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Label Element Value
(John Hancock Variable Insurance Trust) | (500 Index Trust B)  
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 and hold 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 medium 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, 2017
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 medium 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 4% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 4.00%
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 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 29, 2016, the market capitalizations of companies included in the S&P 500 Index ranged from $2 billion to $539.1 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 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 principal risks of investing in the fund include:

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.

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.

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, along with specific additional associated risks, if any, include: futures contracts 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.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.

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.
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. Unless all share classes shown in the table have the same inception date, 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. For periods prior to the inception date of the fund, performance shown is the actual performance of the sole share class of the fund's predecessor fund and has not been adjusted to reflect the Rule 12b-1 fees of any class of shares. As a result, pre-inception performance of the fund may be higher than 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series NAV (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 15.85%

Worst quarter: Q4 '08, –22.11%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (500 Index Trust B) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.38%
5 Years rr_AverageAnnualReturnYear05 12.57%
10 Years rr_AverageAnnualReturnYear10 7.31%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 1996
(John Hancock Variable Insurance Trust) | (500 Index Trust B) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.46%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.03%
Total annual fund operating expenses rr_ExpensesOverAssets 0.54%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.24%) [1]
Total annual fund operating expenses after expense reimbursements 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 1.10%
5 Years rr_AverageAnnualReturnYear05 12.27%
10 Years rr_AverageAnnualReturnYear10 7.06%
Date of Inception rr_AverageAnnualReturnInceptionDate Nov. 05, 2012
(John Hancock Variable Insurance Trust) | (500 Index Trust B) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.46%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.03%
Total annual fund operating expenses rr_ExpensesOverAssets 0.74%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.24%) [1]
Total annual fund operating expenses after expense reimbursements 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 0.86%
5 Years rr_AverageAnnualReturnYear05 12.13%
10 Years rr_AverageAnnualReturnYear10 6.99%
Date of Inception rr_AverageAnnualReturnInceptionDate Nov. 05, 2012
(John Hancock Variable Insurance Trust) | (500 Index Trust B) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.46%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.03%
Total annual fund operating expenses rr_ExpensesOverAssets 0.49%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.24%) [1]
Total annual fund operating expenses after expense reimbursements 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 2006 rr_AnnualReturn2006 15.56%
Annual Return 2007 rr_AnnualReturn2007 5.25%
Annual Return 2008 rr_AnnualReturn2008 (37.19%)
Annual Return 2009 rr_AnnualReturn2009 26.35%
Annual Return 2010 rr_AnnualReturn2010 14.86%
Annual Return 2011 rr_AnnualReturn2011 1.87%
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%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 15.85%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 15.85%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –22.11%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (22.11%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 1.15%
5 Years rr_AverageAnnualReturnYear05 12.31%
10 Years rr_AverageAnnualReturnYear10 7.08%
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 and hold 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 medium 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)

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 medium 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

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 seeks to invest its assets in debt securities and instruments with an average duration of between 4 to 6 years, 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, 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 Standard & Poor's Ratings Services ("S&P") or Moody's Investors Service ("Moody's"). Each 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 increase expenses and affect performance results.

The foreign securities in which the fund invests may be denominated in U.S. dollars or foreign currency.

The fund employs a multi-manager approach with two subadvisors, Declaration Management & Research LLC ("Declaration") and John Hancock Asset Management a division of Manulife Asset Management (US) LLC ("John Hancock Asset Management"), 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%* Declaration

50%* John Hancock Asset Management

*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.

Declaration

Declaration 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. Declaration 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."

John Hancock Asset Management

John Hancock Asset Management uses proprietary research to identify specific bond sectors, industries and bonds that are attractively priced. John Hancock Asset Management tries 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 John Hancock Asset Management 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.
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 principal risks of investing in the fund include:

Changing distribution levels risk. The distribution amounts paid by the fund generally depend on the amount of income and/or dividends received by the fund's investments. As a result of market, interest rate and other circumstances, the amount of cash available for distribution by the fund and the fund's distribution rate may vary or decline. The risk of such variability is accentuated in currently prevailing market and interest rate circumstances.

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.

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.

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. 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.

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, swaps, and swaptions. 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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Inverse interest-only securities Inverse interest-only securities that are mortgage-backed securities are subject to the same risks as other mortgage-backed securities. In addition, the coupon on an inverse interest-only security can be extremely sensitive to changes in prevailing interest rates.

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. For periods prior to the inception of the fund, performance shown for each share class is the actual performance of the sole share class of the fund's predecessor fund. This pre-inception performance for each of the Series I and Series II share classes has not been adjusted to reflect the Rule 12b-1 fees of that class and would be lower if it did. The performance information below does not reflect fees and expenses of any variable insurance contract which may use JHVIT as its underlying investment medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series NAV (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q3 '09, 9.91%

Worst quarter: Q4 '08, –5.91%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Active Bond Trust) | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.55%
5 Years rr_AverageAnnualReturnYear05 3.25%
10 Years rr_AverageAnnualReturnYear10 4.51%
Date of Inception rr_AverageAnnualReturnInceptionDate Mar. 29, 1986
(John Hancock Variable Insurance Trust) | (Active Bond Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.60%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.69%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 70
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 221
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 384
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 859
1 Year rr_AverageAnnualReturnYear01 0.17%
5 Years rr_AverageAnnualReturnYear05 4.48%
10 Years rr_AverageAnnualReturnYear10 5.57%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Active Bond Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.60%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.89%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 91
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 284
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 493
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,096
1 Year rr_AverageAnnualReturnYear01 (0.14%)
5 Years rr_AverageAnnualReturnYear05 4.27%
10 Years rr_AverageAnnualReturnYear10 5.35%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Active Bond Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.60%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.64%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 65
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 205
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 357
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 798
Annual Return 2006 rr_AnnualReturn2006 4.54%
Annual Return 2007 rr_AnnualReturn2007 4.03%
Annual Return 2008 rr_AnnualReturn2008 (10.48%)
Annual Return 2009 rr_AnnualReturn2009 24.86%
Annual Return 2010 rr_AnnualReturn2010 13.91%
Annual Return 2011 rr_AnnualReturn2011 5.97%
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%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q3 '09, 9.91%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 9.91%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –5.91%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (5.91%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 0.12%
5 Years rr_AverageAnnualReturnYear05 4.53%
10 Years rr_AverageAnnualReturnYear10 5.62%
Date of Inception rr_AverageAnnualReturnInceptionDate Mar. 29, 1986
(John Hancock Variable Insurance Trust) | (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 and hold 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 medium 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)

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 medium 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 238% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 238.00%
Strategy [Heading] rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Under normal market conditions, the fund invests in common stocks and other equity securities within all asset classes (small-, mid- and large-cap) of those included in the Russell 3000 Index ($16 million to $536 billion as of February 29, 2016).

The fund may invest in all types of equity securities including common stocks, preferred stocks, convertible securities and depositary receipts for such securities. These securities may be listed on securities exchanges, traded in various over-the-counter markets or have no organized markets. The fund may also invest in U.S. government securities.

The subadvisor blends fundamental equity analysis and quantitative theory into a disciplined and systematic process. The technique minimizes subjectivity and allows the team to analyze the broadest possible universe of stocks. The subadvisor's systematic equity strategy evaluates current market conditions to dynamically weight each stock selection factor in a quantitative model. Stock selection factors include multiple valuation, growth, quality, and sentiment and stability characteristics. The relative weights of these factors in the model vary according to the favorability of current conditions for each factor. Conditions include the phase of the economic cycle, liquidity, and market sentiment, fear and greed.

The subadvisor extensively ranks the Russell 3000 Index universe according to this dynamic model to identify what the subadvisor believes are the most and least attractive securities. Expected returns are generated for each stock relative to its own industry. Securities are then selected based on expected returns, risk control constraints and anticipated transaction costs.

By applying a rigorous portfolio construction process, the subadvisor targets excess return levels similar to traditional managers, while holding a significantly more diversified basket of stocks. Non-linear market impact assumptions are also incorporated into the process to maximize the trade-off between the anticipated pickup from trading and the costs associated with making these trades.

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 principal risks of investing in the fund include:

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.

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.

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.

