments are a type of high-risk derivative which can combine the characteristics of securities, futures and options. Such securities may or may not bear interest or pay dividends at below (or even relatively nominal) rates.
The fund may sell securities for a variety of reasons including to realize gains, limit losses or redeploy assets into more promising opportunities.
In pursuing the fund’s investment objectives, the subadvisor has the discretion to deviate from its normal investment criteria, as described above, and purchase securities the subadvisor believes will provide an opportunity for substantial appreciation. These situations might arise when the subadvisor believes a security could increase in value for a variety of reasons including a change in management, an extraordinary corporate event, a new product introduction or innovation or a favorable competitive development.

The fund is a non-diversified fund, which means that it may invest in a smaller number of issuers than a diversified fund and may invest more of its assets in the securities of a single issuer.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
Consumer discretionary sector risk. The consumer discretionary sector may be affected by fluctuations in supply and demand, and may also be adversely affected by changes in consumer spending as a result of world events, political and economic conditions, commodity price volatility, changes in exchange rates, imposition of import controls, increased competition, depletion of resources, and labor relations.
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.
Currency risk. Fluctuations in exchange rates may adversely affect the U.S. dollar value of a fund’s investments. Foreign currencies may decline in value, which could negatively impact performance.
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.
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.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity risk.
 
Hong Kong Stock Connect Program (Stock Connect) risk. Trading in China A-Shares through Stock Connect, a mutual market access program that enables foreign investment in the People’s Republic of China (PRC), is subject to certain restrictions and risks. Securities listed on Stock Connect may lose purchase eligibility, which could adversely affect the fund’s performance. Trading through Stock Connect is subject to trading, clearance, and settlement procedures that may continue to develop as the program matures. Any changes in laws, regulations and policies applicable to Stock Connect may affect China A-Share prices. These risks are heightened by the underdeveloped state of the PRC’s investment and banking systems in general.
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 the fund intends to utilize include: futures contracts, equity-linked notes (equity-linked notes generally reflect the risks associated with their underlying securities, depend on the credit of the notes’ issuer, may be privately placed, and may have a limited secondary market), and options. Futures contracts and options generally are subject to counterparty risk.
Hybrid instrument risk. Hybrid instruments (a type of potentially high-risk derivative) combine the elements of futures contracts or options with those of debt, preferred equity or a depository instrument. Hybrid instruments entail greater market risk and may be more volatile than traditional debt instruments, may bear interest or pay preferred dividends at below-market rates, and may be illiquid. The risks of investing in hybrid instruments are a combination of the risks of investing in securities, options, futures, and currencies.
Information technology companies risk. Information technology companies can be significantly affected by rapid obsolescence, short product cycles, competition from new market entrants, and heightened cybersecurity risk, among other factors.
Investment company securities risk. The fund may invest in securities of other investment companies. Fund shareholders indirectly bear their proportionate share of the expenses of each such investment company. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
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.
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.
Loan participations risk. Participations and assignments involve special types of risks, including credit risk, interest-rate risk, counterparty risk, liquidity risk, risks associated with extended settlement, and the risks of being a lender.
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.
Media and communications sector risk. Media and communications companies may be significantly affected by product and service obsolescence due to technological advancement or development, competitive pressures, substantial capital requirements, fluctuating demand and changes in regulation.
Non-diversified risk. Adverse events affecting a particular issuer or group of issuers may magnify losses for non-diversified funds, which may invest a large portion of assets in any one issuer or a small number of issuers.
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.
Preferred and convertible securities risk. Preferred stock dividends are payable only if declared by the issuer’s board. Preferred stock may be subject to redemption provisions. The market values of convertible securities tend to fall as interest rates rise and rise as interest rates fall. Convertible preferred stock’s value can depend heavily upon the underlying common stock’s value.
Repurchase agreements risk. The risk of a repurchase agreement transaction is limited to the ability of the seller to pay the agreed-upon sum on the delivery date. In the event of bankruptcy or other default by the seller, the instrument purchased may decline in value, interest payable on the instrument may be lost and there may be possible difficulties and delays in obtaining collateral and delays and expense in liquidating the instrument.
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.
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.
Technology companies risk. Technology companies can be significantly affected by rapid obsolescence, short product cycles, competition, and government regulation, among other factors. Investments in the technology sector may be susceptible to heightened risk of cybersecurity breaches, which may allow an unauthorized party to gain access to personally identifiable information and other customer data.
Warrants risk. The prices of warrants may not precisely reflect the prices of their underlying securities. Warrant holders do not receive dividends or have voting or credit rights. A warrant ceases to have value if not exercised prior to its expiration date.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Risk Nondiversified Status [Text] rr_RiskNondiversifiedStatus Non-diversified risk. Adverse events affecting a particular issuer or group of issuers may magnify losses for non-diversified funds, which may invest a large portion of assets in any one issuer or a small number of issuers.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. The Russell 1000 Growth Index shows how the fund’s performance compares against the returns of similar investments. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 27.72%
Worst quarter: 2018, Q4, -14.26%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Blue Chip Growth Trust) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 28.71%
5 Years rr_AverageAnnualReturnYear05 18.47%
10 Years rr_AverageAnnualReturnYear10 16.55%
(John Hancock Variable Insurance Trust) | (Blue Chip Growth Trust) | Russell 1000 Growth Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 27.60%
5 Years rr_AverageAnnualReturnYear05 25.32%
10 Years rr_AverageAnnualReturnYear10 19.79%
(John Hancock Variable Insurance Trust) | (Blue Chip Growth Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.73%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.82%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [16]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.81%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 83
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 261
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 454
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,013
Annual Return 2012 rr_AnnualReturn2012 18.36%
Annual Return 2013 rr_AnnualReturn2013 41.27%
Annual Return 2014 rr_AnnualReturn2014 9.07%
Annual Return 2015 rr_AnnualReturn2015 11.06%
Annual Return 2016 rr_AnnualReturn2016 0.81%
Annual Return 2017 rr_AnnualReturn2017 36.28%
Annual Return 2018 rr_AnnualReturn2018 1.97%
Annual Return 2019 rr_AnnualReturn2019 29.80%
Annual Return 2020 rr_AnnualReturn2020 34.30%
Annual Return 2021 rr_AnnualReturn2021 16.87%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 27.72%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 27.72%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2018, Q4, -14.26%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (14.26%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2018
1 Year rr_AverageAnnualReturnYear01 16.87%
5 Years rr_AverageAnnualReturnYear05 23.14%
10 Years rr_AverageAnnualReturnYear10 19.18%
Date of inception rr_AverageAnnualReturnInceptionDate Dec. 11, 1992
(John Hancock Variable Insurance Trust) | (Blue Chip Growth Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.73%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.02%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [16]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.01%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 103
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 324
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 562
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,247
1 Year rr_AverageAnnualReturnYear01 16.63%
5 Years rr_AverageAnnualReturnYear05 22.89%
10 Years rr_AverageAnnualReturnYear10 18.94%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Blue Chip Growth Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.73%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.77%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [16]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.76%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 78
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 245
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 427
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 953
1 Year rr_AverageAnnualReturnYear01 16.92%
5 Years rr_AverageAnnualReturnYear05 23.20%
10 Years rr_AverageAnnualReturnYear10 19.24%
Date of inception rr_AverageAnnualReturnInceptionDate Feb. 28, 2005
(John Hancock Variable Insurance Trust) | (Capital Appreciation Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek long-term growth of capital.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 40% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 40.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 65% of its total assets in equity and equity-related securities of companies, at the time of investment, that exceed $1 billion in market capitalization and that the subadvisor believes have above-average growth prospects. These companies are generally medium- to large-capitalization companies.
The subadvisor believes that growth in earnings and cash flows drives share prices over the long term; that excess returns are generated by investing in market-leading companies that create economic value through long-duration competitive advantages; and that a deeply researched understanding of company and industry fundamentals leads to successful stock selection. The subadvisor looks for companies with unique business models that build sustainable competitive advantages; catalysts that drive growth rates well above that of the market; superior financial characteristics; and attractive long-term valuations. The subadvisor seeks to capture acceleration or duration of growth that is not fully reflected in a stock’s price.
Securities in which the fund invests have historically been more volatile than the S&P 500 Index. Also, companies that have an earnings growth rate higher than that of the average S&P 500 company tend to reinvest their earnings rather than distribute them. Therefore, the fund is not likely to receive significant dividend income on its securities. Seeking to invest in companies with above market-average growth, the fund may invest significantly in sectors associated with such growth, including information technology.
In addition to common stocks, nonconvertible preferred stock and convertible securities, equity-related securities in which the fund invests include: (i) American Depositary Receipts (ADRs); (ii) warrants and rights; (iii) investments in various types of business ventures, including partnerships and joint ventures; (iv) real estate investment trusts (REITs); and (v) initial public offerings (IPOs) and similar securities. (Convertible securities are securities — like
bonds, corporate notes and preferred stocks — that the fund can convert into the company’s common stock, cash value of common stock, or some other equity security.)
In addition to the principal strategies discussed above, the fund may also use the following investment strategies to attempt to increase the fund’s return or protect its assets if market conditions warrant:
■
The fund may make short sales of a security including short sales “against the box.”
■
The fund may invest up to 20% of the fund’s total assets in foreign equity securities. (For purposes of this 20% limit, ADRs and other similar receipts or shares traded in U.S. markets are not considered to be foreign securities.)
■
The fund may invest in U.S. government securities issued or guaranteed by the U.S. government or by an agency or instrumentality of the U.S. government.
■
The fund may invest in mortgage-related securities issued or guaranteed by U.S. governmental entities, including collateralized mortgage obligations, multi-class pass-through securities and stripped mortgage-backed securities.
■
The fund may invest in fixed-income securities rated investment grade. These include corporate debt and other debt obligations of U.S. and foreign issuers. The fund may invest in obligations that are not rated, but that the subadvisor believes are of comparable quality to these obligations.
■
The fund may invest in repurchase agreements.
The subadvisor considers selling or reducing a stock position when, in the opinion of the subadvisor, the stock has experienced a fundamental disappointment in earnings, it has reached an intermediate price objective and its outlook no longer seems sufficiently promising, a relatively more attractive stock emerges or the stock has experienced adverse price movement.
The fund’s investment process may, at times, result in a higher than average portfolio turnover ratio and increased trading expenses.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
Consumer discretionary sector risk. The consumer discretionary sector may be affected by fluctuations in supply and demand, and may also be adversely affected by changes in consumer spending as a result of world events, political and economic conditions, commodity price volatility, changes in exchange rates, imposition of import controls, increased competition, depletion of resources, and labor relations.
Credit and counterparty risk. The issuer or guarantor of a fixed-income security 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.
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.
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.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity risk.
High portfolio turnover risk. Trading securities actively and frequently can increase transaction costs (thus lowering performance) and taxable distributions.
Information technology companies risk. Information technology companies can be significantly affected by rapid obsolescence, short product cycles, competition from new market entrants, and heightened cybersecurity risk, among other factors.
Initial public offerings (IPOs) risk. IPO share prices are frequently volatile and may significantly impact fund performance.
Investment company securities risk. The fund may invest in securities of other investment companies. Fund shareholders indirectly bear their proportionate share of the expenses of each such investment company. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
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.
Liquidity risk. The extent (if at all) to which a security may be sold 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.
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.
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.
Preferred and convertible securities risk. Preferred stock dividends are payable only if declared by the issuer’s board. Preferred stock may be subject to redemption provisions. The market values of convertible securities tend to fall as interest rates rise and rise as interest rates fall. Convertible preferred stock’s value can depend heavily upon the underlying common stock’s value.
Real estate investment trust (REIT) risk. REITs, pooled investment vehicles that typically invest in real estate directly or in loans collateralized by real estate, carry risks associated with owning real estate, including the potential for a decline in value due to economic or market conditions.
Real estate securities risk. Securities of companies in the real estate industry carry risks associated with owning real estate, including the potential for a decline in value due to economic or market conditions.
Repurchase agreements risk. The risk of a repurchase agreement transaction is limited to the ability of the seller to pay the agreed-upon sum on the delivery date. In the event of bankruptcy or other default by the seller, the instrument purchased may decline in value, interest payable on the instrument may be lost and there may be possible difficulties and delays in obtaining collateral and delays and expense in liquidating the instrument.
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.
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.
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.
Warrants risk. The prices of warrants may not precisely reflect the prices of their underlying securities. Warrant holders do not receive dividends or have voting or credit rights. A warrant ceases to have value if not exercised prior to its expiration date.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 35.37%
Worst quarter: 2018, Q4, -16.23%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Capital Appreciation Trust) | Russell 1000 Growth Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 27.60%
5 Years rr_AverageAnnualReturnYear05 25.32%
10 Years rr_AverageAnnualReturnYear10 19.79%
(John Hancock Variable Insurance Trust) | (Capital Appreciation Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.70%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.79%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [17]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.78%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 80
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 251
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 438
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 977
Annual Return 2012 rr_AnnualReturn2012 15.98%
Annual Return 2013 rr_AnnualReturn2013 37.41%
Annual Return 2014 rr_AnnualReturn2014 9.65%
Annual Return 2015 rr_AnnualReturn2015 11.46%
Annual Return 2016 rr_AnnualReturn2016 (1.08%)
Annual Return 2017 rr_AnnualReturn2017 36.53%
Annual Return 2018 rr_AnnualReturn2018 (0.80%)
Annual Return 2019 rr_AnnualReturn2019 32.89%
Annual Return 2020 rr_AnnualReturn2020 56.04%
Annual Return 2021 rr_AnnualReturn2021 15.75%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 35.37%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 35.37%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2018, Q4, -16.23%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (16.23%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2018
1 Year rr_AverageAnnualReturnYear01 15.75%
5 Years rr_AverageAnnualReturnYear05 26.59%
10 Years rr_AverageAnnualReturnYear10 20.14%
Date of inception rr_AverageAnnualReturnInceptionDate Nov. 01, 2000
(John Hancock Variable Insurance Trust) | (Capital Appreciation Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.70%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.99%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [17]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.98%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 100
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 314
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 546
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,212
1 Year rr_AverageAnnualReturnYear01 15.64%
5 Years rr_AverageAnnualReturnYear05 26.35%
10 Years rr_AverageAnnualReturnYear10 19.91%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Capital Appreciation Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.70%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.74%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [17]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.73%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 75
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 236
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 410
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 917
1 Year rr_AverageAnnualReturnYear01 15.76%
5 Years rr_AverageAnnualReturnYear05 26.65%
10 Years rr_AverageAnnualReturnYear10 20.19%
Date of inception rr_AverageAnnualReturnInceptionDate Feb. 28, 2005
(John Hancock Variable Insurance Trust) | (Capital Appreciation Value Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek long-term capital appreciation.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 55% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 55.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests primarily in common stocks of established U.S. companies that have above-average potential for capital growth. Common stocks typically constitute at least 50% of the fund’s total assets. The remaining assets are generally invested in other securities, including convertible securities, corporate and government debt (including mortgage- and asset-backed securities), bank loans (which represent an interest in amounts owed by a borrower to a syndicate of lenders), foreign securities, futures and options. The fund may invest up to 20% of its total assets in foreign securities.
The fund’s common stocks generally fall into one of two categories: the larger category comprises long-term core holdings whose prices when purchased by the fund are considered low in terms of company assets, earnings, or other factors; the smaller category comprises opportunistic investments whose prices the subadvisor expects to rise in the short term but not necessarily over the long term. There are no limits on the market capitalization of the issuers of the stocks in which the fund invests. Since the subadvisor attempts to prevent losses as well as achieve gains, the subadvisor typically uses a value approach in selecting investments. The subadvisor’s in-house research team seeks to identify companies that seem undervalued by various measures, such as price/book value, and may be temporarily out of favor but are believed to have good prospects for capital appreciation. The subadvisor may establish relatively large positions in companies it finds particularly attractive.
In addition, the subadvisor searches for risk/reward values among all types of securities. The portion of the fund invested in a particular type of security, such as common stocks, results largely from case-by-case investment decisions, and the size of the fund’s cash reserve may reflect the subadvisor’s ability to find companies that meet valuation criteria rather than its market outlook.
Bonds, bank loans and convertible securities may be purchased to gain additional exposure to a company or for their income or other features; maturity and quality are not necessarily major considerations in determining whether to purchase a particular security. Direct investments in loans may be illiquid and holding a loan could expose the fund to the risks of being a direct lender. The fund’s investments in below-investment grade debt securities and loans are limited to 15% of total assets. The fund may also purchase other securities, including bank debt, loan participations and assignments and futures and options. The fund’s investments in options, if any, will be primarily in an effort to protect against downside risk or to generate additional income.
The fund holds a certain portion of its assets in money market reserves, which can consist of shares of certain internal T. Rowe Price money market funds as well as U.S. dollar and foreign currency-denominated money market securities, including repurchase agreements, in the two highest rating categories, maturing in one year or less.
The fund may invest up to 10% of its total assets in hybrid instruments. Hybrid instruments are a type of high-risk derivative which can combine the characteristics of securities, futures, currencies and options. Such securities may bear interest or pay dividends at below (or even relatively nominal) rates. In addition, the fund may invest up to 10% of its total assets in mortgage- and asset-backed securities.
The fund may sell securities for a variety of reasons including to realize gains, limit losses or redeploy assets into more promising opportunities.
In pursuing the fund’s investment objective, the subadvisor has the discretion to purchase some securities that do not meet its normal investment criteria, as described above, when it perceives an unusual opportunity for gain. These special situations might arise when the subadvisor believes a security could increase in value for a variety of reasons including a change in management, an extraordinary corporate event, a new product introduction or a favorable competitive development.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
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.
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.
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.
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.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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 the fund intends to utilize include: credit default swaps, futures contracts, and options. Futures contracts and options generally are subject to counterparty risk.
Hybrid instrument risk. Hybrid instruments (a type of potentially high-risk derivative) combine the elements of futures contracts or options with those of debt, preferred equity or a depository instrument. Hybrid instruments entail greater market risk and may be more volatile than traditional debt instruments, may bear interest or pay preferred dividends at below-market rates, and may be illiquid. The risks of investing in hybrid instruments are a combination of the risks of investing in securities, options, futures, and currencies.
Investment company securities risk. The fund may invest in securities of other investment companies. Fund shareholders indirectly bear their proportionate share of the expenses of each such investment company. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
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.
LIBOR discontinuation risk. The publication of the London Interbank Offered Rate (LIBOR), which many debt securities, derivatives and other financial instruments use as the reference or benchmark rate for interest rate calculations, was discontinued for certain maturities as of December 31, 2021, and is expected to be discontinued on June 30, 2023 for the remaining maturities. The transition process away from LIBOR may lead to increased volatility and illiquidity in markets that currently rely on LIBOR to determine interest rates, and the eventual use of an alternative reference rate may adversely affect the fund’s performance. In addition, the usefulness of LIBOR may deteriorate in the period leading up to its discontinuation, which could adversely affect the liquidity or market value of securities that use LIBOR.
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.
Loan participations risk. Participations and assignments involve special types of risks, including credit risk, interest-rate risk, counterparty risk, liquidity risk, risks associated with extended settlement, and the risks of being a lender.
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.
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.
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.
Repurchase agreements risk. The risk of a repurchase agreement transaction is limited to the ability of the seller to pay the agreed-upon sum on the delivery date. In the event of bankruptcy or other default by the seller, the instrument purchased may decline in value, interest payable on the instrument may be lost and there may be possible difficulties and delays in obtaining collateral and delays and expense in liquidating the instrument.
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.
Value investment style risk. Value securities may underperform the market as a whole, which may cause value-oriented funds to underperform equity funds with other investment strategies. Securities the manager believes are undervalued may never perform as expected.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. The Combined Index (described below) shows how the fund’s performance compares against the returns of similar investments. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.

The Combined Index represents 60% of the S&P 500 Index and 40% of the Bloomberg U.S. Aggregate Bond Index.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 13.50%
Worst quarter: 2020, Q1, -12.03%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Capital Appreciation Value Trust) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 28.71%
5 Years rr_AverageAnnualReturnYear05 18.47%
10 Years rr_AverageAnnualReturnYear10 16.55%
(John Hancock Variable Insurance Trust) | (Capital Appreciation Value Trust) | Combined Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 15.86%
5 Years rr_AverageAnnualReturnYear05 12.62%
10 Years rr_AverageAnnualReturnYear10 11.14%
(John Hancock Variable Insurance Trust) | (Capital Appreciation Value Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.82%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.06%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.93%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [18]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.92%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 94
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 295
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 514
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,142
Annual Return 2012 rr_AnnualReturn2012 14.59%
Annual Return 2013 rr_AnnualReturn2013 22.32%
Annual Return 2014 rr_AnnualReturn2014 12.22%
Annual Return 2015 rr_AnnualReturn2015 5.28%
Annual Return 2016 rr_AnnualReturn2016 8.12%
Annual Return 2017 rr_AnnualReturn2017 15.15%
Annual Return 2018 rr_AnnualReturn2018 0.39%
Annual Return 2019 rr_AnnualReturn2019 24.31%
Annual Return 2020 rr_AnnualReturn2020 17.40%
Annual Return 2021 rr_AnnualReturn2021 18.13%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 13.50%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 13.50%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -12.03%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (12.03%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 18.13%
5 Years rr_AverageAnnualReturnYear05 14.79%
10 Years rr_AverageAnnualReturnYear10 13.57%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 28, 2008
(John Hancock Variable Insurance Trust) | (Capital Appreciation Value Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.82%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.06%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.13%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [18]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.12%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 114
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 358
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 621
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,374
1 Year rr_AverageAnnualReturnYear01 17.85%
5 Years rr_AverageAnnualReturnYear05 14.56%
10 Years rr_AverageAnnualReturnYear10 13.34%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 28, 2008
(John Hancock Variable Insurance Trust) | (Capital Appreciation Value Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.82%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.06%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.88%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [18]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.87%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 89
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 280
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 487
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,083
1 Year rr_AverageAnnualReturnYear01 18.16%
5 Years rr_AverageAnnualReturnYear05 14.83%
10 Years rr_AverageAnnualReturnYear10 13.62%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 28, 2008
(John Hancock Variable Insurance Trust) | (Core Bond Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek total return consisting of income and capital appreciation.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 269% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 269.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in a broad range of investment-grade debt securities, including U.S. government obligations, corporate bonds, mortgage-backed and other asset-backed securities, and money market instruments. (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.)
The fund invests in debt securities that the subadvisor believes offer attractive yields and are undervalued relative to issues of similar credit quality and interest rate sensitivity. The fund may also invest in unrated bonds that the subadvisor believes are comparable to investment-grade debt securities. The fund may invest to a significant extent in mortgage-backed securities, including collateralized mortgage obligations.
Under normal market conditions, the subadvisor expects to maintain an effective duration within 10% (in either direction) of the duration of the Bloomberg U.S. Aggregate Bond Index (the duration of this index as of February 28, 2022 was 6.6 years).
The fund may invest:
■
Up to 25% of total assets in asset-backed securities, other than mortgage-backed securities;
■
Up to 20% of total assets in U.S. dollar-denominated obligations of foreign issuers; and
■
Up to 10% of total assets in U.S. stripped mortgage-backed securities.
As part of a mortgage-backed securities investment strategy, the fund may enter into dollar rolls. The fund may also enter into reverse repurchase agreements to enhance return.
The fund’s investment process may, at times, result in a higher than average portfolio turnover ratio and increased trading expenses.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
Changing distribution levels risk. The fund may cease or reduce the level of its distribution if income or dividends paid from its investments declines.
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.
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.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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 the fund intends to utilize include reverse repurchase agreements. An event of default or insolvency of the counterparty to a reverse repurchase agreement could result in delays or restrictions with respect to the fund’s ability to dispose of the underlying securities. In addition, a reverse repurchase agreement may be considered a form of leverage and may, therefore, increase fluctuations in the fund’s net asset value per share (NAV).
High portfolio turnover risk. Trading securities actively and frequently can increase transaction costs (thus lowering performance) and taxable distributions.
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.
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.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 4.31%
Worst quarter: 2021, Q1, -3.30%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Core Bond Trust) | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.54%)
5 Years rr_AverageAnnualReturnYear05 3.57%
10 Years rr_AverageAnnualReturnYear10 2.90%
(John Hancock Variable Insurance Trust) | (Core Bond Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.57%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.05%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.67%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [19]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.66%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 67
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 213
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 372
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 834
Annual Return 2012 rr_AnnualReturn2012 6.47%
Annual Return 2013 rr_AnnualReturn2013 (2.16%)
Annual Return 2014 rr_AnnualReturn2014 5.93%
Annual Return 2015 rr_AnnualReturn2015 0.31%
Annual Return 2016 rr_AnnualReturn2016 2.74%
Annual Return 2017 rr_AnnualReturn2017 3.40%
Annual Return 2018 rr_AnnualReturn2018 (0.59%)
Annual Return 2019 rr_AnnualReturn2019 8.32%
Annual Return 2020 rr_AnnualReturn2020 8.62%
Annual Return 2021 rr_AnnualReturn2021 (1.96%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 4.31%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 4.31%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2021, Q1, -3.30%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (3.30%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2021
1 Year rr_AverageAnnualReturnYear01 (1.96%)
5 Years rr_AverageAnnualReturnYear05 3.47%
10 Years rr_AverageAnnualReturnYear10 3.04%
Date of inception rr_AverageAnnualReturnInceptionDate May 02, 2005
(John Hancock Variable Insurance Trust) | (Core Bond Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.57%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.05%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.87%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [19]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.86%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 88
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 277
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 481
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,072
1 Year rr_AverageAnnualReturnYear01 (2.23%)
5 Years rr_AverageAnnualReturnYear05 3.25%
10 Years rr_AverageAnnualReturnYear10 2.83%
Date of inception rr_AverageAnnualReturnInceptionDate May 02, 2005
(John Hancock Variable Insurance Trust) | (Core Bond Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.57%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.05%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.62%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [19]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.61%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 62
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 198
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 345
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 773
1 Year rr_AverageAnnualReturnYear01 (1.99%)
5 Years rr_AverageAnnualReturnYear05 3.52%
10 Years rr_AverageAnnualReturnYear10 3.09%
Date of inception rr_AverageAnnualReturnInceptionDate May 02, 2005
(John Hancock Variable Insurance Trust) | (Disciplined Value International Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek long-term growth of capital.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 60% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 60.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Board of Trustees can change the fund’s investment objective and strategies without shareholder approval.
The fund pursues its investment objective by investing, under normal circumstances, at least 80% of its net assets (plus any borrowings for investment purposes) in a portfolio of equity and equity-related securities issued by non-U.S. companies of any capitalization size. The fund may invest in all types of equity and equity-related securities, including, without limitation, exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, participatory notes, limited partnership interests, shares of other investment companies (including exchange-traded funds (ETFs)), real estate investment trusts (REITs), and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock, or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula.
The fund defines non-U.S. companies as companies: (i) that are organized under the laws of a foreign country; (ii) whose principal trading market is in a foreign country; or (iii) that have a majority of their assets, or that derive a significant portion of their revenue or profits, from businesses, investments, or sales outside of the United States. The fund primarily will be invested in issuers located in countries with developed securities markets, but may also invest in issuers located in emerging markets.
The fund may invest in securities denominated in the currencies of a variety of developed, emerging and frontier market countries.
The fund generally invests in the equity securities of issuers believed by the manager to be undervalued in the marketplace, focusing on issuers that combine attractive valuations with catalysts for change. The manager applies a bottom-up stock selection process (i.e., one that focuses primarily on issuer specific factors) in managing the fund, using a combination of fundamental and quantitative analysis. In selecting investments for the fund, the manager considers various factors, such as price-to-book value, price-to-sales and earnings ratios, dividend yields, strength of management, and cash flow to identify securities that are trading at a price that appears to be lower than the issuer’s inherent value.
The fund may (but is not required to) invest in derivatives, including put and call options, futures, forward contracts, and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and nonhedging purposes, including reducing risk, obtaining efficient market exposure, and/or enhancing investment returns.
The fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.
The fund may participate as a purchaser in Initial Public Offerings (IPOs). An IPO is a company’s first offering of stock to the public. The fund may also seek to increase its income by lending portfolio securities.
The manager will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the manager constantly monitors and adjusts as appropriate.
The fund may invest in cash or money market instruments for the purpose of meeting redemption requests or making other anticipated cash payments.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
Credit and counterparty risk. 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.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions. 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.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity risk.
Frontier-market risk. Frontier-market countries generally have smaller economies and less-developed capital markets and political systems than traditional emerging-market countries, which magnifies emerging-market risks.
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 the fund intends to utilize include: foreign currency forward contracts, futures contracts, swaps, equity-linked notes (equity-linked notes generally reflect the risks associated with their underlying securities, depend on the credit of the note’s issuer, may be privately placed, and may have a limited secondary market), 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.
Illiquid and restricted securities risk. Illiquid and restricted securities may be difficult to value and may involve greater risks than liquid securities. Illiquidity may have an adverse impact on a particular security’s market price and the fund’s ability to sell the security.
Initial public offerings (IPOs) risk. IPO share prices are frequently volatile and may significantly impact fund performance.
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.
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.
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.
Participatory notes risk. Participatory notes (p-notes) represent interests in securities listed on certain foreign exchanges. Due to transaction costs and other expenses, p-notes will not replicate exactly the performance of their underlying securities. P-notes are general unsecured contractual obligations of the financial institutions issuing the notes and are subject to liquidity risk and a high degree of counterparty risk.
Preferred and convertible securities risk. Preferred stock dividends are payable only if declared by the issuer’s board. Preferred stock may be subject to redemption provisions. The market values of convertible securities tend to fall as interest rates rise and rise as interest rates fall. Convertible preferred stock’s value can depend heavily upon the underlying common stock’s value.
Real estate investment trust (REIT) risk. REITs, pooled investment vehicles that typically invest in real estate directly or in loans collateralized by real estate, carry risks associated with owning real estate, including the potential for a decline in value due to economic or market conditions.
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.
Value investment style risk. Value securities may underperform the market as a whole, which may cause value-oriented funds to underperform equity funds with other investment strategies. Securities the manager believes are undervalued may never perform as expected.
Warrants risk. The prices of warrants may not precisely reflect the prices of their underlying securities. Warrant holders do not receive dividends or have voting or credit rights. A warrant ceases to have value if not exercised prior to its expiration date.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
A note on performance
Prior to February 12, 2020, the fund was managed by a different subadvisor pursuant to different strategies, and thus, the performance presented prior to February 12, 2020 should not be attributed to the current subadvisor, Boston Partners Global Investors, Inc. (Boston Partners). The fund’s performance shown below might have differed materially had Boston Partners managed the fund prior to February 12, 2020.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q4, 19.45%
Worst quarter: 2020, Q1, -28.10%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Disciplined Value International Trust) | MSCI EAFE Index (reflects no deduction for fees, expenses, or taxes, except foreign withholding taxes on dividends)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 11.26%
5 Years rr_AverageAnnualReturnYear05 9.55%
10 Years rr_AverageAnnualReturnYear10 8.03%
(John Hancock Variable Insurance Trust) | (Disciplined Value International Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.77%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.11%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.93%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [20]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.92%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 94
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 295
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 514
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,142
Annual Return 2012 rr_AnnualReturn2012 19.38%
Annual Return 2013 rr_AnnualReturn2013 26.15%
Annual Return 2014 rr_AnnualReturn2014 (12.51%)
Annual Return 2015 rr_AnnualReturn2015 (7.81%)
Annual Return 2016 rr_AnnualReturn2016 12.24%
Annual Return 2017 rr_AnnualReturn2017 17.14%
Annual Return 2018 rr_AnnualReturn2018 (15.03%)
Annual Return 2019 rr_AnnualReturn2019 12.33%
Annual Return 2020 rr_AnnualReturn2020 3.27%
Annual Return 2021 rr_AnnualReturn2021 13.06%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q4, 19.45%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 19.45%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -28.10%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (28.10%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 13.06%
5 Years rr_AverageAnnualReturnYear05 5.48%
10 Years rr_AverageAnnualReturnYear10 5.93%
Date of inception rr_AverageAnnualReturnInceptionDate May 03, 1999
(John Hancock Variable Insurance Trust) | (Disciplined Value International Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.77%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.11%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.13%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [20]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.12%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 114
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 358
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 621
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,374
1 Year rr_AverageAnnualReturnYear01 12.86%
5 Years rr_AverageAnnualReturnYear05 5.28%
10 Years rr_AverageAnnualReturnYear10 5.73%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Disciplined Value International Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.77%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.11%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.88%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [20]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.87%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 89
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 280
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 487
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,083
1 Year rr_AverageAnnualReturnYear01 13.15%
5 Years rr_AverageAnnualReturnYear05 5.54%
10 Years rr_AverageAnnualReturnYear10 5.98%
Date of inception rr_AverageAnnualReturnInceptionDate Feb. 28, 2005
(John Hancock Variable Insurance Trust) | (Emerging Markets Value Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek long-term capital appreciation.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 26% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 26.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal circumstances, the fund will invest at least 80% of its net assets (plus any borrowings for investment purposes) in companies associated with emerging markets designated from time to time by the subadvisor. (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.)
The fund seeks long-term capital growth through investment primarily in emerging market equity securities. The fund seeks to achieve its investment objective by investing in companies associated with emerging markets, which may include frontier markets (emerging market countries at an earlier stage of development), authorized for investment by the subadvisor (“Approved Markets”) from time to time. The fund invests its assets primarily in Approved Market equity securities listed on bona fide securities exchanges. (Approved Market Securities are defined below.) These exchanges may be either within or outside the issuer’s domicile country. The securities may be listed or traded in the form of American Depositary Receipts (ADRs), European Depositary Receipts (EDRs), Global Depositary Receipts (GDRs), Non-Voting Depositary Receipts (NVDRs) or other similar securities, including dual-listed securities.
The fund seeks to purchase emerging market equity securities that are deemed by the subadvisor to be value stocks at the time of purchase. An equity issuer is considered to have a low relative price (i.e., a value stock) primarily because it has a low price in relation to its book value. In assessing relative price, the subadvisor may consider additional factors, such as price-to-cash flow or price-to-earnings ratios.
In addition, the subadvisor may adjust the representation in the fund of an eligible company, or exclude a company, after considering such factors as free float, momentum, trading strategies, liquidity, size, relative price, profitability, investment characteristics, and other factors the subadvisor
determines to be appropriate. In assessing profitability, the subadvisor considers different ratios, such as that of earnings or profits from operations relative to book value or assets. In assessing a company’s investment characteristics, the subadvisor considers ratios such as recent changes in assets divided by total assets. The criteria the subadvisor uses for assessing relative price, profitability and investment characteristics are subject to change from time to time.
The fund will also seek to purchase emerging market equity securities across all market capitalizations, and specifically those which are deemed by the subadvisor to be value stocks at the time of purchase, as described in the paragraph above. The fund may not invest in certain eligible companies or Approved Markets described above because of constraints imposed within Approved Markets, restrictions on purchases by foreigners and the fund’s policy to invest no more than 25% of its total assets in any one industry at the time of purchase. The fund may invest in financial services companies.
The fund also may invest up to 10% of its total assets in shares of other investment companies that invest in one or more Approved Markets, although it intends to do so only where access to those markets is otherwise significantly limited.
In determining what countries are eligible markets for the fund, the subadvisor may consider various factors, including without limitation, the data, analysis and classification of countries published or disseminated by the World Bank, the International Finance Corporation, FTSE International, and MSCI. Approved emerging markets may not include all emerging markets classified by such entities. In determining whether to approve markets for investment, the subadvisor may take into account, among other things, market liquidity, relative availability of investor information, and government regulation, including fiscal and foreign exchange repatriation rules and the availability of other access to these markets for the fund.
The fund may use derivatives such as futures contracts and options on futures contracts to increase or decrease equity market exposure based on actual or expected cash inflows to or outflows from the fund. The fund may enter into futures contracts and options on futures contracts for Approved Markets or other equity market securities and indices, including those of the United States. The fund may also enter into forward currency contracts to facilitate the settlement of equity purchases of foreign securities, repatriation of foreign currency balances or exchange of one foreign currency to another currency. In addition to money market instruments and other short-term investments, the fund may invest in affiliated and unaffiliated unregistered money market funds to manage the fund’s cash pending investment in other securities or to maintain liquidity for the payment of redemptions or other purposes. Investments in money market funds may involve a duplication of certain fees and expenses.
The fund’s policy of seeking broad market diversification means the subadvisor will not utilize “fundamental” securities research techniques in identifying security selections. Generally, changes in the composition and relative ranking (in terms of price-to-book ratio) of the stocks that are eligible for purchase by the fund take place with every trade when the securities markets are open for trading due primarily to price changes of such securities. On a periodic basis, the subadvisor will identify value stocks that are eligible for investment and re-evaluate eligible value stocks no less than semiannually.
Generally, the fund does not seek current income as an investment objective, and investments will not be based upon an issuer’s dividend payment policy or record. However, many of the companies whose securities will be held by the fund do pay dividends. It is anticipated, therefore, that the fund will receive dividend income.
Approved Markets
As of the date of this prospectus, the fund is authorized to invest in the countries listed below. The subadvisor will determine in its discretion when and whether to invest in countries that have been authorized, depending on a number of factors, such as asset growth in the fund, constraints imposed within Approved Markets, and characteristics of each country’s markets. The subadvisor also may authorize other countries for investment in the future, in addition to the countries listed below. Also, the fund may continue to hold investments in countries that are not currently authorized for investment, but had been authorized for investment in the past. Emerging markets approved for investment may include countries in an earlier stage of development that are sometimes referred to as frontier markets.
■
Brazil
■
Chile
■
China
■
Colombia
■
Czech Republic
■
Greece
■
Hungary
■
India
■
Indonesia
■
Malaysia
■
Mexico
■
Philippines
■
Poland
■
Qatar
■
Saudi Arabia
■
South Africa
■
South Korea
■
Taiwan
■
Thailand
■
Turkey
■
United Arab Emirates
Approved Market Securities
“Approved Market Securities” are defined as securities that are associated with an Approved Market, and include, among others: (a) securities of companies that are organized under the laws of, or maintain their principal place of business in, an Approved Market; (b) securities for which the principal trading market is in an Approved Market; (c) securities issued or guaranteed by the government of an Approved Market country, its agencies or instrumentalities, or the central bank of such country; (d) securities of companies that derive at least 50% of their revenues or profits from goods produced or sold, investments made or services performed in Approved Markets or have at least 50% of their assets in Approved Markets; (e) securities included in the fund’s benchmark index which tracks Approved Markets; or (f) depositary shares of companies associated with Approved Markets under the criteria above. Securities of Approved Markets may include securities of companies that have characteristics and business relationships common to companies in other countries. As a result, the value of the securities of such companies may reflect economic and market forces in such other countries as well as in the Approved Markets. The subadvisor, however, will select only those companies which, in its view, have sufficiently strong exposure to economic and market forces in Approved Markets that satisfy the criteria described above. The fund also may obtain exposure to Approved Market Securities by investing in derivative instruments that derive their value from Approved Market Securities, or by investing in securities of pooled investment vehicles that invest at least 80% of their assets in Approved Market Securities.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
Credit and counterparty risk. 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.
Currency risk. Fluctuations in exchange rates may adversely affect the U.S. dollar value of a fund’s investments. Foreign currencies may decline in value, which could negatively impact performance.
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.
Emerging-market risk. The risks of investing in foreign securities are magnified in emerging markets. Emerging-market countries may experience higher inflation, interest rates, and unemployment and greater social, economic, and political uncertainties than more developed countries.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions. 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.
Financial services sector risk. Financial services companies can be significantly affected by economic, market, and business developments, borrowing costs, interest-rate fluctuations, competition, and government regulation, among other factors.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity risk.
 