High portfolio turnover risk. Actively trading securities can increase transaction costs (thus lowering 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 17.59%

Worst quarter: Q4 '08, –23.17%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (All Cap Core Trust) | Russell 3000 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.48%
5 Years rr_AverageAnnualReturnYear05 12.18%
10 Years rr_AverageAnnualReturnYear10 7.35%
Date of Inception rr_AverageAnnualReturnInceptionDate Jul. 15, 1996
(John Hancock Variable Insurance Trust) | (All Cap Core Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.77%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.05%
Total annual fund operating expenses rr_ExpensesOverAssets 0.87%
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 2006 rr_AnnualReturn2006 14.75%
Annual Return 2007 rr_AnnualReturn2007 2.66%
Annual Return 2008 rr_AnnualReturn2008 (39.63%)
Annual Return 2009 rr_AnnualReturn2009 28.46%
Annual Return 2010 rr_AnnualReturn2010 13.04%
Annual Return 2011 rr_AnnualReturn2011 0.41%
Annual Return 2012 rr_AnnualReturn2012 16.57%
Annual Return 2013 rr_AnnualReturn2013 34.33%
Annual Return 2014 rr_AnnualReturn2014 9.64%
Annual Return 2015 rr_AnnualReturn2015 2.59%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 17.59%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 17.59%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –23.17%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (23.17%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 2.59%
5 Years rr_AverageAnnualReturnYear05 12.08%
10 Years rr_AverageAnnualReturnYear10 6.21%
Date of Inception rr_AverageAnnualReturnInceptionDate Jul. 15, 1996
(John Hancock Variable Insurance Trust) | (All Cap Core Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.77%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.05%
Total annual fund operating expenses rr_ExpensesOverAssets 1.07%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 109
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 340
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 590
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,306
1 Year rr_AverageAnnualReturnYear01 2.36%
5 Years rr_AverageAnnualReturnYear05 11.85%
10 Years rr_AverageAnnualReturnYear10 5.99%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (All Cap Core Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.77%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.05%
Total annual fund operating expenses rr_ExpensesOverAssets 0.82%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 84
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 262
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 455
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,014
1 Year rr_AverageAnnualReturnYear01 2.64%
5 Years rr_AverageAnnualReturnYear05 12.13%
10 Years rr_AverageAnnualReturnYear10 6.26%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Alpha Opportunities Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

To seek long-term total return.
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 and hold 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 medium 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)

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 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 medium 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 96% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 96.00%
Strategy [Heading] rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

The fund employs a "multiple sleeve structure," which means the fund has several components that are managed separately in different styles. The fund seeks to obtain its objective by combining these different component styles in a single fund.

For each component "sleeve," the subadvisor has a distinct investment philosophy and analytical process to identify specific securities for purchase or sale based on internal, proprietary research. Each component sleeve tends to be flexible, opportunistic, and total return-oriented such that the aggregate portfolio represents a wide range of investment philosophies, companies, industries and market capitalizations. Investment personnel for each component sleeve have complete discretion and responsibility for selection and portfolio construction decisions within their specific sleeve.

The subadvisor is responsible for selecting styles or approaches for component sleeves with a focus on combining complementary investment styles, monitoring the risk profile, strategically rebalancing the portfolio, and maintaining a consistent fund profile. In choosing prospective investments, the subadvisor analyzes a number of factors, such as business environment, management quality, balance sheet, income statement, anticipated earnings, expected growth rates, revenues, dividends and other related measures of value.

Under normal market conditions, the fund invests at least 65% of its total assets in equity and equity-related securities, including common stock, preferred stock, depositary receipts (including American Depositary Receipts ("ADRs") and Global Depositary Receipts), index-related securities (including exchange-traded funds ("ETFs")), real estate investment structures (including REITs), convertible securities, private placements, convertible preferred stock, rights, and warrants. The fund may invest in listed and unlisted domestic and foreign equity and equity-related securities or instruments. These equity and equity-related instruments may include equity securities of, or options linked to, emerging market issuers or indexes.

The fund may invest up to 35% of its total assets in the securities of foreign issuers and foreign currency-denominated securities, including companies that conduct their principal business activities in emerging markets or whose securities are traded principally on exchanges in emerging markets.

The fund may also invest in fixed-income securities, fixed-income related instruments, and cash and cash equivalents. These fixed-income securities may include below-investment-grade instruments (i.e., junk bonds).

The fund may invest in over-the-counter and exchange-traded derivatives, including but not limited to futures, forward contracts, swaps, options, options on futures, swaptions, structured notes, and market access products, to reduce risk and enhance potential income.

The fund may invest in initial public offerings ("IPOs"). 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 principal risks of investing in the fund include:

Convertible securities risk. 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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. 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. 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.

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. Actively trading securities can increase transaction costs (thus lowering performance).

Initial public offerings risk. IPO share prices are frequently volatile and may significantly impact fund performance.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Real estate investment trust 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 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series NAV (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 18.66%

Worst quarter: Q3 '11, –19.40%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Alpha Opportunities Trust) | Russell 3000 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.48%
5 Years rr_AverageAnnualReturnYear05 12.18%
Inception rr_AverageAnnualReturnSinceInception 12.14%
Date of Inception rr_AverageAnnualReturnInceptionDate Oct. 07, 2008
(John Hancock Variable Insurance Trust) | (Alpha Opportunities Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.96%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 1.05%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 107
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 334
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 579
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,283
1 Year rr_AverageAnnualReturnYear01 none
5 Years rr_AverageAnnualReturnYear05 10.29%
Inception rr_AverageAnnualReturnSinceInception 12.32%
Date of Inception rr_AverageAnnualReturnInceptionDate Jun. 02, 2009
(John Hancock Variable Insurance Trust) | (Alpha Opportunities Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.96%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04% [2]
Total annual fund operating expenses rr_ExpensesOverAssets 1.25%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 127
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 397
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 686
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,511
(John Hancock Variable Insurance Trust) | (Alpha Opportunities Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.96%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 1.00%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 102
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 318
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 552
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,225
Annual Return 2009 rr_AnnualReturn2009 39.49%
Annual Return 2010 rr_AnnualReturn2010 16.98%
Annual Return 2011 rr_AnnualReturn2011 (8.02%)
Annual Return 2012 rr_AnnualReturn2012 21.38%
Annual Return 2013 rr_AnnualReturn2013 35.58%
Annual Return 2014 rr_AnnualReturn2014 8.12%
Annual Return 2015 rr_AnnualReturn2015 (0.03%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 18.66%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 18.66%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q3 '11, –19.40%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (19.40%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2011
1 Year rr_AverageAnnualReturnYear01 (0.03%)
5 Years rr_AverageAnnualReturnYear05 10.35%
Inception rr_AverageAnnualReturnSinceInception 12.38%
Date of Inception rr_AverageAnnualReturnInceptionDate Oct. 07, 2008
(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 and hold 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 medium 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)

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 medium 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 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). Although the fund focuses on investments in medium to larger capitalization companies, the fund's investments are not limited to a particular capitalization size. In addition, 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 fund's investment advisor or unrated but determined to be of equivalent quality by the 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. 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.
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 principal risks of investing in the fund include:

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.

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.

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. 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.

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).

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.

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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, performance shown for periods prior to the inception date of a class is the performance of the fund's oldest share class. The performance of the fund's oldest share class, for periods prior to its inception, is the performance of the master fund share class in which the fund invests, adjusted to reflect the expenses of the fund's oldest 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 medium. 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 Barclays U.S. Aggregate Bond Index.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series II (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q3 '09, 11.42%

Worst quarter: Q4 '08, –16.41%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(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 1.38%
5 Years rr_AverageAnnualReturnYear05 12.57%
10 Years rr_AverageAnnualReturnYear10 7.31%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (American Asset Allocation Trust) | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.55%
5 Years rr_AverageAnnualReturnYear05 3.25%
10 Years rr_AverageAnnualReturnYear10 4.51%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(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 1.28%
5 Years rr_AverageAnnualReturnYear05 8.95%
10 Years rr_AverageAnnualReturnYear10 6.48%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (American Asset Allocation Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.28% [3]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.60%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.92%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 94
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 293
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 509
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,131
1 Year rr_AverageAnnualReturnYear01 1.06%
5 Years rr_AverageAnnualReturnYear05 8.86%
10 Years rr_AverageAnnualReturnYear10 6.15%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 28, 2008
(John Hancock Variable Insurance Trust) | (American Asset Allocation Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.28% [3]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.75%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 1.07%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 109
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 340
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 590
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,306
Annual Return 2006 rr_AnnualReturn2006 14.10%
Annual Return 2007 rr_AnnualReturn2007 5.99%
Annual Return 2008 rr_AnnualReturn2008 (29.83%)
Annual Return 2009 rr_AnnualReturn2009 23.27%
Annual Return 2010 rr_AnnualReturn2010 11.90%
Annual Return 2011 rr_AnnualReturn2011 0.86%
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%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q3 '09, 11.42%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 11.42%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –16.41%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (16.41%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 0.91%
5 Years rr_AverageAnnualReturnYear05 8.71%
10 Years rr_AverageAnnualReturnYear10 5.92%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (American Asset Allocation Trust) | Series III  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.28% [3]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.57%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 58
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 183
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 318
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 714
1 Year rr_AverageAnnualReturnYear01 1.34%
5 Years rr_AverageAnnualReturnYear05 9.24%
10 Years rr_AverageAnnualReturnYear10 6.49%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 02, 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 and hold 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 medium 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)

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 medium 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 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

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. Although the fund focuses on investments in medium to larger capitalization companies, the fund's investments are not limited to a particular capitalization size.

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."
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 principal risks of investing in the fund include:

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.