Greater China risk. Investments in the Greater China region may be subject to less developed trading markets, acute political risks such as possible negative repercussions resulting from China’s relationship with Taiwan or Hong Kong, and restrictions on monetary repatriation or other adverse government actions. For example, a government may restrict investment in companies or industries considered important to national interests, or intervene in the financial markets, such as by imposing trading restrictions, or banning or curtailing short selling. A small number of companies and industries may generally represent a relatively large portion of the Greater China market as a whole.
Frontier-market risk. Frontier-market countries generally have smaller economies and less-developed capital markets and political systems than traditional emerging-market countries, which magnifies emerging-market risks.
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 the fund intends to utilize include: foreign currency forward contracts, futures contracts, options on futures, and options. Foreign currency forward contracts, futures contracts, and options generally are subject to counterparty risk. Derivatives associated with foreign currency transactions are subject to currency risk.
Investment company securities risk. The fund may invest in securities of other investment companies. Fund shareholders indirectly bear their proportionate share of the expenses of each such investment company. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
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.
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.
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.
Quantitative modeling risk. Quantitative models may not accurately predict future market movements or characteristics, which may negatively impact performance. Models also may perform differently than expected due to implementation problems, technological malfunction, or programming or data inaccuracies, among other possible issues.
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. To the extent that a fund invests in securities of companies in the financial services sector, the fund may be significantly affected by economic, market, and business developments, borrowing costs, interest-rate fluctuations, competition, and government regulation, among other factors, impacting that sector.
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.
Value investment style risk. Value securities, as a category, may underperform other segments of the market or the market as a whole and following a value-oriented investment strategy may cause the fund, at times, to underperform equity funds that employ a different investment style.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. Performance shown for periods prior to the inception date of a class is the performance of one of the fund’s oldest share classes, Series NAV. This pre-inception performance, with respect to any other share class of the fund, has not been adjusted to reflect the Rule 12b-1 fees of that class. As a result, the pre-inception performance shown for a share class other than the oldest share class may be higher or lower than it would be if adjusted to reflect the Rule 12b-1 fees of the class. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q4, 22.50%
Worst quarter: 2020, Q1, -31.87%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Emerging Markets Value Trust) | MSCI Emerging Markets Index (reflects no deduction for fees, expenses, or taxes, except foreign withholding taxes on dividends)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (2.54%)
5 Years rr_AverageAnnualReturnYear05 9.87%
10 Years rr_AverageAnnualReturnYear10 5.49%
(John Hancock Variable Insurance Trust) | (Emerging Markets Value Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.83% [21]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.16%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.04%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [22]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.03%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 105
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 330
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 573
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,270
Annual Return 2012 rr_AnnualReturn2012 18.53%
Annual Return 2013 rr_AnnualReturn2013 (3.22%)
Annual Return 2014 rr_AnnualReturn2014 (5.50%)
Annual Return 2015 rr_AnnualReturn2015 (19.08%)
Annual Return 2016 rr_AnnualReturn2016 18.00%
Annual Return 2017 rr_AnnualReturn2017 32.70%
Annual Return 2018 rr_AnnualReturn2018 (13.60%)
Annual Return 2019 rr_AnnualReturn2019 10.94%
Annual Return 2020 rr_AnnualReturn2020 3.56%
Annual Return 2021 rr_AnnualReturn2021 11.18%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q4, 22.50%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 22.50%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -31.87%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (31.87%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 11.18%
5 Years rr_AverageAnnualReturnYear05 7.93%
10 Years rr_AverageAnnualReturnYear10 4.25%
Date of inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (Emerging Markets Value Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.83% [21]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.16%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.24%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [22]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.23%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 125
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 392
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 680
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,499
1 Year rr_AverageAnnualReturnYear01 11.08%
5 Years rr_AverageAnnualReturnYear05 7.74%
10 Years rr_AverageAnnualReturnYear10 4.14%
Date of inception rr_AverageAnnualReturnInceptionDate May 27, 2015
(John Hancock Variable Insurance Trust) | (Emerging Markets Value Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.83% [21]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.16%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.99%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [22]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.98%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 100
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 314
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 546
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,212
1 Year rr_AverageAnnualReturnYear01 11.25%
5 Years rr_AverageAnnualReturnYear05 7.99%
10 Years rr_AverageAnnualReturnYear10 4.31%
Date of inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (Equity Income Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To provide substantial dividend income and also long-term growth of capital.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 21% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 21.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in equity securities, with at least 65% in common stocks of well-established companies paying above-average dividends. (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.) The fund typically employs a “value” approach and invests in stocks and other securities that appear to be undervalued by various measures and may be temporarily out of favor but have good prospects for capital appreciation and dividend growth.
Under normal market conditions, substantial dividend income means that the yield on the fund’s portfolio securities generally is expected to exceed the yield on the fund’s benchmark. The subadvisor believes that income can contribute significantly to total return over time and expects the fund’s yield to exceed that of the S&P 500 Index. While the price of a company’s stock can go up or down in response to earnings or to fluctuations in the general market, stocks paying a high level of dividend income tend to be less volatile than those with below-average dividends and may help offset losses in falling markets.
The fund will generally consider companies in the aggregate with one or more of the following characteristics:
■
established operating histories;
■
above-average dividend yield relative to the broader equity market;
■
low price/earnings ratio relative to the broader equity market;
■
sound balance sheets and other positive financial characteristics; and
■
low stock price relative to a company’s underlying value, as measured by assets, cash flow or business franchises.
The fund may also purchase other types of securities in keeping with its investment objective, including:
■
U.S. dollar- and foreign currency-denominated foreign securities including American Depositary Receipts (ADRs) (up to 25% of total assets);
■
preferred stocks;
■
convertible stocks, bonds, and warrants;
■
futures and options; and
■
bank debt, loan participations and assignments.
The fund may invest in fixed-income securities without restrictions on quality or rating, including up to 10% in below-investment-grade fixed-income securities (“junk bonds”). The fund’s fixed-income investments may include privately negotiated notes or loans, including loan participations and assignments (“bank loans”). These investments will only be made in companies, municipalities or entities that meet the fund’s investment criteria. Direct investments in loans may be illiquid and holding a loan could expose the fund to the risks of being a direct lender. Since the fund invests primarily in equity securities, the risks associated with fixed income securities will not affect the fund as much as they would a fund that invests more of its assets in fixed-income securities.
The fund holds a certain portion of its assets in money market reserves, which can consist of shares of certain internal T. Rowe Price money market funds as well as U.S. dollar and foreign currency-denominated money market securities, including repurchase agreements, in the two highest rating categories, maturing in one year or less.
The fund may sell securities for a variety of reasons including to realize gains, limit losses or redeploy assets into more promising opportunities.
The fund may invest up to 10% of its total assets in hybrid instruments. Hybrid instruments are a type of high-risk derivative which can combine the characteristics of securities, futures and options. Such securities may bear interest or pay dividends at below market (or even relatively nominal) rates.
In pursuing the fund’s investment objective, the subadvisor has the discretion to deviate from its normal investment criteria, as described above, and purchase securities the subadvisor believes will provide an opportunity for substantial appreciation. These special situations might arise when the subadvisor believes a security could increase in value for a variety of reasons including a change in management, an extraordinary corporate event, a new product introduction or a favorable competitive development.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
Changing distribution levels risk. The fund may cease or reduce the level of its distribution if income or dividends paid from its investments declines.
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. A downgrade or default affecting any of the fund’s securities could affect the fund’s performance.
Currency risk. Fluctuations in exchange rates may adversely affect the U.S. dollar value of a fund’s investments. Foreign currencies may decline in value, which could negatively impact performance.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions. 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.
Financial services sector risk. Financial services companies can be significantly affected by economic, market, and business developments, borrowing costs, interest-rate fluctuations, competition, and government regulation, among other factors.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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 the fund intends to utilize include: futures contracts, equity-linked notes (equity-linked notes generally reflect the risks associated with their underlying securities, depend on the credit of the notes’ issuer, may be privately placed, and may have a limited secondary market), and options. Futures contracts and options generally are subject to counterparty risk.
Hybrid instrument risk. Hybrid instruments (a type of potentially high-risk derivative) combine the elements of futures contracts or options with those of debt, preferred equity or a depository instrument. Hybrid instruments entail greater market risk and may be more volatile than traditional debt instruments, may bear interest or pay preferred dividends at below-market rates, and may be illiquid. The risks of investing in hybrid instruments are a combination of the risks of investing in securities, options, futures, and currencies.
Investment company securities risk. The fund may invest in securities of other investment companies. Fund shareholders indirectly bear their proportionate share of the expenses of each such investment company. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
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.
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.
Loan participations risk. Participations and assignments involve special types of risks, including credit risk, interest-rate risk, counterparty risk, liquidity risk, risks associated with extended settlement, and the risks of being a lender.
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.
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.
Preferred and convertible securities risk. Preferred stock dividends are payable only if declared by the issuer’s board. Preferred stock may be subject to redemption provisions. The market values of convertible securities tend to fall as interest rates rise and rise as interest rates fall. Convertible preferred stock’s value can depend heavily upon the underlying common stock’s value.
Repurchase agreements risk. The risk of a repurchase agreement transaction is limited to the ability of the seller to pay the agreed-upon sum on the delivery date. In the event of bankruptcy or other default by the seller, the instrument purchased may decline in value, interest payable on the instrument may be lost and there may be possible difficulties and delays in obtaining collateral and delays and expense in liquidating the instrument.
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. To the extent that a fund invests in securities of companies in the financial services sector, the fund may be significantly affected by economic, market, and business developments, borrowing costs, interest-rate fluctuations, competition, and government regulation, among other factors, impacting that sector.
Warrants risk. The prices of warrants may not precisely reflect the prices of their underlying securities. Warrant holders do not receive dividends or have voting or credit rights. A warrant ceases to have value if not exercised prior to its expiration date.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. The S&P 500 Index shows how the fund’s performance compares against the returns of similar investments. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q4, 20.95%
Worst quarter: 2020, Q1, -28.60%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Equity Income Trust) | Russell 1000 Value Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 25.16%
5 Years rr_AverageAnnualReturnYear05 11.16%
10 Years rr_AverageAnnualReturnYear10 12.97%
(John Hancock Variable Insurance Trust) | (Equity Income Trust) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 28.71%
5 Years rr_AverageAnnualReturnYear05 18.47%
10 Years rr_AverageAnnualReturnYear10 16.55%
(John Hancock Variable Insurance Trust) | (Equity Income Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.68%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.77%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [23]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.76%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 78
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 245
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 427
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 953
Annual Return 2012 rr_AnnualReturn2012 17.44%
Annual Return 2013 rr_AnnualReturn2013 29.96%
Annual Return 2014 rr_AnnualReturn2014 7.47%
Annual Return 2015 rr_AnnualReturn2015 (6.75%)
Annual Return 2016 rr_AnnualReturn2016 19.12%
Annual Return 2017 rr_AnnualReturn2017 16.29%
Annual Return 2018 rr_AnnualReturn2018 (9.58%)
Annual Return 2019 rr_AnnualReturn2019 26.34%
Annual Return 2020 rr_AnnualReturn2020 1.02%
Annual Return 2021 rr_AnnualReturn2021 25.42%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q4, 20.95%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 20.95%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -28.60%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (28.60%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 25.42%
5 Years rr_AverageAnnualReturnYear05 10.97%
10 Years rr_AverageAnnualReturnYear10 11.86%
Date of inception rr_AverageAnnualReturnInceptionDate Feb. 19, 1993
(John Hancock Variable Insurance Trust) | (Equity Income Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.68%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.97%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [23]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.96%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 98
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 308
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 535
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,189
1 Year rr_AverageAnnualReturnYear01 25.21%
5 Years rr_AverageAnnualReturnYear05 10.75%
10 Years rr_AverageAnnualReturnYear10 11.64%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Equity Income Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.68%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.72%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [23]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.71%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 73
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 229
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 400
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 894
1 Year rr_AverageAnnualReturnYear01 25.49%
5 Years rr_AverageAnnualReturnYear05 11.02%
10 Years rr_AverageAnnualReturnYear10 11.92%
Date of inception rr_AverageAnnualReturnInceptionDate Feb. 28, 2005
(John Hancock Variable Insurance Trust) | (Financial Industries Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek growth of capital.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 74% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 74.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowing for investment purposes) in companies that are principally engaged in financial services. (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.) These companies include U.S. and foreign financial services companies of any size including banks, thrifts, finance companies, brokerage and advisory firms, real estate-related firms, insurance companies, financial technology companies and financial holding companies. The fund may gain exposure to securities described in these strategies through investing in investment companies and pooled investment vehicles.
In managing the fund, the subadvisor focuses primarily on stock selection rather than industry allocation. In choosing individual stocks, the subadvisor uses fundamental financial analysis to identify securities that appear comparatively undervalued.
The fund concentrates its investments (invests more than 25% of its total assets) in companies that are principally engaged in financial services, and therefore may experience greater volatility than funds investing in a broader range of industries.
Given the industry-wide trend toward consolidation, the subadvisor also invests in companies that appear to be positioned for a merger. The subadvisor generally gathers firsthand information about companies from interviews and company visits.
The fund may invest in U.S. and foreign bonds, including up to 5% of net assets in below investment-grade bonds (i.e., “junk bonds”) rated as low as CCC by S&P Global Ratings (S&P) or Caa by Moody’s Investors Service, Inc. (Moody’s) and their unrated equivalents. It may also invest up to 15% of net assets in investment-grade short-term securities. The fund’s investment policies are based on credit ratings at the time of purchase.
In abnormal circumstances, the fund may temporarily invest up to 80% of its assets in investment-grade short-term securities. In these and other cases, the fund might not achieve its investment objective.
The fund may, to a limited extent, engage in derivative transactions that include futures contracts, options and foreign currency forward contracts, in each case for the purpose of reducing risk, obtaining efficient market exposure and/or enhancing investment returns.
The fund may invest in companies located in emerging market countries.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
Banking industry risk. Commercial banks, savings and loan associations, and holding companies of the foregoing are especially subject to adverse effects of volatile interest rates, concentrations of loans in particular industries, and significant competition. Profitability of these businesses depends significantly upon the availability and cost of capital funds. Commercial banks and savings associations are subject to extensive state regulation.
Concentration risk. Because the fund may focus on one or more industries or sectors of the economy, its performance depends in large part on the performance of those industries or sectors. As a result, the value of an investment may fluctuate more widely since it is more susceptible to market, economic, political, regulatory, and other conditions and risks affecting those industries or sectors than a fund that invests more broadly across industries and sectors.
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. A downgrade or default affecting any of the fund’s securities could affect the fund’s performance.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions. 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.
Financial services sector risk. A fund investing principally in securities of companies in the financial services sector is particularly vulnerable to events affecting that sector. Financial services companies can be significantly affected by economic, market, and business developments, borrowing costs, interest-rate fluctuations, competition, and government regulation, among other factors.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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 the fund intends to utilize include: foreign currency forward contracts, futures contracts, and options. Foreign currency forward contracts, futures contracts, and options generally are subject to counterparty risk. Derivatives associated with foreign currency transactions are subject to currency risk.
Investment company securities risk. The fund may invest in securities of other investment companies. Fund shareholders indirectly bear their proportionate share of the expenses of each such investment company. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
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.
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.
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.
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.
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.
Preferred and convertible securities risk. Preferred stock dividends are payable only if declared by the issuer’s board. Preferred stock may be subject to redemption provisions. The market values of convertible securities tend to fall as interest rates rise and rise as interest rates fall. Convertible preferred stock’s value can depend heavily upon the underlying common stock’s value.
Real estate securities risk. Securities of companies in the real estate industry carry risks associated with owning real estate, including the potential for a decline in value due to economic or market conditions.
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.
Warrants risk. The prices of warrants may not precisely reflect the prices of their underlying securities. Warrant holders do not receive dividends or have voting or credit rights. A warrant ceases to have value if not exercised prior to its expiration date.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. The S&P 500 Index shows how the fund’s performance compares against another broad measure of market performance. The Lipper Financial Services Index shows how the fund’s performance compares against the returns of similar investments. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q4, 22.33%
Worst quarter: 2020, Q1, -30.18%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Financial Industries Trust) | S&P 500 Financials Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 35.04%
5 Years rr_AverageAnnualReturnYear05 13.26%
10 Years rr_AverageAnnualReturnYear10 16.32%
(John Hancock Variable Insurance Trust) | (Financial Industries Trust) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 28.71%
5 Years rr_AverageAnnualReturnYear05 18.47%
10 Years rr_AverageAnnualReturnYear10 16.55%
(John Hancock Variable Insurance Trust) | (Financial Industries Trust) | Lipper Financial Services Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 35.90%
5 Years rr_AverageAnnualReturnYear05 11.56%
10 Years rr_AverageAnnualReturnYear10 14.67%
(John Hancock Variable Insurance Trust) | (Financial Industries Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.77%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.08%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.90%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [24]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.89%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 91
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 286
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 497
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,107
Annual Return 2012 rr_AnnualReturn2012 18.05%
Annual Return 2013 rr_AnnualReturn2013 30.75%
Annual Return 2014 rr_AnnualReturn2014 8.65%
Annual Return 2015 rr_AnnualReturn2015 (2.65%)
Annual Return 2016 rr_AnnualReturn2016 19.37%
Annual Return 2017 rr_AnnualReturn2017 15.28%
Annual Return 2018 rr_AnnualReturn2018 (14.49%)
Annual Return 2019 rr_AnnualReturn2019 31.79%
Annual Return 2020 rr_AnnualReturn2020 2.17%
Annual Return 2021 rr_AnnualReturn2021 29.70%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q4, 22.33%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 22.33%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -30.18%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (30.18%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 29.70%
5 Years rr_AverageAnnualReturnYear05 11.48%
10 Years rr_AverageAnnualReturnYear10 12.87%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 30, 2001
(John Hancock Variable Insurance Trust) | (Financial Industries Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.77%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.08%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.10%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [24]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.09%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 111
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 349
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 605
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,339
1 Year rr_AverageAnnualReturnYear01 29.38%
5 Years rr_AverageAnnualReturnYear05 11.25%
10 Years rr_AverageAnnualReturnYear10 12.64%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Financial Industries Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.77%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.08%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.85%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [24]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.84%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 86
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 270
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 470
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,048
1 Year rr_AverageAnnualReturnYear01 29.70%
5 Years rr_AverageAnnualReturnYear05 11.52%
10 Years rr_AverageAnnualReturnYear10 12.92%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Fundamental All Cap Core Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek long-term growth of capital.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 14% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 14.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in equity securities. Market capitalizations of these companies will span the capitalization spectrum. Equity securities include common, convertible, and preferred securities and their equivalents.
In managing the fund, the subadvisor looks for companies that are highly differentiated with key growth drivers, sustainable cash flow production, and high returns on capital. The subadvisor seeks to identify companies with sustainable competitive advantages and high barriers to entry, strong management and a focus on creating value for fund shareholders. Both growth and value opportunities are evaluated with an approach that uses the present value of estimated future cash flows as the core methodology for measuring intrinsic value.
The subadvisor employs a disciplined fundamental research process which produces bottom-up company assessments using key assumptions that drive sales, margins, and asset intensity. Scenario analysis is designed to provide a meaningful range of outcomes and the ability to assess investors’ embedded expectations. The subadvisor seeks to purchase companies that meet the criteria above when the shares are selling at a significant discount to intrinsic value. Sell decisions are similarly driven by long term fundamental analysis.
The subadvisor constantly reviews portfolio investments and may sell a holding when it has achieved its valuation target, if it believes there is structural or permanent deterioration in the underlying fundamentals of the business, or if it identifies what it believes is a more attractive investment opportunity.
The fund may invest up to 20% of its net assets in equity securities of foreign issuers, including American Depositary Receipts (ADRs) and similar investments. For purposes of reducing risk and/or obtaining efficient investment exposure, the fund may invest in exchange-traded funds (ETFs) and derivative instruments that include options, futures contracts, and swaps. The fund may also invest in U.S. government securities and other short-term securities such as money market instruments and repurchase agreements.
The fund may focus its investments in a particular sector or sectors of the economy.
Use of Hedging and Other Strategic Transactions. The fund is authorized to use all of the various investment strategies referred to under “Additional Information About the Funds’ Principal Risks — Hedging, derivatives and other strategic transactions risk.”

The manager considers environmental, social, and/or governance (ESG) factors, alongside other relevant factors, as part of its investment process. 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.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
Consumer discretionary sector risk. The consumer discretionary sector may be affected by fluctuations in supply and demand, and may also be adversely affected by changes in consumer spending as a result of world events, political and economic conditions, commodity price volatility, changes in exchange rates, imposition of import controls, increased competition, depletion of resources, and labor relations.
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.
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.
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.
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. 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.
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.
Financial services sector risk. Financial services companies can be significantly affected by economic, market, and business developments, borrowing costs, interest-rate fluctuations, competition, and government regulation, among other factors.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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 the fund intends to utilize if any, include: futures contracts, interest-rate swaps, options and swaps. 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 obligations.
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.
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.
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.
Preferred and convertible securities risk. Preferred stock dividends are payable only if declared by the issuer’s board. Preferred stock may be subject to redemption provisions. The market values of convertible securities tend to fall as interest rates rise and rise as interest rates fall. Convertible preferred stock’s value can depend heavily upon the underlying common stock’s value.
Repurchase agreements risk. The risk of a repurchase agreement transaction is limited to the ability of the seller to pay the agreed-upon sum on the delivery date. In the event of bankruptcy or other default by the seller, the instrument purchased may decline in value, interest payable on the instrument may be lost and there may be possible difficulties and delays in obtaining collateral and delays and expense in liquidating the instrument.
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. To the extent that a fund invests in securities of companies in the financial services sector, the fund may be significantly affected by economic, market, and business developments, borrowing costs, interest-rate fluctuations, competition, and government regulation, among other factors, impacting that sector.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 32.27%
Worst quarter: 2020, Q1, -24.67%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Fundamental All Cap Core Trust) | Russell 3000 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 25.66%
5 Years rr_AverageAnnualReturnYear05 17.97%
10 Years rr_AverageAnnualReturnYear10 16.30%
(John Hancock Variable Insurance Trust) | (Fundamental All Cap Core Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.67%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.76%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [25]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.75%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 77
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 242
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 421
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 941
Annual Return 2012 rr_AnnualReturn2012 23.52%
Annual Return 2013 rr_AnnualReturn2013 35.88%
Annual Return 2014 rr_AnnualReturn2014 9.74%
Annual Return 2015 rr_AnnualReturn2015 4.01%
Annual Return 2016 rr_AnnualReturn2016 8.34%
Annual Return 2017 rr_AnnualReturn2017 27.70%
Annual Return 2018 rr_AnnualReturn2018 (13.16%)
Annual Return 2019 rr_AnnualReturn2019 36.45%
Annual Return 2020 rr_AnnualReturn2020 26.87%
Annual Return 2021 rr_AnnualReturn2021 30.63%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 32.27%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 32.27%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -24.67%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (24.67%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 30.63%
5 Years rr_AverageAnnualReturnYear05 20.19%
10 Years rr_AverageAnnualReturnYear10 17.93%
Date of inception rr_AverageAnnualReturnInceptionDate May 05, 2003
(John Hancock Variable Insurance Trust) | (Fundamental All Cap Core Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.67%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.96%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [25]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.95%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 97
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 305
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 530
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,177
1 Year rr_AverageAnnualReturnYear01 30.34%
5 Years rr_AverageAnnualReturnYear05 19.94%
10 Years rr_AverageAnnualReturnYear10 17.70%
Date of inception rr_AverageAnnualReturnInceptionDate May 05, 2003
(John Hancock Variable Insurance Trust) | (Fundamental All Cap Core Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.67%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.71%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [25]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.70%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 72
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 226
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 394
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 882
1 Year rr_AverageAnnualReturnYear01 30.68%
5 Years rr_AverageAnnualReturnYear05 20.25%
10 Years rr_AverageAnnualReturnYear10 18.00%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Fundamental Large Cap Value Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek long-term capital appreciation.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 29% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 29.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets in equity securities of large-capitalization companies. The fund considers large-capitalization companies to be those that at the time of purchase have a market capitalization equal to or greater than that of the top 80% of the companies that comprise the Russell 1000 Index. As of February 28, 2022, the lowest market capitalization in this group was $6.3 billion. Equity securities include common, convertible, and preferred securities and their equivalents.
In managing the fund, the subadvisor looks for companies that are highly differentiated with key growth drivers, sustainable cash flow production, and high returns on capital. The subadvisor seeks to identify companies with sustainable competitive advantages and high barriers to entry, strong management and a focus on creating value for fund shareholders. Value opportunities are evaluated with an approach that uses the present value of estimated future cash flows as the core methodology for measuring intrinsic value.
The subadvisor employs a disciplined fundamental research process which produces bottom-up company assessments using key assumptions that drive sales, margins, and asset intensity. Scenario analysis is designed to provide a meaningful range of outcomes and the ability to assess investors’ embedded expectations. The subadvisor seeks to purchase companies that meet the criteria above when the shares are selling at a significant discount to intrinsic value. Sell decisions are similarly driven by long term fundamental analysis.
The subadvisor constantly reviews portfolio investments and may sell a holding when it has achieved its valuation target, if it believes there is structural or permanent deterioration in the underlying fundamentals of the business, or if it identifies what it believes is a more attractive investment opportunity.

The fund may focus its investments in a particular sector or sectors of the economy.
The fund may invest up to 20% of its net assets in equity securities of foreign issuers, including American Depositary Receipts (ADRs) and similar investments. For purposes of reducing risk and/or obtaining efficient investment exposure, the fund may invest in exchange-traded funds (ETFs) and derivative instruments that include options, futures contracts, and swaps. The fund may also invest in U.S. government securities and other short-term securities such as money market instruments and repurchase agreements.

The manager considers environmental, social, and/or governance (ESG) factors, alongside other relevant factors, as part of its investment process. 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.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
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.
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.
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.
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. 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.
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.
Financial services sector risk. Financial services companies can be significantly affected by economic, market, and business developments, borrowing costs, interest-rate fluctuations, competition, and government regulation, among other factors.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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 the fund intends to utilize include: futures contracts, options, and swaps. 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.
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.
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.
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.
Preferred and convertible securities risk. Preferred stock dividends are payable only if declared by the issuer’s board. Preferred stock may be subject to redemption provisions. The market values of convertible securities tend to fall as interest rates rise and rise as interest rates fall. Convertible preferred stock’s value can depend heavily upon the underlying common stock’s value.
Repurchase agreements risk. The risk of a repurchase agreement transaction is limited to the ability of the seller to pay the agreed-upon sum on the delivery date. In the event of bankruptcy or other default by the seller, the instrument purchased may decline in value, interest payable on the instrument may be lost and there may be possible difficulties and delays in obtaining collateral and delays and expense in liquidating the instrument.
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. To the extent that a fund invests in securities of companies in the financial services sector, the fund may be significantly affected by economic, market, and business developments, borrowing costs, interest-rate fluctuations, competition, and government regulation, among other factors, impacting that sector.
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.
Value investment style risk. Value securities may underperform the market as a whole, which may cause value-oriented funds to underperform equity funds with other investment strategies. Securities the manager believes are undervalued may never perform as expected.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 19.70%
Worst quarter: 2020, Q1, -24.95%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Fundamental Large Cap Value Trust) | Russell 1000 Value Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 25.16%
5 Years rr_AverageAnnualReturnYear05 11.16%
10 Years rr_AverageAnnualReturnYear10 12.97%
(John Hancock Variable Insurance Trust) | (Fundamental Large Cap Value Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.68%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.77%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [26]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.76%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 78
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 245
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 427
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 953
Annual Return 2012 rr_AnnualReturn2012 24.42%
Annual Return 2013 rr_AnnualReturn2013 32.41%
Annual Return 2014 rr_AnnualReturn2014 10.61%
Annual Return 2015 rr_AnnualReturn2015 (1.11%)
Annual Return 2016 rr_AnnualReturn2016 10.17%
Annual Return 2017 rr_AnnualReturn2017 17.43%
Annual Return 2018 rr_AnnualReturn2018 (17.03%)
Annual Return 2019 rr_AnnualReturn2019 35.85%
Annual Return 2020 rr_AnnualReturn2020 11.96%
Annual Return 2021 rr_AnnualReturn2021 29.96%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 19.70%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 19.70%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -24.95%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (24.95%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 29.96%
5 Years rr_AverageAnnualReturnYear05 14.01%
10 Years rr_AverageAnnualReturnYear10 14.35%
Date of inception rr_AverageAnnualReturnInceptionDate May 04, 2004
(John Hancock Variable Insurance Trust) | (Fundamental Large Cap Value Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.68%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.97%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [26]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.96%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 98
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 308
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 535
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,189
1 Year rr_AverageAnnualReturnYear01 29.72%
5 Years rr_AverageAnnualReturnYear05 13.78%
10 Years rr_AverageAnnualReturnYear10 14.13%
Date of inception rr_AverageAnnualReturnInceptionDate May 04, 2004
(John Hancock Variable Insurance Trust) | (Fundamental Large Cap Value Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.68%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.72%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [26]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.71%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 73
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 229
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 400
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 894
1 Year rr_AverageAnnualReturnYear01 30.00%
5 Years rr_AverageAnnualReturnYear05 14.06%
10 Years rr_AverageAnnualReturnYear10 14.41%
Date of inception rr_AverageAnnualReturnInceptionDate Feb. 28, 2005
(John Hancock Variable Insurance Trust) | (Global Equity Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek long-term capital appreciation.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 64% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 64.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The fund seeks to generate capital appreciation by investing at least 80% of net assets (plus borrowings for investment purposes) in a diversified portfolio of equity securities. This policy is subject to change only upon 60 days’ notice to shareholders. Under normal market conditions, at least 40% of the value of the fund’s net assets will be invested in issuers domiciled outside of the United States, including in emerging markets, which includes securities for which the relevant reference entity is domiciled outside the United States, such as American Depositary Receipts (ADRs), that trade on U.S. exchanges. There are no limits on the market capitalization ranges of the companies in which the fund may invest. The fund may invest in the securities of large, medium, or small companies.
In managing the fund, the manager seeks to identify undervalued companies that exhibit attractive valuations, solid business franchises, sustainable margins/cash flow, disciplined capital allocation, strong management teams, and strong balance sheets.
The manager employs an unconstrained, bottom-up stock selection process based on disciplined fundamental research with the aim to create a diversified portfolio of quality global stocks of any size that not only demonstrate compelling value but also generate sustainable cash flows. Equity securities include common and preferred stocks and their equivalents, including depositary receipts, warrants, rights, and securities convertible into common or preferred stocks.
The decision-making process involves candidate companies being screened for valuation, quality, and dividends, together with a detailed examination of the challenges and opportunities that exist for that business. The manager will assess the valuation opportunity for that company by establishing base-case, upside, and downside price targets. The manager will take into consideration the diversification benefits and the liquidity of the security before making the final investment decision.
The fund may invest in cash, money market instruments, repurchase agreements, or other short-term instruments for the purposes of meeting redemption requests or making other anticipated cash payments.

The manager considers environmental, social, and/or governance (ESG) factors, alongside other relevant factors, as part of its investment process. 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.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions. 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.
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. 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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity risk.
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.
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.
Preferred and convertible securities risk. Preferred stock dividends are payable only if declared by the issuer’s board. Preferred stock may be subject to redemption provisions. The market values of convertible securities tend to fall as interest rates rise and rise as interest rates fall. Convertible preferred stock’s value can depend heavily upon the underlying common stock’s value.
Repurchase agreements risk. The risk of a repurchase agreement transaction is limited to the ability of the seller to pay the agreed-upon sum on the delivery date. In the event of bankruptcy or other default by the seller, the instrument purchased may decline in value, interest payable on the instrument may be lost and there may be possible difficulties and delays in obtaining collateral and delays and expense in liquidating the instrument.
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.
Warrants risk. The prices of warrants may not precisely reflect the prices of their underlying securities. Warrant holders do not receive dividends or have voting or credit rights. A warrant ceases to have value if not exercised prior to its expiration date.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
A note on performance
Prior to April 27, 2020, the fund was managed by a different subadvisor pursuant to different strategies, and thus, the performance presented prior to April 27, 2020 should not be attributed to the current subadvisor, Manulife Investment Management (US) LLC (Manulife IM (US)). The fund’s performance shown below might have differed materially had Manulife IM (US) managed the fund prior to April 27, 2020.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 14.77%
Worst quarter: 2020, Q1, -21.96%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Global Equity Trust) | MSCI World Index (reflects no deduction for fees, expenses, or taxes, except foreign withholding taxes on dividends)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 21.82%
5 Years rr_AverageAnnualReturnYear05 15.03%
10 Years rr_AverageAnnualReturnYear10 12.70%
(John Hancock Variable Insurance Trust) | (Global Equity Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.80%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.08%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.93%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [27]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.92%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 94
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 295
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 514
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,142
Annual Return 2012 rr_AnnualReturn2012 21.74%
Annual Return 2013 rr_AnnualReturn2013 31.09%
Annual Return 2014 rr_AnnualReturn2014 (2.60%)
Annual Return 2015 rr_AnnualReturn2015 (6.42%)
Annual Return 2016 rr_AnnualReturn2016 9.47%
Annual Return 2017 rr_AnnualReturn2017 18.88%
Annual Return 2018 rr_AnnualReturn2018 (14.49%)
Annual Return 2019 rr_AnnualReturn2019 16.04%
Annual Return 2020 rr_AnnualReturn2020 6.60%
Annual Return 2021 rr_AnnualReturn2021 21.30%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 14.77%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 14.77%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -21.96%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (21.96%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 21.30%
5 Years rr_AverageAnnualReturnYear05 8.81%
10 Years rr_AverageAnnualReturnYear10 9.28%
Date of inception rr_AverageAnnualReturnInceptionDate Mar. 18, 1988
(John Hancock Variable Insurance Trust) | (Global Equity Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.80%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.08%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.13%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [27]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.12%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 114
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 358
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 621
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,374
1 Year rr_AverageAnnualReturnYear01 21.01%
5 Years rr_AverageAnnualReturnYear05 8.60%
10 Years rr_AverageAnnualReturnYear10 9.06%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Global Equity Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.80%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.08%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.88%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [27]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.87%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 89
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 280
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 487
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,083
1 Year rr_AverageAnnualReturnYear01 21.32%
5 Years rr_AverageAnnualReturnYear05 8.86%
10 Years rr_AverageAnnualReturnYear10 9.33%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Health Sciences Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek long-term capital appreciation.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 29% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 29.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in common stocks of companies engaged, at the time of investment, in the research, development, production, or distribution of products or services related to health care, medicine, or the life sciences (collectively, “health sciences”). (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.)
While the fund may invest in companies of any size, the majority of its assets are expected to be invested in large- and mid-capitalization companies.
The subadvisor’s portfolio managers divide the health sciences sector into four main areas: pharmaceutical companies, health care services companies, medical products and devices providers, and biotechnology firms. Their allocation among these four areas will vary depending on the relative potential within each area and the outlook for the overall health sciences sector. While most assets will be invested in U.S. common stocks, the fund may purchase other securities, including foreign securities, futures, and options in keeping with its investment objective. In addition, the fund writes call and put options primarily as a means of generating additional income. The fund may also use options to seek protection against a decline in the value of its securities or an increase in prices of securities that may be purchased. Normally, the fund will own the securities on which it writes these options. The premium income received by writing covered calls can help reduce but not eliminate portfolio volatility.
The fund concentrates its investments (invests more than 25% of its total assets) in securities of companies in the health sciences sector, a comparatively narrow segment of the economy, and therefore may experience greater volatility than funds investing in a broader range of industries.
In managing the fund, the subadvisor uses a fundamental, bottom-up analysis that seeks to identify high quality companies and the most compelling investment opportunities. In general, the fund will follow a growth investment strategy, seeking companies whose earnings are expected to grow faster than inflation and the economy in general. When stock valuations seem unusually high, however, a “value” approach, which gives preference to seemingly undervalued companies, may also be emphasized.
The fund may invest up to 35% of its total assets in foreign securities (including emerging market securities) and may have exposure to foreign currencies through its investment in these securities, its direct holdings of foreign currencies or through its use of foreign currency exchange contracts for the purchase or sale of a fixed quantity of a foreign currency at a future date.
In pursuing its investment objective, the fund’s management has the discretion to purchase some securities that do not meet its normal investment criteria, as described above, when it perceives an opportunity for substantial appreciation. These situations might arise when the fund’s management believes a security could increase in value for a variety of reasons including a change in management, an extraordinary corporate event, or a new product introduction or innovation or a favorable competitive development.
The fund holds a certain portion of its assets in money market reserves, which can consist of shares of certain internal T. Rowe Price money market funds as well as U.S. dollar and foreign currency-denominated money market securities, including repurchase agreements, in the two highest rating categories, maturing in one year or less.
The fund may sell securities for a variety of reasons including to realize gains, limit losses or redeploy assets into more promising opportunities.
Use of Hedging and Other Strategic Transactions. The fund is authorized to use all of the various investment strategies referred to under “Additional Information About the Funds’ Principal Risks — Hedging, derivatives and other strategic transactions risk” including entering into option transactions.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
Concentration risk. Because the fund may focus on one or more industries or sectors of the economy, its performance depends in large part on the performance of those industries or sectors. As a result, the value of an investment may fluctuate more widely since it is more susceptible to market, economic, political, regulatory, and other conditions and risks affecting those industries or sectors than a fund that invests more broadly across industries and sectors.
Credit and counterparty risk. 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.
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.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity risk.
 