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.

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.

Foreign securities risk. Less information may be publicly available regarding foreign 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.

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).

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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, performance shown for periods prior to the inception date of a class is the performance of the fund's oldest share class. The performance of the fund's oldest share class, for periods prior to its inception, is the performance of the master fund share class in which the fund invests, adjusted to reflect the expenses of the fund's oldest 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series II (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 22.00%

Worst quarter: Q4 '08, –20.17%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (American Global Growth Trust) | MSCI All Country World Index (gross of foreign withholding taxes on dividends) (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.84%)
5 Years rr_AverageAnnualReturnYear05 6.66%
10 Years rr_AverageAnnualReturnYear10 5.31%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (American Global Growth Trust) | Lipper Global Fund Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.15%)
5 Years rr_AverageAnnualReturnYear05 6.14%
10 Years rr_AverageAnnualReturnYear10 4.80%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (American Global Growth Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.52% [3]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.60%
Other expenses rr_OtherExpensesOverAssets 0.07%
Total annual fund operating expenses rr_ExpensesOverAssets 1.19%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 121
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 378
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 654
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,443
1 Year rr_AverageAnnualReturnYear01 6.64%
5 Years rr_AverageAnnualReturnYear05 9.16%
10 Years rr_AverageAnnualReturnYear10 7.53%
Date of Inception rr_AverageAnnualReturnInceptionDate Nov. 05, 2010
(John Hancock Variable Insurance Trust) | (American Global Growth Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.52% [3]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.75%
Other expenses rr_OtherExpensesOverAssets 0.07%
Total annual fund operating expenses rr_ExpensesOverAssets 1.34%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 136
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 425
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 734
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,613
Annual Return 2006 rr_AnnualReturn2006 19.84%
Annual Return 2007 rr_AnnualReturn2007 14.21%
Annual Return 2008 rr_AnnualReturn2008 (38.68%)
Annual Return 2009 rr_AnnualReturn2009 41.42%
Annual Return 2010 rr_AnnualReturn2010 11.17%
Annual Return 2011 rr_AnnualReturn2011 (9.40%)
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%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 22.00%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 22.00%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –20.17%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (20.17%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 6.50%
5 Years rr_AverageAnnualReturnYear05 9.01%
10 Years rr_AverageAnnualReturnYear10 7.34%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (American Global Growth Trust) | Series III  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.52% [3]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.07%
Total annual fund operating expenses rr_ExpensesOverAssets 0.84%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 86
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 268
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 466
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,037
1 Year rr_AverageAnnualReturnYear01 7.02%
5 Years rr_AverageAnnualReturnYear05 9.54%
10 Years rr_AverageAnnualReturnYear10 7.92%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 02, 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 and hold 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 medium 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)

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 medium 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 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

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 a portion of its assets in common stocks and other securities of issuers domiciled outside the U.S. Although the fund focuses on investments in medium to larger capitalization companies, the fund's investments are not limited to a particular capitalization size.
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 principal risks of investing in the fund include:

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.

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.

Foreign securities risk. Less information may be publicly available regarding foreign 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.

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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, performance shown for periods prior to the inception date of a class is the performance of the fund's oldest share class. The performance of the fund's oldest share class, for periods prior to its inception, is the performance of the master fund share class in which the fund invests, adjusted to reflect the expenses of the fund's oldest 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series II (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 18.33%

Worst quarter: Q4 '08, –26.20%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(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 1.38%
5 Years rr_AverageAnnualReturnYear05 12.57%
10 Years rr_AverageAnnualReturnYear10 7.31%
Date of Inception rr_AverageAnnualReturnInceptionDate May 05, 2003
(John Hancock Variable Insurance Trust) | (American Growth Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.33% [3]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.60%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.97%
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 6.44%
5 Years rr_AverageAnnualReturnYear05 10.82%
10 Years rr_AverageAnnualReturnYear10 6.53%
Date of Inception rr_AverageAnnualReturnInceptionDate Jul. 09, 2003
(John Hancock Variable Insurance Trust) | (American Growth Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.33% [3]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.75%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 1.12%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 114
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 356
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 617
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,363
Annual Return 2006 rr_AnnualReturn2006 9.64%
Annual Return 2007 rr_AnnualReturn2007 11.73%
Annual Return 2008 rr_AnnualReturn2008 (44.28%)
Annual Return 2009 rr_AnnualReturn2009 38.68%
Annual Return 2010 rr_AnnualReturn2010 18.14%
Annual Return 2011 rr_AnnualReturn2011 (4.79%)
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%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 18.33%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 18.33%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –26.20%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (26.20%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 6.35%
5 Years rr_AverageAnnualReturnYear05 10.66%
10 Years rr_AverageAnnualReturnYear10 6.38%
Date of Inception rr_AverageAnnualReturnInceptionDate May 05, 2003
(John Hancock Variable Insurance Trust) | (American Growth Trust) | Series III  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.33% [3]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.62%
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 6.87%
5 Years rr_AverageAnnualReturnYear05 11.21%
10 Years rr_AverageAnnualReturnYear10 6.84%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 02, 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 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 and hold 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 medium 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)

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 medium 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 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

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. Although the Growth-Income Fund focuses on investments in medium to larger capitalization companies, its investments are not limited to a particular capitalization size. 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.
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 principal risks of investing in the fund include:

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.

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.

Foreign securities risk. Less information may be publicly available regarding foreign 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.

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.

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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, performance shown for periods prior to the inception date of a class is the performance of the fund's oldest share class. The performance of the fund's oldest share class, for periods prior to its inception, is the performance of the master fund share class in which the fund invests, adjusted to reflect the expenses of the fund's oldest 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series II (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 15.93%

Worst quarter: Q4 '08, –22.05%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(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 1.38%
5 Years rr_AverageAnnualReturnYear05 12.57%
10 Years rr_AverageAnnualReturnYear10 7.31%
Date of Inception rr_AverageAnnualReturnInceptionDate May 05, 2003
(John Hancock Variable Insurance Trust) | (American Growth-Income Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.27% [3]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.60%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.91%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 93
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 290
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 504
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,120
1 Year rr_AverageAnnualReturnYear01 1.11%
5 Years rr_AverageAnnualReturnYear05 11.19%
10 Years rr_AverageAnnualReturnYear10 6.27%
Date of Inception rr_AverageAnnualReturnInceptionDate Jul. 09, 2003
(John Hancock Variable Insurance Trust) | (American Growth-Income Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.27% [3]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.75%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 1.06%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 108
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 337
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 585
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,294
Annual Return 2006 rr_AnnualReturn2006 14.62%
Annual Return 2007 rr_AnnualReturn2007 4.48%
Annual Return 2008 rr_AnnualReturn2008 (38.17%)
Annual Return 2009 rr_AnnualReturn2009 30.67%
Annual Return 2010 rr_AnnualReturn2010 10.91%
Annual Return 2011 rr_AnnualReturn2011 (2.31%)
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%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 15.93%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 15.93%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –22.05%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (22.05%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 0.96%
5 Years rr_AverageAnnualReturnYear05 11.03%
10 Years rr_AverageAnnualReturnYear10 6.12%
Date of Inception rr_AverageAnnualReturnInceptionDate May 05, 2003
(John Hancock Variable Insurance Trust) | (American Growth-Income Trust) | Series III  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.27% [3]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.56%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 57
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 179
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 313
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 701
1 Year rr_AverageAnnualReturnYear01 1.46%
5 Years rr_AverageAnnualReturnYear05 11.57%
10 Years rr_AverageAnnualReturnYear10 6.65%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 02, 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 and hold 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 medium 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)

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 medium 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 15% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 15.00%
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 developing countries, that the advisor believes have the potential for growth. Although the fund focuses on investments in medium to larger capitalization companies, the fund's investments are not limited to a particular capitalization size.
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 principal risks of investing in the fund include:

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.

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.

Foreign securities risk. Less information may be publicly available regarding foreign 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.