Hong Kong Stock Connect Program (Stock Connect) risk. Trading in China A-Shares through Stock Connect, a mutual market access program that enables foreign investment in the People’s Republic of China (PRC), is subject to certain restrictions and risks. Securities listed on Stock Connect may lose purchase eligibility, which could adversely affect the fund’s performance. Trading through Stock Connect is subject to trading, clearance, and settlement procedures that may continue to develop as the program matures. Any changes in laws, regulations and policies applicable to Stock Connect may affect China A-Share prices. These risks are heightened by the underdeveloped state of the PRC’s investment and banking systems in general.
Healthcare sector risk. Health sciences companies may be significantly affected by product obsolescence, thin capitalization, limited product lines and markets, civil liability claims, and legislative or regulatory activities, among other factors.
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 the fund intends to utilize include: foreign currency forward contracts, futures contracts, and options. Foreign currency forward contracts, futures contracts, and options generally are subject to counterparty risk. Derivatives associated with foreign currency transactions are subject to currency risk.
Investment company securities risk. The fund may invest in securities of other investment companies. Fund shareholders indirectly bear their proportionate share of the expenses of each such investment company. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
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.
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.
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.
Repurchase agreements risk. The risk of a repurchase agreement transaction is limited to the ability of the seller to pay the agreed-upon sum on the delivery date. In the event of bankruptcy or other default by the seller, the instrument purchased may decline in value, interest payable on the instrument may be lost and there may be possible difficulties and delays in obtaining collateral and delays and expense in liquidating the instrument.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. The Lipper Health/Biotechnology Index shows how the fund’s performance compares against the returns of similar investments. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 23.63%
Worst quarter: 2018, Q4, -16.07%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Health Sciences Trust) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 28.71%
5 Years rr_AverageAnnualReturnYear05 18.47%
10 Years rr_AverageAnnualReturnYear10 16.55%
(John Hancock Variable Insurance Trust) | (Health Sciences Trust) | Lipper Health/Biotechnology Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 3.24%
5 Years rr_AverageAnnualReturnYear05 16.77%
10 Years rr_AverageAnnualReturnYear10 17.77%
(John Hancock Variable Insurance Trust) | (Health Sciences Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.90% [28]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.06%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.01%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [29]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.00%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 102
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 321
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 557
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,235
Annual Return 2012 rr_AnnualReturn2012 31.89%
Annual Return 2013 rr_AnnualReturn2013 51.15%
Annual Return 2014 rr_AnnualReturn2014 31.83%
Annual Return 2015 rr_AnnualReturn2015 12.69%
Annual Return 2016 rr_AnnualReturn2016 (10.57%)
Annual Return 2017 rr_AnnualReturn2017 27.51%
Annual Return 2018 rr_AnnualReturn2018 0.69%
Annual Return 2019 rr_AnnualReturn2019 28.68%
Annual Return 2020 rr_AnnualReturn2020 27.17%
Annual Return 2021 rr_AnnualReturn2021 11.19%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 23.63%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 23.63%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2018, Q4, -16.07%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (16.07%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2018
1 Year rr_AverageAnnualReturnYear01 11.19%
5 Years rr_AverageAnnualReturnYear05 18.49%
10 Years rr_AverageAnnualReturnYear10 19.99%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 30, 2001
(John Hancock Variable Insurance Trust) | (Health Sciences Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.90% [28]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.06%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.21%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [29]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.20%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 122
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 383
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 664
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,465
1 Year rr_AverageAnnualReturnYear01 10.97%
5 Years rr_AverageAnnualReturnYear05 18.26%
10 Years rr_AverageAnnualReturnYear10 19.75%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Health Sciences Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.90% [28]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.06%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.96%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [29]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.95%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 97
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 305
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 530
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,177
1 Year rr_AverageAnnualReturnYear01 11.23%
5 Years rr_AverageAnnualReturnYear05 18.55%
10 Years rr_AverageAnnualReturnYear10 20.05%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (High Yield Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To realize an above-average total return over a market cycle of three to five years, consistent with reasonable risk.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 76% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 76.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowings for investment purposes) at the time of investment in high yield securities. (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.) The fund’s investments may include corporate bonds, preferred stocks, U.S. government and foreign securities, mortgage-backed securities, loan assignments or participations and convertible securities which have the following ratings (or, if unrated, are considered by the subadvisor to be of equivalent quality):
Corporate Bonds, Preferred Stocks and Convertible Securities
Moody’s Investors Service, Inc........................ Ba through C
S&P Global Ratings........................... BB through D
Below-investment-grade securities are commonly referred to as “junk bonds.” The fund may also invest in investment-grade securities.
As part of its investment strategy, the fund will generally invest without restrictions within these ratings category ranges, or in unrated securities considered to be of equivalent quality by the subadvisor.
The fund may invest in foreign bonds and other fixed-income securities denominated in foreign currencies, where, in the opinion of the subadvisor, the combination of current yield and currency value offer attractive expected returns. Foreign securities in which the fund may invest include emerging market securities. The fund may invest up to 100% of its assets in foreign securities.
The fund may also enter into various derivative transactions for both hedging and non-hedging purposes, including for purposes of enhancing returns. These derivative transactions include, but are not limited to, futures, options, swaps and forwards. In particular, the fund may use interest rate swaps, credit default swaps (on individual securities and/or baskets of securities), futures contracts and/or mortgage-backed securities to a significant extent, although the amounts invested in these instruments may change from time to time.
The fund may invest in fixed- and floating-rate loans, generally in the form of loan participations and assignments of such loans.
The fund normally maintains an average portfolio duration of between three and seven years. However, the fund may invest in individual securities of any duration. Duration is an approximate measure of the sensitivity of the market value of a security to changes in interest rates.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
Changing distribution levels risk. The fund may cease or reduce the level of its distribution if income or dividends paid from its investments declines.
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.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions.
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.
Floating rate loans risk. Floating rate loans are generally rated below investment-grade and are generally considered speculative because they present a greater risk of loss, including default, than higher quality debt instruments.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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 the fund intends to utilize include: credit default swaps; foreign currency forward contracts; foreign currency swaps; 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.
LIBOR discontinuation risk. The publication of the London Interbank Offered Rate (LIBOR), which many debt securities, derivatives and other financial instruments use as the reference or benchmark rate for interest rate calculations, was discontinued for certain maturities as of December 31, 2021, and is expected to be discontinued on June 30, 2023 for the remaining maturities. The transition process away from LIBOR may lead to increased volatility and illiquidity in markets that currently rely on LIBOR to determine interest rates, and the eventual use of an alternative reference rate may adversely affect the fund’s performance. In addition, the usefulness of LIBOR may deteriorate in the period leading up to its discontinuation, which could adversely affect the liquidity or market value of securities that use LIBOR.
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.
Loan participations risk. Participations and assignments involve special types of risks, including credit risk, interest-rate risk, counterparty risk, liquidity risk, risks associated with extended settlement, and the risks of being a lender.
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.
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.
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.
Preferred and convertible securities risk. Preferred stock dividends are payable only if declared by the issuer’s board. Preferred stock may be subject to redemption provisions. The market values of convertible securities tend to fall as interest rates rise and rise as interest rates fall. Convertible preferred stock’s value can depend heavily upon the underlying common stock’s value.
Repurchase agreements risk. The risk of a repurchase agreement transaction is limited to the ability of the seller to pay the agreed-upon sum on the delivery date. In the event of bankruptcy or other default by the seller, the instrument purchased may decline in value, interest payable on the instrument may be lost and there may be possible difficulties and delays in obtaining collateral and delays and expense in liquidating the instrument.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 11.06%
Worst quarter: 2020, Q1, -14.88%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (High Yield Trust) | Bloomberg U.S. High Yield 2% Issuer Capped Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 5.26%
5 Years rr_AverageAnnualReturnYear05 6.28%
10 Years rr_AverageAnnualReturnYear10 6.82%
(John Hancock Variable Insurance Trust) | (High Yield Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.70%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.08%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.83%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [30]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.82%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 84
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 264
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 460
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,024
Annual Return 2012 rr_AnnualReturn2012 18.99%
Annual Return 2013 rr_AnnualReturn2013 8.35%
Annual Return 2014 rr_AnnualReturn2014 0.28%
Annual Return 2015 rr_AnnualReturn2015 (8.32%)
Annual Return 2016 rr_AnnualReturn2016 16.26%
Annual Return 2017 rr_AnnualReturn2017 7.50%
Annual Return 2018 rr_AnnualReturn2018 (3.01%)
Annual Return 2019 rr_AnnualReturn2019 15.66%
Annual Return 2020 rr_AnnualReturn2020 5.81%
Annual Return 2021 rr_AnnualReturn2021 5.82%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 11.06%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 11.06%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -14.88%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (14.88%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 5.82%
5 Years rr_AverageAnnualReturnYear05 6.19%
10 Years rr_AverageAnnualReturnYear10 6.41%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 02, 1997
(John Hancock Variable Insurance Trust) | (High Yield Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.70%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.08%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.03%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [30]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.02%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 104
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 327
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 568
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,259
1 Year rr_AverageAnnualReturnYear01 5.67%
5 Years rr_AverageAnnualReturnYear05 6.00%
10 Years rr_AverageAnnualReturnYear10 6.21%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (High Yield Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.70%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.08%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.78%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [30]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.77%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 79
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 248
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 432
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 965
1 Year rr_AverageAnnualReturnYear01 5.78%
5 Years rr_AverageAnnualReturnYear05 6.22%
10 Years rr_AverageAnnualReturnYear10 6.45%
Date of inception rr_AverageAnnualReturnInceptionDate Feb. 28, 2005
(John Hancock Variable Insurance Trust) | (International Equity Index Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek to track the performance of a broad-based equity index of foreign companies primarily in developed countries and, to a lesser extent, in emerging markets.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 5% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 5.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its assets in securities listed in the MSCI All Country World Excluding U.S. Index (the “Index”), or American Depositary Receipts (ADRs) or Global Depositary Receipts (GDRs) representing such securities. (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.) As of February 28, 2022, the market capitalization range of the Index was $65.8 million to $530.7 billion.
The fund is an index fund and differs from an actively-managed fund. Actively-managed funds seek to outperform their benchmark indices through research and analysis. Over time, their performance may differ significantly from their benchmark indices. Index funds are passively managed funds that seek to track the risk and return profile of market indices. An index is an unmanaged group of securities whose overall performance is used as an investment benchmark. Indices may track broad investment markets, such as the global equity market, or more narrow investment markets, such as the U.S. small cap equity market. However, an index fund has operating expenses and transaction costs, while a market index does not. Therefore, the fund, while it attempts to track its target index, typically will be unable to match the performance of the index exactly due to such fees and expenses.
The fund uses “sampling” methodology in seeking to track the total return performance of the Index. This means that the fund does not intend and is not required to purchase all of the securities in the Index, but rather intends to hold a representative sample of the securities in the Index in an effort to
achieve the fund’s investment objective. The quantity of holdings in the fund will be based on a number of factors, including asset size of the fund. Although the subadvisor generally expects the fund to hold less than the total number of securities in the Index, it reserves the right to hold as many securities as it believes necessary to achieve the fund’s investment objective.
The fund’s assets are normally fully invested. The subadvisor invests in stock index futures to maintain market exposure and manage cash flow. Although the subadvisor may employ foreign currency hedging techniques, it normally maintains the currency exposure of the underlying equity investments.
The fund may purchase other types of securities that are not primary investment vehicles, for example, European Depositary Receipts (EDRs), certain exchange-traded funds (ETFs), cash equivalents, and certain derivatives (investments whose value is based on indices or other securities). In addition, the fund may invest in securities that are not included in the Index, including futures, options, swap contracts and other derivatives, cash and cash equivalents or money market instruments, such as repurchase agreements and money market funds (including money market funds advised by the advisor or subadvisor).
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance.
Credit and counterparty risk. 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.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions.
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.
Financial services sector risk. Financial services companies can be significantly affected by economic, market, and business developments, borrowing costs, interest-rate fluctuations, competition, and government regulation, among other factors.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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 the fund intends to utilize include: futures contracts, options, and swaps. 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.
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 transaction expenses, 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.
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.
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.
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.
Quantitative modeling risk. Quantitative models may not accurately predict future market movements or characteristics, which may negatively impact performance. Models also may perform differently than expected due to implementation problems, technological malfunction, or programming or data inaccuracies, among other possible issues.
Repurchase agreements risk. The risk of a repurchase agreement transaction is limited to the ability of the seller to pay the agreed-upon sum on the delivery date. In the event of bankruptcy or other default by the seller, the instrument purchased may decline in value, interest payable on the instrument may be lost and there may be possible difficulties and delays in obtaining collateral and delays and expense in liquidating the instrument.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. Performance shown for periods prior to the inception date of a class is the performance of the fund’s oldest share class. This pre-inception performance, with respect to any other share class of the fund, has not been adjusted to reflect the Rule 12b-1 fees of that class. As a result, the pre-inception performance shown for a share class other than the oldest share class may be higher or lower than it would be if adjusted to reflect the Rule 12b-1 fees of the class. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series NAV 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 17.11%
Worst quarter: 2020, Q1, -23.62%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (International Equity Index Trust) | MSCI ACWI ex-USA Index (reflects no deduction for fees, expenses, or taxes, except foreign withholding taxes on dividends)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 7.82%
5 Years rr_AverageAnnualReturnYear05 9.61%
10 Years rr_AverageAnnualReturnYear10 7.28%
(John Hancock Variable Insurance Trust) | (International Equity Index Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.52%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.08%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.65%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.26%) [31]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.39%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 40
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 182
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 336
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 786
1 Year rr_AverageAnnualReturnYear01 7.59%
5 Years rr_AverageAnnualReturnYear05 9.58%
10 Years rr_AverageAnnualReturnYear10 7.16%
Date of inception rr_AverageAnnualReturnInceptionDate Nov. 05, 2012
(John Hancock Variable Insurance Trust) | (International Equity Index Trust) | Series II  
Prospectus: rr_ProspectusTable  
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 0.08%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.85%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.26%) [31]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.59%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 60
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 245
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 446
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,025
1 Year rr_AverageAnnualReturnYear01 7.33%
5 Years rr_AverageAnnualReturnYear05 9.36%
10 Years rr_AverageAnnualReturnYear10 6.96%
Date of inception rr_AverageAnnualReturnInceptionDate Nov. 05, 2012
(John Hancock Variable Insurance Trust) | (International Equity Index Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
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 0.08%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.60%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.26%) [31]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.34%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 35
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 166
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 309
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 725
Annual Return 2012 rr_AnnualReturn2012 17.76%
Annual Return 2013 rr_AnnualReturn2013 14.54%
Annual Return 2014 rr_AnnualReturn2014 (4.57%)
Annual Return 2015 rr_AnnualReturn2015 (5.80%)
Annual Return 2016 rr_AnnualReturn2016 4.43%
Annual Return 2017 rr_AnnualReturn2017 27.45%
Annual Return 2018 rr_AnnualReturn2018 (14.10%)
Annual Return 2019 rr_AnnualReturn2019 21.44%
Annual Return 2020 rr_AnnualReturn2020 10.76%
Annual Return 2021 rr_AnnualReturn2021 7.59%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 17.11%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 17.11%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -23.62%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (23.62%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 7.59%
5 Years rr_AverageAnnualReturnYear05 9.64%
10 Years rr_AverageAnnualReturnYear10 7.21%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (International Small Company Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek long-term capital appreciation.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 23% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 23.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in securities of small cap companies in the particular markets in which the fund invests. (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.) Based on market capitalization data as of February 28, 2022, the market capitalization of a small company in any country in which the fund invests would be below $7.6 million. This threshold will vary by country or region. The fund will primarily invest in a broad and diverse group of equity securities of foreign small companies of developed markets, but may also hold equity securities of companies located in emerging markets.
The fund invests its assets in securities listed on bona fide securities exchanges. These exchanges may be either within or outside the issuer’s domicile country. The securities may be listed or traded in the form of American Depositary Receipts (ADRs), European Depositary Receipts (EDRs), Global Depositary Receipts (GDRs), Non-Voting Depositary Receipts (NVDRs) or other similar securities, including dual-listed securities.
The subadvisor determines company size on a country or region specific basis and based primarily on market capitalization. In the countries or regions authorized for investment, the subadvisor first ranks eligible companies listed on selected exchanges based on the companies’ market capitalizations. The subadvisor then determines the universe of eligible stocks by defining the maximum market capitalization of a small company that may be purchased by the fund with respect to each country or region. This threshold will vary by country or region, and dollar amounts will change due to market conditions.
The fund intends to purchase securities in each applicable country using a market capitalization weighted approach. The subadvisor, using this approach and its judgment, will seek to set country weights based on the relative market capitalizations of eligible small companies within each country. See “Market Capitalization Weighted Approach” below. The weightings of countries in the fund may vary from their weightings in international indices, such as those published by FTSE International or MSCI.
The fund also may use derivatives such as futures contracts and options on futures contracts, to increase or decrease equity market exposure based on actual or expected cash inflows to or outflows from the fund. The fund may enter into futures contracts and options on futures contracts for foreign or U.S. equity securities and indices. The fund may also enter into forward currency contracts to facilitate the settlement of equity purchases of foreign securities, repatriation of foreign currency balances or exchange of one foreign currency for another currency. In addition to money market instruments and other short-term investments, the fund may invest in affiliated and unaffiliated unregistered money market funds to manage the fund’s cash pending investment in other securities or to maintain liquidity for the payment of redemptions or other purposes. Investments in money market funds may involve a duplication of certain fees and expenses.
Generally, the fund does not seek current income as an investment objective and investments will not be based upon an issuer’s dividend payment policy or record. However, many of the companies whose securities will be included in the fund do pay dividends. It is anticipated, therefore, that the fund will receive dividend income.
The subadvisor will determine in its discretion when and whether to invest in countries that have been authorized for investment by its Investment Committee, depending on a number of factors such as asset growth in the fund, constraints imposed within a country’s market, and characteristics of each country’s market. The subadvisor’s Investment Committee may authorize other countries for investment in the future and the fund may continue to hold investments in countries not currently authorized for investment but that had previously been authorized for investment.
Market Capitalization Weighted Approach
The fund structure involves market capitalization weighting in determining individual security weights and, where applicable, country or region weights. Market capitalization weighting means each security is generally purchased based on the issuer’s relative market capitalization. Market capitalization weighting may be modified by the subadvisor for a variety of reasons. The subadvisor may adjust the representation in the fund of an eligible company, or exclude a company, after considering such factors as free float, momentum, trading strategies, liquidity, size, relative price, profitability, investment characteristics, and other factors the subadvisor determines to be appropriate. An equity issuer is considered to have a low relative price (i.e., a value stock) primarily because it has a low price in relation to its book value. In assessing relative price, the subadvisor may consider additional factors such as price to cash flow or price to earnings ratios. In assessing profitability, the subadvisor considers different ratios, such as that of earnings or profits from operations relative to book value or assets. In assessing a company’s investment characteristics, the subadvisor considers ratios such as recent changes in assets divided by total assets. The criteria the subadvisor uses for assessing relative price, profitability and investment characteristics are subject to change from time to time. The subadvisor may deviate from market capitalization weighting to limit or fix the exposure of the fund to a particular country or issuer to a maximum proportion of the assets of the fund. The subadvisor may exclude the stock of a company that meets applicable market capitalization criteria if the subadvisor determines, in its judgment, that the purchase of such stock is inappropriate in light of other conditions. The subadvisor may decrease the allocation of the fund’s assets to eligible small capitalization companies that generally have lower profitability and/or higher relative prices. These adjustments will result in a deviation from traditional market capitalization weighting.
Country weights may be based on the total market capitalization of companies within each country. The calculation of country weights may take into consideration the free float of companies within a country or whether these companies are eligible to be purchased for the particular strategy. In addition, to maintain a satisfactory level of diversification, the Investment Committee may limit or fix the exposure to a particular country or region to a maximum proportion of the assets of that vehicle. Country weights may also vary due to general day-to-day trading patterns and price movements. The weighting of countries may vary from their weighting in published international indices.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
Credit and counterparty risk. 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.
Currency risk. Fluctuations in exchange rates may adversely affect the U.S. dollar value of a fund’s investments. Foreign currencies may decline in value, which could negatively impact performance.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions. 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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity risk.
Geographic focus risk. The fund’s performance will be closely tied to the market, currency, economic, political, regulatory, geopolitical, and other conditions in the countries or regions in which the fund’s assets are invested and may be more volatile than the performance of more geographically-diversified funds.
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 the fund intends to utilize include: foreign currency forward contracts, futures contracts, options on futures contracts, and options. Foreign currency forward contracts, futures contracts, and options generally are subject to counterparty risk. Derivatives associated with foreign currency transactions are subject to currency risk.
Industrials sector risk. Companies in the industrials sector may be affected by general economic conditions, commodity production and pricing, supply and demand fluctuations, environmental and other government regulations, geopolitical events, interest rates, insurance costs, technological developments, liabilities arising from governmental or civil actions, labor relations, input controls, and government spending.
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.
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.
Quantitative modeling risk. Quantitative models may not accurately predict future market movements or characteristics, which may negatively impact performance. Models also may perform differently than expected due to implementation problems, technological malfunction, or programming or data inaccuracies, among other possible issues.
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.
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.
Value investment style risk. Value securities, as a category, may underperform other segments of the market or the market as a whole and following a value-oriented investment strategy may cause the fund, at times, to underperform equity funds that employ a different investment style.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. The MSCI EAFE Small Cap Index shows how the fund’s performance compares against the returns of similar investments. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series NAV 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 20.80%
Worst quarter: 2020, Q1, -30.16%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (International Small Company Trust) | MSCI World ex-USA Small Cap Index (reflects no deduction for fees, expenses, or taxes, except foreign withholding taxes on dividends)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 11.14%
5 Years rr_AverageAnnualReturnYear05 11.03%
10 Years rr_AverageAnnualReturnYear10 9.99%
(John Hancock Variable Insurance Trust) | (International Small Company Trust) | MSCI EAFE Small Cap Index (reflects no deduction for fees, expenses, or taxes, except foreign withholding taxes on dividends)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 10.10%
5 Years rr_AverageAnnualReturnYear05 11.04%
10 Years rr_AverageAnnualReturnYear10 10.80%
(John Hancock Variable Insurance Trust) | (International Small Company Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.80% [32]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.16%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.01%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [33]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.00%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 102
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 321
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 557
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,235
1 Year rr_AverageAnnualReturnYear01 13.72%
5 Years rr_AverageAnnualReturnYear05 9.34%
10 Years rr_AverageAnnualReturnYear10 9.37%
Date of inception rr_AverageAnnualReturnInceptionDate Nov. 16, 2009
(John Hancock Variable Insurance Trust) | (International Small Company Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.80% [32]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.16%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.21%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [33]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.20%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 122
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 383
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 664
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,465
1 Year rr_AverageAnnualReturnYear01 13.47%
5 Years rr_AverageAnnualReturnYear05 9.11%
10 Years rr_AverageAnnualReturnYear10 9.15%
Date of inception rr_AverageAnnualReturnInceptionDate Nov. 16, 2009
(John Hancock Variable Insurance Trust) | (International Small Company Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.80% [32]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.16%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.96%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [33]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.95%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 97
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 305
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 530
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,177
Annual Return 2012 rr_AnnualReturn2012 19.24%
Annual Return 2013 rr_AnnualReturn2013 26.29%
Annual Return 2014 rr_AnnualReturn2014 (6.85%)
Annual Return 2015 rr_AnnualReturn2015 6.68%
Annual Return 2016 rr_AnnualReturn2016 4.95%
Annual Return 2017 rr_AnnualReturn2017 29.60%
Annual Return 2018 rr_AnnualReturn2018 (20.08%)
Annual Return 2019 rr_AnnualReturn2019 22.70%
Annual Return 2020 rr_AnnualReturn2020 8.41%
Annual Return 2021 rr_AnnualReturn2021 13.77%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 20.80%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 20.80%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -30.16%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (30.16%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 13.77%
5 Years rr_AverageAnnualReturnYear05 9.41%
10 Years rr_AverageAnnualReturnYear10 9.43%
Date of inception rr_AverageAnnualReturnInceptionDate May 01, 2006
(John Hancock Variable Insurance Trust) | (Investment Quality Bond Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To provide a high level of current income consistent with the maintenance of principal and liquidity.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 37% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 37.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in bonds rated investment grade at the time of investment. (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.) The fund will tend to focus on corporate bonds and U.S. government bonds with intermediate-to longer-term maturities.
The subadvisor’s investment decisions derive from a three-pronged analysis, including:
■
sector analysis,
■
credit research, and
■
call protection.
Sector analysis focuses on the differences in yields among security types, issuers, and industry sectors. Credit research focuses on both quantitative and qualitative criteria established by the subadvisor, such as call protection (payment guarantees), an issuer’s industry, operating and financial profiles, business strategy, management quality, and projected financial and business conditions. Individual purchase and sale decisions are made on the basis of relative value and the contribution of a security to the desired characteristics of the overall fund. Factors considered include:
■
relative valuation of available alternatives,
■
impact on portfolio yield, quality and liquidity, and
■
impact on portfolio maturity and sector weights.
The subadvisor attempts to maintain a high, steady and possibly growing income stream.
At least 80% of the fund’s net assets are invested in bonds and debentures, including:
■
marketable debt securities of U.S. and foreign issuers (payable in U.S. dollars), rated as investment grade by Moody’s or S&P at the time of purchase, including privately placed debt securities, corporate bonds, asset-backed securities, mortgage-backed securities and commercial mortgage-backed securities;
■
securities issued or guaranteed as to principal or interest by the U.S. government or its agencies or instrumentalities, including mortgage-backed securities; and
■
cash and cash equivalent securities which are authorized for purchase by Money Market Trust, a series of the Trust.
The balance (no more than 20%) of the fund’s net assets may be invested in below-investment-grade bonds and other securities including privately placed debt securities:
■
U.S. and foreign debt securities,
■
preferred stocks,
■
convertible securities (including those issued in the Euromarket),
■
securities carrying warrants to purchase equity securities,
■
foreign exchange contracts for purposes of hedging portfolio exposures to foreign currencies or for purposes of obtaining exposure to foreign currencies,
■
hybrid securities, and
■
below-investment-grade and investment-grade foreign currency fixed-income securities, including up to 5% emerging market fixed-income securities.
In pursuing its investment objective, the fund may invest up to 20% of its net assets in U.S. and foreign high yield (high risk) corporate and government debt securities (commonly known as “junk bonds”). These instruments are rated “Ba” or below by Moody’s or “BB” or below by S&P (or, if unrated, are deemed of comparable quality as determined by the subadvisor). No minimum rating standard is required for a purchase of high yield securities by the fund. While the fund may only invest up to 20% of its net assets in securities rated in these rating categories, it is not required to dispose of bonds that may be downgraded after purchase, even though such downgrade may cause the fund to hold more than 20% of its net assets in high yield securities. The fund’s investment policies are based on credit ratings at the time of purchase.
The fund normally maintains an average portfolio duration of between three and seven years. However, the fund may invest in individual securities of any duration. Duration is an approximate measure of the sensitivity of the market value of a security to changes in interest rates.
The fund may invest in derivatives such as interest rate futures and options, interest rate swaps, currency forwards, options on financial indices and credit default swaps to manage duration and yield curve positioning, implement foreign interest rate and currency positions, hedge against risk and/or as a substitute for investing directly in a security.
The fund may make short sales of a security including short sales “against the box.”
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
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.
Changing distribution levels risk. The fund may cease or reduce the level of its distribution if income or dividends paid from its investments declines.
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.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions.
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.
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. If applicable, depositary
receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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 the fund intends to utilize include: credit default swaps, foreign currency forward contracts, futures contracts, options, and interest-rate 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.
Hybrid instrument risk. Hybrid instruments (a type of potentially high-risk derivative) combine the elements of futures contracts or options with those of debt, preferred equity or a depository instrument. Hybrid instruments entail greater market risk and may be more volatile than traditional debt instruments, may bear interest or pay preferred dividends at below-market rates, and may be illiquid. The risks of investing in hybrid instruments are a combination of the risks of investing in securities, options, futures, and currencies.
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.
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.
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.
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.
 
TBA mortgage contracts. To-be-announced (TBA) mortgage contracts involve a risk of loss if the value of the underlying security to be purchased declines prior to delivery date. The yield obtained for such securities may be higher or lower than yields available in the market on delivery date.
Preferred and convertible securities risk. Preferred stock dividends are payable only if declared by the issuer’s board. Preferred stock may be subject to redemption provisions. The market values of convertible securities tend to fall as interest rates rise and rise as interest rates fall. Convertible preferred stock’s value can depend heavily upon the underlying common stock’s value.
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.
Warrants risk. The prices of warrants may not precisely reflect the prices of their underlying securities. Warrant holders do not receive dividends or have voting or credit rights. A warrant ceases to have value if not exercised prior to its expiration date.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 5.96%
Worst quarter: 2013, Q2, -3.48%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Investment Quality Bond Trust) | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.54%)
5 Years rr_AverageAnnualReturnYear05 3.57%
10 Years rr_AverageAnnualReturnYear10 2.90%
(John Hancock Variable Insurance Trust) | (Investment Quality Bond Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.60%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.09%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.74%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [34]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.73%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 75
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 236
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 410
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 917
Annual Return 2012 rr_AnnualReturn2012 7.59%
Annual Return 2013 rr_AnnualReturn2013 (1.93%)
Annual Return 2014 rr_AnnualReturn2014 5.47%
Annual Return 2015 rr_AnnualReturn2015 (0.82%)
Annual Return 2016 rr_AnnualReturn2016 4.29%
Annual Return 2017 rr_AnnualReturn2017 4.60%
Annual Return 2018 rr_AnnualReturn2018 (0.82%)
Annual Return 2019 rr_AnnualReturn2019 9.36%
Annual Return 2020 rr_AnnualReturn2020 9.37%
Annual Return 2021 rr_AnnualReturn2021 (1.26%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 5.96%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 5.96%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2013, Q2, -3.48%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (3.48%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2013
1 Year rr_AverageAnnualReturnYear01 (1.26%)
5 Years rr_AverageAnnualReturnYear05 4.15%
10 Years rr_AverageAnnualReturnYear10 3.50%
Date of inception rr_AverageAnnualReturnInceptionDate Jun. 19, 1985
(John Hancock Variable Insurance Trust) | (Investment Quality Bond Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.60%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.09%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.94%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [34]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.93%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 95
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 299
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 519
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,154
1 Year rr_AverageAnnualReturnYear01 (1.45%)
5 Years rr_AverageAnnualReturnYear05 3.94%
10 Years rr_AverageAnnualReturnYear10 3.29%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Investment Quality Bond Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.60%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.09%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.69%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [34]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.68%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 69
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 220
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 383
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 858
1 Year rr_AverageAnnualReturnYear01 (1.21%)
5 Years rr_AverageAnnualReturnYear05 4.22%
10 Years rr_AverageAnnualReturnYear10 3.56%
Date of inception rr_AverageAnnualReturnInceptionDate Feb. 28, 2005
(John Hancock Variable Insurance Trust) | (Lifestyle Balanced Portfolio)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek a balance between a high level of current income and growth of capital, with a greater emphasis on growth of capital.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees 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.”
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
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 10% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 10.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The fund, except as otherwise described below, operates as a fund of funds and normally invests approximately 50% of its assets in underlying funds that invest primarily in equity securities or in futures contracts on equity markets (the “Equity Allocation”) and approximately 50% of its assets in underlying funds that invest primarily in fixed-income securities or in futures contracts on fixed-income markets (the “Fixed Income Allocation”). Underlying funds may include exchange traded funds (“ETFs”) and the fund may invest a significant portion of its assets in ETFs. At the discretion of the subadvisor, the Equity Allocation may also include direct investments in equity securities and the Fixed Income Allocation may also include direct investments in fixed-income securities. The subadvisor may also determine in light of market or economic conditions that the normal percentage limitations should be exceeded to protect the fund or achieve its investment objective.
Within the prescribed percentage allocation, the subadvisor selects the percentage level to be maintained in specific underlying funds and in futures contracts on equity or fixed-income markets. These allocations may be changed at any time by the subadvisor.
The fund may invest in various underlying 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 underlying 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 underlying funds that purchase futures contracts on equity markets.
Certain of these underlying funds focus their investment strategy on fixed-income securities, which may include investment grade and below-investment-grade debt securities with maturities that range from short to longer term. The fixed-income underlying funds collectively hold
various types of debt instruments such as corporate bonds and mortgage backed, U.S. and foreign government issued, domestic and international securities.
The fund may invest in derivatives, which are financial contracts with a value that depends on, or is derived from, the value of underlying assets, reference rates or indexes. Derivatives may relate to stocks, bonds, interest rates, currencies or currency exchange rates and related indexes. The fund may use derivatives for hedging and nonhedging purposes including, without limitation, the following purposes:
■
To establish a position in the derivatives markets as a method of gaining exposure to a particular security or market;
■
To attempt to protect against possible changes in the market value of securities held or to be purchased by the fund or an underlying fund;
■
To manage the effective maturity or duration of the securities of the fund or an underlying fund; and
■
To facilitate the repatriation of foreign currency and the settlement of purchases of foreign securities.
The fund may invest in other types of investments including exchange-traded notes (ETNs) as described under “Other Permitted Investments of the Fund of Funds.”
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.
Risk [Heading] rr_RiskHeading Principal risks of investing in the fund of funds
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund of funds is subject to risks, and you could lose money by investing in the fund. The fund’s investment strategy may not produce the intended results. The principal risks of investing in the fund of funds include:
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.
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.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions.
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 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.
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.
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.
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: futures contracts and options. Futures contracts and options generally are subject to counterparty risk.
Investment company securities risk. The fund may invest in securities of other investment companies. Fund shareholders indirectly bear their proportionate share of the expenses of each such investment company. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
JHVIT Lifestyle Portfolio asset transfer risk. The Lifestyle Balanced Portfolio (the “JHVIT Lifestyle Portfolio”) is offered in connection with specific guaranteed benefits under variable annuity contracts (the “Contracts”) issued by John Hancock Life Insurance Company (U.S.A.) and John Hancock Life Insurance Company of New York (collectively, the “John Hancock Issuers”).
The Contracts provide that the John Hancock Issuers can automatically transfer contract value between the JHVIT Lifestyle Portfolio and the Select Bond Trust through a non-discretionary, systematic mathematical process. The purpose of these transfers is to attempt to protect contract value from declines due to market volatility, and thereby limit the John Hancock Issuers’ exposure to risk under the guaranteed benefits under the Contracts. The
timing and amount of any transfer of contract value under the John Hancock Issuers’ process will depend on several factors including market movements. In general, the higher the equity component of a JHVIT Lifestyle Portfolio, the more likely that contract value will be reallocated from the JHVIT Lifestyle Portfolio to the Select Bond Trust when equity markets fall. These asset flows may negatively affect the performance of an underlying fund in which the JHVIT Lifestyle Portfolio invests by increasing the underlying fund’s transaction costs and causing it to purchase or sell securities when it would not normally do so. It could be particularly disadvantageous for the underlying fund if it experiences outflows and needs to sell securities at a time of volatility in the markets, when values could be falling. Because the JHVIT Lifestyle Portfolio bear their proportionate share of the transaction costs of the underlying funds, increased underlying fund expenses may indirectly negatively affect the performance of the JHVIT Lifestyle Portfolio.
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.
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.
Target allocation risk. The fund’s risk profile will change due to reallocation or rebalancing of portfolio assets.
Principal risks of investing in the underlying funds
The principal risks of investing in the Underlying Funds include:
Advance trade estimate risk. The JHVIT Lifestyle Portfolio may seek to mitigate asset transfer risk by adjusting its portfolio based on advance estimates of automatic transfers of Contract value under the Contracts. The John Hancock Issuers have provided the JHVIT Lifestyle Portfolio’s subadvisor with an analytical tool that calculates estimates of automatic transfers based on several factors, including the mathematical process for automatic transfers and market movements before the daily close of trading. The subadvisor may, but is not required to, use the tool to adjust the JHVIT Lifestyle Portfolio’s portfolio with the goal of trading in securities or purchasing shares of underlying funds as close to the market close as possible in order to limit the JHVIT Lifestyle Portfolio’s exposure to cash drag (i.e., holding cash while markets are rising) and adverse overnight market fluctuations. For example, in a rising market, if the analytical tool suggests that the JHVIT Lifestyle Portfolio will receive inflows that day (the “Trade Date”), the subadvisor could buy securities or shares of an underlying fund close to or at the closing prices on the Trade Date, as opposed to the following business day, when the actual transfer amount would be known. In a falling market, if the analytical tool suggests that the JHVIT Lifestyle Portfolio will experience outflows on Trade Date, the subadvisor could sell securities or shares of an underlying fund close to or at the closing prices on Trade Date, as opposed to the following business day, when the actual transfer amount would be known.
If the subadvisor relies on the analytical tool or its own judgment and places trades in anticipation of purchases and redemptions of JHVIT Lifestyle shares, there can be no assurance that the prices paid by the JHVIT Lifestyle Portfolio will be better than if the JHVIT Lifestyle Portfolio had traded the following business day. The estimated transfer amount may be different from the actual transfer amount for various reasons, including changes in market direction, contract owner behavior and faulty inputs. If the estimated transfer amount is different from the actual transfer amount, the JHVIT Lifestyle Portfolio will buy or sell securities or shares of an underlying fund the following business day to adjust for this difference. For example, if cash flows into the JHVIT Lifestyle Portfolio are less than estimated, the JHVIT Lifestyle Portfolio could be forced to liquidate positions it had purchased. Conversely, if cash flows out of the JHVIT Lifestyle Portfolio are less than estimated, the JHVIT Lifestyle Portfolio may be required to repurchase positions it had sold. In addition, purchasing securities or shares of an underlying fund early could cause the JHVIT Lifestyle Portfolio to spend more money than it has available and, in the event of a market decline, such leverage will magnify losses because the decline also affects the securities purchased with amounts in excess of the JHVIT Lifestyle Portfolio’s assets. Due to these various factors, trading on the basis of advance estimates of automatic transfers may cause higher portfolio turnover than that based solely on automatic transfers of Contract value under the Contracts, increase JHVIT Lifestyle Portfolio expenses and adversely affect the performance of the JHVIT Lifestyle Portfolio.
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.
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.
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.
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.
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.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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: futures contracts and options. Futures contracts and options generally are subject to counterparty risk.
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 transaction expenses, 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.
Initial public offerings (IPOs) risk. IPO share prices are frequently volatile and may significantly impact fund performance.
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.
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.
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.
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.
Non-diversified risk. Adverse events affecting a particular issuer or group of issuers may magnify losses for non-diversified funds, which may invest a large portion of assets in any one issuer or a small number of issuers.
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.
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.
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.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund of funds is subject to risks, and you could lose money by investing in the fund.
Risk Nondiversified Status [Text] rr_RiskNondiversifiedStatus Non-diversified risk. Adverse events affecting a particular issuer or group of issuers may magnify losses for non-diversified funds, which may invest a large portion of assets in any one issuer or a small number of issuers.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index, the S&P 500 Index and the Combined Index (described below) show how the fund’s performance compares against the returns of similar investments. Performance shown for periods prior to the inception date of a class is the performance of the fund’s oldest share class. This
pre-inception performance, with respect to any other share class of the fund, has not been adjusted to reflect the Rule 12b-1 fees of that class. As a result, the pre-inception performance shown for a share class other than the oldest share class may be higher or lower than it would be if adjusted to reflect the Rule 12b-1 fees of the class. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
The Combined Index represents 35% of the Russell 3000 Index, 15% of the MSCI EAFE Index, and 50% of the Bloomberg U.S. Aggregate Bond Index.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series II 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 12.11%
Worst quarter: 2020, Q1, -10.80%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Lifestyle Balanced Portfolio) | Morningstar U.S. Moderate Target Allocation Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 12.37% [35]
5 Years rr_AverageAnnualReturnYear05 11.21% [35]
10 Years rr_AverageAnnualReturnYear10 9.88% [35]
(John Hancock Variable Insurance Trust) | (Lifestyle Balanced Portfolio) | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.54%)
5 Years rr_AverageAnnualReturnYear05 3.57%
10 Years rr_AverageAnnualReturnYear10 2.90%
(John Hancock Variable Insurance Trust) | (Lifestyle Balanced Portfolio) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 28.71%
5 Years rr_AverageAnnualReturnYear05 18.47%
10 Years rr_AverageAnnualReturnYear10 8.49%
(John Hancock Variable Insurance Trust) | (Lifestyle Balanced Portfolio) | Combined Index (reflects no deduction for fees, expenses, or taxes, except foreign withholding taxes on dividends)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 9.43%
5 Years rr_AverageAnnualReturnYear05 9.68%
10 Years rr_AverageAnnualReturnYear10 16.55%
(John Hancock Variable Insurance Trust) | (Lifestyle Balanced Portfolio) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.04%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.03%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.55% [36]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.67% [37]
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
1 Year rr_AverageAnnualReturnYear01 9.44%
5 Years rr_AverageAnnualReturnYear05 9.30%
10 Years rr_AverageAnnualReturnYear10 8.13%
Date of inception rr_AverageAnnualReturnInceptionDate Nov. 01, 2013
(John Hancock Variable Insurance Trust) | (Lifestyle Balanced Portfolio) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.04%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.03%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.55% [36]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.87% [37]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 89
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 278
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 482
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,073
Annual Return 2012 rr_AnnualReturn2012 10.54%
Annual Return 2013 rr_AnnualReturn2013 12.68%
Annual Return 2014 rr_AnnualReturn2014 5.74%
Annual Return 2015 rr_AnnualReturn2015 (0.22%)
Annual Return 2016 rr_AnnualReturn2016 5.89%
Annual Return 2017 rr_AnnualReturn2017 12.16%
Annual Return 2018 rr_AnnualReturn2018 (4.63%)
Annual Return 2019 rr_AnnualReturn2019 17.56%
Annual Return 2020 rr_AnnualReturn2020 12.47%
Annual Return 2021 rr_AnnualReturn2021 9.21%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 12.11%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 12.11%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -10.80%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (10.80%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 9.21%
5 Years rr_AverageAnnualReturnYear05 9.08%
10 Years rr_AverageAnnualReturnYear10 7.95%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Balanced Portfolio) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.04%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.03%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.55% [36]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.62% [37]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 63
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 199
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 346
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 774
1 Year rr_AverageAnnualReturnYear01 9.51%
5 Years rr_AverageAnnualReturnYear05 9.34%
10 Years rr_AverageAnnualReturnYear10 8.17%
Date of inception rr_AverageAnnualReturnInceptionDate Nov. 01, 2013
(John Hancock Variable Insurance Trust) | (Lifestyle Conservative Portfolio)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek a high level of current income with some consideration given to growth of capital.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination April 30, 2023
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees 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.”
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
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 22% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 22.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The fund, except as otherwise described below, operates as a fund of funds and normally invests approximately 20% of its assets in underlying funds that invest primarily in equity securities or in futures contracts on equity markets (the “Equity Allocation”) and approximately 80% of its assets in underlying funds that invest primarily in fixed-income securities or in futures contracts on fixed-income markets (the “Fixed Income Allocation”). Underlying funds may include exchange-traded funds (“ETFs”) and the fund may invest a significant portion of its assets in ETFs. At the discretion of the subadvisor, the Equity Allocation may also include direct investments in equity securities and the Fixed Income Allocation may also include direct investments in fixed-income securities. The subadvisor may also determine in light of market or economic conditions that the normal percentage limitations should be exceeded to protect the fund or achieve its investment objective.
Within the prescribed percentage allocation, the subadvisor selects the percentage level to be maintained in specific underlying funds and in futures contracts on equity or fixed-income markets. These allocations may be changed at any time by the subadvisor.
The fund may invest in various underlying 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 underlying 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 underlying funds that purchase futures contracts on equity markets.
Certain of these underlying funds focus their investment strategy on fixed-income securities, which may include investment grade and below investment grade debt securities with maturities that range from short to longer term. The fixed-income underlying funds collectively hold various types of debt instruments such as corporate bonds and mortgage backed, U.S. and foreign government issued, domestic and international securities.
The fund may invest in derivatives, which are financial contracts with a value that depends on, or is derived from, the value of underlying assets, reference rates or indexes. Derivatives may relate to stocks, bonds, interest rates, currencies or currency exchange rates and related indexes. The fund may use derivatives for hedging and nonhedging purposes including, without limitation, the following purposes:
■
To establish a position in the derivatives markets as a method of gaining exposure to a particular security or market;
■
To attempt to protect against possible changes in the market value of securities held or to be purchased by the fund or an underlying fund;
■
To manage the effective maturity or duration of the securities of the fund or an underlying fund; and
■
To facilitate the repatriation of foreign currency and the settlement of purchases of foreign securities.
The fund may invest in other types of investments including exchange-traded notes (ETNs) as described under “Other Permitted Investments of the Fund of Funds.”
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.
Risk [Heading] rr_RiskHeading Principal risks of investing in the fund of funds
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund of funds is subject to risks, and you could lose money by investing in the fund. The fund’s investment strategy may not produce the intended results. The principal risks of investing in the fund of funds include:
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.
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.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions.
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 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.
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.
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.
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: futures contracts and options. Futures contracts and options generally are subject to counterparty risk.
Investment company securities risk. The fund may invest in securities of other investment companies. Fund shareholders indirectly bear their proportionate share of the expenses of each such investment company. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
JHVIT Lifestyle Portfolio asset transfer risk. The Lifestyle Conservative Portfolio (the “JHVIT Lifestyle Portfolio”) is offered in connection with specific guaranteed benefits under variable annuity contracts (the “Contracts”) issued by John Hancock Life Insurance Company (U.S.A.) and John Hancock Life Insurance Company of New York (collectively, the “John Hancock Issuers”).
The Contracts provide that the John Hancock Issuers can automatically transfer contract value between the JHVIT Lifestyle Portfolio and the Select Bond Trust through a non-discretionary, systematic mathematical process. The purpose of these transfers is to attempt to protect contract value from declines due to market volatility, and thereby limit the John Hancock Issuers’ exposure to risk under the guaranteed benefits under the Contracts. The timing and amount of any transfer of contract value under the John Hancock Issuers’ process will depend on several factors including market movements. In general, the higher the equity component of a JHVIT Lifestyle Portfolio, the more likely that contract value will be reallocated from the JHVIT Lifestyle Portfolio to the Select Bond Trust when equity markets fall. These asset flows may negatively affect the performance of an underlying fund in which the JHVIT Lifestyle Portfolio invests by increasing the underlying fund’s transaction costs and causing it to purchase or sell securities when it would not normally do so. It could be particularly disadvantageous for the underlying fund if it experiences outflows and needs to sell securities at a time of volatility in the markets, when values could be falling. Because the JHVIT Lifestyle Portfolio bear their proportionate share of the transaction costs of the underlying funds, increased underlying fund expenses may indirectly negatively affect the performance of the JHVIT Lifestyle Portfolio.
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.
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.
Target allocation risk. The fund’s risk profile will change due to reallocation or rebalancing of portfolio assets.
Principal risks of investing in the underlying funds
The principal risks of investing in the Underlying Funds include:
Advance trade estimate risk. The JHVIT Lifestyle Portfolio may seek to mitigate asset transfer risk by adjusting its portfolio based on advance estimates of automatic transfers of Contract value under the Contracts. The John Hancock Issuers have provided the JHVIT Lifestyle Portfolio’s subadvisor with an analytical tool that calculates estimates of automatic transfers based on several factors, including the mathematical process for automatic transfers and market movements before the daily close of trading. The subadvisor may, but is not required to, use the tool to adjust the JHVIT Lifestyle Portfolio’s portfolio with the goal of trading in securities or purchasing shares of underlying funds as close to the market close as possible in order to limit the JHVIT Lifestyle Portfolio’s exposure to cash drag (i.e., holding cash while markets are rising) and adverse overnight market fluctuations. For example, in a rising market, if the analytical tool suggests that the JHVIT Lifestyle Portfolio will receive inflows that day (the “Trade Date”), the subadvisor could buy securities or shares of an underlying fund close to or at the closing prices on the Trade Date, as opposed to the following business day, when the actual transfer amount would be known. In a falling market, if the analytical tool suggests that the JHVIT Lifestyle Portfolio will experience outflows on Trade Date, the subadvisor could sell securities or shares of an underlying fund close to or at the closing prices on Trade Date, as opposed to the following business day, when the actual transfer amount would be known.
If the subadvisor relies on the analytical tool or its own judgment and places trades in anticipation of purchases and redemptions of JHVIT Lifestyle shares, there can be no assurance that the prices paid by the JHVIT Lifestyle Portfolio will be better than if the JHVIT Lifestyle Portfolio had traded the following business day. The estimated transfer amount may be different from the actual transfer amount for various reasons, including changes in market direction, contract owner behavior and faulty inputs. If the estimated transfer amount is different from the actual transfer amount, the JHVIT Lifestyle Portfolio will buy or sell securities or shares of an underlying fund the following business day to adjust for this difference. For example, if cash flows into the JHVIT Lifestyle Portfolio are less than estimated, the JHVIT Lifestyle Portfolio could be forced to liquidate positions it had purchased. Conversely, if cash flows out of the JHVIT Lifestyle Portfolio are less than estimated, the JHVIT Lifestyle Portfolio may be required to repurchase positions it had sold. In addition, purchasing securities or shares of an underlying fund early could cause the JHVIT Lifestyle Portfolio to spend more money than it has available and, in the event of a market decline, such leverage will magnify losses because the decline also affects the securities purchased with amounts in excess of the JHVIT Lifestyle Portfolio’s assets. Due to these various factors, trading on the basis of advance estimates of automatic transfers may cause higher portfolio turnover than that based solely on automatic transfers of Contract value under the Contracts, increase JHVIT Lifestyle Portfolio expenses and adversely affect the performance of the JHVIT Lifestyle Portfolio.
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.
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.
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.
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.
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.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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: futures contracts and options. Futures contracts and options generally are subject to counterparty risk.
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 transaction expenses, 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.
Initial public offerings (IPOs) risk. IPO share prices are frequently volatile and may significantly impact fund performance.
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.
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.
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.
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.
Non-diversified risk. Adverse events affecting a particular issuer or group of issuers may magnify losses for non-diversified funds, which may invest a large portion of assets in any one issuer or a small number of issuers.
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.
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.
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.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund of funds is subject to risks, and you could lose money by investing in the fund.
Risk Nondiversified Status [Text] rr_RiskNondiversifiedStatus Non-diversified risk. Adverse events affecting a particular issuer or group of issuers may magnify losses for non-diversified funds, which may invest a large portion of assets in any one issuer or a small number of issuers.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index, the S&P 500 Index and the Combined Index (described below) show how the fund’s performance compares against the returns of similar investments. Performance shown for periods prior to the inception date of a class is the performance of the fund’s oldest share class. This pre-inception performance, with respect to any other share class of the fund, has not been adjusted to reflect the Rule 12b-1 fees of that class. As a result, the pre-inception performance shown for a share class other than the oldest share class may be higher or lower than it would be if adjusted to reflect the Rule 12b-1 fees of the class. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
The Combined Index represents 14% of the Russell 3000 Index, 6% of the MSCI EAFE Index, and 80% of the Bloomberg U.S. Aggregate Bond Index.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series II 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 8.06%
Worst quarter: 2020, Q1, -4.01%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Lifestyle Conservative Portfolio) | Morningstar U.S. Conservative Target Allocation Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 3.61% [38]
5 Years rr_AverageAnnualReturnYear05 6.21% [38]
10 Years rr_AverageAnnualReturnYear10 5.37% [38]
(John Hancock Variable Insurance Trust) | (Lifestyle Conservative Portfolio) | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.54%)
5 Years rr_AverageAnnualReturnYear05 3.57%
10 Years rr_AverageAnnualReturnYear10 2.90%
(John Hancock Variable Insurance Trust) | (Lifestyle Conservative Portfolio) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 28.71%
5 Years rr_AverageAnnualReturnYear05 18.47%
10 Years rr_AverageAnnualReturnYear10 16.55%
(John Hancock Variable Insurance Trust) | (Lifestyle Conservative Portfolio) | Combined Index (reflects no deduction for fees, expenses, or taxes, except foreign withholding taxes on dividends)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 2.75%
5 Years rr_AverageAnnualReturnYear05 6.05%
10 Years rr_AverageAnnualReturnYear10 5.16%
(John Hancock Variable Insurance Trust) | (Lifestyle Conservative Portfolio) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.04%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.05%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.56% [39]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.70% [40]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [41]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.69%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 70
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 223
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 389
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 870
1 Year rr_AverageAnnualReturnYear01 2.96%
5 Years rr_AverageAnnualReturnYear05 6.10%
10 Years rr_AverageAnnualReturnYear10 5.19%
Date of inception rr_AverageAnnualReturnInceptionDate Nov. 01, 2013
(John Hancock Variable Insurance Trust) | (Lifestyle Conservative Portfolio) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.04%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.05%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.56% [39]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.90% [40]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [41]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.89%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 91
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 286
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 497
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,107
Annual Return 2012 rr_AnnualReturn2012 7.53%
Annual Return 2013 rr_AnnualReturn2013 3.86%
Annual Return 2014 rr_AnnualReturn2014 5.41%
Annual Return 2015 rr_AnnualReturn2015 (0.03%)
Annual Return 2016 rr_AnnualReturn2016 4.17%
Annual Return 2017 rr_AnnualReturn2017 6.74%
Annual Return 2018 rr_AnnualReturn2018 (2.17%)
Annual Return 2019 rr_AnnualReturn2019 12.22%
Annual Return 2020 rr_AnnualReturn2020 10.53%
Annual Return 2021 rr_AnnualReturn2021 2.68%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 8.06%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 8.06%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -4.01%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (4.01%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 2.68%
5 Years rr_AverageAnnualReturnYear05 5.87%
10 Years rr_AverageAnnualReturnYear10 5.01%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Conservative Portfolio) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.04%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.05%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.56% [39]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.65% [40]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [41]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.64%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 65
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 207
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 361
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 809
1 Year rr_AverageAnnualReturnYear01 2.94%
5 Years rr_AverageAnnualReturnYear05 6.14%
10 Years rr_AverageAnnualReturnYear10 5.23%
Date of inception rr_AverageAnnualReturnInceptionDate Nov. 01, 2013
(John Hancock Variable Insurance Trust) | (Lifestyle Growth Portfolio)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek long-term growth of capital. Current income is also a consideration.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees 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.”
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
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 12% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 12.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The fund, except as otherwise described below, operates as a fund of funds and normally invests approximately 70% of its assets in underlying funds that invest primarily in equity securities or in futures contracts on equity markets (the “Equity Allocation”) and approximately 30% of its assets in underlying funds that invest primarily in fixed-income securities or in futures contracts on fixed-income markets (the “Fixed Income Allocation”). Underlying funds may include exchange traded funds (“ETFs”) and the fund may invest a significant portion of its assets in ETFs. At the discretion of the subadvisor, the Equity Allocation may also include direct investments in equity securities and the Fixed Income Allocation may also include direct investments in fixed-income securities. The subadvisor may also determine in light of market or economic conditions that the normal percentage limitations should be exceeded to protect the fund or achieve its investment objective.
Within the prescribed percentage allocation, the subadvisor selects the percentage level to be maintained in specific underlying funds and in futures contracts on equity or fixed-income markets. These allocations may be changed at any time by the subadvisor.
The fund may invest in various underlying 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 underlying 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 underlying funds that purchase futures contracts on equity markets.
Certain of these underlying funds focus their investment strategy on fixed-income securities, which may include investment grade and below investment grade debt securities with maturities that range from short to longer term. The fixed-income underlying funds collectively hold various types of debt instruments such as corporate bonds and mortgage backed, U.S. and foreign government issued, domestic and international securities.
The fund may invest in derivatives, which are financial contracts with a value that depends on, or is derived from, the value of underlying assets, reference rates or indexes. Derivatives may relate to stocks, bonds, interest rates, currencies or currency exchange rates and related indexes. The fund may use derivatives for hedging and nonhedging purposes including, without limitation, the following purposes:
■
To establish a position in the derivatives markets as a method of gaining exposure to a particular security or market;
■
To attempt to protect against possible changes in the market value of securities held or to be purchased by the fund or an underlying fund;
■
To manage the effective maturity or duration of the securities of the fund or an underlying fund; and
■
To facilitate the repatriation of foreign currency and the settlement of purchases of foreign securities.
The fund may invest in other types of investments including exchange-traded notes (ETNs) as described under “Other Permitted Investments of the Fund of Funds.”
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.
Risk [Heading] rr_RiskHeading Principal risks of investing in the fund of funds
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund of funds is subject to risks, and you could lose money by investing in the fund. The fund’s investment strategy may not produce the intended results. The principal risks of investing in the fund of funds include:
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.
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.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions.
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 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.
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.
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.
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: futures contracts and options. Futures contracts and options generally are subject to counterparty risk.
Investment company securities risk. The fund may invest in securities of other investment companies. Fund shareholders indirectly bear their proportionate share of the expenses of each such investment company. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
JHVIT Lifestyle Portfolio asset transfer risk. The Lifestyle Growth Portfolio (the “JHVIT Lifestyle Portfolio”) is offered in connection with specific guaranteed benefits under variable annuity contracts (the “Contracts”) issued by John Hancock Life Insurance Company (U.S.A.) and John Hancock Life Insurance Company of New York (collectively, the “John Hancock Issuers”).
The Contracts provide that the John Hancock Issuers can automatically transfer contract value between the JHVIT Lifestyle Portfolio and the Select Bond Trust through a non-discretionary, systematic mathematical process. The purpose of these transfers is to attempt to protect contract value from
declines due to market volatility, and thereby limit the John Hancock Issuers’ exposure to risk under the guaranteed benefits under the Contracts. The timing and amount of any transfer of contract value under the John Hancock Issuers’ process will depend on several factors including market movements. In general, the higher the equity component of a JHVIT Lifestyle Portfolio, the more likely that contract value will be reallocated from the JHVIT Lifestyle Portfolio to the Select Bond Trust when equity markets fall. These asset flows may negatively affect the performance of an underlying fund in which the JHVIT Lifestyle Portfolio invests by increasing the underlying fund’s transaction costs and causing it to purchase or sell securities when it would not normally do so. It could be particularly disadvantageous for the underlying fund if it experiences outflows and needs to sell securities at a time of volatility in the markets, when values could be falling. Because the JHVIT Lifestyle Portfolio bear their proportionate share of the transaction costs of the underlying funds, increased underlying fund expenses may indirectly negatively affect the performance of the JHVIT Lifestyle Portfolio.
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.
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.
Target allocation risk. The fund’s risk profile will change due to reallocation or rebalancing of portfolio assets.
Principal risks of investing in the underlying funds
The principal risks of investing in the Underlying Funds include:
Advance trade estimate risk. The JHVIT Lifestyle Portfolio may seek to mitigate asset transfer risk by adjusting its portfolio based on advance estimates of automatic transfers of Contract value under the Contracts. The John Hancock Issuers have provided the JHVIT Lifestyle Portfolio’s subadvisor with an analytical tool that calculates estimates of automatic transfers based on several factors, including the mathematical process for automatic transfers and market movements before the daily close of trading. The subadvisor may, but is not required to, use the tool to adjust the JHVIT Lifestyle Portfolio’s portfolio with the goal of trading in securities or purchasing shares of underlying funds as close to the market close as possible in order to limit the JHVIT Lifestyle Portfolio’s exposure to cash drag (i.e., holding cash while markets are rising) and adverse overnight market fluctuations. For example, in a rising market, if the analytical tool suggests that the JHVIT Lifestyle Portfolio will receive inflows that day (the “Trade Date”), the subadvisor could buy securities or shares of an underlying fund close to or at the closing prices on the Trade Date, as opposed to the following business day, when the actual transfer amount would be known. In a falling market, if the analytical tool suggests that the JHVIT Lifestyle Portfolio will experience outflows on Trade Date, the subadvisor could sell securities or shares of an underlying fund close to or at the closing prices on Trade Date, as opposed to the following business day, when the actual transfer amount would be known.
If the subadvisor relies on the analytical tool or its own judgment and places trades in anticipation of purchases and redemptions of JHVIT Lifestyle shares, there can be no assurance that the prices paid by the JHVIT Lifestyle Portfolio will be better than if the JHVIT Lifestyle Portfolio had traded the following business day. The estimated transfer amount may be different from the actual transfer amount for various reasons, including changes in market direction, contract owner behavior and faulty inputs. If the estimated transfer amount is different from the actual transfer amount, the JHVIT Lifestyle Portfolio will buy or sell securities or shares of an underlying fund the following business day to adjust for this difference. For example, if cash flows into the JHVIT Lifestyle Portfolio are less than estimated, the JHVIT Lifestyle Portfolio could be forced to liquidate positions it had purchased. Conversely, if cash flows out of the JHVIT Lifestyle Portfolio are less than estimated, the JHVIT Lifestyle Portfolio may be required to repurchase positions it had sold. In addition, purchasing securities or shares of an underlying fund early could cause the JHVIT Lifestyle Portfolio to spend more money than it has available and, in the event of a market decline, such leverage will magnify losses because the decline also affects the securities purchased with amounts in excess of the JHVIT Lifestyle Portfolio’s assets. Due to these various factors, trading on the basis of advance estimates of automatic transfers may cause higher portfolio turnover than that based solely on automatic transfers of Contract value under the Contracts, increase JHVIT Lifestyle Portfolio expenses and adversely affect the performance of the JHVIT Lifestyle Portfolio.
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.
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.
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.
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.
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.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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: futures contracts and options. Futures contracts and options generally are subject to counterparty risk.
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 transaction expenses, 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.
Initial public offerings (IPOs) risk. IPO share prices are frequently volatile and may significantly impact fund performance.
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.
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.
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.
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.
Non-diversified risk. Adverse events affecting a particular issuer or group of issuers may magnify losses for non-diversified funds, which may invest a large portion of assets in any one issuer or a small number of issuers.
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.
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.
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.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund of funds is subject to risks, and you could lose money by investing in the fund.
Risk Nondiversified Status [Text] rr_RiskNondiversifiedStatus Non-diversified risk. Adverse events affecting a particular issuer or group of issuers may magnify losses for non-diversified funds, which may invest a large portion of assets in any one issuer or a small number of issuers.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index, the S&P 500 Index and the Combined Index (described below) show how the fund’s performance compares against the returns of similar investments. Performance shown for periods prior to the inception date of a class is the performance of the fund’s oldest share class. This
pre-inception performance, with respect to any other share class of the fund, has not been adjusted to reflect the Rule 12b-1 fees of that class. As a result, the pre-inception performance shown for a share class other than the oldest share class may be higher or lower than it would be if adjusted to reflect the Rule 12b-1 fees of the class. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
The Combined Index represents 49% of the Russell 3000 Index, 21% of the MSCI EAFE Index and 30% of the Bloomberg U.S. Aggregate Bond Index.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series II 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 14.93%
Worst quarter: 2020, Q1, -15.41%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Lifestyle Growth Portfolio) | Morningstar U.S. Moderately Aggressive Target Allocation Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 15.65% [42]
5 Years rr_AverageAnnualReturnYear05 13.05% [42]
10 Years rr_AverageAnnualReturnYear10 11.51% [42]
(John Hancock Variable Insurance Trust) | (Lifestyle Growth Portfolio) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 28.71%
5 Years rr_AverageAnnualReturnYear05 18.47%
10 Years rr_AverageAnnualReturnYear10 16.55%
(John Hancock Variable Insurance Trust) | (Lifestyle Growth Portfolio) | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.54%)
5 Years rr_AverageAnnualReturnYear05 3.57%
10 Years rr_AverageAnnualReturnYear10 2.90%
(John Hancock Variable Insurance Trust) | (Lifestyle Growth Portfolio) | Combined Index (reflects no deduction for fees, expenses, or taxes, except foreign withholding taxes on dividends)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 14.05%
5 Years rr_AverageAnnualReturnYear05 12.04%
10 Years rr_AverageAnnualReturnYear10 10.66%
(John Hancock Variable Insurance Trust) | (Lifestyle Growth Portfolio) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.04%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.02%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.54% [43]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.65% [44]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 66
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 208
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 362
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 810
1 Year rr_AverageAnnualReturnYear01 14.07%
5 Years rr_AverageAnnualReturnYear05 11.40%
10 Years rr_AverageAnnualReturnYear10 10.06%
Date of inception rr_AverageAnnualReturnInceptionDate Nov. 01, 2013
(John Hancock Variable Insurance Trust) | (Lifestyle Growth Portfolio) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.04%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.02%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.54% [43]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.85% [44]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 87
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 271
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 471
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,049
Annual Return 2012 rr_AnnualReturn2012 12.45%
Annual Return 2013 rr_AnnualReturn2013 18.86%
Annual Return 2014 rr_AnnualReturn2014 5.88%
Annual Return 2015 rr_AnnualReturn2015 (0.25%)
Annual Return 2016 rr_AnnualReturn2016 7.02%
Annual Return 2017 rr_AnnualReturn2017 15.90%
Annual Return 2018 rr_AnnualReturn2018 (6.31%)
Annual Return 2019 rr_AnnualReturn2019 21.20%
Annual Return 2020 rr_AnnualReturn2020 13.37%
Annual Return 2021 rr_AnnualReturn2021 13.84%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 14.93%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 14.93%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -15.41%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (15.41%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 13.84%
5 Years rr_AverageAnnualReturnYear05 11.18%
10 Years rr_AverageAnnualReturnYear10 9.88%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Growth Portfolio) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.04%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.02%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.54% [43]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.60% [44]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 61
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 192
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 335
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 750
1 Year rr_AverageAnnualReturnYear01 14.13%
5 Years rr_AverageAnnualReturnYear05 11.46%
10 Years rr_AverageAnnualReturnYear10 10.11%
Date of inception rr_AverageAnnualReturnInceptionDate Nov. 01, 2013
(John Hancock Variable Insurance Trust) | (Lifestyle Moderate Portfolio)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek a balance between a high level of current income and growth of capital, with a greater emphasis on income.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees 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.”
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
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 13% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 13.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The fund, except as otherwise described below, operates as a fund of funds and normally invests approximately 40% of its assets in underlying funds that invest primarily in equity securities or in futures contracts on equity markets (the “Equity Allocation”) and approximately 60% of its assets in underlying funds that invest primarily in fixed-income securities or in futures contracts on fixed-income markets (the “Fixed Income Allocation”). Underlying funds may include exchange traded funds (“ETFs”) and the fund may invest a significant portion of its assets in ETFs. At the discretion of the subadvisor, the Equity Allocation may also include direct investments in equity securities and the Fixed Income Allocation may also include direct investments in fixed-income securities. The subadvisor may also determine in light of market or economic conditions that the normal percentage limitations should be exceeded to protect the fund or achieve its investment objective.
Within the prescribed percentage allocation, the subadvisor selects the percentage level to be maintained in specific underlying funds and in futures contracts on equity or fixed-income markets. These allocations may be changed at any time by the subadvisor.
The fund may invest in various underlying 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 underlying 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 underlying funds that purchase futures contracts on equity markets.
Certain of these underlying funds focus their investment strategy on fixed-income securities, which may include investment grade and below investment grade debt securities with maturities that range from short to longer term. The fixed-income underlying funds collectively hold various types of debt instruments such as corporate bonds and mortgage backed, U.S. and foreign government issued, domestic and international securities.
The fund may invest in derivatives, which are financial contracts with a value that depends on, or is derived from, the value of underlying assets, reference rates or indexes. Derivatives may relate to stocks, bonds, interest rates, currencies or currency exchange rates and related indexes. The fund may use derivatives for hedging and nonhedging purposes including, without limitation, the following purposes:
■
To establish a position in the derivatives markets as a method of gaining exposure to a particular security or market;
■
To attempt to protect against possible changes in the market value of securities held or to be purchased by the fund or an underlying fund;
■
To manage the effective maturity or duration of the securities of the fund or an underlying fund; and
■
To facilitate the repatriation of foreign currency and the settlement of purchases of foreign securities.
The fund may invest in other types of investments including exchange-traded notes (ETNs) as described under “Other Permitted Investments of the Fund of Funds.”
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.
Risk [Heading] rr_RiskHeading Principal risks of investing in the fund of funds
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund of funds is subject to risks, and you could lose money by investing in the fund. The fund’s investment strategy may not produce the intended results. The principal risks of investing in the fund of funds include:
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.
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.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions.
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 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.
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.
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.
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: futures contracts and options. Futures contracts and options generally are subject to counterparty risk.
Investment company securities risk. The fund may invest in securities of other investment companies. Fund shareholders indirectly bear their proportionate share of the expenses of each such investment company. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
JHVIT Lifestyle Portfolio asset transfer risk. The Lifestyle Moderate Portfolio (the “JHVIT Lifestyle Portfolio”) is offered in connection with specific guaranteed benefits under variable annuity contracts (the “Contracts”) issued by John Hancock Life Insurance Company (U.S.A.) and John Hancock Life Insurance Company of New York (collectively, the “John Hancock Issuers”).
The Contracts provide that the John Hancock Issuers can automatically transfer contract value between the JHVIT Lifestyle Portfolio and the Select Bond Trust through a non-discretionary, systematic mathematical process. The purpose of these transfers is to attempt to protect contract value from
declines due to market volatility, and thereby limit the John Hancock Issuers’ exposure to risk under the guaranteed benefits under the Contracts. The timing and amount of any transfer of contract value under the John Hancock Issuers’ process will depend on several factors including market movements. In general, the higher the equity component of a JHVIT Lifestyle Portfolio, the more likely that contract value will be reallocated from the JHVIT Lifestyle Portfolio to the Select Bond Trust when equity markets fall. These asset flows may negatively affect the performance of an underlying fund in which the JHVIT Lifestyle Portfolio invests by increasing the underlying fund’s transaction costs and causing it to purchase or sell securities when it would not normally do so. It could be particularly disadvantageous for the underlying fund if it experiences outflows and needs to sell securities at a time of volatility in the markets, when values could be falling. Because the JHVIT Lifestyle Portfolio bear their proportionate share of the transaction costs of the underlying funds, increased underlying fund expenses may indirectly negatively affect the performance of the JHVIT Lifestyle Portfolio.
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.
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.
Target allocation risk. The fund’s risk profile will change due to reallocation or rebalancing of portfolio assets.
Principal risks of investing in the underlying funds
The principal risks of investing in the Underlying Funds include:
Advance trade estimate risk. The JHVIT Lifestyle Portfolio may seek to mitigate asset transfer risk by adjusting its portfolio based on advance estimates of automatic transfers of Contract value under the Contracts. The John Hancock Issuers have provided the JHVIT Lifestyle Portfolio’s subadvisor with an analytical tool that calculates estimates of automatic transfers based on several factors, including the mathematical process for automatic transfers and market movements before the daily close of trading. The subadvisor may, but is not required to, use the tool to adjust the JHVIT Lifestyle Portfolio’s portfolio with the goal of trading in securities or purchasing shares of underlying funds as close to the market close as possible in order to limit the JHVIT Lifestyle Portfolio’s exposure to cash drag (i.e., holding cash while markets are rising) and adverse overnight market fluctuations. For example, in a rising market, if the analytical tool suggests that the JHVIT Lifestyle Portfolio will receive inflows that day (the “Trade Date”), the subadvisor could buy securities or shares of an underlying fund close to or at the closing prices on the Trade Date, as opposed to the following business day, when the actual transfer amount would be known. In a falling market, if the analytical tool suggests that the JHVIT Lifestyle Portfolio will experience outflows on Trade Date, the subadvisor could sell securities or shares of an underlying fund close to or at the closing prices on Trade Date, as opposed to the following business day, when the actual transfer amount would be known.
If the subadvisor relies on the analytical tool or its own judgment and places trades in anticipation of purchases and redemptions of JHVIT Lifestyle shares, there can be no assurance that the prices paid by the JHVIT Lifestyle Portfolio will be better than if the JHVIT Lifestyle Portfolio had traded the following business day. The estimated transfer amount may be different from the actual transfer amount for various reasons, including changes in market direction, contract owner behavior and faulty inputs. If the estimated transfer amount is different from the actual transfer amount, the JHVIT Lifestyle Portfolio will buy or sell securities or shares of an underlying fund the following business day to adjust for this difference. For example, if cash flows into the JHVIT Lifestyle Portfolio are less than estimated, the JHVIT Lifestyle Portfolio could be forced to liquidate positions it had purchased. Conversely, if cash flows out of the JHVIT Lifestyle Portfolio are less than estimated, the JHVIT Lifestyle Portfolio may be required to repurchase positions it had sold. In addition, purchasing securities or shares of an underlying fund early could cause the JHVIT Lifestyle Portfolio to spend more money than it has available and, in the event of a market decline, such leverage will magnify losses because the decline also affects the securities purchased with amounts in excess of the JHVIT Lifestyle Portfolio’s assets. Due to these various factors, trading on the basis of advance estimates of automatic transfers may cause higher portfolio turnover than that based solely on automatic transfers of Contract value under the Contracts, increase JHVIT Lifestyle Portfolio expenses and adversely affect the performance of the JHVIT Lifestyle Portfolio.
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.
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.
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.
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.
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.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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: futures contracts and options. Futures contracts and options generally are subject to counterparty risk.
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 transaction expenses, 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.
Initial public offerings (IPOs) risk. IPO share prices are frequently volatile and may significantly impact fund performance.
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.
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.
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.
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.
Non-diversified risk. Adverse events affecting a particular issuer or group of issuers may magnify losses for non-diversified funds, which may invest a large portion of assets in any one issuer or a small number of issuers.
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.
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.
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.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund of funds is subject to risks, and you could lose money by investing in the fund.
Risk Nondiversified Status [Text] rr_RiskNondiversifiedStatus Non-diversified risk. Adverse events affecting a particular issuer or group of issuers may magnify losses for non-diversified funds, which may invest a large portion of assets in any one issuer or a small number of issuers.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index, the S&P 500 Index and the Combined Index (described below) show how the fund’s performance compares against the returns of similar investments. Performance shown for periods prior to the inception date of a class is the performance of the fund’s oldest share class. This
pre-inception performance, with respect to any other share class of the fund, has not been adjusted to reflect the Rule 12b-1 fees of that class. As a result, the pre-inception performance shown for a share class other than the oldest share class may be higher or lower than it would be if adjusted to reflect the Rule 12b-1 fees of the class. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
The Combined Index represents 28% of the Russell 3000 Index, 12% of the MSCI EAFE Index, and 60% of the Bloomberg U.S. Aggregate Bond Index.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series II 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 10.81%
Worst quarter: 2020, Q1, -8.60%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Lifestyle Moderate Portfolio) | Morningstar U.S. Moderately Conservative Target Allocation Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 7.19% [45]
5 Years rr_AverageAnnualReturnYear05 8.36% [45]
10 Years rr_AverageAnnualReturnYear10 7.36% [45]
(John Hancock Variable Insurance Trust) | (Lifestyle Moderate Portfolio) | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.54%)
5 Years rr_AverageAnnualReturnYear05 3.57%
10 Years rr_AverageAnnualReturnYear10 2.90%
(John Hancock Variable Insurance Trust) | (Lifestyle Moderate Portfolio) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 28.71%
5 Years rr_AverageAnnualReturnYear05 18.47%
10 Years rr_AverageAnnualReturnYear10 16.55%
(John Hancock Variable Insurance Trust) | (Lifestyle Moderate Portfolio) | Combined Index (reflects no deduction for fees, expenses, or taxes, except foreign withholding taxes on dividends)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 7.17%
5 Years rr_AverageAnnualReturnYear05 8.49%
10 Years rr_AverageAnnualReturnYear10 7.39%
(John Hancock Variable Insurance Trust) | (Lifestyle Moderate Portfolio) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.04%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.55% [46]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.68% [47]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 69
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 218
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 379
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 847
1 Year rr_AverageAnnualReturnYear01 7.25%
5 Years rr_AverageAnnualReturnYear05 8.22%
10 Years rr_AverageAnnualReturnYear10 7.19%
Date of inception rr_AverageAnnualReturnInceptionDate Nov. 01, 2013
(John Hancock Variable Insurance Trust) | (Lifestyle Moderate Portfolio) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.04%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.55% [46]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.88% [47]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 90
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 281
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 488
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,084
Annual Return 2012 rr_AnnualReturn2012 9.55%
Annual Return 2013 rr_AnnualReturn2013 10.12%
Annual Return 2014 rr_AnnualReturn2014 5.61%
Annual Return 2015 rr_AnnualReturn2015 (0.10%)
Annual Return 2016 rr_AnnualReturn2016 5.28%
Annual Return 2017 rr_AnnualReturn2017 10.28%
Annual Return 2018 rr_AnnualReturn2018 (3.77%)
Annual Return 2019 rr_AnnualReturn2019 15.72%
Annual Return 2020 rr_AnnualReturn2020 11.87%
Annual Return 2021 rr_AnnualReturn2021 7.03%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 10.81%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 10.81%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -8.60%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (8.60%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 7.03%
5 Years rr_AverageAnnualReturnYear05 8.01%
10 Years rr_AverageAnnualReturnYear10 7.02%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Moderate Portfolio) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.04%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.55% [46]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.63% [47]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 64
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 202
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 351
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 786
1 Year rr_AverageAnnualReturnYear01 7.23%
5 Years rr_AverageAnnualReturnYear05 8.28%
10 Years rr_AverageAnnualReturnYear10 7.23%
Date of inception rr_AverageAnnualReturnInceptionDate Nov. 01, 2013
(John Hancock Variable Insurance Trust) | (Managed Volatility Balanced Portfolio)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
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 Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees 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.”
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
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 11% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 11.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
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 limit 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, used to cover derivative positions. 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.
Risk [Heading] rr_RiskHeading Principal risks of investing in the fund of funds
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund of funds is subject to risks, and you could lose money by investing in the fund. The fund’s investment strategy may not produce the intended results. The principal risks of investing in the fund of funds include:
Affiliated insurance companies. 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.
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.
Cash collateral risk. To the extent a fund maintains cash collateral required to cover its obligations under the derivative instruments used in its risk management strategy, 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.
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.
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.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions.
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 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.
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.
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.
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 may 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 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 underperform funds that do not use a risk management strategy.
Investment company securities risk. The fund may invest in securities of other investment companies. Fund shareholders indirectly bear their proportionate share of the expenses of each such investment company. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
Leveraging risk. Certain of the risk management techniques that would be used in the strategy may involve indirect leverage. While these techniques would be intended to reduce downside exposure, in some cases leverage may magnify losses.
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.
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.
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.
Risk management strategies may not be successful, may limit upside potential or may permit or result in losses. 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.
Short positions. 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.
Swaps. 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.
Target allocation risk. The fund’s risk profile will change due to reallocation or rebalancing of portfolio assets as the fund approaches its target date.
Use of index futures. 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.
Principal risks of investing in the underlying funds
The principal risks of investing in the Underlying Funds include:
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.
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.
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.
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.
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.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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 may 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.
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 transaction expenses, 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.
Initial public offerings (IPOs) risk. IPO share prices are frequently volatile and may significantly impact fund performance.
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.
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.
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.
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.
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.
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.
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.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund of funds is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index, the S&P 500 Index and the Combined Index (described below) show how the fund’s performance compares against the returns of similar investments. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
On March 3, 2014, the fund changed its investment objective and principal investment strategies. The performance information below for the period prior to this date does not reflect these changes. Under the fund’s prior investment objective and principal investment strategies, the fund normally invested approximately 50% of its assets in underlying funds that invest primarily in equity securities and approximately 50% of its assets in underlying funds that invest primarily in fixed-income securities and did not use certain risk management techniques to seek to manage the volatility of returns (i.e. standard deviation) and limit the magnitude of portfolio losses.
The Combined Index represents 35% of the Russell 3000 Index, 15% of the MSCI EAFE Index, and 50% of the Bloomberg U.S. Aggregate Bond Index.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q4, 7.81%
Worst quarter: 2020, Q1, -13.22%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Managed Volatility Balanced Portfolio) | Morningstar U.S. Moderate Target Allocation Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 12.37% [48]
5 Years rr_AverageAnnualReturnYear05 11.21% [48]
10 Years rr_AverageAnnualReturnYear10 9.88% [48]
(John Hancock Variable Insurance Trust) | (Managed Volatility Balanced Portfolio) | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.54%)
5 Years rr_AverageAnnualReturnYear05 3.57%
10 Years rr_AverageAnnualReturnYear10 2.90%
(John Hancock Variable Insurance Trust) | (Managed Volatility Balanced Portfolio) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 28.71%
5 Years rr_AverageAnnualReturnYear05 18.47%
10 Years rr_AverageAnnualReturnYear10 16.55%
(John Hancock Variable Insurance Trust) | (Managed Volatility Balanced Portfolio) | Combined Index (reflects no deduction for fees, expenses, or taxes, except foreign withholding taxes on dividends)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 9.43%
5 Years rr_AverageAnnualReturnYear05 9.68%
10 Years rr_AverageAnnualReturnYear10 8.49%
(John Hancock Variable Insurance Trust) | (Managed Volatility Balanced Portfolio) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.17%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.02%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.54% [49]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.78% [50]
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 2012 rr_AnnualReturn2012 11.87%
Annual Return 2013 rr_AnnualReturn2013 12.78%
Annual Return 2014 rr_AnnualReturn2014 4.29%
Annual Return 2015 rr_AnnualReturn2015 (2.25%)
Annual Return 2016 rr_AnnualReturn2016 4.79%
Annual Return 2017 rr_AnnualReturn2017 14.13%
Annual Return 2018 rr_AnnualReturn2018 (4.89%)
Annual Return 2019 rr_AnnualReturn2019 17.92%
Annual Return 2020 rr_AnnualReturn2020 1.81%
Annual Return 2021 rr_AnnualReturn2021 9.76%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q4, 7.81%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 7.81%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -13.22%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (13.22%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 9.76%
5 Years rr_AverageAnnualReturnYear05 7.42%
10 Years rr_AverageAnnualReturnYear10 6.79%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Managed Volatility Balanced Portfolio) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.17%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.02%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.54% [49]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.98% [50]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 100
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 312
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 542
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,201
1 Year rr_AverageAnnualReturnYear01 9.54%
5 Years rr_AverageAnnualReturnYear05 7.20%
10 Years rr_AverageAnnualReturnYear10 6.58%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Managed Volatility Balanced Portfolio) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.17%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.02%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.54% [49]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.73% [50]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 75
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 233
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 406
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 906
1 Year rr_AverageAnnualReturnYear01 9.88%
5 Years rr_AverageAnnualReturnYear05 7.47%
10 Years rr_AverageAnnualReturnYear10 6.84%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Managed Volatility Conservative Portfolio)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek current income and growth of capital, while seeking to both manage the volatility of return and limit the magnitude of portfolio losses.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees 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.”
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
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 7% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 7.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Managed Volatility Conservative 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 22% 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 5.5% to 6.5% (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 limit 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, used to cover derivative positions. 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 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/or 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.
Risk [Heading] rr_RiskHeading Principal risks of investing in the fund of funds
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund of funds is subject to risks, and you could lose money by investing in the fund. The fund’s investment strategy may not produce the intended results. The principal risks of investing in the fund of funds include:
Affiliated insurance companies. 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.
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.
Cash collateral risk. To the extent a fund maintains cash collateral required to cover its obligations under the derivative instruments used in its risk management strategy, 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.
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.
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.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions.
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 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.
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.
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.
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 may 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 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 underperform funds that do not use a risk management strategy.
Investment company securities risk. The fund may invest in securities of other investment companies. Fund shareholders indirectly bear their proportionate share of the expenses of each such investment company. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
Leveraging risk. Certain of the risk management techniques that would be used in the strategy may involve indirect leverage. While these techniques would be intended to reduce downside exposure, in some cases leverage may magnify losses.
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.
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.
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.
Risk management strategies may not be successful, may limit upside potential or may permit or result in losses. 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.
Short positions. 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.
Swaps. 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.
Target allocation risk. The fund’s risk profile will change due to reallocation or rebalancing of portfolio assets as the fund approaches its target date.
Use of index futures. 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.
Principal risks of investing in the underlying funds
The principal risks of investing in the Underlying Funds include:
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.
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.
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.
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.
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.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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 may 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.
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 transaction expenses, 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.
Initial public offerings (IPOs) risk. IPO share prices are frequently volatile and may significantly impact fund performance.
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.
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.
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.
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.
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.
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.
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.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund of funds is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index, the S&P 500 Index and the Combined Index (described below) show how the fund’s performance compares against the returns of similar investments. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
On March 3, 2014, the fund changed its investment objective and principal investment strategies. The performance information below for the period prior to this date does not reflect these changes. Under the fund’s prior investment objective and principal investment strategies, the fund normally invested approximately 20% of its assets in underlying funds that invest primarily in equity securities and approximately 80% of its assets in underlying funds that invest primarily in fixed-income securities and did not use certain risk management techniques to seek to manage the volatility of returns (i.e., standard deviation) and limit the magnitude of portfolio losses.
The Combined Index represents 14% of the Russell 3000 Index, 6% of the MSCI EAFE Index, and 80% of the Bloomberg U.S. Aggregate Bond Index.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2019, Q1, 5.56%
Worst quarter: 2020, Q1, -6.38%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Managed Volatility Conservative Portfolio) | Morningstar U.S. Conservative Target Allocation Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 3.61% [51]
5 Years rr_AverageAnnualReturnYear05 6.21% [51]
10 Years rr_AverageAnnualReturnYear10 5.37% [51]
(John Hancock Variable Insurance Trust) | (Managed Volatility Conservative Portfolio) | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.54%)
5 Years rr_AverageAnnualReturnYear05 3.57%
10 Years rr_AverageAnnualReturnYear10 2.90%
(John Hancock Variable Insurance Trust) | (Managed Volatility Conservative Portfolio) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 28.71%
5 Years rr_AverageAnnualReturnYear05 18.47%
10 Years rr_AverageAnnualReturnYear10 16.55%
(John Hancock Variable Insurance Trust) | (Managed Volatility Conservative Portfolio) | Combined Index (reflects no deduction for fees, expenses, or taxes, except foreign withholding taxes on dividends)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 2.75%
5 Years rr_AverageAnnualReturnYear05 6.05%
10 Years rr_AverageAnnualReturnYear10 5.16%
(John Hancock Variable Insurance Trust) | (Managed Volatility Conservative Portfolio) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.17%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.03%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.52% [52]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.77% [53]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 79
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 246
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 428
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 954
Annual Return 2012 rr_AnnualReturn2012 8.52%
Annual Return 2013 rr_AnnualReturn2013 3.88%
Annual Return 2014 rr_AnnualReturn2014 5.02%
Annual Return 2015 rr_AnnualReturn2015 0.05%
Annual Return 2016 rr_AnnualReturn2016 4.58%
Annual Return 2017 rr_AnnualReturn2017 7.82%
Annual Return 2018 rr_AnnualReturn2018 (2.18%)
Annual Return 2019 rr_AnnualReturn2019 13.38%
Annual Return 2020 rr_AnnualReturn2020 3.39%
Annual Return 2021 rr_AnnualReturn2021 3.48%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2019, Q1, 5.56%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 5.56%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2019
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -6.38%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (6.38%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 3.48%
5 Years rr_AverageAnnualReturnYear05 5.05%
10 Years rr_AverageAnnualReturnYear10 4.71%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Managed Volatility Conservative Portfolio) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.17%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.03%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.52% [52]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.97% [53]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 99
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 309
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 536
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,190
1 Year rr_AverageAnnualReturnYear01 3.31%
5 Years rr_AverageAnnualReturnYear05 4.85%
10 Years rr_AverageAnnualReturnYear10 4.50%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Managed Volatility Conservative Portfolio) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.17%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.03%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.52% [52]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.72% [53]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 74
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 230
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 401
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 894
1 Year rr_AverageAnnualReturnYear01 3.52%
5 Years rr_AverageAnnualReturnYear05 5.11%
10 Years rr_AverageAnnualReturnYear10 4.76%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Managed Volatility Growth Portfolio)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek long term growth of capital while seeking to both manage the volatility of return and limit the magnitude of portfolio losses.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees 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.”
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
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 12% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 12.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Managed Volatility Growth 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 77% 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 11% to 13% (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 limit 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, used to cover derivative positions. 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.
Risk [Heading] rr_RiskHeading Principal risks of investing in the fund of funds
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund of funds is subject to risks, and you could lose money by investing in the fund. The fund’s investment strategy may not produce the intended results. The principal risks of investing in the fund of funds include:
Affiliated insurance companies. 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.
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.
Cash collateral risk. To the extent a fund maintains cash collateral required to cover its obligations under the derivative instruments used in its risk management strategy, 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.
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.
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.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions.
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 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.
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.
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.
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 may 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 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 underperform funds that do not use a risk management strategy.
Investment company securities risk. The fund may invest in securities of other investment companies. Fund shareholders indirectly bear their proportionate share of the expenses of each such investment company. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
Leveraging risk. Certain of the risk management techniques that would be used in the strategy may involve indirect leverage. While these techniques would be intended to reduce downside exposure, in some cases leverage may magnify losses.
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.
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.
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.
Risk management strategies may not be successful, may limit upside potential or may permit or result in losses. 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.
Short positions. 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.
Swaps. 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.
Target allocation risk. The fund’s risk profile will change due to reallocation or rebalancing of portfolio assets as the fund approaches its target date.
Use of index futures. 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.
Principal risks of investing in the underlying funds
The principal risks of investing in the Underlying Funds include:
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.
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.
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.
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.
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.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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 may 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.
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 transaction expenses, 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.
Initial public offerings (IPOs) risk. IPO share prices are frequently volatile and may significantly impact fund performance.
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.
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.
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.
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.
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.
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.
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.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund of funds is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index, the S&P 500 Index and the Combined Index (described below) show how the fund’s performance compares against the returns of similar investments. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
On March 3, 2014, the fund changed its investment objective and principal investment strategies. The performance information below for the period prior to this date does not reflect these changes. Under the fund’s prior investment objective and principal investment strategies, the fund normally invested approximately 70% of its assets in underlying funds that invest primarily in equity securities and approximately 30% of its assets in underlying funds that invest primarily in fixed-income securities and did not use certain risk management techniques to seek to manage the volatility of returns (i.e. standard deviation) and limit the magnitude of portfolio losses.
The Combined Index represents 49% of the Russell 3000 Index, 21% of the MSCI EAFE Index and 30% of the Bloomberg U.S. Aggregate Bond Index.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2012, Q1, 9.71%
Worst quarter: 2020, Q1, -16.79%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Managed Volatility Growth Portfolio) | Morningstar U.S. Moderately Aggressive Target Allocation Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 15.65% [54]
5 Years rr_AverageAnnualReturnYear05 13.05% [54]
10 Years rr_AverageAnnualReturnYear10 11.51% [54]
(John Hancock Variable Insurance Trust) | (Managed Volatility Growth Portfolio) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 28.71%
5 Years rr_AverageAnnualReturnYear05 18.47%
10 Years rr_AverageAnnualReturnYear10 16.55%
(John Hancock Variable Insurance Trust) | (Managed Volatility Growth Portfolio) | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.54%)
5 Years rr_AverageAnnualReturnYear05 3.57%
10 Years rr_AverageAnnualReturnYear10 2.90%
(John Hancock Variable Insurance Trust) | (Managed Volatility Growth Portfolio) | Combined Index (reflects no deduction for fees, expenses, or taxes, except foreign withholding taxes on dividends)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 14.05%
5 Years rr_AverageAnnualReturnYear05 12.04%
10 Years rr_AverageAnnualReturnYear10 10.66%
(John Hancock Variable Insurance Trust) | (Managed Volatility Growth Portfolio) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.18%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.02%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.56% [55]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.81% [56]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 83
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 259
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 450
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,002
Annual Return 2012 rr_AnnualReturn2012 13.87%
Annual Return 2013 rr_AnnualReturn2013 19.34%
Annual Return 2014 rr_AnnualReturn2014 2.16%
Annual Return 2015 rr_AnnualReturn2015 (4.53%)
Annual Return 2016 rr_AnnualReturn2016 3.34%
Annual Return 2017 rr_AnnualReturn2017 18.59%
Annual Return 2018 rr_AnnualReturn2018 (6.54%)
Annual Return 2019 rr_AnnualReturn2019 19.56%
Annual Return 2020 rr_AnnualReturn2020 (1.42%)
Annual Return 2021 rr_AnnualReturn2021 12.82%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2012, Q1, 9.71%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 9.71%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2012
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -16.79%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (16.79%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 12.82%
5 Years rr_AverageAnnualReturnYear05 8.06%
10 Years rr_AverageAnnualReturnYear10 7.28%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Managed Volatility Growth Portfolio) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.18%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.02%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.56% [55]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.01% [56]
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 12.58%
5 Years rr_AverageAnnualReturnYear05 7.85%
10 Years rr_AverageAnnualReturnYear10 7.06%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Managed Volatility Growth Portfolio) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.18%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.02%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.56% [55]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.76% [56]
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
1 Year rr_AverageAnnualReturnYear01 12.85%
5 Years rr_AverageAnnualReturnYear05 8.12%
10 Years rr_AverageAnnualReturnYear10 7.33%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Managed Volatility Moderate Portfolio)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek current income and growth of capital while seeking to both manage the volatility of return and limit the magnitude of portfolio losses.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees 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.”
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
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 10% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 10.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The Managed Volatility Moderate 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 44% 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 7% to 9% (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, used to cover derivative positions. 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.
Risk [Heading] rr_RiskHeading Principal risks of investing in the fund of funds
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund of funds is subject to risks, and you could lose money by investing in the fund. The fund’s investment strategy may not produce the intended results. The principal risks of investing in the fund of funds include:
Affiliated insurance companies. 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.
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.
Cash collateral risk. To the extent a fund maintains cash collateral required to cover its obligations under the derivative instruments used in its risk management strategy, 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.
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.
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.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions.
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 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.
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.
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.
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 may 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 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 underperform funds that do not use a risk management strategy.
Investment company securities risk. The fund may invest in securities of other investment companies. Fund shareholders indirectly bear their proportionate share of the expenses of each such investment company. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
Leveraging risk. Certain of the risk management techniques that would be used in the strategy may involve indirect leverage. While these techniques would be intended to reduce downside exposure, in some cases leverage may magnify losses.
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.
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.
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.
Risk management strategies may not be successful, may limit upside potential or may permit or result in losses. 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.
Short positions. 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.
Swaps. 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.
Target allocation risk. The fund’s risk profile will change due to reallocation or rebalancing of portfolio assets as the fund approaches its target date.
Use of index futures. 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.
Principal risks of investing in the underlying funds
The principal risks of investing in the Underlying Funds include:
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.
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.
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.
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.
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.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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 may 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.
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 transaction expenses, 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.
Initial public offerings (IPOs) risk. IPO share prices are frequently volatile and may significantly impact fund performance.
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.
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.
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.
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.
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.
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.
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.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund of funds is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index, the S&P 500 Index and the Combined Index (described below) show how the fund’s performance compares against the returns of similar investments. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
On March 3, 2014, the fund changed its investment objective and principal investment strategies. The performance information below for the period prior to this date does not reflect these changes. Under the fund’s prior investment objective and principal investment strategies, the fund normally invested approximately 40% of its assets in underlying funds that invest primarily in equity securities and approximately 60% of its assets in underlying funds that invest primarily in fixed-income securities and did not use certain risk management techniques to seek to manage the volatility of returns (i.e. standard deviation) and limit the magnitude of portfolio losses.
The Combined Index represents 28% of the Russell 3000 Index, 12% of the MSCI EAFE Index, and 60% of the Bloomberg U.S. Aggregate Bond Index.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2019, Q1, 7.10%
Worst quarter: 2020, Q1, -10.97%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Managed Volatility Moderate Portfolio) | Morningstar U.S. Moderately Conservative Target Allocation Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 7.19% [57]
5 Years rr_AverageAnnualReturnYear05 8.36% [57]
10 Years rr_AverageAnnualReturnYear10 7.36% [57]
(John Hancock Variable Insurance Trust) | (Managed Volatility Moderate Portfolio) | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.54%)
5 Years rr_AverageAnnualReturnYear05 3.57%
10 Years rr_AverageAnnualReturnYear10 2.90%
(John Hancock Variable Insurance Trust) | (Managed Volatility Moderate Portfolio) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 28.71%
5 Years rr_AverageAnnualReturnYear05 18.47%
10 Years rr_AverageAnnualReturnYear10 16.55%
(John Hancock Variable Insurance Trust) | (Managed Volatility Moderate Portfolio) | Combined Index (reflects no deduction for fees, expenses, or taxes, except foreign withholding taxes on dividends)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 7.17%
5 Years rr_AverageAnnualReturnYear05 8.49%
10 Years rr_AverageAnnualReturnYear10 7.39%
(John Hancock Variable Insurance Trust) | (Managed Volatility Moderate Portfolio) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.16%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.03%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.54% [58]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.78% [59]
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 2012 rr_AnnualReturn2012 10.67%
Annual Return 2013 rr_AnnualReturn2013 10.22%
Annual Return 2014 rr_AnnualReturn2014 4.94%
Annual Return 2015 rr_AnnualReturn2015 (0.91%)
Annual Return 2016 rr_AnnualReturn2016 5.29%
Annual Return 2017 rr_AnnualReturn2017 11.88%
Annual Return 2018 rr_AnnualReturn2018 (3.99%)
Annual Return 2019 rr_AnnualReturn2019 16.72%
Annual Return 2020 rr_AnnualReturn2020 3.31%
Annual Return 2021 rr_AnnualReturn2021 7.90%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2019, Q1, 7.10%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 7.10%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2019
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -10.97%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (10.97%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 7.90%
5 Years rr_AverageAnnualReturnYear05 6.92%
10 Years rr_AverageAnnualReturnYear10 6.44%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Managed Volatility Moderate Portfolio) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.16%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.03%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.54% [58]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.98% [59]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 100
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 312
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 542
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,201
1 Year rr_AverageAnnualReturnYear01 7.76%
5 Years rr_AverageAnnualReturnYear05 6.72%
10 Years rr_AverageAnnualReturnYear10 6.23%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Managed Volatility Moderate Portfolio) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.16%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.03%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.54% [58]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.73% [59]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 75
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 233
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 406
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 906
1 Year rr_AverageAnnualReturnYear01 8.03%
5 Years rr_AverageAnnualReturnYear05 7.00%
10 Years rr_AverageAnnualReturnYear10 6.49%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Mid Cap Growth Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek long-term growth of capital.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 91% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 91.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in equity securities of medium-sized companies with significant capital appreciation potential. (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.) For the fund, “medium-sized companies” are those with market capitalizations within the collective market capitalization range of companies represented in either the Russell Midcap Index ($608 million to $58 billion as of February 28, 2022) or the S&P Midcap 400 Index ($1.4 billion to $17.9 billion as of February 28, 2022).
The subadvisor’s investment approach is based primarily on proprietary fundamental analysis. Fundamental analysis involves the assessment of a company through such factors as its business environment, management, balance sheet, income statement, anticipated earnings, revenues and other related measures of value. In analyzing companies for investment, the subadvisor looks for, among other things, a strong balance sheet, strong earnings growth, attractive industry dynamics, strong competitive advantages (e.g., strong management teams), and attractive relative value within the context of a security’s primary trading market. Securities are sold when the investment has achieved its intended purpose, or because it is no longer considered attractive. The fund may invest up to 25% of its total assets in foreign securities, including emerging market securities.
The fund’s investment process may, at times, result in a higher than average portfolio turnover ratio and increased trading expenses.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
Consumer discretionary sector risk. The consumer discretionary sector may be affected by fluctuations in supply and demand, and may also be adversely affected by changes in consumer spending as a result of world events, political and economic conditions, commodity price volatility, changes in exchange rates, imposition of import controls, increased competition, depletion of resources, and labor relations.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity risk.
High portfolio turnover risk. Trading securities actively and frequently can increase transaction costs (thus lowering performance) and taxable distributions.
Information technology companies risk. Information technology companies can be significantly affected by rapid obsolescence, short product cycles, competition from new market entrants, and heightened cybersecurity risk, among other factors.
Liquidity risk. The extent (if at all) to which a security may be sold without negatively impacting its market value may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.
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.
Privately held and newly public companies risk. Investments in the stocks of privately held companies and newly public companies involve greater risks than investments in stocks of companies that have traded publicly on an exchange for extended time periods. Investments in such companies are less liquid and may be difficult to value. There may be significantly less information available about these companies’ business models, quality of management, earnings growth potential, and other criteria used to evaluate their investment prospects. The extent (if at all) to which securities of privately held companies or newly public companies may be sold without negatively impacting its market value may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments. Funds with principal investment strategies that involve investments in securities of privately held companies tend to have a greater exposure to liquidity risk than funds that do not invest in securities of privately held companies.
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.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 42.22%
Worst quarter: 2018, Q4, -18.31%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Mid Cap Growth Trust) | Russell Midcap Growth Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 12.73%
5 Years rr_AverageAnnualReturnYear05 19.83%
10 Years rr_AverageAnnualReturnYear10 16.63%
(John Hancock Variable Insurance Trust) | (Mid Cap Growth Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.83%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.92%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [60]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.91%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 93
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 292
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 508
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,130
Annual Return 2012 rr_AnnualReturn2012 22.21%
Annual Return 2013 rr_AnnualReturn2013 36.82%
Annual Return 2014 rr_AnnualReturn2014 8.02%
Annual Return 2015 rr_AnnualReturn2015 3.00%
Annual Return 2016 rr_AnnualReturn2016 0.59%
Annual Return 2017 rr_AnnualReturn2017 28.54%
Annual Return 2018 rr_AnnualReturn2018 (1.56%)
Annual Return 2019 rr_AnnualReturn2019 34.53%
Annual Return 2020 rr_AnnualReturn2020 65.39%
Annual Return 2021 rr_AnnualReturn2021 3.54%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 42.22%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 42.22%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2018, Q4, -18.31%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (18.31%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2018
1 Year rr_AverageAnnualReturnYear01 3.54%
5 Years rr_AverageAnnualReturnYear05 23.86%
10 Years rr_AverageAnnualReturnYear10 18.49%
Date of inception rr_AverageAnnualReturnInceptionDate May 03, 1999
(John Hancock Variable Insurance Trust) | (Mid Cap Growth Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.83%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.12%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [60]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.11%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 113
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 355
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 616
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,362
1 Year rr_AverageAnnualReturnYear01 3.30%
5 Years rr_AverageAnnualReturnYear05 23.60%
10 Years rr_AverageAnnualReturnYear10 18.25%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Mid Cap Growth Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.83%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.87%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [60]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.86%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 88
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 277
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 481
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,072
1 Year rr_AverageAnnualReturnYear01 3.58%
5 Years rr_AverageAnnualReturnYear05 23.93%
10 Years rr_AverageAnnualReturnYear10 18.54%
Date of inception rr_AverageAnnualReturnInceptionDate Feb. 28, 2005
(John Hancock Variable Insurance Trust) | (Mid Cap Index Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
Seeks to approximate the aggregate total return of a mid cap U.S. domestic equity market index.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 17% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 17.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowings for investment purposes) at the time of investment in: (a) the common stocks that are included in the S&P Midcap 400 Index; and (b) securities (which may or may not be included in the S&P Midcap 400 Index) that the subadvisor believes as a group will behave in a manner similar to the index. (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.) As of February 28, 2022, the market capitalizations of companies included in the S&P Midcap 400 Index ranged from $1.4 billion to $17.9 billion.
An index is an unmanaged group of securities whose overall performance is used as an investment benchmark. Indexes may track broad investment markets, such as the global equity market, or more narrow investment markets, such as the U.S. small cap equity market. In contrast to actively managed funds, which seek to outperform their respective benchmark indexes through research and analysis, index funds are passively managed funds that seek to mirror the performance of their target indexes, minimizing performance differences over time. The fund attempts to match the performance of the S&P Midcap 400 Index by: (a) holding all, or a representative sample, of the securities that comprise that index; and/or (b) by holding securities (which may or may not be included in the index) that the subadvisor believes as a group will behave in a manner similar to the index. However, the fund has operating expenses and transaction costs, while a market index does not. Therefore, the fund, while it attempts to track its target index closely, typically will be unable to match the performance of the target index exactly. The composition of an index changes from time to time, and the subadvisor will reflect those changes in the composition of the fund’s portfolio as soon as practicable.
The fund may invest in index futures for the purposes of replicating an index and depositary receipts.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance.
Credit and counterparty risk. 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.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions.
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 the fund intends to utilize include: futures contracts and depositary receipts. Futures contracts generally are subject to counterparty risk.
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 transaction expenses, 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.
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.
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.
Quantitative modeling risk. Quantitative models may not accurately predict future market movements or characteristics, which may negatively impact performance. Models also may perform differently than expected due to implementation problems, technological malfunction, or programming or data inaccuracies, among other possible issues.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q4, 24.19%
Worst quarter: 2020, Q1, -29.73%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Mid Cap Index Trust) | S&P Midcap 400 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 24.76%
5 Years rr_AverageAnnualReturnYear05 13.09%
10 Years rr_AverageAnnualReturnYear10 14.20%
(John Hancock Variable Insurance Trust) | (Mid Cap Index Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.47%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.56%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.11%) [61]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.45%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 46
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 168
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 302
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 691
Annual Return 2012 rr_AnnualReturn2012 17.48%
Annual Return 2013 rr_AnnualReturn2013 33.03%
Annual Return 2014 rr_AnnualReturn2014 9.35%
Annual Return 2015 rr_AnnualReturn2015 (2.59%)
Annual Return 2016 rr_AnnualReturn2016 20.11%
Annual Return 2017 rr_AnnualReturn2017 15.81%
Annual Return 2018 rr_AnnualReturn2018 (11.46%)
Annual Return 2019 rr_AnnualReturn2019 25.59%
Annual Return 2020 rr_AnnualReturn2020 13.22%
Annual Return 2021 rr_AnnualReturn2021 24.21%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q4, 24.19%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 24.19%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -29.73%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (29.73%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 24.21%
5 Years rr_AverageAnnualReturnYear05 12.61%
10 Years rr_AverageAnnualReturnYear10 13.73%
Date of inception rr_AverageAnnualReturnInceptionDate May 02, 2000
(John Hancock Variable Insurance Trust) | (Mid Cap Index Trust) | Series II  
Prospectus: rr_ProspectusTable  
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 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.76%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.11%) [61]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.65%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 66
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 232
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 412
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 932
1 Year rr_AverageAnnualReturnYear01 23.96%
5 Years rr_AverageAnnualReturnYear05 12.38%
10 Years rr_AverageAnnualReturnYear10 13.51%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Mid Cap Index Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
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 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.51%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.11%) [61]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.40%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 41
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 152
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 274
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 630
1 Year rr_AverageAnnualReturnYear01 24.27%
5 Years rr_AverageAnnualReturnYear05 12.67%
10 Years rr_AverageAnnualReturnYear10 13.79%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Mid Value Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek long-term capital appreciation.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 26% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 26.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in companies with market capitalizations that are within the Russell Midcap Value Index ($608 million to $58 billion as of February 28, 2022). The fund invests in a diversified mix of common stocks of mid-size U.S. companies that are believed to be undervalued by various measures and offer good prospects for capital appreciation.
The subadvisor employs a value approach in selecting investments. The subadvisor’s in-house research team seeks to identify companies whose stock prices do not appear to reflect their underlying values. The subadvisor generally looks for companies with one or more of the following characteristics:
■
Low stock prices relative to net assets, earnings, cash flow, sales, book value, or private market value;
■
Demonstrated or potentially attractive operating margins, profits and/or cash flow;
■
Sound balance sheets;
■
Stock ownership by management/employees; or
■
Experienced and capable management.
The fund’s sector exposure is broadly diversified as a result of stock selection and therefore may vary significantly from its benchmark, the Russell Midcap Value Index. The market capitalization of companies held by the fund and included in the index changes over time. The fund will not automatically sell or cease to purchase stock of a company it already owns just because the company’s market capitalization grows or falls outside these ranges.
The fund may sell securities for a variety of reasons, including to realize gains, limit losses, or redeploy assets into more promising opportunities.
In pursuing the fund’s investment objective, the subadvisor has the discretion to deviate from its normal investment criteria, as described above, and purchase securities that the subadvisor believes will provide an opportunity for substantial appreciation. These situations might arise when the subadvisor believes a security could increase in value for a variety of reasons, including a change in management, an extraordinary corporate event, a new product introduction or innovation or a favorable competitive development.
The fund may invest in IPOs. While most assets will be invested in U.S. common stocks, the fund may purchase other types of securities, for example: convertible securities and warrants, foreign securities (up to 20% of total assets), certain exchange-traded funds (ETFs), and certain derivatives (investments whose value is based on indices or other securities). For purposes of the fund, ETFs are considered securities with a market capitalization equal to the weighted average market capitalization of the basket of securities comprising the ETF.
The fund holds a certain portion of its assets in money market reserves, which can consist of shares of certain internal T. Rowe Price money market funds as well as U.S. dollar and foreign currency-denominated money market securities, including repurchase agreements, in the two highest rating categories, maturing in one year or less.
The fund may invest up to 10% of its total assets in hybrid instruments. Hybrid instruments are a type of high-risk derivative that can combine the characteristics of securities, futures and options. Such securities may bear interest or pay dividends at below (or even relatively nominal) rates.
Except when engaged in temporary defensive investing, the fund normally has less than 10% of its assets in cash and cash equivalents. The fund may focus its investments in a particular sector or sectors of the economy.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
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.
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.
Credit and counterparty risk. 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.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions. 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.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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 the fund intends to utilize include: futures contracts and options. Futures contracts and options generally are subject to counterparty risk.
Hybrid instrument risk. Hybrid instruments (a type of potentially high-risk derivative) combine the elements of futures contracts or options with those of debt, preferred equity or a depository instrument. Hybrid instruments entail greater market risk and may be more volatile than traditional debt instruments, may bear interest or pay preferred dividends at below-market rates, and may be illiquid. The risks of investing in hybrid instruments are a combination of the risks of investing in securities, options, futures, and currencies.
Initial public offerings (IPOs) risk. IPO share prices are frequently volatile and may significantly impact fund performance.
Investment company securities risk. The fund may invest in securities of other investment companies. Fund shareholders indirectly bear their proportionate share of the expenses of each such investment company. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
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.
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.
Repurchase agreements risk. The risk of a repurchase agreement transaction is limited to the ability of the seller to pay the agreed-upon sum on the delivery date. In the event of bankruptcy or other default by the seller, the instrument purchased may decline in value, interest payable on the instrument may be lost and there may be possible difficulties and delays in obtaining collateral and delays and expense in liquidating the instrument.
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.
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.
Value investment style risk. Value securities may underperform the market as a whole, which may cause value-oriented funds to underperform equity funds with other investment strategies. Securities the manager believes are undervalued may never perform as expected.
Warrants risk. The prices of warrants may not precisely reflect the prices of their underlying securities. Warrant holders do not receive dividends or have voting or credit rights. A warrant ceases to have value if not exercised prior to its expiration date.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series NAV 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 22.19%
Worst quarter: 2020, Q1, -28.72%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Mid Value Trust) | Russell Midcap Value Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 28.34%
5 Years rr_AverageAnnualReturnYear05 11.22%
10 Years rr_AverageAnnualReturnYear10 13.44%
(John Hancock Variable Insurance Trust) | (Mid Value Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.88% [62]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.97%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [63]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.96%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 98
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 308
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 535
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,189
1 Year rr_AverageAnnualReturnYear01 24.34%
5 Years rr_AverageAnnualReturnYear05 10.11%
10 Years rr_AverageAnnualReturnYear10 12.90%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Mid Value Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.88% [62]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.17%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [63]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.16%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 118
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 371
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 643
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,419
1 Year rr_AverageAnnualReturnYear01 24.10%
5 Years rr_AverageAnnualReturnYear05 9.88%
10 Years rr_AverageAnnualReturnYear10 12.68%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Mid Value Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.88% [62]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.92%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [63]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.91%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 93
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 292
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 508
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,130
Annual Return 2012 rr_AnnualReturn2012 19.43%
Annual Return 2013 rr_AnnualReturn2013 31.47%
Annual Return 2014 rr_AnnualReturn2014 10.70%
Annual Return 2015 rr_AnnualReturn2015 (3.40%)
Annual Return 2016 rr_AnnualReturn2016 24.09%
Annual Return 2017 rr_AnnualReturn2017 11.46%
Annual Return 2018 rr_AnnualReturn2018 (10.68%)
Annual Return 2019 rr_AnnualReturn2019 19.49%
Annual Return 2020 rr_AnnualReturn2020 9.72%
Annual Return 2021 rr_AnnualReturn2021 24.26%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 22.19%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 22.19%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -28.72%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (28.72%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 24.26%
5 Years rr_AverageAnnualReturnYear05 10.15%
10 Years rr_AverageAnnualReturnYear10 12.95%
Date of inception rr_AverageAnnualReturnInceptionDate May 01, 1998
(John Hancock Variable Insurance Trust) | (Money Market Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To obtain maximum current income consistent with preservation of principal and liquidity.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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 Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The fund operates as a “government money market fund” in accordance with Rule 2a-7 under the Investment Company Act of 1940, as amended, and is managed in the following manner:
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under normal market conditions, the fund invests at least 99.5% of its total assets in cash, U.S. government securities and/or repurchase agreements that are fully collateralized by U.S. government securities or cash;
   