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.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, performance shown for periods prior to the inception date of a class is the performance of the fund's oldest share class. The performance of the fund's oldest share class, for periods prior to its inception, is the performance of the master fund share class in which the fund invests, adjusted to reflect the expenses of the fund's oldest 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series II (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 24.34%

Worst quarter: Q3 '11, –21.95%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (American International Trust) | MSCI All Country World ex-U.S. Index (gross of foreign withholding taxes on dividends) (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (5.25%)
5 Years rr_AverageAnnualReturnYear05 1.51%
10 Years rr_AverageAnnualReturnYear10 3.38%
Date of Inception rr_AverageAnnualReturnInceptionDate May 05, 2003
(John Hancock Variable Insurance Trust) | (American International Trust) | MSCI EAFE Index (gross of foreign withholding taxes on dividends) (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (0.39%)
5 Years rr_AverageAnnualReturnYear05 4.07%
10 Years rr_AverageAnnualReturnYear10 3.50%
Date of Inception rr_AverageAnnualReturnInceptionDate May 05, 2003
(John Hancock Variable Insurance Trust) | (American International Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.50% [3]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.60%
Other expenses rr_OtherExpensesOverAssets 0.07%
Total annual fund operating expenses rr_ExpensesOverAssets 1.17%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 119
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 372
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 644
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,420
1 Year rr_AverageAnnualReturnYear01 (4.82%)
5 Years rr_AverageAnnualReturnYear05 2.39%
10 Years rr_AverageAnnualReturnYear10 3.43%
Date of Inception rr_AverageAnnualReturnInceptionDate Jul. 09, 2003
(John Hancock Variable Insurance Trust) | (American International Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.50% [3]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.75%
Other expenses rr_OtherExpensesOverAssets 0.07%
Total annual fund operating expenses rr_ExpensesOverAssets 1.32%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 134
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 418
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 723
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,590
Annual Return 2006 rr_AnnualReturn2006 18.32%
Annual Return 2007 rr_AnnualReturn2007 19.41%
Annual Return 2008 rr_AnnualReturn2008 (42.47%)
Annual Return 2009 rr_AnnualReturn2009 42.41%
Annual Return 2010 rr_AnnualReturn2010 6.68%
Annual Return 2011 rr_AnnualReturn2011 (14.38%)
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%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 24.34%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 24.34%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q3 '11, –21.95%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (21.95%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2011
1 Year rr_AverageAnnualReturnYear01 (4.98%)
5 Years rr_AverageAnnualReturnYear05 2.25%
10 Years rr_AverageAnnualReturnYear10 3.28%
Date of Inception rr_AverageAnnualReturnInceptionDate May 05, 2003
(John Hancock Variable Insurance Trust) | (American International Trust) | Series III  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.50% [3]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.07%
Total annual fund operating expenses rr_ExpensesOverAssets 0.82%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 84
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 262
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 455
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,014
1 Year rr_AverageAnnualReturnYear01 (4.54%)
5 Years rr_AverageAnnualReturnYear05 2.75%
10 Years rr_AverageAnnualReturnYear10 3.72%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 02, 2008
(John Hancock Variable Insurance Trust) | (American New World 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 and hold 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 medium 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)

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 medium 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 15% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 15.00%
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 New World Fund, a series of American Funds Insurance Series. The New World Fund invests primarily in stocks of companies with significant exposure to countries with developing economies and/or markets that the advisor believes have potential of providing capital appreciation. The fund may invest in companies without regard to market capitalization, including companies with small market capitalizations.

The New World Fund may also invest in debt securities of issuers, including issuers of lower rated bonds (rated Ba1 or below and BB+ or below by NRSROs designated by the fund's investment advisor or unrated but determined to be of equivalent quality by the fund's advisor), with exposure to these countries. Bonds rated Ba1 or below or BB+ or below are sometimes referred to as "junk bonds."

Under normal market conditions, the fund invests at least 35% of its assets in equity and debt securities of issuers primarily based in qualified countries that have developing economies and/or markets.

In determining whether a country is qualified, the New World Fund will consider such factors as the country's per capita gross domestic product; the percentage of the country's economy that is industrialized; market capital as a percentage of gross domestic product; the overall regulatory environment; the presence of government regulation limiting or banning foreign ownership; and restrictions on repatriation of initial capital, dividends, interest and/or capital gains. The New World Fund's investment advisor will maintain a list of qualified countries and securities in which the fund may invest. Qualified developing countries in which the fund may invest currently include, but are not limited to, Argentina, Bahrain, Bangladesh, Brazil, Bulgaria, Chile, China, Colombia, Côte d'Ivoire, Croatia, Cyprus, Czech Republic, Dominican Republic, Ecuador, Egypt, Gabon, Ghana, Greece, Hungary, India, Indonesia, Jamaica, Jordan, Kazakhstan, Kenya, Kuwait, Lebanon, Macau, Malaysia, Malta, Mexico, Morocco, Nigeria, Oman, Pakistan, Panama, Paraguay, Peru, Philippines, Poland, Qatar, Romania, Russian Federation, Saudi Arabia, Slovenia, South Africa, Sri Lanka, Thailand, Turkey, Ukraine, United Arab Emirates, Uruguay, Venezuela, Vietnam and Zambia.

The New World Fund may invest in equity securities of any company, regardless of where it is based, if the New World Fund's investment advisor determines that a significant portion of the company's assets or revenues (generally 20% or more) is attributable to developing countries. In addition, the New World Fund may invest up to 25% of its assets in nonconvertible debt securities of issuers, including issuers of lower rated bonds ("junk bonds") and government bonds, that are primarily based in qualified countries or that have a significant portion of their assets or revenues attributable to developing countries. The New World Fund may also, to a limited extent, invest in securities of issuers based in nonqualified developing 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 principal risks of investing in the fund include:

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.

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.

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. 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.

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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, performance shown for periods prior to the inception date of a class is the performance of the fund's oldest share class. The performance of the fund's oldest share class, for periods prior to its inception, is the performance of the master fund share class in which the fund invests, adjusted to reflect the expenses of the fund's oldest 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series II (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 23.90%

Worst quarter: Q4 '08, –22.35%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (American New World Trust) | MSCI All Country World Index (gross of foreign withholding taxes on dividends) (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.84%)
5 Years rr_AverageAnnualReturnYear05 6.66%
10 Years rr_AverageAnnualReturnYear10 5.31%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (American New World Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.72% [3]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.60%
Other expenses rr_OtherExpensesOverAssets 0.15%
Total annual fund operating expenses rr_ExpensesOverAssets 1.47%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 150
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 465
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 803
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,757
1 Year rr_AverageAnnualReturnYear01 (3.66%)
5 Years rr_AverageAnnualReturnYear05 (0.28%)
10 Years rr_AverageAnnualReturnYear10 5.63%
Date of Inception rr_AverageAnnualReturnInceptionDate May 06, 2009
(John Hancock Variable Insurance Trust) | (American New World Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.72% [3]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.75%
Other expenses rr_OtherExpensesOverAssets 0.15%
Total annual fund operating expenses rr_ExpensesOverAssets 1.62%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 165
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 511
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 881
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,922
Annual Return 2006 rr_AnnualReturn2006 31.90%
Annual Return 2007 rr_AnnualReturn2007 31.39%
Annual Return 2008 rr_AnnualReturn2008 (42.66%)
Annual Return 2009 rr_AnnualReturn2009 48.82%
Annual Return 2010 rr_AnnualReturn2010 17.18%
Annual Return 2011 rr_AnnualReturn2011 (14.41%)
Annual Return 2012 rr_AnnualReturn2012 17.12%
Annual Return 2013 rr_AnnualReturn2013 10.74%
Annual Return 2014 rr_AnnualReturn2014 (8.37%)
Annual Return 2015 rr_AnnualReturn2015 (3.73%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 23.90%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 23.90%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –22.35%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (22.35%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (3.73%)
5 Years rr_AverageAnnualReturnYear05 (0.42%)
10 Years rr_AverageAnnualReturnYear10 5.43%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (American New World Trust) | Series III  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.72% [3]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.15%
Total annual fund operating expenses rr_ExpensesOverAssets 1.12%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 114
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 356
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 617
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,363
1 Year rr_AverageAnnualReturnYear01 (3.24%)
5 Years rr_AverageAnnualReturnYear05 0.07%
10 Years rr_AverageAnnualReturnYear10 6.00%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 02, 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 and hold 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 medium 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)

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 medium 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 the common stocks of large and medium-sized blue chip growth companies. 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 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"). Bank loans may be illiquid. These investments will only be made 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 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 such as to secure 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.

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 principal risks of investing in the fund include:

Convertible securities risk. 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.

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.

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. 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.

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 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 risk. Information technology companies can be significantly affected by rapid obsolescence, short product cycles, competition, and government regulation, 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.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q1 '12, 18.74%

Worst quarter: Q4 '08, –24.87%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(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 1.38%
5 Years rr_AverageAnnualReturnYear05 12.57%
10 Years rr_AverageAnnualReturnYear10 7.31%
Date of Inception rr_AverageAnnualReturnInceptionDate Dec. 11, 1992
(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 5.67%
5 Years rr_AverageAnnualReturnYear05 13.53%
10 Years rr_AverageAnnualReturnYear10 8.53%
Date of Inception rr_AverageAnnualReturnInceptionDate Dec. 11, 1992
(John Hancock Variable Insurance Trust) | (Blue Chip Growth Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.78%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.87%
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 2006 rr_AnnualReturn2006 9.58%
Annual Return 2007 rr_AnnualReturn2007 12.75%
Annual Return 2008 rr_AnnualReturn2008 (42.53%)
Annual Return 2009 rr_AnnualReturn2009 42.89%
Annual Return 2010 rr_AnnualReturn2010 16.15%
Annual Return 2011 rr_AnnualReturn2011 1.44%
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%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q1 '12, 18.74%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 18.74%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2012
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –24.87%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (24.87%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 11.06%
5 Years rr_AverageAnnualReturnYear05 15.49%
10 Years rr_AverageAnnualReturnYear10 9.25%
Date of Inception rr_AverageAnnualReturnInceptionDate Dec. 11, 1992
(John Hancock Variable Insurance Trust) | (Blue Chip Growth Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.78%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 1.07%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 109
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 340
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 590
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,306
1 Year rr_AverageAnnualReturnYear01 10.83%
5 Years rr_AverageAnnualReturnYear05 15.26%
10 Years rr_AverageAnnualReturnYear10 9.03%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Blue Chip Growth Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.78%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.82%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 84
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 262
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 455
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,014
1 Year rr_AverageAnnualReturnYear01 11.13%
5 Years rr_AverageAnnualReturnYear05 15.55%
10 Years rr_AverageAnnualReturnYear10 9.30%
Date of Inception rr_AverageAnnualReturnInceptionDate Feb. 28, 2005
(John Hancock Variable Insurance Trust) | (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 and hold 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 medium 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)

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 medium 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 62% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 62.00%
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 seeks to invest its assets in debt securities and instruments with an average duration of between 4 to 6 years, however, there is no limit on the fund's average maturity.

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.
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 principal risks of investing in the fund include:

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.

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.

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. 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.

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, along with specific additional associated risks, if any, 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. Actively trading securities can increase transaction costs (thus lowering performance).

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series NAV (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '10, 2.97%

Worst quarter: Q2 '13, –2.49%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Bond Trust) | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.55%
5 Years rr_AverageAnnualReturnYear05 3.25%
Inception rr_AverageAnnualReturnSinceInception 4.04%
Date of Inception rr_AverageAnnualReturnInceptionDate Jul. 29, 2009
(John Hancock Variable Insurance Trust) | (Bond Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.56%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.65%
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 0.24%
5 Years rr_AverageAnnualReturnYear05 3.28%
Inception rr_AverageAnnualReturnSinceInception 4.09%
Date of Inception rr_AverageAnnualReturnInceptionDate Oct. 31, 2011
(John Hancock Variable Insurance Trust) | (Bond Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.56%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.85%
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
1 Year rr_AverageAnnualReturnYear01 0.04%
5 Years rr_AverageAnnualReturnYear05 3.11%
Inception rr_AverageAnnualReturnSinceInception 3.96%
Date of Inception rr_AverageAnnualReturnInceptionDate Oct. 31, 2011
(John Hancock Variable Insurance Trust) | (Bond Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.56%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.60%
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
Annual Return 2010 rr_AnnualReturn2010 6.65%
Annual Return 2011 rr_AnnualReturn2011 5.58%
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%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '10, 2.97%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 2.97%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2010
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q2 '13, –2.49%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (2.49%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2013
1 Year rr_AverageAnnualReturnYear01 0.29%
5 Years rr_AverageAnnualReturnYear05 3.24%
Inception rr_AverageAnnualReturnSinceInception 4.06%
Date of Inception rr_AverageAnnualReturnInceptionDate Jul. 29, 2009
(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 and hold 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 medium 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)

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 medium 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 30% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 30.00%
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 follows a highly disciplined investment selection and management process that seeks to identify companies that show superior absolute and relative earnings growth and also are attractively valued. The subadvisor looks for companies that experience some or all of the following: (i) above-average revenue and earnings per share growth, (ii) strong market position, (iii) improving profitability and distinctive attributes such as unique marketing ability, (iv) strong research and development and productive new product flow, and (v) financial strength. Such companies generally trade at high prices relative to their current earnings. Earnings predictability and confidence in earnings forecasts are important parts of the selection process.

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 principal risks of investing in the fund include:

Convertible securities risk. 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 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.

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.

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. 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.

High portfolio turnover risk. Actively trading securities can increase transaction costs (thus lowering performance).

Information technology risk. Information technology companies can be significantly affected by rapid obsolescence, short product cycles, competition, and government regulation, among other factors.

Initial public offerings 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

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.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small capitalization securities may underperform the market as a whole.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q1 '12, 19.52%

Worst quarter: Q4 '08, –20.87%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(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 5.67%
5 Years rr_AverageAnnualReturnYear05 13.53%
10 Years rr_AverageAnnualReturnYear10 8.53%
Date of Inception rr_AverageAnnualReturnInceptionDate Nov. 01, 2000
(John Hancock Variable Insurance Trust) | (Capital Appreciation Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.70%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.79%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 81
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 252
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 439
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 978
Annual Return 2006 rr_AnnualReturn2006 2.26%
Annual Return 2007 rr_AnnualReturn2007 11.61%
Annual Return 2008 rr_AnnualReturn2008 (37.22%)
Annual Return 2009 rr_AnnualReturn2009 42.29%
Annual Return 2010 rr_AnnualReturn2010 11.83%
Annual Return 2011 rr_AnnualReturn2011 0.08%
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%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q1 '12, 19.52%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 19.52%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2012
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –20.87%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (20.87%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 11.46%
5 Years rr_AverageAnnualReturnYear05 14.28%
10 Years rr_AverageAnnualReturnYear10 8.31%
Date of Inception rr_AverageAnnualReturnInceptionDate Nov. 01, 2000
(John Hancock Variable Insurance Trust) | (Capital Appreciation Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.70%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.99%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 101
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 315
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 547
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,213
1 Year rr_AverageAnnualReturnYear01 11.17%
5 Years rr_AverageAnnualReturnYear05 14.05%
10 Years rr_AverageAnnualReturnYear10 8.09%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Capital Appreciation Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.70%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.74%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 76
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 237
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 411
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 918
1 Year rr_AverageAnnualReturnYear01 11.48%
5 Years rr_AverageAnnualReturnYear05 14.33%
10 Years rr_AverageAnnualReturnYear10 8.36%
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 and hold 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 medium 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 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 medium 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 73% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 73.00%
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. Bank loans may be illiquid. 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. Some bank loans may be illiquid. 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 and options. Such securities may bear interest or pay dividends at below (or even relatively nominal) rates.

The fund may sell securities for a variety of reasons such as to secure 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 principal risks of investing in the fund include:

Convertible securities risk. 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.

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.

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, 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. 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.

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 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.

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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 17.59%

Worst quarter: Q3 '11, –11.31%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(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 1.38%
5 Years rr_AverageAnnualReturnYear05 12.57%
Inception rr_AverageAnnualReturnSinceInception 7.39%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 28, 2008
(John Hancock Variable Insurance Trust) | (Capital Appreciation Value Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.81%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.05%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.94% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 96
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 300
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 520
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,155
Annual Return 2009 rr_AnnualReturn2009 30.18%
Annual Return 2010 rr_AnnualReturn2010 13.83%
Annual Return 2011 rr_AnnualReturn2011 3.13%
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%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 17.59%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 17.59%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q3 '11, –11.31%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (11.31%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2011
1 Year rr_AverageAnnualReturnYear01 5.28%
5 Years rr_AverageAnnualReturnYear05 11.30%
Inception rr_AverageAnnualReturnSinceInception 8.27%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 28, 2008
(John Hancock Variable Insurance Trust) | (Capital Appreciation Value Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.81%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.05%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.14% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 116
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 362
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 628
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,386
1 Year rr_AverageAnnualReturnYear01 5.10%
5 Years rr_AverageAnnualReturnYear05 11.08%
Inception rr_AverageAnnualReturnSinceInception 8.04%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 28, 2008
(John Hancock Variable Insurance Trust) | (Capital Appreciation Value Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.81%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.05%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.89% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 91
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 284
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 493
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,096
1 Year rr_AverageAnnualReturnYear01 5.27%
5 Years rr_AverageAnnualReturnYear05 11.35%
Inception rr_AverageAnnualReturnSinceInception 8.30%
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 and hold 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 medium 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)

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 medium 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 425% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 425.00%
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 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 Barclays U.S. Aggregate Bond Index (the duration of this index as of December 31, 2015 was 5.68 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 principal risks of investing in the fund include:

Changing distribution levels risk. The distribution amounts paid by the fund generally depend on the amount of income and/or dividends received by the fund's investments. As a result of market, interest rate and other circumstances, the amount of cash available for distribution by the fund and the fund's distribution rate may vary or decline. The risk of such variability is accentuated in currently prevailing market and interest rate circumstances.

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.

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.

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. 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.

High portfolio turnover risk. Actively trading securities can increase transaction costs (thus lowering performance).