° U.S. government securities include both securities issued or guaranteed by the U.S. Treasury and securities issued by entities that are chartered or sponsored by Congress but are not issued or guaranteed by the U.S. Treasury;
■
the fund seeks to maintain a stable net asset value (“NAV”) of $1.00 per share and its portfolio is valued using the amortized cost method as permitted by Rule 2a-7;
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the fund invests only in U.S. dollar-denominated securities;
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the fund buys securities that have remaining maturities of 397 days or less (as calculated pursuant to Rule 2a-7);
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the fund maintains a dollar-weighted average maturity of 60 days or less and a dollar-weighted average life to maturity of 120 days or less;
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the fund must meet certain other criteria, including those relating to maturity, liquidity and credit quality; and
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as a government money market fund, the fund is not subject to liquidity fees or redemption gates, although the fund’s Board of Trustees may elect to impose such fees or gates in the future.
The fund generally expects to declare and pay dividends from net investment income on a daily basis on each share class as long as the income attributable to a class exceeds the expenses attributable to that class on each day. If class expenses exceed class income on any day, the fund will not pay a dividend on the class on that day and will resume paying dividends only when, on a future date, the accumulated net investment income of the
class is positive. The fund has adopted this policy because, in the current investment environment of low interest rates, it may find that on any given day or on a number of consecutive days, its investment returns may be less than the expenses attributable to a class. For a more complete description of this policy, which can result in the fund not paying dividends on one or more classes for one or more periods that may be as short as a day or quite lengthy, see “General Information — Dividends” below. For a description of the allocation of expenses among fund share classes, see “Rule 12b-1 plans” in the prospectus.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. 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. The fund’s sponsor has no legal obligation to provide financial support to the fund, and you should not expect that the sponsor will provide financial support to the fund at any time.
The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
Changing distribution levels risk. The fund may cease or reduce the level of its distribution if income or dividends paid from its investments declines.
Credit and counterparty risk. The issuer or guarantor of a fixed-income security 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.
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.
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.
Liquidity risk. The extent (if at all) to which a security may be sold 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.
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.
Redemption risk. The fund may experience periods of heavy redemptions that could cause it to liquidate its assets at inopportune times or at a loss or depressed value, particularly during periods of declining or illiquid markets, and that could affect the fund’s ability to maintain a $1.00 share price. Redemption risk is greater to the extent that the fund has investors with large shareholdings, short investment horizons or unpredictable cash flow needs. The redemption by one or more large shareholders of their holdings in the fund could cause the remaining shareholders in the fund to lose money. In addition, the fund may suspend redemptions and liquidate the fund when permitted by applicable regulations.
Repurchase agreements risk. The risk of a repurchase agreement transaction is limited to the ability of the seller to pay the agreed-upon sum on the delivery date. In the event of bankruptcy or other default by the seller, the instrument purchased may decline in value, interest payable on the instrument may be lost and there may be possible difficulties and delays in obtaining collateral and delays and expense in liquidating the instrument.
Tax diversification risk. As described above, the fund operates as a “government money market fund” in accordance with Rule 2a-7 under the Investment Company Act of 1940, as amended, (a “Government Fund”). Additionally, the fund intends to meet the diversification requirements that are applicable to insurance company separate accounts under Subchapter L of the Internal Revenue Code of 1986, as amended (the “Diversification Requirements”). To satisfy the Diversification Requirements applicable to variable annuity contracts, the value of the assets of the fund invested in securities issued by the United States government must remain below specified thresholds. For these purposes, each United States government agency or instrumentality is treated as a separate issuer.
Operating as a Government Fund may make it difficult for the fund to meet the Diversification Requirements. This difficulty may be exacerbated by the potential increase in demand for the types of securities in which each fund invests as a result of changes to the rules that govern SEC registered money market funds. A failure to satisfy the Diversification Requirements could have significant adverse tax consequences for variable annuity contract owners whose contract values are determined by investment in the fund.
U.S. Government agency obligations risk. U.S. 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. Treasury obligations risk. The market value of direct obligations of the U.S. Treasury may vary due to changes in interest rates. In addition, changes to the financial condition or credit rating of the U.S. government may cause the value of the fund’s investments in obligations issued by the U.S. Treasury to decline.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution 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.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year. Since Series NAV commenced operations on May 2, 2016, performance shown for Series NAV prior to that date is the performance of the fund’s oldest share class, Series I. This pre-inception performance would be higher if adjusted to reflect that Series NAV does not have a Rule 12b-1 fee. The performance information below does not reflect fees and expenses of any variable insurance contract that may use JHVIT as its underlying investment option. If such fees and expenses had been reflected, performance would be lower. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2019, Q2, 0.53%
Worst quarter: 2012, Q1, 0.00%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Money Market Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.35%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.44%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.11%) [64]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.33%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 34
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 130
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 235
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 544
Annual Return 2012 rr_AnnualReturn2012 0.01%
Annual Return 2013 rr_AnnualReturn2013 0.01%
Annual Return 2014 rr_AnnualReturn2014 none
Annual Return 2015 rr_AnnualReturn2015 none
Annual Return 2016 rr_AnnualReturn2016 0.07%
Annual Return 2017 rr_AnnualReturn2017 0.59%
Annual Return 2018 rr_AnnualReturn2018 1.54%
Annual Return 2019 rr_AnnualReturn2019 1.92%
Annual Return 2020 rr_AnnualReturn2020 0.31%
Annual Return 2021 rr_AnnualReturn2021 none
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2019, Q2, 0.53%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 0.53%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2019
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2012, Q1, 0.00%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn none
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2012
1 Year rr_AverageAnnualReturnYear01 none
5 Years rr_AverageAnnualReturnYear05 0.87%
10 Years rr_AverageAnnualReturnYear10 0.44%
Date of inception rr_AverageAnnualReturnInceptionDate Jun. 18, 1985
(John Hancock Variable Insurance Trust) | (Money Market Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.35%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.64%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.11%) [64]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.53%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 54
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 194
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 346
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 788
1 Year rr_AverageAnnualReturnYear01 none
5 Years rr_AverageAnnualReturnYear05 0.74%
10 Years rr_AverageAnnualReturnYear10 0.37%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Money Market Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.35%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.39%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.11%) [64]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.28%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 29
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 114
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 208
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 482
1 Year rr_AverageAnnualReturnYear01 none
5 Years rr_AverageAnnualReturnYear05 0.91%
10 Years rr_AverageAnnualReturnYear10 0.47%
Date of inception rr_AverageAnnualReturnInceptionDate May 02, 2016
(John Hancock Variable Insurance Trust) | (Opportunistic Fixed Income Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek maximum total return, consistent with preservation of capital and prudent investment management.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees 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.”
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 126% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 126.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in fixed income instruments. (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.) Fixed income instruments include, but are not limited to the following securities, which may be denominated in U.S. dollars or foreign currencies: sovereign debt, inflation-linked bonds, corporate and high yield credit (also known as “junk bonds”), securitized debt, bank loans and floating rate loans and emerging markets debt, convertible and hybrid securities. Direct investments in loans may be illiquid and holding a loan could expose the fund to the risks of being a lender.
In order to achieve its investment objective, the manager seeks to:
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invest across multiple asset types, geographies, credit tiers, and time horizons;
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provide timely and dynamic exposure to a portfolio of global fixed income securities consisting of sovereign debt, inflation-linked bonds, corporate and high yield credit, securitized debt, bank loans and floating rate loans and emerging markets debt, convertible and hybrid securities;
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manage the fund’s overall performance volatility within a range as reflected by the Bloomberg Global Aggregate Bond Index hedged to USD over the medium to long-term;
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generate total returns through three main approaches: strategic sector positioning, market-neutral strategies, and tactical asset allocation:
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the strategic sector component of the portfolio provides exposure to non-core investment opportunities (e.g. emerging markets debt, high yield credit, bank loans etc.) that are designed to capture the repricing of long-term structural themes in the business cycle;
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the market neutral component of the portfolio is primarily expressed via relative value positioning, aimed at providing incremental return with low correlation to the direction of global fixed income markets. Market neutral positions are typically taken on interest rates, currencies, corporate and high yield credit, and emerging market debt positions; and
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tactical asset allocation is used to capture both short and medium term dislocations in the market. Tactical opportunities are primarily expressed via sector rotation, country selection, security selection, currency management strategies and duration management strategies.
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combine the three approaches noted above in a holistic manner while managing aggregate portfolio risk.
The fund may invest in securities that at times may have equity-like characteristics including, but not limited to convertible securities or preferred equity. Additionally, the fund may hold equities received as part of a corporate action. The fund also may hold all or a portion of its assets in cash, money market instruments, bonds or other debt securities for defensive or other purposes. The fund may engage in active trading and may have a high portfolio turnover rate.
The fund makes significant use of derivative instruments and may take both long and short positions in securities. Derivatives may be used for purposes of hedging and/or efficient portfolio management and/or investment purposes. Derivatives may be exchange-traded or over-the-counter and may include futures contracts, options, credit default swaps, foreign currency swaps, interest rate swaps, total return swaps and foreign currency forward contracts. In its use of derivatives, the fund aims to contribute to the target return and the volatility strategies of the fund. The use of derivative instruments as part of the investment strategy means that the fund may, from time to time, have substantial holdings in liquid assets, including deposits and money market instruments.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
Changing distribution levels risk. The fund may cease or reduce the level of its distribution if income or dividends paid from its investments declines.
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.
Currency risk. Fluctuations in exchange rates may adversely affect the U.S. dollar value of a fund’s investments. Foreign currencies may decline in value, which could negatively impact performance.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions.
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. Additionally, the value of inflation-indexed securities is subject to the effects of changes in market interest rates caused by factors other than inflation (“real interest rates”). Generally, when real interest rates rise, the value of inflation-indexed securities will fall and the fund’s value may decline as a result of this exposure to these securities.
Floating rate loans risk. Floating rate loans are generally rated below investment-grade and are generally considered speculative because they present a greater risk of loss, including default, than higher quality debt instruments.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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 the fund intends to utilize include: credit default swaps, foreign currency forward contracts, foreign currency swaps, futures contracts, interest-rate swaps, options, options on futures, swaps, and total return 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. An event of default or insolvency of the counterparty to a reverse repurchase agreement could result in delays or restrictions with respect to the fund’s ability to
dispose of the underlying securities, in addition, a reverse repurchase agreement may be considered a form of leverage and may, therefore, increase fluctuations in the fund’s net asset value per share (NAV).
High portfolio turnover risk. Trading securities actively and frequently can increase transaction costs (thus lowering performance) and taxable distributions.
Hybrid instrument risk. Hybrid instruments (a type of potentially high-risk derivative) combine the elements of futures contracts or options with those of debt, preferred equity or a depository instrument. Hybrid instruments entail greater market risk and may be more volatile than traditional debt instruments, may bear interest or pay preferred dividends at below-market rates, and may be illiquid. The risks of investing in hybrid instruments are a combination of the risks of investing in securities, options, futures, and currencies.
LIBOR discontinuation risk. The publication of the London Interbank Offered Rate (LIBOR), which many debt securities, derivatives and other financial instruments use as the reference or benchmark rate for interest rate calculations, was discontinued for certain maturities as of December 31, 2021, and is expected to be discontinued on June 30, 2023 for the remaining maturities. The transition process away from LIBOR may lead to increased volatility and illiquidity in markets that currently rely on LIBOR to determine interest rates, and the eventual use of an alternative reference rate may adversely affect the fund’s performance. In addition, the usefulness of LIBOR may deteriorate in the period leading up to its discontinuation, which could adversely affect the liquidity or market value of securities that use LIBOR.
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.
Loan participations risk. Participations and assignments involve special types of risks, including credit risk, interest-rate risk, counterparty risk, liquidity risk, risks associated with extended settlement, and the risks of being a lender.
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.
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.
Preferred and convertible securities risk. Preferred stock dividends are payable only if declared by the issuer’s board. Preferred stock may be subject to redemption provisions. The market values of convertible securities tend to fall as interest rates rise and rise as interest rates fall. Convertible preferred stock’s value can depend heavily upon the underlying common stock’s value.
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.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
A note on performance
Prior to February 28, 2020, the fund was managed by a different subadvisor pursuant to different strategies, and thus, the performance presented prior to February 28, 2020 should not be attributed to the current subadvisor, Wellington Management Company LLP (Wellington Management). The fund’s performance shown below might have differed materially had Wellington Management managed the fund prior to February 28, 2020.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 10.08%
Worst quarter: 2016, Q4, -7.74%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Opportunistic Fixed Income Trust) | Bloomberg Global Aggregate Bond Index (USD Hedged) (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.38%)
5 Years rr_AverageAnnualReturnYear05 3.39%
10 Years rr_AverageAnnualReturnYear10 3.49%
(John Hancock Variable Insurance Trust) | (Opportunistic Fixed Income Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.65%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.15%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02% [65]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.87% [66]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [67]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.86%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 88
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 277
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 481
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,072
Annual Return 2012 rr_AnnualReturn2012 7.03%
Annual Return 2013 rr_AnnualReturn2013 (5.42%)
Annual Return 2014 rr_AnnualReturn2014 2.28%
Annual Return 2015 rr_AnnualReturn2015 (3.50%)
Annual Return 2016 rr_AnnualReturn2016 3.05%
Annual Return 2017 rr_AnnualReturn2017 8.75%
Annual Return 2018 rr_AnnualReturn2018 (1.90%)
Annual Return 2019 rr_AnnualReturn2019 6.38%
Annual Return 2020 rr_AnnualReturn2020 13.79%
Annual Return 2021 rr_AnnualReturn2021 (2.02%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 10.08%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 10.08%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2016, Q4, -7.74%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (7.74%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2016
1 Year rr_AverageAnnualReturnYear01 (2.02%)
5 Years rr_AverageAnnualReturnYear05 4.82%
10 Years rr_AverageAnnualReturnYear10 2.68%
Date of inception rr_AverageAnnualReturnInceptionDate Mar. 21, 1988
(John Hancock Variable Insurance Trust) | (Opportunistic Fixed Income Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.65%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.15%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02% [65]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.07% [66]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [67]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.06%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 108
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 339
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 589
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,305
1 Year rr_AverageAnnualReturnYear01 (2.26%)
5 Years rr_AverageAnnualReturnYear05 4.60%
10 Years rr_AverageAnnualReturnYear10 2.47%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Opportunistic Fixed Income Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.65%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.15%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02% [65]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.82% [66]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [67]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.81%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 83
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 261
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 454
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,013
1 Year rr_AverageAnnualReturnYear01 (2.06%)
5 Years rr_AverageAnnualReturnYear05 4.86%
10 Years rr_AverageAnnualReturnYear10 2.72%
Date of inception rr_AverageAnnualReturnInceptionDate Feb. 28, 2005
(John Hancock Variable Insurance Trust) | (Real Estate Securities Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek to achieve a combination of long-term capital appreciation and current income.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 63% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 63.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in equity securities of real estate investment trusts (“REITs”) and real estate companies. Equity securities include common stock, preferred stock and securities convertible into common stock.
A company is considered to be a real estate company if the Global Industry Classification Standards (or some other common industry accepted sector or industry classification schema) includes the company within its Real Estate sector or Hotels, Restaurants & Leisure Industry or Homebuilding sub-industry.
The manager looks for real estate securities it believes will provide superior returns to the fund, and attempts to focus on companies with the potential for stock price appreciation and a record of paying dividends.
The manager’s approach to real estate investing is based on a bottom-up analysis of factors affecting individual securities, combined with a top-down analysis of the real estate market. The manager believes that property markets overly discount and extrapolate short-term events and that a research-intensive and long-term focus are the keys to sustainable alpha generation. By focusing on multiple valuation metrics and leveraging the analytical resources at both the team and firm level, the manager is able to identify short-term dislocations between stock prices and fundamentals, and ultimately invest in what the manager believes are long-term winners at below market valuations. The bottom-up research coupled with top-down trends in the property markets allow the manager to effectively capture inflection points and own companies with dominant and improving market positions before their true value is recognized by the broader investment community.
A REIT invests primarily in income-producing real estate or makes loans to persons involved in the real estate industry.
Some REITs, called equity REITs, buy real estate and pay investors income from the rents received from the real estate owned by the REIT and from any profits on the sale of its properties. Other REITs, called mortgage REITs, lend money to building developers and other real estate companies and pay investors income from the interest paid on those loans. There are also hybrid REITs which engage in both owning real estate and making loans.
If a REIT meets certain requirements, it is not taxed on the income it distributes to its investors.
The fund may realize some short-term gains or losses if the manager chooses to sell a security because it believes that one or more of the following is true:
■
A security is not fulfilling its investment purpose;
■
A security has reached its optimum valuation; or
■
A particular company or general economic conditions have changed.
Based on its recent practices, the manager expects that the fund’s assets will be invested primarily in equity REITs. In changing market conditions, the fund may invest in other types of REITs.
When the manager believes that it is prudent, the fund may invest a portion of its assets in other types of securities. These securities may include convertible securities, short-term securities, bonds, notes, securities of companies not principally engaged in the real estate industry, non-leveraged stock index futures contracts and other similar securities. (Stock index futures contracts can help the fund’s cash assets remain liquid while performing more like stocks.)
The fund may invest up to 10% of its total assets in securities of foreign real estate companies.
The fund is a non-diversified fund, which means that it may invest in a smaller number of issuers than a diversified fund and may invest more of its assets in the securities of a single issuer. The fund concentrates its investments in securities of issuers in the real estate industry.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
Concentration risk. Because the fund may focus on one or more industries or sectors of the economy, its performance depends in large part on the performance of those industries or sectors. As a result, the value of an investment may fluctuate more widely since it is more susceptible to market, economic, political, regulatory, and other conditions and risks affecting those industries or sectors than a fund that invests more broadly across industries and sectors. A downturn in the real estate industry may significantly detract from 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. A downgrade or default affecting any of the fund’s securities could affect the fund’s performance.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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 the fund intends to utilize include: futures contracts. Futures contracts generally are subject to counterparty risk.
High portfolio turnover risk. Trading securities actively and frequently can increase transaction costs (thus lowering performance) and taxable distributions.
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.
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.
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.
Non-diversified risk. Adverse events affecting a particular issuer or group of issuers may magnify losses for non-diversified funds, which may invest a large portion of assets in any one issuer or a small number of issuers.
Preferred and convertible securities risk. Preferred stock dividends are payable only if declared by the issuer’s board. Preferred stock may be subject to redemption provisions. The market values of convertible securities tend to fall as interest rates rise and rise as interest rates fall. Convertible preferred stock’s value can depend heavily upon the underlying common stock’s value.
Real estate investment trust (REIT) risk. REITs, pooled investment vehicles that typically invest in real estate directly or in loans collateralized by real estate, carry risks associated with owning real estate, including the potential for a decline in value due to economic or market conditions.
Real estate securities risk. Securities of companies in the real estate industry carry risks associated with owning real estate, including the potential for a decline in value due to economic or market conditions.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Risk Nondiversified Status [Text] rr_RiskNondiversifiedStatus Non-diversified risk. Adverse events affecting a particular issuer or group of issuers may magnify losses for non-diversified funds, which may invest a large portion of assets in any one issuer or a small number of issuers.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
A note on performance
Prior to November 16, 2020, the fund was managed by a different subadvisor pursuant to different strategies, and thus, the performance presented prior to this date should not be attributed to the current subadvisor, Wellington Management Company LLP (“Wellington Management”). The fund’s performance shown below might have differed materially had Wellington Management managed the fund prior to November 16, 2020.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2021, Q4, 17.19%
Worst quarter: 2020, Q1, -22.97%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Real Estate Securities Trust) | Dow Jones U.S. Select REIT Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 45.91%
5 Years rr_AverageAnnualReturnYear05 9.65%
10 Years rr_AverageAnnualReturnYear10 10.70%
(John Hancock Variable Insurance Trust) | (Real Estate Securities Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.70%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.05%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.80%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [68]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.79%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 81
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 254
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 443
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 989
Annual Return 2012 rr_AnnualReturn2012 17.26%
Annual Return 2013 rr_AnnualReturn2013 (0.10%)
Annual Return 2014 rr_AnnualReturn2014 31.73%
Annual Return 2015 rr_AnnualReturn2015 2.68%
Annual Return 2016 rr_AnnualReturn2016 6.92%
Annual Return 2017 rr_AnnualReturn2017 6.24%
Annual Return 2018 rr_AnnualReturn2018 (3.46%)
Annual Return 2019 rr_AnnualReturn2019 29.40%
Annual Return 2020 rr_AnnualReturn2020 (5.64%)
Annual Return 2021 rr_AnnualReturn2021 46.79%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2021, Q4, 17.19%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 17.19%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2021
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -22.97%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (22.97%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 46.79%
5 Years rr_AverageAnnualReturnYear05 12.95%
10 Years rr_AverageAnnualReturnYear10 12.03%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 30, 1987
(John Hancock Variable Insurance Trust) | (Real Estate Securities Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.70%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.05%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.00%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [68]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.99%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 101
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 317
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 551
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,224
1 Year rr_AverageAnnualReturnYear01 46.46%
5 Years rr_AverageAnnualReturnYear05 12.72%
10 Years rr_AverageAnnualReturnYear10 11.81%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Real Estate Securities Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.70%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.05%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.75%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [68]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.74%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 76
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 239
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 416
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 929
1 Year rr_AverageAnnualReturnYear01 46.80%
5 Years rr_AverageAnnualReturnYear05 12.99%
10 Years rr_AverageAnnualReturnYear10 12.08%
Date of inception rr_AverageAnnualReturnInceptionDate Feb. 28, 2005
(John Hancock Variable Insurance Trust) | (Science & Technology Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek long-term growth of capital. Current income is incidental to the fund’s objective.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 87% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 87.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in the common stocks of companies expected to benefit from the development, and/or use of science and/or technology. (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.) For purposes of satisfying this requirement, common stock may include equity-linked notes and derivatives relating to common stocks, such as options on equity-linked notes.
The fund employs a multi-manager approach with two subadvisors, each of which employs its own investment approach and independently manages its portion of the fund. The fund will be rebalanced periodically so that the subadvisors manage the following portions of the fund:
50%* T. Rowe Price Associates, Inc. (“T. Rowe Price”)
50%* Allianz Global Investors U.S. LLC (“AllianzGI US”)
*Percentages are approximate. Since the fund is only rebalanced periodically, the actual portion of the fund managed by each subadvisor will vary.
This allocation methodology may change in the future.
Some industries likely to be represented in the fund include:
■
information technology including hardware, software, semiconductors and technology equipment
■
telecommunications equipment and services
■
media including advertising, broadcasting, cable and satellite, movies, entertainment, publishing and information services
■
environmental services
■
internet commerce and advertising
■
life sciences and health care, including pharmaceuticals, health care equipment and services, and biotechnology
■
chemicals and synthetic materials
■
defense and aerospace
■
alternative energy
While most of the fund’s assets are invested in U.S. common stocks, the fund may also purchase other types of securities, including U.S. dollar- and foreign currency-denominated foreign securities, convertible stocks and bonds, and warrants, and use futures and options, in keeping with the fund’s investment objectives.
Stock selection for the fund generally reflects a growth approach based on an assessment of a company’s fundamental prospects for above-average earnings, rather than on a company’s size. As a result, fund holdings can range from securities of small companies developing new technologies to securities of blue chip firms with established track records. The fund may also invest in companies that are expected to benefit from technological advances even if they are not directly involved in research and development. The fund may invest in suitable companies through IPOs.
The fund holds a certain portion of its assets in money market reserves, which can consist of shares of certain internal T. Rowe Price money market funds as well as U.S. dollar and foreign currency-denominated money market securities, including repurchase agreements, in the two highest rating categories, maturing in one year or less.
The fund may invest up to 10% of its total assets in hybrid instruments. Hybrid instruments are a type of high-risk derivative which can combine the characteristics of securities, futures and options. Such securities may bear interest or pay dividends at below market (or even relatively nominal) rates.
In managing its portion of the fund, AllianzGI US may enter into short sales including short sales against the box.
In pursuing the fund’s investment objective, each subadvisor has the discretion to purchase some securities that do not meet its normal investment criteria, as described above, when they perceive an unusual opportunity for gain. These special situations might arise when a subadvisor believes a security could increase in value for a variety of reasons including a change in management, an extraordinary corporate event, a new product introduction or a favorable competitive development.
The fund may sell securities for a variety of reasons, including to realize gains, limit losses, or redeploy assets into more promising opportunities.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
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.
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. A downgrade or default affecting any of the fund’s securities could affect the fund’s performance.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity risk.
 