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.
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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q3 '09, 4.52%

Worst quarter: Q2 '13, –2.80%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Core Bond Trust) | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.55%
5 Years rr_AverageAnnualReturnYear05 3.25%
10 Years rr_AverageAnnualReturnYear10 4.51%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Core Bond Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.59%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.68%
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
Annual Return 2006 rr_AnnualReturn2006 3.72%
Annual Return 2007 rr_AnnualReturn2007 6.26%
Annual Return 2008 rr_AnnualReturn2008 3.38%
Annual Return 2009 rr_AnnualReturn2009 9.93%
Annual Return 2010 rr_AnnualReturn2010 7.08%
Annual Return 2011 rr_AnnualReturn2011 8.32%
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%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q3 '09, 4.52%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 4.52%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q2 '13, –2.80%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (2.80%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2013
1 Year rr_AverageAnnualReturnYear01 0.31%
5 Years rr_AverageAnnualReturnYear05 3.70%
10 Years rr_AverageAnnualReturnYear10 4.87%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Core Bond Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.59%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.88%
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
1 Year rr_AverageAnnualReturnYear01 0.11%
5 Years rr_AverageAnnualReturnYear05 3.48%
10 Years rr_AverageAnnualReturnYear10 4.66%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Core Bond Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.59%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.63%
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 0.36%
5 Years rr_AverageAnnualReturnYear05 3.75%
10 Years rr_AverageAnnualReturnYear10 4.92%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Core Strategy Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

Seeks 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 and hold 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 medium 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 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 medium 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 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

Under normal market conditions, the fund invests in other funds of JHVIT and other investment companies (including exchange-traded funds ("ETFs")) ("Underlying Funds") as well as other types of investments, see "Other Permitted Investments by the Funds of Funds." The fund invests approximately 70% of its total assets in equity securities and Underlying Funds that invest primarily in equity securities ("Equity Investments") and approximately 30% of its total assets in fixed-income securities and Underlying Funds that invest primarily in fixed-income securities ("Fixed-Income Investments").

The fund may also invest in various Underlying Funds that as a group hold a wide range of equity type securities in their portfolios. These include small-, mid- and large-capitalization stocks, domestic and foreign securities (including emerging market securities) and sector holdings such as utilities and science and technology stocks. Each of the Underlying Funds has its own investment strategy that, 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. Certain of the Underlying Funds in which the fund invests 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, government-issued, domestic and international securities.

Variations in the target percentage allocations between Equity Investments and Fixed-Income Investments are permitted up to 10% in either direction. For example, based on its investment allocation of approximately 70% of assets in Equity Investments and 30% of assets in Fixed-Income Investments, the fund may have an equity/fixed-income allocation of 80%/20% or 60%/40%. Variations beyond the permissible deviation range of 10% are not permitted except that, in light of market or economic conditions, the subadvisor may determine that the normal percentage limitations should be exceeded to protect the fund or to achieve the fund's investment objective.

The fund is monitored daily. To maintain target allocations in the Underlying Funds, daily cash flow for the fund will be directed to the Underlying Fund that most deviates from target. Quarterly, the subadvisor may also rebalance the fund's Underlying Funds to maintain target allocations. The subadvisor may from time to time adjust the percent of assets invested in any specific Underlying Fund held by the fund. Such adjustments may be made to increase or decrease the fund's holdings of particular asset classes, such as common stocks of foreign issuers, or to adjust portfolio quality or the duration of fixed-income securities. Adjustments may also be made to increase or reduce the percent of the fund's assets subject to the management of a particular Underlying Fund subadvisor. In addition, changes may be made to reflect fundamental changes in the investment environment.

The fund may also invest in the securities of other investment companies including exchange traded funds (ETFs) and may invest directly in other type of investments, such as equity and fixed-income securities including U.S. government securities, closed-end funds and partnerships. See "Other Permitted Investments by the Funds of Funds." The fund may also engage in short selling.

The investment performance of the fund will reflect both its subadvisor's allocation decisions with respect to Underlying Funds and the investment decisions made by the Underlying Funds' subadvisors. 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.

When purchasing shares of other JHVIT funds, the fund only purchases Class NAV shares (which are not subject to Rule 12b-1 fees).

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, without limitation, investing in credit default swaps, foreign currency forward contracts, futures contracts, interest rate swaps and options.
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 principal risks of investing in the fund of funds include:

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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. 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.

Fund of funds risk. The fund is subject to risks related to: (i) the underlying funds' performance, expenses, and ability to meet their investment objectives; (ii) properly rebalancing assets among underlying funds and different asset classes; (iii) layering of fees of the underlying funds; and (iv) conflicts of interest associated with the subadvisor's ability to allocate fund assets without limit to underlying funds advised by the subadvisor and/or other affiliated subadvisors.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, options, credit default swaps, 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.

Investment company securities risk. A fund bears underlying fund fees and expenses indirectly.

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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Principal risks of investing in the underlying funds

The principal risks of investing in the Underlying Funds include:

Convertible securities risk. 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.

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.

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. 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.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, options, credit default swaps, 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.

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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Initial public offerings 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small capitalization securities may underperform the market as a whole.
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.
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. Unless all share classes shown in the table have the same inception date, 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 medium. 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 1 represents 70% of the S&P 500 Index and 30% of the Barclays U.S. Aggregate Bond Index.

The Combined Index 2 represents 49% of the Russell 3000 Index, 21% of the MSCI EAFE Index and 30% of the Barclays U.S. Aggregate Bond Index.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series II (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 13.17%

Worst quarter: Q4 '08, –14.86%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Core Strategy Trust) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.38%
5 Years rr_AverageAnnualReturnYear05 12.57%
Inception rr_AverageAnnualReturnSinceInception 7.21%
Date of Inception rr_AverageAnnualReturnInceptionDate Feb. 10, 2006
(John Hancock Variable Insurance Trust) | (Core Strategy Trust) | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.55%
5 Years rr_AverageAnnualReturnYear05 3.25%
Inception rr_AverageAnnualReturnSinceInception 4.59%
Date of Inception rr_AverageAnnualReturnInceptionDate Feb. 10, 2006
(John Hancock Variable Insurance Trust) | (Core Strategy Trust) | Combined Index 1 (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.34%
5 Years rr_AverageAnnualReturnYear05 9.87%
Inception rr_AverageAnnualReturnSinceInception 6.69%
Date of Inception rr_AverageAnnualReturnInceptionDate Feb. 10, 2006
(John Hancock Variable Insurance Trust) | (Core Strategy Trust) | Combined Index 2 (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.55%
5 Years rr_AverageAnnualReturnYear05 7.95%
Inception rr_AverageAnnualReturnSinceInception 5.90%
Date of Inception rr_AverageAnnualReturnInceptionDate Feb. 10, 2006
(John Hancock Variable Insurance Trust) | (Core Strategy Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.04%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.02%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.55% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.66% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 67
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 211
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 368
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 822
1 Year rr_AverageAnnualReturnYear01 (0.11%)
5 Years rr_AverageAnnualReturnYear05 7.33%
Inception rr_AverageAnnualReturnSinceInception 5.35%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 28, 2008
(John Hancock Variable Insurance Trust) | (Core Strategy Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.04%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.02%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.55% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.86% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 88
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 274
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 477
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,061
Annual Return 2007 rr_AnnualReturn2007 6.55%
Annual Return 2008 rr_AnnualReturn2008 (26.47%)
Annual Return 2009 rr_AnnualReturn2009 21.65%
Annual Return 2010 rr_AnnualReturn2010 12.17%
Annual Return 2011 rr_AnnualReturn2011 0.01%
Annual Return 2012 rr_AnnualReturn2012 12.27%
Annual Return 2013 rr_AnnualReturn2013 19.03%
Annual Return 2014 rr_AnnualReturn2014 5.91%
Annual Return 2015 rr_AnnualReturn2015 (0.37%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 13.17%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 13.17%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –14.86%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (14.86%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (0.37%)
5 Years rr_AverageAnnualReturnYear05 7.12%
Inception rr_AverageAnnualReturnSinceInception 5.20%
Date of Inception rr_AverageAnnualReturnInceptionDate Feb. 10, 2006
(John Hancock Variable Insurance Trust) | (Core Strategy Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.04%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.02%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.55% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.61% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 62
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 195
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 340
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 762
1 Year rr_AverageAnnualReturnYear01 (0.06%)
5 Years rr_AverageAnnualReturnYear05 7.37%
Inception rr_AverageAnnualReturnSinceInception 5.39%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 28, 2008
(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 and hold 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 medium 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 Restated to Reflect Current [Text] rr_ExpensesRestatedToReflectCurrent "Other expenses" have been restated from fiscal year amounts to reflect current 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 medium 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 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 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 Markets equity securities listed on bona fide securities exchanges or actively traded on over-the-counter markets. (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. The subadvisor believes securities are considered value stocks primarily because they have a high book value in relation to their market value. In assessing value, the subadvisor may consider additional factors, such as price-to-cash flow or price-to-earnings ratios, as well as economic conditions and developments in the issuer's industry. The criteria the subadvisor uses for assessing value 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 have significant investments in the financial services sector.

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 tends 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, MSCI and Citigroup. Approved emerging markets may not include all emerging markets classified by such entities. In determining whether to approve markets for investment, the subadvisor takes 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 and other affiliated funds.

The fund may use derivatives such as futures contracts and options on futures contracts to adjust market exposure based on expected cash inflows to or outflows from the fund. The fund does not intend to use derivatives for the purposes of speculation or leveraging investment returns. 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.

The fund's policy of seeking broad market diversification means the subadvisor will not utilize "fundamental" securities research techniques in identifying security selections. Changes in the composition and relative ranking (in terms of book-to-market 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 fluctuations 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.

In addition, the subadvisor may adjust the representation in the fund of an eligible company, or exclude a company, after considering profitability relative to other eligible companies. In assessing profitability, the subadvisor may consider different ratios, such as that of earnings or profits from operations relative to book value or assets.

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 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

  • Russia

  • South Africa

  • South Korea

  • Taiwan

  • Thailand

  • Turkey

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 denominated in an Approved Market currency issued by companies to finance operations in Approved Markets; (e) 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; (f) Approved Market equity securities in the form of depositary shares; (g) securities of pooled investment vehicles that invest primarily in Approved Markets securities or derivative instruments that derive their value from Approved Market securities; or (h) securities included in the fund's benchmark index. 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. For example, the subadvisor may invest in companies organized and located in the United States or other countries outside of Approved Markets, including companies having their entire production facilities outside of Approved Markets, when such companies meet the definition of 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 principal risks of investing in the fund include:

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.

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.

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, 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. 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.

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, along with specific additional associated risks, if any, 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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Investment company securities risk. A fund bears underlying fund fees and expenses indirectly.

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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 49.54%

Worst quarter: Q4 '08, –27.57%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Emerging Markets Value Trust) | MSCI Emerging Markets Index (gross of foreign withholding taxes on dividends) (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (14.60%)
5 Years rr_AverageAnnualReturnYear05 (4.47%)
Inception rr_AverageAnnualReturnSinceInception 0.42%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (Emerging Markets Value Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.95%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.09% [6]
Total annual fund operating expenses rr_ExpensesOverAssets 1.09%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 111
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 347
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 601
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,329
Annual Return 2008 rr_AnnualReturn2008 (52.17%)
Annual Return 2009 rr_AnnualReturn2009 101.12%
Annual Return 2010 rr_AnnualReturn2010 23.02%
Annual Return 2011 rr_AnnualReturn2011 (27.06%)
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%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 49.54%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 49.54%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –27.57%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (27.57%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (19.08%)
5 Years rr_AverageAnnualReturnYear05 (8.54%)
Inception rr_AverageAnnualReturnSinceInception (1.04%)
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (Emerging Markets Value Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.95%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.09% [6]
Total annual fund operating expenses rr_ExpensesOverAssets 1.29%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 131
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 409
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 708
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,556
1 Year rr_AverageAnnualReturnYear01 (19.06%)
5 Years rr_AverageAnnualReturnYear05 (8.50%)
Inception rr_AverageAnnualReturnSinceInception (1.00%)
Date of Inception rr_AverageAnnualReturnInceptionDate May 27, 2015
(John Hancock Variable Insurance Trust) | (Emerging Markets Value Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.95%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.09% [6]
Total annual fund operating expenses rr_ExpensesOverAssets 1.04%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 106
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 331
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 574
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,271
1 Year rr_AverageAnnualReturnYear01 (19.05%)
5 Years rr_AverageAnnualReturnYear05 (8.50%)
Inception rr_AverageAnnualReturnSinceInception (1.00%)
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 and hold 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 medium 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 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 medium 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 34% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 34.00%
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 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 S&P 500 Index;

  • low price/earnings ratios relative to the S&P 500 Index;

  • 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 non-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 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 such as to secure 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 principal risks of investing in the fund include:

Convertible securities risk. 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.

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.

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, 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. 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.

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 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.

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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.
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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 19.64%

Worst quarter: Q4 '08, –22.37%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(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 (3.83%)
5 Years rr_AverageAnnualReturnYear05 11.27%
10 Years rr_AverageAnnualReturnYear10 6.16%
Date of Inception rr_AverageAnnualReturnInceptionDate Feb. 19, 1993
(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 1.38%
5 Years rr_AverageAnnualReturnYear05 12.57%
10 Years rr_AverageAnnualReturnYear10 7.31%
Date of Inception rr_AverageAnnualReturnInceptionDate Feb. 19, 1993
(John Hancock Variable Insurance Trust) | (Equity Income Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.75% [7]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.04%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [8]
Total annual fund operating expenses rr_ExpensesOverAssets 0.85% [9]
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 2006 rr_AnnualReturn2006 19.02%
Annual Return 2007 rr_AnnualReturn2007 3.35%
Annual Return 2008 rr_AnnualReturn2008 (35.96%)
Annual Return 2009 rr_AnnualReturn2009 25.72%
Annual Return 2010 rr_AnnualReturn2010 15.12%
Annual Return 2011 rr_AnnualReturn2011 (0.81%)
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%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 19.64%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 19.64%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –22.37%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (22.37%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (6.75%)
5 Years rr_AverageAnnualReturnYear05 8.69%
10 Years rr_AverageAnnualReturnYear10 5.63%
Date of Inception rr_AverageAnnualReturnInceptionDate Feb. 19, 1993
(John Hancock Variable Insurance Trust) | (Equity Income Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.75% [7]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [8]
Total annual fund operating expenses rr_ExpensesOverAssets 1.05% [9]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 107
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 334
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 579
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,283
1 Year rr_AverageAnnualReturnYear01 (6.91%)
5 Years rr_AverageAnnualReturnYear05 8.48%
10 Years rr_AverageAnnualReturnYear10 5.42%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Equity Income Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.75% [7]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.04%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [8]
Total annual fund operating expenses rr_ExpensesOverAssets 0.80% [9]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 82
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 255
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 444
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 990
1 Year rr_AverageAnnualReturnYear01 (6.66%)
5 Years rr_AverageAnnualReturnYear05 8.76%
10 Years rr_AverageAnnualReturnYear10 5.69%
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 and hold 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 medium 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 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 medium 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 27% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 27.00%
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 and financial holding companies.

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 Standard & Poor's Rating Services (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.

The fund is non-diversified, which means that it may invest its assets in a smaller number of issuers than a diversified fund.
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 principal risks of investing in the fund include:

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.

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.

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, 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. 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.

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, along with specific additional associated risks, if any, 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.

High portfolio turnover risk. Actively trading securities can increase transaction costs (thus lowering performance).

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

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.

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.
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.
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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 27.71%

Worst quarter: Q4 '08, –27.18%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(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 1.38%
5 Years rr_AverageAnnualReturnYear05 12.57%
10 Years rr_AverageAnnualReturnYear10 7.31%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 30, 2001
(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 (1.53%)
5 Years rr_AverageAnnualReturnYear05 10.45%
10 Years rr_AverageAnnualReturnYear10 (0.66%)
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 30, 2001
(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 0.26%
5 Years rr_AverageAnnualReturnYear05 9.77%
10 Years rr_AverageAnnualReturnYear10 1.08%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 30, 2001
(John Hancock Variable Insurance Trust) | (Financial Industries Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.76%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.06%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.20% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.07% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 109
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 340
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 590
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,306
Annual Return 2006 rr_AnnualReturn2006 23.12%
Annual Return 2007 rr_AnnualReturn2007 (6.82%)
Annual Return 2008 rr_AnnualReturn2008 (44.65%)
Annual Return 2009 rr_AnnualReturn2009 41.41%
Annual Return 2010 rr_AnnualReturn2010 12.25%
Annual Return 2011 rr_AnnualReturn2011 (9.51%)
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%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 27.71%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 27.71%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –27.18%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (27.18%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (2.65%)
5 Years rr_AverageAnnualReturnYear05 8.12%
10 Years rr_AverageAnnualReturnYear10 4.06%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 30, 2001
(John Hancock Variable Insurance Trust) | (Financial Industries Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.76%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.06%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.20% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.27% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 129
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 403
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 697
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,534
1 Year rr_AverageAnnualReturnYear01 (2.88%)
5 Years rr_AverageAnnualReturnYear05 7.90%
10 Years rr_AverageAnnualReturnYear10 3.84%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Financial Industries Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.76%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.06%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.20% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.02% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 104
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 325
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 563
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,248
1 Year rr_AverageAnnualReturnYear01 (2.58%)
5 Years rr_AverageAnnualReturnYear05 8.17%
10 Years rr_AverageAnnualReturnYear10 4.11%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Franklin Templeton Founding Allocation 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 and hold 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 medium 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 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 medium 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 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 invests in other funds and in other investment companies (collectively, "Underlying Funds") as well as other types of investments as described below.

The fund currently invests primarily in three JHVIT Underlying Funds: Global Trust, Income Trust and Mutual Shares Trust. However, it is also authorized to invest without limitation in other Underlying Funds, including exchange-traded funds, and in other types of investments.

The fund may purchase any funds except other JHVIT funds of funds and the JHVIT American Feeder Funds. When purchasing shares of other JHVIT funds, the fund only purchases Class NAV shares (which are not subject to Rule 12b-1 fees).