Greater China risk. Investments in the Greater China region may be subject to less developed trading markets, acute political risks such as possible negative repercussions resulting from China’s relationship with Taiwan or Hong Kong, and restrictions on monetary repatriation or other adverse government actions. For example, a government may restrict investment in companies or industries considered important to national interests, or intervene in the financial markets, such as by imposing trading restrictions, or banning or curtailing short selling. A small number of companies and industries may generally represent a relatively large portion of the Greater China market as a whole.
 
Hong Kong Stock Connect Program (Stock Connect) risk. Trading in China A-Shares through Stock Connect, a mutual market access program that enables foreign investment in the People’s Republic of China (PRC), is subject to certain restrictions and risks. Securities listed on Stock Connect may lose purchase eligibility, which could adversely affect the fund’s performance. Trading through Stock Connect is subject to trading, clearance, and settlement procedures that may continue to develop as the program matures. Any changes in laws, regulations and policies applicable to Stock Connect may affect China A-Share prices. These risks are heightened by the underdeveloped state of the PRC’s investment and banking systems in general.
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 the fund intends to utilize include: futures contracts, equity-linked notes (equity-linked notes generally reflect the risks associated with their underlying securities, depend on the credit of the notes’ issuer, may be privately placed, and may have a limited secondary market), and options. Futures contracts and options generally are subject to counterparty risk.
High portfolio turnover risk. Trading securities actively and frequently can increase transaction costs (thus lowering performance) and taxable distributions.
Hybrid instrument risk. Hybrid instruments (a type of potentially high-risk derivative) combine the elements of futures contracts or options with those of debt, preferred equity or a depository instrument. Hybrid instruments entail greater market risk and may be more volatile than traditional debt instruments, may bear interest or pay preferred dividends at below-market rates, and may be illiquid. The risks of investing in hybrid instruments are a combination of the risks of investing in securities, options, futures, and currencies.
Information technology companies risk. Information technology companies can be significantly affected by rapid obsolescence, short product cycles, competition from new market entrants, and heightened cybersecurity risk, among other factors.
Investment company securities risk. The fund may invest in securities of other investment companies. Fund shareholders indirectly bear their proportionate share of the expenses of each such investment company. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
Initial public offerings (IPOs) risk. IPO share prices are frequently volatile and may significantly impact fund performance.
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.
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.
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.
Repurchase agreements risk. The risk of a repurchase agreement transaction is limited to the ability of the seller to pay the agreed-upon sum on the delivery date. In the event of bankruptcy or other default by the seller, the instrument purchased may decline in value, interest payable on the instrument may be lost and there may be possible difficulties and delays in obtaining collateral and delays and expense in liquidating the instrument.
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.
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.
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.
Warrants risk. The prices of warrants may not precisely reflect the prices of their underlying securities. Warrant holders do not receive dividends or have voting or credit rights. A warrant ceases to have value if not exercised prior to its expiration date.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. The Lipper Science and Technology Index shows how the fund’s performance compares against the returns of similar investments. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 33.24%
Worst quarter: 2018, Q4, -16.88%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Science & Technology Trust) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 28.71%
5 Years rr_AverageAnnualReturnYear05 18.47%
10 Years rr_AverageAnnualReturnYear10 16.55%
(John Hancock Variable Insurance Trust) | (Science & Technology Trust) | Lipper Science and Technology Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 18.51%
5 Years rr_AverageAnnualReturnYear05 27.14%
10 Years rr_AverageAnnualReturnYear10 20.99%
(John Hancock Variable Insurance Trust) | (Science & Technology Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 1.02%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.11%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [69]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.10%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 112
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 352
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 611
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,351
Annual Return 2012 rr_AnnualReturn2012 10.45%
Annual Return 2013 rr_AnnualReturn2013 43.53%
Annual Return 2014 rr_AnnualReturn2014 12.89%
Annual Return 2015 rr_AnnualReturn2015 6.69%
Annual Return 2016 rr_AnnualReturn2016 8.39%
Annual Return 2017 rr_AnnualReturn2017 41.13%
Annual Return 2018 rr_AnnualReturn2018 (0.61%)
Annual Return 2019 rr_AnnualReturn2019 38.06%
Annual Return 2020 rr_AnnualReturn2020 57.46%
Annual Return 2021 rr_AnnualReturn2021 8.53%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 33.24%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 33.24%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2018, Q4, -16.88%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (16.88%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2018
1 Year rr_AverageAnnualReturnYear01 8.53%
5 Years rr_AverageAnnualReturnYear05 27.04%
10 Years rr_AverageAnnualReturnYear10 21.22%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 01, 1997
(John Hancock Variable Insurance Trust) | (Science & Technology Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 1.02%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.31%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [69]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.30%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 132
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 414
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 717
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,578
1 Year rr_AverageAnnualReturnYear01 8.31%
5 Years rr_AverageAnnualReturnYear05 26.78%
10 Years rr_AverageAnnualReturnYear10 20.98%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Science & Technology Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 1.02%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.06%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [69]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.05%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 107
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 336
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 584
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,293
1 Year rr_AverageAnnualReturnYear01 8.58%
5 Years rr_AverageAnnualReturnYear05 27.10%
10 Years rr_AverageAnnualReturnYear10 21.28%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Select Bond Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek income and capital appreciation.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 132% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 132.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in a diversified mix of debt securities and instruments. (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.) The fund seeks to invest its assets in debt securities and instruments with an average duration of plus or minus one year of its benchmark, Bloomberg US Aggregate Bond Index, however, there is no limit on the fund’s average maturity. The fund does not invest in bonds rated below investment-grade at time of purchase.
Eligible investments include, but are not limited to:
■
U.S. Treasury and agency securities as well as notes backed by the Federal Deposit Insurance Corporation,
■
Mortgage-backed securities, including mortgage pass-through securities, commercial mortgage-backed securities (“CMBS”) and collateralized mortgage obligations (“CMOs”),
■
U.S. and foreign corporate bonds, and
■
Foreign government and agency securities.
The subadvisor uses proprietary research and economic and industry analysis to identify specific bonds, bond sectors and industries that are attractively priced. Due to this process, the fund may have a higher than average portfolio turnover ratio which may affect performance results.
The foreign securities in which the fund invests may be denominated in U.S. dollars or foreign currency.
Use of Hedging and Other Strategic Transactions. The fund is authorized to use all of the various investment strategies referred to under “Additional Information About the Funds’ Principal Risks — Hedging, derivatives and other strategic transactions risk” including, but not limited to, U.S. Treasury futures and options, index derivatives, credit default swaps and forwards.

The manager considers environmental, social, and/or governance (ESG) factors, alongside other relevant factors, as part of its investment process. 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.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
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.
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.
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. 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.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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 the fund intends to utilize include: credit default swaps; foreign currency forward contracts; foreign currency swaps; 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.
High portfolio turnover risk. Trading securities actively and frequently can increase transaction costs (thus lowering performance) and taxable distributions.
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.
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.
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.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series NAV 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 5.34%
Worst quarter: 2021, Q1, -2.95%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Select Bond Trust) | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.54%)
5 Years rr_AverageAnnualReturnYear05 3.57%
10 Years rr_AverageAnnualReturnYear10 2.90%
(John Hancock Variable Insurance Trust) | (Select Bond Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.57%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.03%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.65%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [70]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.64%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 65
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 207
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 361
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 809
1 Year rr_AverageAnnualReturnYear01 (1.20%)
5 Years rr_AverageAnnualReturnYear05 3.92%
10 Years rr_AverageAnnualReturnYear10 3.32%
Date of inception rr_AverageAnnualReturnInceptionDate Oct. 31, 2011
(John Hancock Variable Insurance Trust) | (Select Bond Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.57%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.03%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.85%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [70]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.84%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 86
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 270
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 470
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,048
1 Year rr_AverageAnnualReturnYear01 (1.39%)
5 Years rr_AverageAnnualReturnYear05 3.71%
10 Years rr_AverageAnnualReturnYear10 3.11%
Date of inception rr_AverageAnnualReturnInceptionDate Oct. 31, 2011
(John Hancock Variable Insurance Trust) | (Select Bond Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.57%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.03%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.60%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [70]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.59%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 60
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 191
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 334
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 749
Annual Return 2012 rr_AnnualReturn2012 6.31%
Annual Return 2013 rr_AnnualReturn2013 (1.32%)
Annual Return 2014 rr_AnnualReturn2014 5.59%
Annual Return 2015 rr_AnnualReturn2015 0.29%
Annual Return 2016 rr_AnnualReturn2016 3.19%
Annual Return 2017 rr_AnnualReturn2017 3.65%
Annual Return 2018 rr_AnnualReturn2018 (0.38%)
Annual Return 2019 rr_AnnualReturn2019 9.01%
Annual Return 2020 rr_AnnualReturn2020 9.14%
Annual Return 2021 rr_AnnualReturn2021 (1.15%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 5.34%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 5.34%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2021, Q1, -2.95%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (2.95%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2021
1 Year rr_AverageAnnualReturnYear01 (1.15%)
5 Years rr_AverageAnnualReturnYear05 3.96%
10 Years rr_AverageAnnualReturnYear10 3.36%
Date of inception rr_AverageAnnualReturnInceptionDate Jul. 29, 2009
(John Hancock Variable Insurance Trust) | (Short Term Government Income Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek a high level of current income consistent with preservation of capital. Maintaining a stable share price is a secondary goal.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 32% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 32.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The fund seeks to achieve its investment objective by investing under normal circumstances at least 80% of its net assets in obligations issued or guaranteed by the U.S. government and its agencies, authorities or instrumentalities (U.S. government securities). Under normal circumstances, the fund’s effective duration is no more than three years.
U.S. government securities may be supported by:
■
The full faith and credit of the United States government, such as Treasury bills, notes and bonds, and Government National Mortgage Association Certificates.
■
The right of the issuer to borrow from the U.S. Treasury, such as obligations of the Federal Home Loan Mortgage Corporation.
■
The credit of the instrumentality, such as obligations of the Federal National Mortgage Association.
The fund may invest in higher-risk securities, including U.S. dollar-denominated foreign government securities and asset-backed securities. It may also invest up to 10% of its net assets in foreign government high-yield securities (junk bonds) rated as low as B and their unrated equivalents.
In managing the portfolio of the fund, the subadvisor considers interest rate trends to determine which types of bonds to emphasize at a given time. The fund typically favors mortgage-related securities when it anticipates that interest rates will be relatively stable, and favors U.S. Treasuries at other times. Because high yield bonds often respond to market movements differently from U.S. government bonds, the fund may use them to manage volatility.
The fund may invest in mortgage-related securities and Treasury futures to protect against adverse changes and manage risks.
The fund may invest in other investment companies, including exchange traded funds (“ETFs”), and engage in short sales.
Under normal circumstances, the fund’s effective duration is no more than three years which means that the fund may purchase securities with a duration of greater than three years, as long as the fund’s average duration does not exceed three years.
The fund may trade securities actively which could increase transaction costs (thus lowering performance).
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
Changing distribution levels risk. The fund may cease or reduce the level of its distribution if income or dividends paid from its investments declines.
Credit and counterparty risk. The issuer or guarantor of a fixed-income security 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.
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.
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.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity risk.
High portfolio turnover risk. Trading securities actively and frequently can increase transaction costs (thus lowering performance) and taxable distributions.
Investment company securities risk. The fund may invest in securities of other investment companies. Fund shareholders indirectly bear their proportionate share of the expenses of each such investment company. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
Liquidity risk. The extent (if at all) to which a security may be sold 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.
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.
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.
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.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series NAV 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q1, 2.73%
Worst quarter: 2013, Q2, -1.24%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Short Term Government Income Trust) | Bloomberg U.S. Government 1-5 Year Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.18%)
5 Years rr_AverageAnnualReturnYear05 1.90%
10 Years rr_AverageAnnualReturnYear10 1.35%
(John Hancock Variable Insurance Trust) | (Short Term Government Income Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.57%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.08%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.70%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [71]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.69%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 70
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 223
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 389
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 870
1 Year rr_AverageAnnualReturnYear01 (1.59%)
5 Years rr_AverageAnnualReturnYear05 1.34%
10 Years rr_AverageAnnualReturnYear10 0.94%
Date of inception rr_AverageAnnualReturnInceptionDate May 03, 2010
(John Hancock Variable Insurance Trust) | (Short Term Government Income Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.57%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.08%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.90%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [71]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.89%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 91
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 286
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 497
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,107
1 Year rr_AverageAnnualReturnYear01 (1.78%)
5 Years rr_AverageAnnualReturnYear05 1.14%
10 Years rr_AverageAnnualReturnYear10 0.74%
Date of inception rr_AverageAnnualReturnInceptionDate May 03, 2010
(John Hancock Variable Insurance Trust) | (Short Term Government Income Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.57%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.08%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.65%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [71]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.64%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 65
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 207
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 361
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 809
Annual Return 2012 rr_AnnualReturn2012 1.18%
Annual Return 2013 rr_AnnualReturn2013 (0.74%)
Annual Return 2014 rr_AnnualReturn2014 1.20%
Annual Return 2015 rr_AnnualReturn2015 0.69%
Annual Return 2016 rr_AnnualReturn2016 0.62%
Annual Return 2017 rr_AnnualReturn2017 0.62%
Annual Return 2018 rr_AnnualReturn2018 0.89%
Annual Return 2019 rr_AnnualReturn2019 3.44%
Annual Return 2020 rr_AnnualReturn2020 3.65%
Annual Return 2021 rr_AnnualReturn2021 (1.54%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q1, 2.73%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 2.73%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2013, Q2, -1.24%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (1.24%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2013
1 Year rr_AverageAnnualReturnYear01 (1.54%)
5 Years rr_AverageAnnualReturnYear05 1.39%
10 Years rr_AverageAnnualReturnYear10 0.99%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 05, 2009
(John Hancock Variable Insurance Trust) | (Small Cap Index Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
Seeks to approximate the aggregate total return of a small cap U.S. domestic equity market index.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 20% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 20.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowings for investment purposes) at the time of investment in: (a) the common stocks that are included in the Russell 2000 Index; and (b) securities (which may or may not be included in the Russell 2000 Index) that the subadvisor believes as a group will behave in a manner similar to the index. (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.) As of February 28, 2022, the market capitalizations of companies included in the Russell 2000 Index ranged from $19.5 million to $10.6 billion.
An index is an unmanaged group of securities whose overall performance is used as an investment benchmark. Indexes may track broad investment markets, such as the global equity market, or more narrow investment markets, such as the U.S. small cap equity market. In contrast to actively managed funds, which seek to outperform their respective benchmark indexes through research and analysis, index funds are passively managed funds that seek to mirror the performance of their target indexes, minimizing performance differences over time. The fund attempts to match the performance of the Russell 2000 Index by: (a) holding all, or a representative sample, of the securities that comprise that index; and/or (b) by holding securities (which may or may not be included in the index) that the subadvisor believes as a group will behave in a manner similar to the index. However, the fund has operating expenses and transaction costs, while a market index does not. Therefore, the fund, while it attempts to track its target index closely, typically will be unable to match the performance of the target index exactly. The composition of an index changes from time to time, and the subadvisor will reflect those changes in the composition of the fund’s portfolio as soon as practicable.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions.
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 transaction expenses, 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.
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.
Quantitative modeling risk. Quantitative models may not accurately predict future market movements or characteristics, which may negatively impact performance. Models also may perform differently than expected due to implementation problems, technological malfunction, or programming or data inaccuracies, among other possible issues.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q4, 31.14%
Worst quarter: 2020, Q1, -30.72%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Small Cap Index Trust) | Russell 2000 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 14.82%
5 Years rr_AverageAnnualReturnYear05 12.02%
10 Years rr_AverageAnnualReturnYear10 13.23%
(John Hancock Variable Insurance Trust) | (Small Cap Index Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.48%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.57%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [72]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.51%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 52
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 177
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 312
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 708
Annual Return 2012 rr_AnnualReturn2012 16.10%
Annual Return 2013 rr_AnnualReturn2013 38.58%
Annual Return 2014 rr_AnnualReturn2014 4.59%
Annual Return 2015 rr_AnnualReturn2015 (4.58%)
Annual Return 2016 rr_AnnualReturn2016 20.98%
Annual Return 2017 rr_AnnualReturn2017 14.39%
Annual Return 2018 rr_AnnualReturn2018 (11.42%)
Annual Return 2019 rr_AnnualReturn2019 25.04%
Annual Return 2020 rr_AnnualReturn2020 19.29%
Annual Return 2021 rr_AnnualReturn2021 14.49%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q4, 31.14%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 31.14%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -30.72%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (30.72%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 14.49%
5 Years rr_AverageAnnualReturnYear05 11.59%
10 Years rr_AverageAnnualReturnYear10 12.89%
Date of inception rr_AverageAnnualReturnInceptionDate May 02, 2000
(John Hancock Variable Insurance Trust) | (Small Cap Index Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.48%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.77%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [72]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.71%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 73
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 240
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 422
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 949
1 Year rr_AverageAnnualReturnYear01 14.25%
5 Years rr_AverageAnnualReturnYear05 11.38%
10 Years rr_AverageAnnualReturnYear10 12.66%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Small Cap Index Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.48%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.52%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [72]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.46%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 47
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 161
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 285
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 647
1 Year rr_AverageAnnualReturnYear01 14.59%
5 Years rr_AverageAnnualReturnYear05 11.66%
10 Years rr_AverageAnnualReturnYear10 12.94%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Small Cap Opportunities Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek long-term capital appreciation.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 28% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 28.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in equity securities of small-capitalization companies. (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.) The fund has two subadvisors: Dimensional Fund Advisors LP (“Dimensional”) and GW&K Investment Management, LLC (“GW&K”). The Advisor to the fund, John Hancock Variable Trust Advisers LLC, may allocate fund assets between Dimensional and GW&K without restriction. Each subadvisor’s investment strategy is described below.
Dimensional
Dimensional will manage its portion of the fund’s assets (the “Dimensional Subadvised Assets”) as follows:
Dimensional generally will invest the Dimensional Subadvised Assets, using a market capitalization weighted approach, in a broad and diverse group of readily marketable securities of U.S. small and mid cap companies traded on a U.S. national securities exchange that Dimensional determines to be value stocks with higher profitability at time of purchase. A company’s market capitalization is the number of its shares outstanding times its price per share. See “Market Capitalization Weighted Approach” below. An equity issuer is considered to have a low relative price (i.e., a value stock) primarily because it has a low price in relation to its book value. In assessing relative price, Dimensional may consider additional factors, such as price-to-cash flow or price-to-earnings ratios. The criteria Dimensional uses for assessing relative price are subject to change from time to time. As of the date of this Prospectus, Dimensional generally considers for investment companies whose market capitalizations are generally smaller than the 500th largest U.S.
company. Dimensional does not intend to purchase or sell securities based on the prospects for the economy, the securities markets or the individual issuers whose shares are eligible for purchase.
Dimensional may sell portfolio securities when the issuer’s market capitalization increases to a level that exceeds that of the issuer with the largest market capitalization that is then eligible for investment by the Dimensional Subadvised Assets. In addition, Dimensional may sell portfolio securities when their price-to-book ratios rise above those of the security with the highest such ratio that is then eligible for purchase by the Dimensional Subadvised Assets. However, Dimensional may retain securities of issuers with relatively larger market capitalizations for longer periods, despite an increase in the issuers’ price-to-book ratios.
The total market capitalization ranges, and the value criteria used by Dimensional for the Dimensional Subadvised Assets, as described above, generally apply at the time of purchase. Dimensional will not be required to dispose of a security if the security’s issuer is no longer within the total market capitalization range or does not meet current value criteria. Securities that do meet the market capitalization and/or value criteria nevertheless may be sold at any time when, in Dimensional’s judgment, circumstances warrant their sale.
Dimensional may use derivatives such as futures contracts and options on futures contracts, to increase or decrease equity market exposure based on actual or expected cash inflows to or outflows from the fund. Dimensional may enter into futures contracts and options on futures contracts for U.S. equity securities and indices. Dimensional may also invest in exchange-traded funds (“ETFs”) and similarly structured pooled investments for the purpose of gaining exposure to the U.S. equity markets while maintaining liquidity. In addition to money market instruments and other short-term investments, the fund may invest in affiliated and unaffiliated unregistered money market funds to manage the fund’s cash pending investment in other securities or to maintain liquidity for the payment of redemptions or other purposes. Investments in ETFs and money market funds may involve a duplication of certain fees and expenses.
Market Capitalization Weighted Approach
The strategy used by Dimensional in managing the Dimensional Subadvised Assets involves market capitalization weighting in determining individual security weights. Market capitalization weighting means each security is generally purchased based on the issuer’s relative market capitalization.
Market capitalization weighting may be modified by Dimensional for a variety of reasons. Dimensional may adjust the representation in the Dimensional Subadvised Assets of an eligible company, or exclude a company, after considering such factors as free float, momentum, trading strategies, liquidity, size, relative price, profitability, investment characteristics and other factors determined to be appropriate. An equity issuer is considered to have a low relative price (i.e., a value stock) primarily because it has a low price in relation to its book value. In assessing relative price, Dimensional considers additional factors such as price to cash flow or price to earnings ratios. In assessing profitability, Dimensional considers different ratios, such as that of earnings or profits from operations relative to book value or assets. In assessing a company’s investment characteristics, Dimensional considers ratios such as recent changes in assets divided by total assets. The criteria Dimensional uses for assessing relative price, profitability and investment characteristics are subject to change from time to time.
Dimensional may deviate from market capitalization weighting to limit or fix the exposure of the Dimensional Subadvised Assets to a particular issuer to a maximum proportion of the assets of the Dimensional Subadvised Assets. Dimensional may exclude the stock of a company that meets applicable market capitalization criteria if Dimensional determines, in its judgment, that the purchase of such stock is inappropriate in light of other conditions. The subadvisor may decrease the allocation of the fund’s assets to eligible small capitalization companies that generally have lower profitability and/or higher relative prices. These adjustments will result in a deviation from traditional market capitalization weighting.
GW&K
GW&K will manage its portion of the fund’s assets as follows:
GW&K utilizes fundamental research and bottom-up stock selection to identify undervalued small cap companies with sustainable earnings growth, and whose management is focused on enhancing value for shareholders. GW&K seeks to hold securities for the long term.

GW&K focuses on quality small-cap companies with sound management and long-term sustainable growth, regardless of style. In selecting companies, GW&K looks for firms with the following key attributes:
■
Experienced, tenured, high-quality management;
■
Business models that deliver consistent long-term growth;
■
Leading companies in attractive and defensible niche markets;
■
Strong financial characteristics; and
■
Appropriate valuation.
Various factors may lead GW&K to consider selling a particular security, such as a significant change in the relevant company’s senior management or its products, deterioration in its fundamental characteristics, if the company has corporate governance issues, or if GW&K believes that the security has become overvalued.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
Credit and counterparty risk. 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.
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.
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.
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.
Financial services sector risk. Financial services companies can be significantly affected by economic, market, and business developments, borrowing costs, interest-rate fluctuations, competition, and government regulation, among other factors.
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 the fund intends to utilize include: futures contracts, options on futures contracts and options. Futures contracts and options generally are subject to counterparty risk.
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.
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.
Quantitative modeling risk. Quantitative models may not accurately predict future market movements or characteristics, which may negatively impact performance. Models also may perform differently than expected due to implementation problems, technological malfunction, or programming or data inaccuracies, among other possible issues.
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.
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.
Value investment style risk. Value securities may underperform the market as a whole, which may cause value-oriented funds to underperform equity funds with other investment strategies. Securities the manager believes are undervalued may never perform as expected.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. The Russell 2000 Value Index shows how the fund’s performance compares against the returns of similar investments. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q4, 30.49%
Worst quarter: 2020, Q1, -35.31%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Small Cap Opportunities Trust) | Russell 2000 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 14.82%
5 Years rr_AverageAnnualReturnYear05 12.02%
10 Years rr_AverageAnnualReturnYear10 13.23%
(John Hancock Variable Insurance Trust) | (Small Cap Opportunities Trust) | Russell 2000 Value Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 28.27%
5 Years rr_AverageAnnualReturnYear05 9.07%
10 Years rr_AverageAnnualReturnYear10 12.03%
(John Hancock Variable Insurance Trust) | (Small Cap Opportunities Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.99%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.10%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.14%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.26%) [73]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.88%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 90
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 336
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 603
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,363
Annual Return 2012 rr_AnnualReturn2012 16.84%
Annual Return 2013 rr_AnnualReturn2013 40.16%
Annual Return 2014 rr_AnnualReturn2014 2.38%
Annual Return 2015 rr_AnnualReturn2015 (5.17%)
Annual Return 2016 rr_AnnualReturn2016 19.47%
Annual Return 2017 rr_AnnualReturn2017 11.07%
Annual Return 2018 rr_AnnualReturn2018 (13.84%)
Annual Return 2019 rr_AnnualReturn2019 25.54%
Annual Return 2020 rr_AnnualReturn2020 9.88%
Annual Return 2021 rr_AnnualReturn2021 31.10%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q4, 30.49%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 30.49%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -35.31%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (35.31%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 31.10%
5 Years rr_AverageAnnualReturnYear05 11.59%
10 Years rr_AverageAnnualReturnYear10 12.64%
Date of inception rr_AverageAnnualReturnInceptionDate May 05, 2003
(John Hancock Variable Insurance Trust) | (Small Cap Opportunities Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.99%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.10%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.34%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.26%) [73]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.08%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 110
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 399
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 709
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,590
1 Year rr_AverageAnnualReturnYear01 30.85%
5 Years rr_AverageAnnualReturnYear05 11.37%
10 Years rr_AverageAnnualReturnYear10 12.41%
Date of inception rr_AverageAnnualReturnInceptionDate May 05, 2003
(John Hancock Variable Insurance Trust) | (Small Cap Opportunities Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.99%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.10%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.09%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.26%) [73]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.83%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 85
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 321
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 576
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,305
1 Year rr_AverageAnnualReturnYear01 31.16%
5 Years rr_AverageAnnualReturnYear05 11.66%
10 Years rr_AverageAnnualReturnYear10 12.70%
Date of inception rr_AverageAnnualReturnInceptionDate Feb. 28, 2005
(John Hancock Variable Insurance Trust) | (Small Cap Stock Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek long-term capital appreciation.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 107% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 107.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in stocks of small cap companies. (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.) For the purposes of the fund, “small cap companies” are those with market capitalizations, at the time of investment, not exceeding the maximum market capitalization of any company represented in either the Russell 2000 Index (approximately $10.6 billion as of February 28, 2022) or the S&P Small Cap 600 Index (approximately $5.9 billion as of February 28, 2022).
The fund invests in small-cap companies that are believed to offer above-average potential for growth in revenues and earnings. Market capitalizations of companies in the indices change over time; however, the fund will not sell a security just because a company has grown to a market capitalization outside the maximum range of the indices.
The subadvisor selects stocks using a combination of quantitative screens and bottom-up, fundamental security research. Quantitative screening seeks to narrow the list of small capitalization companies and to identify a group of companies with strong revenue growth and accelerating earnings. Fundamental equity research seeks to identify individual companies from that group with a higher potential for earnings growth and capital appreciation.
The subadvisor looks for companies based on a combination of criteria including one or more of the following:
■
Improving market shares and positive financial trends;
■
Superior management with significant equity ownership; and
■
Attractive valuations relative to earnings growth outlook.
The fund is likely to experience periods of higher turnover in portfolio securities because the subadvisor frequently adjusts the selection of companies and/or their position size based on these criteria. The fund’s sector exposures are broadly diversified, but are primarily a result of stock selection and therefore may vary significantly from its benchmark. The fund may invest up to 25% of its total assets in foreign securities, including emerging market securities. The fund may invest significantly in the information technology sector.
Except as otherwise stated under “Additional Information About the Funds — Temporary Defensive Investing,” the fund normally has 10% or less (usually lower) of its total assets in cash and cash equivalents.
The fund may invest in Initial Public Offerings (IPOs). The fund may also purchase each of the following types of securities:
U.S. dollar-denominated foreign securities and certain exchange-traded funds (ETFs).
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
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.
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.
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.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity risk.
Healthcare sector risk. Health sciences companies may be significantly affected by product obsolescence, thin capitalization, limited product lines and markets, civil liability claims, and legislative or regulatory activities, among other factors.
High portfolio turnover risk. Trading securities actively and frequently can increase transaction costs (thus lowering performance) and taxable distributions.
Information technology companies risk. Information technology companies can be significantly affected by rapid obsolescence, short product cycles, competition from new market entrants, and heightened cybersecurity risk, among other factors.
Initial public offerings (IPOs) risk. IPO share prices are frequently volatile and may significantly impact fund performance.
Liquidity risk. The extent (if at all) to which a security may be sold without negatively impacting its market value may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.
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.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series NAV 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 38.05%
Worst quarter: 2020, Q1, -25.00%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Small Cap Stock Trust) | Russell 2000 Growth Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 2.83%
5 Years rr_AverageAnnualReturnYear05 14.53%
10 Years rr_AverageAnnualReturnYear10 14.14%
(John Hancock Variable Insurance Trust) | (Small Cap Stock Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 1.01%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.05%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.11%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [74]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.10%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 112
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 352
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 611
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,351
1 Year rr_AverageAnnualReturnYear01 1.20%
5 Years rr_AverageAnnualReturnYear05 20.48%
10 Years rr_AverageAnnualReturnYear10 15.63%
Date of inception rr_AverageAnnualReturnInceptionDate May 02, 2005
(John Hancock Variable Insurance Trust) | (Small Cap Stock Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 1.01%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.05%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.31%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [74]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.30%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 132
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 414
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 717
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,578
1 Year rr_AverageAnnualReturnYear01 1.06%
5 Years rr_AverageAnnualReturnYear05 20.24%
10 Years rr_AverageAnnualReturnYear10 15.41%
Date of inception rr_AverageAnnualReturnInceptionDate May 02, 2005
(John Hancock Variable Insurance Trust) | (Small Cap Stock Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 1.01%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.05%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.06%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [74]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.05%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 107
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 336
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 584
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,293
Annual Return 2012 rr_AnnualReturn2012 16.52%
Annual Return 2013 rr_AnnualReturn2013 44.21%
Annual Return 2014 rr_AnnualReturn2014 7.60%
Annual Return 2015 rr_AnnualReturn2015 (8.78%)
Annual Return 2016 rr_AnnualReturn2016 2.27%
Annual Return 2017 rr_AnnualReturn2017 26.70%
Annual Return 2018 rr_AnnualReturn2018 (5.22%)
Annual Return 2019 rr_AnnualReturn2019 38.10%
Annual Return 2020 rr_AnnualReturn2020 51.62%
Annual Return 2021 rr_AnnualReturn2021 1.27%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 38.05%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 38.05%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -25.00%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (25.00%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 1.27%
5 Years rr_AverageAnnualReturnYear05 20.55%
10 Years rr_AverageAnnualReturnYear10 15.69%
Date of inception rr_AverageAnnualReturnInceptionDate May 01, 1996
(John Hancock Variable Insurance Trust) | (Small Cap Value Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek long-term capital appreciation.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees 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.”
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 32% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 32.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in small-cap companies that are believed to be undervalued by various measures and offer good prospects for capital appreciation. (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.) For the purposes of the fund, “small cap companies” are those with market capitalizations, at the time of investment, not exceeding the maximum market capitalization of any company represented in either the Russell 2000 Index (approximately $10.6 billion as of February 28, 2022) or the S&P SmallCap 600 Index (approximately $5.9 billion as of February 28, 2022).
The fund invests primarily in a diversified mix of common stocks of U.S. small-cap companies. The subadvisor employs a value-oriented investment approach in selecting stocks, using proprietary fundamental research to identify stocks the subadvisor believes have distinct value characteristics based on industry-specific valuation criteria. The subadvisor focuses on high quality companies with a proven record of above-average rates of profitability that sell at a discount relative to the overall small-cap market.
Fundamental research is then used to identify those companies demonstrating one or more of the following characteristics:
■
Sustainable competitive advantages within a market niche;
■
Strong profitability and free cash flows;
■
Strong market share positions and trends;
■
Quality of and share ownership by management; and
■
Financial structures that are more conservative than the relevant industry average.
The fund’s sector exposures are broadly diversified, but are primarily a result of stock selection and may, therefore, vary significantly from its benchmark. The fund may invest up to 15% of its total assets in foreign securities (with no more than 5% in emerging market securities). The fund may have significant investments in the financial services sector.
Except as otherwise stated under “Additional Information about the Funds — Temporary Defensive Investing,” the fund normally has 10% or less (usually lower) of its total assets invested in cash and cash equivalents.
The fund may invest in initial public offerings (“IPOs”). The fund may also purchase each of the following types of securities: real estate investment trusts (“REITs”) or other real estate related equity securities, U.S. dollar-denominated foreign securities and certain exchange-traded funds (“ETFs”). For purposes of the fund, ETFs are considered securities with a market capitalization equal to the weighted average market capitalization of the basket of securities comprising the ETF.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
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.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions. 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.
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.
Financial services sector risk. Financial services companies can be significantly affected by economic, market, and business developments, borrowing costs, interest-rate fluctuations, competition, and government regulation, among other factors.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity risk.
Industrials sector risk. Companies in the industrials sector may be affected by general economic conditions, commodity production and pricing, supply and demand fluctuations, environmental and other government regulations, geopolitical events, interest rates, insurance costs, technological developments, liabilities arising from governmental or civil actions, labor relations, input controls, and government spending.
Initial public offerings (IPOs) risk. IPO share prices are frequently volatile and may significantly impact fund performance.
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.
Real estate investment trust (REIT) risk. REITs, pooled investment vehicles that typically invest in real estate directly or in loans collateralized by real estate, carry risks associated with owning real estate, including the potential for a decline in value due to economic or market conditions.
Real estate securities risk. Securities of companies in the real estate industry carry risks associated with owning real estate, including the potential for a decline in value due to economic or market conditions.
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. To the extent that a fund invests in securities of companies in the financial services sector, the fund may be significantly affected by economic, market, and business developments, borrowing costs, interest-rate fluctuations, competition, and government regulation, among other factors, impacting that sector.
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.
Value investment style risk. Value securities may underperform the market as a whole, which may cause value-oriented funds to underperform equity funds with other investment strategies. Securities the manager believes are undervalued may never perform as expected.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series NAV 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q4, 34.84%
Worst quarter: 2020, Q1, -36.20%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Small Cap Value Trust) | Russell 2000 Value Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 28.27%
5 Years rr_AverageAnnualReturnYear05 9.07%
10 Years rr_AverageAnnualReturnYear10 12.03%
(John Hancock Variable Insurance Trust) | (Small Cap Value Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.94%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.07% [75]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.10% [76]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [77]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.09%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 111
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 349
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 605
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,339
1 Year rr_AverageAnnualReturnYear01 26.19%
5 Years rr_AverageAnnualReturnYear05 6.22%
10 Years rr_AverageAnnualReturnYear10 10.46%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Small Cap Value Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.94%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.07% [75]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.30% [76]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [77]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.29%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 131
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 411
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 712
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,567
1 Year rr_AverageAnnualReturnYear01 25.97%
5 Years rr_AverageAnnualReturnYear05 6.01%
10 Years rr_AverageAnnualReturnYear10 10.24%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Small Cap Value Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.94%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.07% [75]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.05% [76]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [77]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.04%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 106
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 333
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 578
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,282
Annual Return 2012 rr_AnnualReturn2012 15.78%
Annual Return 2013 rr_AnnualReturn2013 33.33%
Annual Return 2014 rr_AnnualReturn2014 7.25%
Annual Return 2015 rr_AnnualReturn2015 (1.31%)
Annual Return 2016 rr_AnnualReturn2016 22.68%
Annual Return 2017 rr_AnnualReturn2017 3.79%
Annual Return 2018 rr_AnnualReturn2018 (12.45%)
Annual Return 2019 rr_AnnualReturn2019 26.62%
Annual Return 2020 rr_AnnualReturn2020 (6.68%)
Annual Return 2021 rr_AnnualReturn2021 26.30%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q4, 34.84%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 34.84%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -36.20%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (36.20%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 26.30%
5 Years rr_AverageAnnualReturnYear05 6.28%
10 Years rr_AverageAnnualReturnYear10 10.52%
Date of inception rr_AverageAnnualReturnInceptionDate Aug. 31, 1999
(John Hancock Variable Insurance Trust) | (Small Company Value Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek long-term growth of capital.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees 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.”
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 23% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 23.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in companies with market capitalizations, at the time of investment, that do not exceed the maximum market capitalization of any security in the Russell 2000 Index ($19.5 million to $10.6 billion as of February 28, 2022). (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.) The fund invests in small companies whose common stocks are believed to be undervalued. The market capitalization of the companies in the fund’s portfolio and the Russell 2000 Index changes over time, and the fund will not sell a stock just because the company has grown to a market capitalization outside the range. The fund may, on occasion, purchase companies with a market capitalization above the range.
Reflecting a value approach to investing, the fund will seek the stocks of companies whose current stock prices do not appear to adequately reflect their underlying value as measured by assets, earnings, cash flow, or business franchises. The subadvisor’s in house research team seeks to identify companies that appear to be undervalued by various measures, and may be temporarily out of favor, but have good prospects for capital appreciation. In selecting investments, they generally look for some of the following factors:
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Low price/earnings, price/book value, or price/cash flow ratios relative to the Russell 2000 Index, a company’s peers, or company’s historical norm;
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Low stock price relative to a company’s underlying asset values;
■
Above-average dividend yield relative to a company’s peers or its own historic norm;
■
A plan to improve the business through restructuring; and/or
■
A sound balance sheet and other positive financial characteristics.
While most assets will be invested in U.S. common stocks, including real estate investment trusts (REITs) that pool money to invest in properties and mortgages, the fund may purchase other securities, including foreign securities (up to 20% of its total net assets), futures, and options. The fund may invest in fixed-income and convertible securities without restrictions on quality or rating, including up to 10% of total assets in below-investment-grade fixed-income securities (“junk bonds”) and loans. The fund’s fixed-income investments may include privately negotiated notes or loans, including loan participations and assignments (“bank loans”). These investments in bank loans will be made only in companies, municipalities or entities that meet the fund’s investment criteria. Direct investments in bank loans may be illiquid and holding a loan could expose the fund to the risks of being a direct lender. Since the fund invests primarily in equity securities, the risks associated with fixed-income securities will not affect the fund as much as they would a fund that invests more of its assets in fixed-income securities.
The fund holds a certain portion of its assets in money market reserves, which can consist of shares of certain internal T. Rowe Price money market funds as well as U.S. dollar and foreign currency-denominated money market securities, including repurchase agreements, in the two highest rating categories, maturing in one year or less.
The fund may sell securities for a variety of reasons, including to realize gains, limit losses or redeploy assets into more promising opportunities.
The fund may invest up to 10% of its total assets in hybrid instruments. Hybrid instruments are a type of high-risk derivatives which can combine the characteristics of securities, futures and options. Such securities may bear interest or pay dividends at below (or even relatively nominal) rates. The fund may focus its investments in a particular sector or sectors of the economy.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
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.
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. A downgrade or default affecting any of the fund’s securities could affect the fund’s performance.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions. 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.
Financial services sector risk. Financial services companies can be significantly affected by economic, market, and business developments, borrowing costs, interest-rate fluctuations, competition, and government regulation, among other factors.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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 the fund intends to utilize include: futures contracts and options. Futures contracts and options generally are subject to counterparty risk.
Hybrid instrument risk. Hybrid instruments (a type of potentially high-risk derivative) combine the elements of futures contracts or options with those of debt, preferred equity or a depository instrument. Hybrid instruments entail greater market risk and may be more volatile than traditional debt instruments, may bear interest or pay preferred dividends at below-market rates, and may be illiquid. The risks of investing in hybrid instruments are a combination of the risks of investing in securities, options, futures, and currencies.
Illiquid and restricted securities risk. Illiquid and restricted securities may be difficult to value and may involve greater risks than liquid securities. Illiquidity may have an adverse impact on a particular security’s market price and the fund’s ability to sell the security.
Investment company securities risk. The fund may invest in securities of other investment companies. Fund shareholders indirectly bear their proportionate share of the expenses of each such investment company. The total return on such investments will be reduced by the operating expenses and fees of such other investment companies, including advisory fees.
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.
Loan participations risk. Participations and assignments involve special types of risks, including credit risk, interest-rate risk, counterparty risk, liquidity risk, risks associated with extended settlement, and the risks of being a lender.
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.
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.
Real estate investment trust (REIT) risk. REITs, pooled investment vehicles that typically invest in real estate directly or in loans collateralized by real estate, carry risks associated with owning real estate, including the potential for a decline in value due to economic or market conditions.
Real estate securities risk. Securities of companies in the real estate industry carry risks associated with owning real estate, including the potential for a decline in value due to economic or market conditions.
Repurchase agreements risk. The risk of a repurchase agreement transaction is limited to the ability of the seller to pay the agreed-upon sum on the delivery date. In the event of bankruptcy or other default by the seller, the instrument purchased may decline in value, interest payable on the instrument may be lost and there may be possible difficulties and delays in obtaining collateral and delays and expense in liquidating the instrument.
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. To the extent that a fund invests in securities of companies in the financial services sector, the fund may be significantly affected by economic, market, and business developments, borrowing costs, interest-rate fluctuations, competition, and government regulation, among other factors, impacting that sector.
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.
Value investment style risk. Value securities may underperform the market as a whole, which may cause value-oriented funds to underperform equity funds with other investment strategies. Securities the manager believes are undervalued may never perform as expected.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q4, 28.47%
Worst quarter: 2020, Q1, -31.27%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Small Company Value Trust) | Russell 2000 Value Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 28.27%
5 Years rr_AverageAnnualReturnYear05 9.07%
10 Years rr_AverageAnnualReturnYear10 12.03%
(John Hancock Variable Insurance Trust) | (Small Company Value Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 1.05%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.08%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.06% [78]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.24% [79]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [80]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.23%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 125
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 392
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 680
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,499
Annual Return 2012 rr_AnnualReturn2012 16.30%
Annual Return 2013 rr_AnnualReturn2013 31.61%
Annual Return 2014 rr_AnnualReturn2014 0.11%
Annual Return 2015 rr_AnnualReturn2015 (5.60%)
Annual Return 2016 rr_AnnualReturn2016 32.32%
Annual Return 2017 rr_AnnualReturn2017 11.49%
Annual Return 2018 rr_AnnualReturn2018 (12.94%)
Annual Return 2019 rr_AnnualReturn2019 25.53%
Annual Return 2020 rr_AnnualReturn2020 9.24%
Annual Return 2021 rr_AnnualReturn2021 22.70%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q4, 28.47%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 28.47%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -31.27%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (31.27%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 22.70%
5 Years rr_AverageAnnualReturnYear05 10.31%
10 Years rr_AverageAnnualReturnYear10 12.07%
Date of inception rr_AverageAnnualReturnInceptionDate Oct. 01, 1997
(John Hancock Variable Insurance Trust) | (Small Company Value Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 1.05%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.08%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.06% [78]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.44% [79]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [80]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.43%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 146
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 455
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 786
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,723
1 Year rr_AverageAnnualReturnYear01 22.51%
5 Years rr_AverageAnnualReturnYear05 10.10%
10 Years rr_AverageAnnualReturnYear10 11.86%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Small Company Value Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 1.05%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.08%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.06% [78]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.19% [79]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [80]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.18%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 120
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 377
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 653
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,442
1 Year rr_AverageAnnualReturnYear01 22.81%
5 Years rr_AverageAnnualReturnYear05 10.37%
10 Years rr_AverageAnnualReturnYear10 12.13%
Date of inception rr_AverageAnnualReturnInceptionDate Feb. 28, 2005
(John Hancock Variable Insurance Trust) | (Strategic Equity Allocation Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek capital appreciation.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Other Expenses, New Fund, Based on Estimates [Text] rr_OtherExpensesNewFundBasedOnEstimates “Other expenses” have been estimated for the first year of operations of the fund’s Series I and Series II shares.
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. 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%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The fund seeks to achieve its investment objective by investing under normal market conditions at least 80% of its net assets (plus any borrowings for investment purposes) in U.S. and foreign equity securities of any market capitalization, including futures on indexes of equity securities. The fund’s allocation to various markets and types of securities will be actively managed.
The fund may invest in both developed and emerging markets. The fund’s investment in equity securities will vary both with respect to types of securities and markets in response to changing market and economic trends. The precise mix of securities will depend on the subadvisor’s outlook for the markets and generally reflect the subadvisor’s strategic asset allocation analysis and its assessment of the relative attractiveness of a particular asset class. When determining whether to invest in a particular market, the subadvisor considers various factors, including economic and political conditions, potential for economic growth and possible changes in currency exchange rates.
The fund also may invest in exchange-traded funds and fixed-income securities, including, but not limited to:
■
U.S. Treasury and agency securities as well as notes backed by the Federal Deposit Insurance Corporation,
■
U.S. Treasury futures contracts,
■
Mortgage-backed securities, including mortgage pass-through securities, commercial mortgage-backed securities (“CMBS”) and collateralized mortgage obligations (“CMOs”),
■
U.S. and foreign corporate bonds,
■
Foreign government and agency securities, and
■
Lower Rated Fixed Income Securities and High Yield Securities (also known as “junk bonds”).
The foreign securities in which the fund invests may be denominated in U.S. dollars or foreign currency. The fund may actively manage its exposure to foreign currencies through the use of foreign currency forward contracts and other currency derivatives. The fund may own foreign cash equivalents and foreign bank deposits as part of its investment strategy. The fund may invest in foreign currencies for hedging and speculative purposes.
The fund will engage in derivatives transactions, including but not limited to, futures and options contracts, foreign currency forward contracts and swaps including credit default swaps and total return swaps, for hedging and nonhedging purposes including, without limitation, the following purposes:
■
to attempt to protect against possible changes in the market value of securities held or to be purchased by the fund resulting from securities markets or currency exchange rate fluctuations,
■
to protect the fund’s unrealized gains in the value of its securities,
■
to facilitate the sale of the fund’s securities for investment purposes,
■
to manage the effective maturity or duration of the fund’s securities,
■
to establish a position in the derivatives markets as a method of gaining exposure to a particular security or market,
■
to facilitate the repatriation of foreign currency and the settlement of purchases of foreign securities, and
■
to increase or decrease exposure to a foreign currency or to shift exposure to foreign currency fluctuations from one country to another.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
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.
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.
Currency risk. Fluctuations in exchange rates may adversely affect the U.S. dollar value of a fund’s investments. Foreign currencies may decline in value, which could negatively impact performance.
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.
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.
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.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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 the fund intends to utilize include: credit default swaps, foreign currency forward contracts, futures contracts, options, total return swaps, 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.
High portfolio turnover risk. Trading securities actively and frequently can increase transaction costs (thus lowering performance) and taxable distributions.
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.
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.
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.
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.
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.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. The Combined Index (described below) shows how the fund’s performance compares against the returns of similar investments. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
The Combined Index represents 70% of the Russell 3000 Index and 30% of the MSCI EAFE Index.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series NAV 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 19.39%
Worst quarter: 2020, Q1, -22.02%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Strategic Equity Allocation Trust) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 28.71%
5 Years rr_AverageAnnualReturnYear05 18.47%
Inception rr_AverageAnnualReturnSinceInception 15.98%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 16, 2012
(John Hancock Variable Insurance Trust) | (Strategic Equity Allocation Trust) | Combined Index (reflects no deduction for fees, expenses, or taxes, except foreign withholding taxes on dividends)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 21.23%
5 Years rr_AverageAnnualReturnYear05 15.44%
Inception rr_AverageAnnualReturnSinceInception 13.28%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 16, 2012
(John Hancock Variable Insurance Trust) | (Strategic Equity Allocation Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.62%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04% [81]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.71%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [82]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.70%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 72
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 226
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 394
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 882
(John Hancock Variable Insurance Trust) | (Strategic Equity Allocation Trust) | Series II  
Prospectus: rr_ProspectusTable  
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 0.04% [81]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.91%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [82]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.90%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 92
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 289
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 503
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,119
(John Hancock Variable Insurance Trust) | (Strategic Equity Allocation Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
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 0.04%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.66%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [82]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.65%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 66
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 210
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 367
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 822
Annual Return 2013 rr_AnnualReturn2013 29.23%
Annual Return 2014 rr_AnnualReturn2014 6.40%
Annual Return 2015 rr_AnnualReturn2015 (0.35%)
Annual Return 2016 rr_AnnualReturn2016 8.81%
Annual Return 2017 rr_AnnualReturn2017 21.77%
Annual Return 2018 rr_AnnualReturn2018 (8.52%)
Annual Return 2019 rr_AnnualReturn2019 27.15%
Annual Return 2020 rr_AnnualReturn2020 14.34%
Annual Return 2021 rr_AnnualReturn2021 21.15%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 19.39%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 19.39%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -22.02%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (22.02%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 21.15%
5 Years rr_AverageAnnualReturnYear05 14.43%
Inception rr_AverageAnnualReturnSinceInception 12.50%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 16, 2012
(John Hancock Variable Insurance Trust) | (Strategic Income Opportunities Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek a high level of current income.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 61% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 61.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests primarily in the following types of securities: foreign government and corporate debt securities from developed and emerging markets, U.S. government and agency securities, and high-yield bonds.
The fund may also invest in preferred stock and other types of debt securities.
Although the fund may invest up to 10% of its net assets in securities rated as low as D (in default) by S&P Global Ratings (“S&P”) or Moody’s Investors Service, Inc. (“Moody’s”) (or their unrated equivalents) (i.e., “junk bonds”), it seeks to keep its average credit quality in the investment-grade range (AAA to BBB). There is no limit on the fund’s average maturity. The fund’s investment policies are based on credit ratings at the time of purchase.
In managing the fund, the subadvisor allocates assets among the three major types of securities (U.S. government debt and mortgages; corporate debt — primarily high yield; and foreign debt — both government and corporate, including emerging markets) based on analysis of economic factors, such as projected international interest rate movements, industry cycles and political trends. However, the subadvisor may invest up to 100% of the fund’s total assets in any one sector. Within each type of security, the subadvisor looks for investments that are appropriate for the overall fund in terms of yield, credit quality, structure and industry distribution. In selecting securities, relative yields and risk/reward ratios are the primary considerations.
The fund may use certain higher-risk investments, including restricted or illiquid securities and derivatives, which include futures contracts on securities, indices and foreign currency; options on futures contracts, securities, indices and foreign currency; interest rate, foreign currency and credit default
swaps; and foreign currency forward contracts, in each case, for the purposes of reducing risk, obtaining efficient market exposure and/or enhancing investment returns. In addition, the fund may invest up to 10% of its net assets in domestic or foreign common stocks.
Use of Hedging and Other Strategic Transactions. The fund is authorized to use all of the various investment strategies referred to under “Additional Information About the Funds’ Principal Risks — Hedging, derivatives and other strategic transactions risk” including, but not limited to, U.S. Treasury futures and options, index derivatives, credit default swaps and currency forwards and options.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
Changing distribution levels risk. The fund may cease or reduce the level of its distribution if income or dividends paid from its investments declines.
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.
Currency risk. Fluctuations in exchange rates may adversely affect the U.S. dollar value of a fund’s investments. Foreign currencies may decline in value, which could negatively impact performance.
Defaulted debt risk. Investing in defaulted debt securities is speculative and involves substantial risks in addition to those of non-defaulted high-yield securities. Defaulted debt securities generally do not generate interest payments. Principal on defaulted debt might not be repaid, and a fund could lose up to its entire investment.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity risk.
 
Hong Kong Bond Connect Program (Bond Connect) risk. Trading in China bonds through Bond Connect, a mutual market access program that enables foreign investment in the People’s Republic of China (PRC), is subject to certain restrictions and risks. Bonds listed on Bond Connect may lose purchase eligibility, which could adversely affect the fund’s performance. Trading through Bond Connect is subject to trading, clearance, and settlement procedures that may continue to develop as the program matures. Any changes in laws, regulations and policies applicable to Bond Connect may affect bond prices. These risks are heightened by the underdeveloped state of the PRC’s investment and banking systems in general.
 
Hong Kong Stock Connect Program (Stock Connect) risk. Trading in China A-Shares through Stock Connect, a mutual market access program that enables foreign investment in the People’s Republic of China (PRC), is subject to certain restrictions and risks. Securities listed on Stock Connect may lose purchase eligibility, which could adversely affect the fund’s performance. Trading through Stock Connect is subject to trading, clearance, and settlement procedures that may continue to develop as the program matures. Any changes in laws, regulations and policies applicable to Stock Connect may affect China A-Share prices. These risks are heightened by the underdeveloped state of the PRC’s investment and banking systems in general.
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 the fund intends to utilize include: credit default swaps, foreign currency forward contracts, futures contracts, options on futures contracts, options, interest rate swaps, 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.
Illiquid and restricted securities risk. Illiquid and restricted securities may be difficult to value and may involve greater risks than liquid securities. Illiquidity may have an adverse impact on a particular security’s market price and the fund’s ability to sell the security.
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.
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.
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.
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.
Preferred and convertible securities risk. Preferred stock dividends are payable only if declared by the issuer’s board. Preferred stock may be subject to redemption provisions. The market values of convertible securities tend to fall as interest rates rise and rise as interest rates fall. Convertible preferred stock’s value can depend heavily upon the underlying common stock’s value.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 7.06%
Worst quarter: 2020, Q1, -6.73%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Strategic Income Opportunities Trust) | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.54%)
5 Years rr_AverageAnnualReturnYear05 3.57%
10 Years rr_AverageAnnualReturnYear10 2.90%
(John Hancock Variable Insurance Trust) | (Strategic Income Opportunities Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.64%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.07%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.76%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [83]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.75%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 77
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 242
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 421
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 941
Annual Return 2012 rr_AnnualReturn2012 12.86%
Annual Return 2013 rr_AnnualReturn2013 3.74%
Annual Return 2014 rr_AnnualReturn2014 5.14%
Annual Return 2015 rr_AnnualReturn2015 1.22%
Annual Return 2016 rr_AnnualReturn2016 5.12%
Annual Return 2017 rr_AnnualReturn2017 5.59%
Annual Return 2018 rr_AnnualReturn2018 (5.03%)
Annual Return 2019 rr_AnnualReturn2019 10.91%
Annual Return 2020 rr_AnnualReturn2020 8.59%
Annual Return 2021 rr_AnnualReturn2021 0.90%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 7.06%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 7.06%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -6.73%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (6.73%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 0.90%
5 Years rr_AverageAnnualReturnYear05 4.03%
10 Years rr_AverageAnnualReturnYear10 4.79%
Date of inception rr_AverageAnnualReturnInceptionDate May 03, 2004
(John Hancock Variable Insurance Trust) | (Strategic Income Opportunities Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.64%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.07%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.96%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [83]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.95%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 97
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 305
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 530
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,177
1 Year rr_AverageAnnualReturnYear01 0.70%
5 Years rr_AverageAnnualReturnYear05 3.82%
10 Years rr_AverageAnnualReturnYear10 4.58%
Date of inception rr_AverageAnnualReturnInceptionDate May 03, 2004
(John Hancock Variable Insurance Trust) | (Strategic Income Opportunities Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.64%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.07%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.71%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [83]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.70%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 72
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 226
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 394
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 882
1 Year rr_AverageAnnualReturnYear01 0.95%
5 Years rr_AverageAnnualReturnYear05 4.08%
10 Years rr_AverageAnnualReturnYear10 4.84%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Total Bond Market Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
To seek to track the performance of the Bloomberg U.S. Aggregate Bond Index (the “Bloomberg Index”) (which represents the U.S. investment grade bond market).
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees 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.”
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 32% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 32.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowing for investment purposes) in securities listed in the Bloomberg U.S. Aggregate Bond Index (the Bloomberg Index). (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.)
The fund is an index fund, which differs from actively managed funds. Actively managed funds seek to outperform their respective indices through research and analysis. Over time, their performance may differ significantly from their respective indices. The fund is a passively managed fund that seeks to mirror the performance of its target index, minimizing performance differences over time.
An index is an unmanaged group of securities whose overall performance is used as an investment benchmark. Indices may track broad investment markets, such as the global equity market, or more narrow investment markets, such as the U.S. small cap equity market. The fund attempts to match
the performance of the Bloomberg Index by holding a representative sample of the securities that comprise the Bloomberg Index. However, an index fund has operating expenses and transaction costs, while a market index does not. Therefore, the fund, while it attempts to track its target index closely, typically will be unable to match the performance of the target index exactly.
The fund is an intermediate term bond fund of high and medium credit quality that seeks to track the performance of the Bloomberg Index, which broadly represents the U.S. investment grade bond market. The fund’s investment policies are based on credit ratings at the time of purchase.
The subadvisor employs a passive management strategy using quantitative techniques to select individual securities that provide a representative sample of the securities in the Bloomberg Index.
The Bloomberg Index consists of U.S. dollar-denominated, fixed rate, investment grade debt securities with maturities generally greater than one year and outstanding par values of at least $200 million, including:
■
U.S. Treasury and agency securities;
■
Asset-backed and mortgage-backed securities, including mortgage pass-through securities and commercial mortgage-backed securities (“CMBS”) and collateralized mortgage offerings (“CMOs”);
■
Corporate bonds, both U.S. and foreign (if U.S. dollar-denominated); and
■
Foreign government and agency securities (if U.S. dollar-denominated).
The subadvisor selects securities to match, as closely as practicable, the Bloomberg Index’s duration, cash flow, sector, credit quality, callability and other key performance characteristics.
The Bloomberg Index composition may change from time to time. The subadvisor will reflect those changes as soon as practicable.
The fund may purchase other types of securities that are not primary investment vehicles. These would include, for example, certain derivatives (investments whose value is based on indexes or other securities) such as futures contracts, interest-rate swaps and options.
Use of Hedging and Other Strategic Transactions. The fund is authorized to use all of the various investment strategies referred to under “Additional Information About the Funds’ Principal Risks — Hedging, derivatives and other strategic transactions risk” such as futures contracts, interest-rate swaps and options.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
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.
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.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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 the fund intends to utilize include: futures contracts, options, and interest-rate swaps. 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.
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 transaction expenses, 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.
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.
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.
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.
Quantitative modeling risk. Quantitative models may not accurately predict future market movements or characteristics, which may negatively impact performance. Models also may perform differently than expected due to implementation problems, technological malfunction, or programming or data inaccuracies, among other possible issues.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. Performance shown for periods prior to the inception date of a class is the performance of the fund’s oldest share class. This pre-inception performance, with respect to any other share class of the fund, has not been adjusted to reflect the Rule 12b-1 fees of that class. As a result, the pre-inception performance shown for a share class other than the oldest share class may be higher or lower than it would be if adjusted to reflect the Rule 12b-1 fees of the class. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series NAV 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q1, 3.56%
Worst quarter: 2021, Q1, -3.58%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Total Bond Market Trust) | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.54%)
5 Years rr_AverageAnnualReturnYear05 3.57%
10 Years rr_AverageAnnualReturnYear10 2.90%
(John Hancock Variable Insurance Trust) | (Total Bond Market Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.47%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.05%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [84]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.58% [85]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.27%) [86]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.31%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 32
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 159
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 297
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 700
1 Year rr_AverageAnnualReturnYear01 (1.81%)
5 Years rr_AverageAnnualReturnYear05 3.25%
10 Years rr_AverageAnnualReturnYear10 2.63%
Date of inception rr_AverageAnnualReturnInceptionDate Nov. 05, 2012
(John Hancock Variable Insurance Trust) | (Total Bond Market Trust) | Series II  
Prospectus: rr_ProspectusTable  
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 0.05%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [84]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.78% [85]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.27%) [86]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.51%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 52
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 222
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 407
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 941
1 Year rr_AverageAnnualReturnYear01 (2.10%)
5 Years rr_AverageAnnualReturnYear05 3.05%
10 Years rr_AverageAnnualReturnYear10 2.44%
Date of inception rr_AverageAnnualReturnInceptionDate Nov. 05, 2012
(John Hancock Variable Insurance Trust) | (Total Bond Market Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
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 0.05%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [84]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.53% [85]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.27%) [86]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.26%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 27
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 143
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 269
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 639
Annual Return 2012 rr_AnnualReturn2012 4.08%
Annual Return 2013 rr_AnnualReturn2013 (2.44%)
Annual Return 2014 rr_AnnualReturn2014 6.06%
Annual Return 2015 rr_AnnualReturn2015 0.30%
Annual Return 2016 rr_AnnualReturn2016 2.45%
Annual Return 2017 rr_AnnualReturn2017 3.34%
Annual Return 2018 rr_AnnualReturn2018 (0.24%)
Annual Return 2019 rr_AnnualReturn2019 8.30%
Annual Return 2020 rr_AnnualReturn2020 7.39%
Annual Return 2021 rr_AnnualReturn2021 (1.86%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q1, 3.56%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 3.56%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2021, Q1, -3.58%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (3.58%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2021
1 Year rr_AverageAnnualReturnYear01 (1.86%)
5 Years rr_AverageAnnualReturnYear05 3.31%
10 Years rr_AverageAnnualReturnYear10 2.68%
Date of inception rr_AverageAnnualReturnInceptionDate May 01, 1998
(John Hancock Variable Insurance Trust) | (Total Stock Market Index Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
Seeks to approximate the aggregate total return of a broad U.S. domestic equity market index.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees 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.”
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 8% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 8.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the fund invests at least 80% of its net assets (plus any borrowings for investment purposes) at the time of investment in (a) the common stocks that are included in the Wilshire 5000 Total Market Full Cap Index and (b) securities (which may or may not be included in the Wilshire 5000 Total Market Full Cap Index) that the subadvisor believes as a group will behave in a manner similar to the index. (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.) As of February 28, 2022, the market capitalizations of companies included in the Wilshire 5000 Total Market Full Cap Index ranged from less than $5.5 billion to $2.7 trillion.
An index is an unmanaged group of securities whose overall performance is used as an investment benchmark. Indexes may track broad investment markets, such as the global equity market, or more narrow investment markets, such as the U.S. small cap equity market. In contrast to actively managed funds, which seek to outperform their respective benchmark indexes through research and analysis, index funds are passively managed funds that seek to mirror the performance of their target indexes, minimizing performance differences over time. The fund attempts to match the performance of the Wilshire 5000 Total Market Full Cap Index by: (a) holding all, or a representative sample, of the securities that comprise that index; and/or (b) holding securities (which may or may not be included in the index) that the subadvisor believes as a group will behave in a manner similar to the index. However, the fund has operating expenses and transaction costs, while a market index does not. Therefore, the fund, while it attempts to
track its target index closely, typically will be unable to match the performance of the index exactly. The composition of an index changes from time to time, and the subadvisor will reflect those changes in the composition of the fund’s portfolio as soon as practicable.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance.
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.
Equity securities risk. The price of equity securities may decline due to changes in a company’s financial condition or overall market conditions.
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 transaction expenses, 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.
Information technology companies risk. Information technology companies can be significantly affected by rapid obsolescence, short product cycles, competition from new market entrants, and heightened cybersecurity risk, among other factors.
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.
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.
Quantitative modeling risk. Quantitative models may not accurately predict future market movements or characteristics, which may negatively impact performance. Models also may perform differently than expected due to implementation problems, technological malfunction, or programming or data inaccuracies, among other possible issues.
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.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 22.54%
Worst quarter: 2020, Q1, -21.01%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Total Stock Market Index Trust) | Wilshire 5000 Total Market Full Cap Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 24.51%
5 Years rr_AverageAnnualReturnYear05 17.82%
10 Years rr_AverageAnnualReturnYear10 16.14%
(John Hancock Variable Insurance Trust) | (Total Stock Market Index Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.47%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.04%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [87]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.57% [88]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [89]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.56%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 57
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 182
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 317
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 713
Annual Return 2012 rr_AnnualReturn2012 15.50%
Annual Return 2013 rr_AnnualReturn2013 33.39%
Annual Return 2014 rr_AnnualReturn2014 11.47%
Annual Return 2015 rr_AnnualReturn2015 (0.64%)
Annual Return 2016 rr_AnnualReturn2016 12.38%
Annual Return 2017 rr_AnnualReturn2017 20.59%
Annual Return 2018 rr_AnnualReturn2018 (5.70%)
Annual Return 2019 rr_AnnualReturn2019 29.63%
Annual Return 2020 rr_AnnualReturn2020 21.45%
Annual Return 2021 rr_AnnualReturn2021 24.45%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 22.54%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 22.54%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -21.01%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (21.01%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 24.45%
5 Years rr_AverageAnnualReturnYear05 17.37%
10 Years rr_AverageAnnualReturnYear10 15.63%
Date of inception rr_AverageAnnualReturnInceptionDate May 02, 2000
(John Hancock Variable Insurance Trust) | (Total Stock Market Index Trust) | Series II  
Prospectus: rr_ProspectusTable  
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 0.04%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [87]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.77% [88]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [89]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.76%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 78
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 245
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 427
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 953
1 Year rr_AverageAnnualReturnYear01 24.19%
5 Years rr_AverageAnnualReturnYear05 17.13%
10 Years rr_AverageAnnualReturnYear10 15.39%
Date of inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Total Stock Market Index Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
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 0.04%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [87]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.52% [88]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [89]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.51%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 52
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 166
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 290
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 652
1 Year rr_AverageAnnualReturnYear01 24.51%
5 Years rr_AverageAnnualReturnYear05 17.43%
10 Years rr_AverageAnnualReturnYear10 15.68%
Date of inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Ultra Short Term Bond Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The fund seeks a high level of current income consistent with the maintenance of liquidity and the preservation of capital.
Expense [Heading] rr_ExpenseHeading Fees and expenses
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 contract that may use the fund as its underlying investment option and would be higher if they did.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual fund operating expenses (%) (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 31, 2023
Expense Example [Heading] rr_ExpenseExampleHeading Expense example
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:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). 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 fund’s performance. During its most recent fiscal year, the fund’s portfolio turnover rate was 47% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 47.00%
Strategy [Heading] rr_StrategyHeading Principal investment strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal circumstances, the fund invests at least 80% of its net assets in a diversified portfolio of domestic, investment grade, debt securities. (The fund will provide written notice to shareholders at least 60 days prior to a change in its 80% investment policy.) Debt securities may be issued by governments, companies or special purpose entities and may include notes, discount notes, bonds, debentures, commercial paper, repurchase agreements, mortgage-backed and other asset-backed securities and assignments, participations and other interests in bank loans. Some loans may be illiquid. The fund may also invest in cash and cash equivalents. The fund’s investment policies are based on credit ratings at the time of purchase.
Investment grade securities include securities that are rated in one of the four highest rating categories as determined by a nationally recognized statistical rating organization, such as S&P Global Ratings (“S&P”), Fitch Ratings (“Fitch”) or Moody’s Investors Service (“Moody’s”), or are unrated securities determined by the subadvisor to be of comparable quality.
The fund may invest up to 20% of its net assets in securities that are rated BBB by S&P or Fitch, Baa by Moody’s, or unrated securities determined by the subadvisor to be of comparable quality. The fund may invest up to 20% of its net assets in foreign debt securities, including up to 5% of its net assets in foreign debt securities that are denominated in a foreign currency.
Under normal circumstances, the fund’s dollar weighted average maturity will be two years or less and its duration will be one year or less. Up to 15% of the fund’s net assets may be invested in securities with maturities greater than three years.
Use of Hedging and Other Strategic Transactions. The fund is authorized to use various hedging, derivatives and other strategic transactions described under “Additional Information about the Funds’ Principal Risks – Hedging, derivatives and other strategic transactions risk.”
The fund may invest in derivatives, including futures, currency forwards, options, swap contracts and other derivative instruments. The fund may invest in derivatives for both hedging and non-hedging purposes, including, for example, to seek to enhance returns or as a substitute for a position in an underlying asset.

The manager considers environmental, social, and/or governance (ESG) factors, alongside other relevant factors, as part of its investment process. 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.
Risk [Heading] rr_RiskHeading Principal risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The fund is subject to risks, and you could lose money by investing in the fund. The fund’s main risks are listed below in alphabetical order, not in order of importance. The fund’s investment strategy may not produce the intended results.
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.
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.
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.
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. 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.
Financial services sector risk. Financial services companies can be significantly affected by economic, market, and business developments, borrowing costs, interest-rate fluctuations, competition, and government regulation, among other factors.
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.
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. If applicable, depositary receipts are subject to most of the risks associated with investing in foreign securities directly because the value of a depositary receipt is dependent upon the market price of the underlying foreign equity security. Depositary receipts are also subject to liquidity 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 the fund intends to utilize include: foreign currency forward contracts, futures contracts, 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.
Illiquid and restricted securities risk. Illiquid and restricted securities may be difficult to value and may involve greater risks than liquid securities. Illiquidity may have an adverse impact on a particular security’s market price and the fund’s ability to sell the security.
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.
Loan participations risk. Participations and assignments involve special types of risks, including credit risk, interest-rate risk, counterparty risk, liquidity risk, risks associated with extended settlement, and the risks of being a lender.
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.
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.
Repurchase agreements risk. The risk of a repurchase agreement transaction is limited to the ability of the seller to pay the agreed-upon sum on the delivery date. In the event of bankruptcy or other default by the seller, the instrument purchased may decline in value, interest payable on the instrument may be lost and there may be possible difficulties and delays in obtaining collateral and delays and expense in liquidating the instrument.
Risk Lose Money [Text] rr_RiskLoseMoney The fund is subject to risks, and you could lose money by investing in the fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance. 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. The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar year total returns (%)—Series I 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Best quarter: 2020, Q2, 2.02%
Worst quarter: 2020, Q1, -0.87%
Performance Table Heading rr_PerformanceTableHeading Average annual total returns (%)—as of 12/31/21
(John Hancock Variable Insurance Trust) | (Ultra Short Term Bond Trust) | ICE Bank of America 6 Month U.S. Treasury Bill Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.09%
5 Years rr_AverageAnnualReturnYear05 1.31%
10 Years rr_AverageAnnualReturnYear10 0.79%
(John Hancock Variable Insurance Trust) | (Ultra Short Term Bond Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.55%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.07%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.67%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [90]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.66%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 67
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 213
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 372
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 834
Annual Return 2012 rr_AnnualReturn2012 0.54%
Annual Return 2013 rr_AnnualReturn2013 (0.07%)
Annual Return 2014 rr_AnnualReturn2014 (0.02%)
Annual Return 2015 rr_AnnualReturn2015 (0.04%)
Annual Return 2016 rr_AnnualReturn2016 0.52%
Annual Return 2017 rr_AnnualReturn2017 0.66%
Annual Return 2018 rr_AnnualReturn2018 1.40%
Annual Return 2019 rr_AnnualReturn2019 3.12%
Annual Return 2020 rr_AnnualReturn2020 1.47%
Annual Return 2021 rr_AnnualReturn2021 (0.46%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: 2020, Q2, 2.02%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 2.02%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: 2020, Q1, -0.87%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (0.87%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
1 Year rr_AverageAnnualReturnYear01 (0.46%)
5 Years rr_AverageAnnualReturnYear05 1.23%
10 Years rr_AverageAnnualReturnYear10 0.71%
Date of inception rr_AverageAnnualReturnInceptionDate Jul. 29, 2010
(John Hancock Variable Insurance Trust) | (Ultra Short Term Bond Trust) | Series II  
Prospectus: rr_ProspectusTable  
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 0.07%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.87%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [90]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.86%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 88
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 277
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 481
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,072
1 Year rr_AverageAnnualReturnYear01 (0.66%)
5 Years rr_AverageAnnualReturnYear05 1.03%
10 Years rr_AverageAnnualReturnYear10 0.51%
Date of inception rr_AverageAnnualReturnInceptionDate Jul. 29, 2010
(John Hancock Variable Insurance Trust) | (Ultra Short Term Bond Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
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 0.07%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.62%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [90]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.61%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 62
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 198
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 345
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 773
1 Year rr_AverageAnnualReturnYear01 (0.41%)
5 Years rr_AverageAnnualReturnYear05 1.28%
10 Years rr_AverageAnnualReturnYear10 0.77%
Date of inception rr_AverageAnnualReturnInceptionDate Jul. 29, 2010
[1]
1 The advisor contractually agrees to reduce its management fee or, if necessary, make payment to the fund in an amount equal to the amount by which expenses of the fund exceed 0.25% of average daily net assets of the fund. For purposes of this agreement, “expenses of the fund” means all fund expenses, excluding (a) taxes, (b) brokerage commissions, (c) interest expense, (d) litigation and indemnification expenses and other extraordinary expenses not incurred in the ordinary course of the fund’s business, (e) class-specific expenses, (f) borrowing costs, (g) prime brokerage fees, (h) acquired fund fees and expenses paid indirectly, and (i) short dividend expense. This agreement expires on April 30, 2023, unless renewed by mutual agreement of the advisor and the fund based upon a determination that this is appropriate under the circumstances at that time. The advisor also contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[2]
1 “Acquired fund fees and expenses” are based on indirect net expenses associated with the fund’s investments in underlying investment companies.
[3]
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.”
[4]
3 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[5]
1 The table reflects the combined fees of the feeder fund and the master fund.
[6]
2 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[7]
1 Restated to reflect current fees. The table reflects the combined fees of the feeder fund and the master fund.
[8]
2 The investment advisor of the master fund, Capital Research and Management Company, contractually agrees to waive a portion of its management fee. The waiver will be in effect through at least May 1, 2023, and the waiver may only be modified or terminated with the approval of the master fund’s Board of Trustees.
[9]
3 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[10]
1 The table reflects the combined fees of the feeder fund and the master fund.
[11]
2 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[12]
1 The table reflects the combined fees of the feeder fund and the master fund.
[13]
2 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[14]
1 Restated to reflect current fees. The table reflects the combined fees of the feeder fund and the master fund.
[15]
2 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[16]
1 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[17]
1 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[18]
1 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[19]
1 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[20]
1 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[21]
1 “Management fee” has been restated to reflect the contractual management fee schedule effective March 1, 2022.
[22]
2 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[23]
1 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[24]
1 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[25]
1 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[26]
1 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[27]
1 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[28]
1 “Management fee” has been restated to reflect the contractual management fee schedule effective February 1, 2022.
[29]
2 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[30]
1 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[31]
1 The advisor contractually agrees to reduce its management fee or, if necessary, make payment to the fund in an amount equal to the amount by which expenses of the fund exceed 0.34% of average daily net assets of the fund. For purposes of this agreement, “expenses of the fund” means all fund expenses, excluding (a) taxes, (b) brokerage commissions, (c) interest expense, (d) litigation and indemnification expenses and other extraordinary expenses not incurred in the ordinary course of the fund’s business, (e) class-specific expenses, (f) borrowing costs, (g) prime brokerage fees, (h) acquired fund fees and expenses paid indirectly, and (i) short dividend expense. This agreement expires on April 30, 2023, unless renewed by mutual agreement of the advisor and the fund based upon a determination that this is appropriate under the circumstances at that time. The advisor also contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[32]
1 “Management fee” has been restated to reflect the contractual management fee schedule effective March 1, 2022.
[33]
2 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[34]
1 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[35]
* Prior to April 26, 2021, the fund’s primary benchmark was the Bloomberg U.S. Aggregate Bond Index. Effective April 26, 2021, the fund’s primary benchmark index is the Morningstar U.S. Moderate Target Allocation Index. The Morningstar U.S. Moderate Target Allocation Index better reflects the universe of investment opportunities based on the fund’s investment strategy.
[36]
1 “Acquired fund fees and expenses” are based on indirect net expenses associated with the fund’s investments in underlying investment companies.
[37]
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.”
[38]
* Prior to April 26, 2021, the fund’s primary benchmark was the Bloomberg U.S. Aggregate Bond Index. Effective April 26, 2021, the fund’s primary benchmark index is the Morningstar U.S. Conservative Target Allocation Index. The Morningstar U.S. Conservative Target Allocation Index better reflects the universe of investment opportunities based on the fund’s investment strategy.
[39]
1 “Acquired fund fees and expenses” are based on indirect net expenses associated with the fund’s investments in underlying investment companies.
[40]
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.”
[41]
3 The advisor has contractually agreed to reduce its management fee and/or make payment to the fund in an amount equal to the amount by which “Other expenses” of the fund exceed 0.04% of the average daily net assets of the fund. “Other expenses” means all of the expenses of the fund, excluding certain expenses such as advisory fees, taxes, brokerage commissions, interest expense, litigation and indemnification expenses and other extraordinary expenses not incurred in the ordinary course of the fund’s business, distribution and service (Rule 12b-1) fees, underlying fund expenses (acquired fund fees), and short dividend expense. The current expense limitation agreement expires on April 30, 2023 unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[42]
* Prior to April 26, 2021, the fund’s primary benchmark was the S&P 500 Index. Effective April 26, 2021, the fund’s primary benchmark index is the Morningstar U.S. Moderately Aggressive Target Allocation Index. The Morningstar U.S. Moderately Aggressive Target Allocation Index better reflects the universe of investment opportunities based on the fund’s investment strategy.
[43]
1 “Acquired fund fees and expenses” are based on indirect net expenses associated with the fund’s investments in underlying investment companies.
[44]
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.”
[45]
* Prior to April 26, 2021, the fund’s primary benchmark was the Bloomberg U.S. Aggregate Bond Index. Effective April 26, 2021, the fund’s primary benchmark index is the Morningstar U.S. Moderately Conservative Target Allocation Index. The Morningstar U.S. Moderately Conservative Target Allocation Index better reflects the universe of investment opportunities based on the fund’s investment strategy.
[46]
1 “Acquired fund fees and expenses” are based on indirect net expenses associated with the fund’s investments in underlying investment companies.
[47]
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.”
[48]
* Prior to April 26, 2021, the fund’s primary benchmark was the Bloomberg U.S. Aggregate Bond Index. Effective April 26, 2021, the fund’s primary benchmark index is the Morningstar U.S. Moderate Target Allocation Index. The Morningstar U.S. Moderate Target Allocation Index better reflects the universe of investment opportunities based on the fund’s investment strategy.
[49]
1 “Acquired fund fees and expenses” are based on indirect net expenses associated with the fund’s investments in underlying investment companies.
[50]
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.”
[51]
* Prior to April 26, 2021, the fund’s primary benchmark was the Bloomberg U.S. Aggregate Bond Index. Effective April 26, 2021, the fund’s primary benchmark index is the Morningstar U.S. Conservative Target Allocation Index. The Morningstar U.S. Conservative Target Allocation Index better reflects the universe of investment opportunities based on the fund’s investment strategy.
[52]
1 “Acquired fund fees and expenses” are based on indirect net expenses associated with the fund’s investments in underlying investment companies.
[53]
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.”
[54]
* Prior to April 26, 2021, the fund’s primary benchmark was the S&P 500 Index. Effective April 26, 2021, the fund’s primary benchmark index is the Morningstar U.S. Moderately Aggressive Target Allocation Index. The Morningstar U.S. Moderately Aggressive Target Allocation Index better reflects the universe of investment opportunities based on the fund’s investment strategy.
[55]
1 “Acquired fund fees and expenses” are based on indirect net expenses associated with the fund’s investments in underlying investment companies.
[56]
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.”
[57]
* Prior to April 26, 2021, the fund’s primary benchmark was the Bloomberg U.S. Aggregate Bond Index. Effective April 26, 2021, the fund’s primary benchmark index is the Morningstar U.S. Moderately Conservative Target Allocation Index. The Morningstar U.S. Moderately Conservative Target Allocation Index better reflects the universe of investment opportunities based on the fund’s investment strategy.
[58]
1 “Acquired fund fees and expenses” are based on indirect net expenses associated with the fund’s investments in underlying investment companies.
[59]
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.”
[60]
1 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[61]
1 The advisor contractually agrees to reduce its management fee by an annual rate of 0.10% of the fund’s average daily net assets. This agreement expires on April 30, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time. The advisor also contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[62]
1 “Management fee” has been restated to reflect the contractual management fee schedule effective February 1, 2022.
[63]
2 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[64]
1 The advisor contractually agrees to reduce its management fee or, if necessary, make payment to the fund in an amount equal to the amount by which expenses of the fund exceed 0.28% of average daily net assets of the fund. For purposes of this agreement, “expenses of the fund” means all fund expenses, excluding (a) taxes, (b) brokerage commissions, (c) interest expense, (d) litigation and indemnification expenses and other extraordinary expenses not incurred in the ordinary course of the fund’s business, (e) class-specific expenses, (f) borrowing costs, (g) prime brokerage fees, (h) acquired fund fees and expenses paid indirectly, and (i) short dividend expense. This agreement expires on April 30, 2023, unless renewed by mutual agreement of the advisor and the fund based upon a determination that this is appropriate under the circumstances at that time. The advisor also contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[65]
1 “Acquired fund fees and expenses” are based on indirect net expenses associated with the fund’s investments in underlying investment companies.
[66]
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.”
[67]
3 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[68]
1 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[69]
1 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[70]
1 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[71]
1 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[72]
1 The advisor contractually agrees to reduce its management fee by an annual rate of 0.05% of the fund’s average daily net assets. This agreement expires on April 30, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time. The advisor also contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[73]
1 The advisor contractually agrees to waive its management fee so that the amount retained by the advisor after payment of subadvisory fees does not exceed 0.45% of the fund’s average daily net assets. The current expense limitation agreement expires on April 30, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time. The advisor also contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[74]
1 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[75]
1 “Acquired fund fees and expenses” are based on indirect net expenses associated with the fund’s investments in underlying investment companies.
[76]
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.”
[77]
3 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[78]
1 “Acquired fund fees and expenses” are based on indirect net expenses associated with the fund’s investments in underlying investment companies.
[79]
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.”
[80]
3 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[81]
1 “Other expenses” have been estimated for the first year of operations of the fund’s Series I and Series II shares.
[82]
2 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[83]
1 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[84]
1 “Acquired fund fees and expenses” are based on indirect net expenses associated with the fund’s investments in underlying investment companies.
[85]
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.”
[86]
3 The advisor contractually agrees to reduce its management fee or, if necessary, make payment to the fund in an amount equal to the amount by which expenses of the fund exceed 0.25% of average daily net assets of the fund. For purposes of this agreement, “expenses of the fund” means all fund expenses, excluding (a) taxes, (b) brokerage commissions, (c) interest expense, (d) litigation and indemnification expenses and other extraordinary expenses not incurred in the ordinary course of the fund’s business, (e) class-specific expenses, (f) borrowing costs, (g) prime brokerage fees, (h) acquired fund fees and expenses paid indirectly, and (i) short dividend expense. This agreement expires on April 30, 2023, unless renewed by mutual agreement of the advisor and the fund based upon a determination that this is appropriate under the circumstances at that time. The advisor also contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[87]
1 “Acquired fund fees and expenses” are based on indirect net expenses associated with the fund’s investments in underlying investment companies.
[88]
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.”
[89]
3 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.
[90]
1 The advisor contractually agrees to waive a portion of its management fee and/or reimburse expenses for the fund and certain other John Hancock funds according to an asset level breakpoint schedule that is based on the aggregate net assets of all the funds participating in the waiver or reimbursement. This waiver is allocated proportionally among the participating funds. During its most recent fiscal year, the fund’s reimbursement amounted to 0.01% of the fund’s average daily net assets. This agreement expires on July 31, 2023, unless renewed by mutual agreement of the fund and the advisor based upon a determination that this is appropriate under the circumstances at that time.