The fund may invest in other types of investments, such as equity and fixed-income securities, including U.S. government securities, closed-end funds and partnerships, described under "Other Permitted Investments by the Funds of Funds." The fund may also engage in short selling.

The fund is monitored daily. To maintain target allocations in the Underlying Funds, daily cash flow for the fund will be directed to its Underlying Funds that most deviate from its target allocation. Quarterly, the subadvisor may also rebalance the fund's Underlying Funds to maintain target allocations.

The fund may at any time invest any percentage of its assets in any of the different investments described above. The subadvisor may from time to time adjust the percentage of assets invested in any specific investment held by the fund. Such adjustments may be made, for example, to increase or decrease the fund's holdings of particular asset classes, to adjust portfolio quality or the duration of fixed-income securities or to increase or reduce the percentage of the fund's assets subject to the management of a particular Underlying Fund subadvisor. In addition, changes may be made to reflect fundamental changes in the investment environment.

The investment performance of the fund will reflect both its subadvisor's allocation decisions with respect to its investments, and the investment decisions made by the advisor or subadvisor to the investment companies or similar entities in which the fund invests.

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 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, without limitation, investing in credit default swaps, foreign currency forward contracts, futures contracts, interest rate swaps and options.
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 principal risks of investing in the fund of funds include:

Commodity risk. Commodity investments involve the risk of volatile market price fluctuations of commodities resulting from fluctuating demand, supply disruption, speculation and other factors.

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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. 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.

Fund of funds risk. The fund is subject to risks related to: (i) the underlying funds' performance, expenses, and ability to meet their investment objectives; (ii) properly rebalancing assets among underlying funds and different asset classes; (iii) layering of fees of the underlying funds; and (iv) conflicts of interest associated with the subadvisor's ability to allocate fund assets without limit to underlying funds advised by the subadvisor and/or other affiliated subadvisors.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, options, credit default swaps, 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.

Investment company securities risk. A fund bears underlying fund fees and expenses indirectly.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Principal risks of investing in the underlying funds

The principal risks of investing in the Underlying Funds include:

Convertible securities risk. 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.

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.

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. 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.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, options, credit default swaps, 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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Initial public offerings 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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 1 represents 70% of the S&P 500 Index and 30% of the Barclays U.S. Aggregate Bond Index.

The Combined Index 2 represents 50% of the Russell 3000 Index, 35% of the MSCI EAFE Index, and 15% of the Barclays Credit Index.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 17.60%

Worst quarter: Q4 '08, –18.07%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Franklin Templeton Founding Allocation Trust) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.38%
5 Years rr_AverageAnnualReturnYear05 12.57%
Inception rr_AverageAnnualReturnSinceInception 6.04%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (Franklin Templeton Founding Allocation Trust) | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.55%
5 Years rr_AverageAnnualReturnYear05 3.25%
Inception rr_AverageAnnualReturnSinceInception 4.47%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (Franklin Templeton Founding Allocation Trust) | Combined Index 1 (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.34%
5 Years rr_AverageAnnualReturnYear05 9.87%
Inception rr_AverageAnnualReturnSinceInception 5.86%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (Franklin Templeton Founding Allocation Trust) | Combined Index 2 (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.14%
5 Years rr_AverageAnnualReturnYear05 8.28%
Inception rr_AverageAnnualReturnSinceInception 4.12%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (Franklin Templeton Founding Allocation Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.04%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.03%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.89% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.01% [5]
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
Annual Return 2008 rr_AnnualReturn2008 (35.53%)
Annual Return 2009 rr_AnnualReturn2009 31.47%
Annual Return 2010 rr_AnnualReturn2010 10.67%
Annual Return 2011 rr_AnnualReturn2011 (1.41%)
Annual Return 2012 rr_AnnualReturn2012 16.26%
Annual Return 2013 rr_AnnualReturn2013 24.43%
Annual Return 2014 rr_AnnualReturn2014 3.01%
Annual Return 2015 rr_AnnualReturn2015 (5.80%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 17.60%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 17.60%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –18.07%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (18.07%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (5.80%)
5 Years rr_AverageAnnualReturnYear05 6.71%
Inception rr_AverageAnnualReturnSinceInception 2.68%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2008
(John Hancock Variable Insurance Trust) | (Franklin Templeton Founding Allocation Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.04%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.03%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.89% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.21% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 123
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 384
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 665
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,466
1 Year rr_AverageAnnualReturnYear01 (5.99%)
5 Years rr_AverageAnnualReturnYear05 6.50%
Inception rr_AverageAnnualReturnSinceInception 2.50%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (Franklin Templeton Founding Allocation Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.04%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.03%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.89% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.96% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 98
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 306
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 531
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,178
1 Year rr_AverageAnnualReturnYear01 (5.76%)
5 Years rr_AverageAnnualReturnYear05 6.75%
Inception rr_AverageAnnualReturnSinceInception 2.72%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 28, 2008
(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 and hold 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 medium 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)

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 medium 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 49% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 49.00%
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.

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."
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 principal risks of investing in the fund include:

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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. 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. 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.

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, 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 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q3 '09, 18.02%

Worst quarter: Q4 '08, –24.37%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(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 0.48%
5 Years rr_AverageAnnualReturnYear05 12.18%
10 Years rr_AverageAnnualReturnYear10 7.35%
Date of Inception rr_AverageAnnualReturnInceptionDate May 05, 2003
(John Hancock Variable Insurance Trust) | (Fundamental All Cap Core Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.68%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.03%
Total annual fund operating expenses rr_ExpensesOverAssets 0.76%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 78
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 243
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 422
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 942
Annual Return 2006 rr_AnnualReturn2006 15.17%
Annual Return 2007 rr_AnnualReturn2007 3.78%
Annual Return 2008 rr_AnnualReturn2008 (43.18%)
Annual Return 2009 rr_AnnualReturn2009 28.27%
Annual Return 2010 rr_AnnualReturn2010 19.65%
Annual Return 2011 rr_AnnualReturn2011 (2.16%)
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%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q3 '09, 18.02%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 18.02%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –24.37%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (24.37%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 4.01%
5 Years rr_AverageAnnualReturnYear05 13.39%
10 Years rr_AverageAnnualReturnYear10 6.93%
Date of Inception rr_AverageAnnualReturnInceptionDate May 05, 2003
(John Hancock Variable Insurance Trust) | (Fundamental All Cap Core Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.68%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.03%
Total annual fund operating expenses rr_ExpensesOverAssets 0.96%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 98
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 306
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 531
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,178
1 Year rr_AverageAnnualReturnYear01 3.83%
5 Years rr_AverageAnnualReturnYear05 13.15%
10 Years rr_AverageAnnualReturnYear10 6.72%
Date of Inception rr_AverageAnnualReturnInceptionDate May 05, 2003
(John Hancock Variable Insurance Trust) | (Fundamental All Cap Core Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.68%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.03%
Total annual fund operating expenses rr_ExpensesOverAssets 0.71%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 73
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 227
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 395
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 883
1 Year rr_AverageAnnualReturnYear01 4.09%
5 Years rr_AverageAnnualReturnYear05 13.44%
10 Years rr_AverageAnnualReturnYear10 6.99%
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 and hold 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 medium 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)

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 medium 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 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

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 29, 2016, the lowest market capitalization in this group was $3.2 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 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.
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 principal risks of investing in the fund include:

Convertible securities risk. 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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. 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. 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.

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, 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 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 18.95%

Worst quarter: Q4 '08, –24.04%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(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 (3.83%)
5 Years rr_AverageAnnualReturnYear05 11.27%
10 Years rr_AverageAnnualReturnYear10 6.16%
Date of Inception rr_AverageAnnualReturnInceptionDate May 03, 2004
(John Hancock Variable Insurance Trust) | (Fundamental Large Cap Value Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.62%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.71%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 73
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 227
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 395
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 883
Annual Return 2006 rr_AnnualReturn2006 21.09%
Annual Return 2007 rr_AnnualReturn2007 (5.13%)
Annual Return 2008 rr_AnnualReturn2008 (41.20%)
Annual Return 2009 rr_AnnualReturn2009 24.47%
Annual Return 2010 rr_AnnualReturn2010 13.56%
Annual Return 2011 rr_AnnualReturn2011 1.75%
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%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 18.95%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 18.95%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –24.04%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (24.04%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (1.11%)
5 Years rr_AverageAnnualReturnYear05 12.89%
10 Years rr_AverageAnnualReturnYear10 5.76%
Date of Inception rr_AverageAnnualReturnInceptionDate May 03, 2004
(John Hancock Variable Insurance Trust) | (Fundamental Large Cap Value Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.62%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.91%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 93
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 290
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 504
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,120
1 Year rr_AverageAnnualReturnYear01 (1.30%)
5 Years rr_AverageAnnualReturnYear05 12.69%
10 Years rr_AverageAnnualReturnYear10 5.57%
Date of Inception rr_AverageAnnualReturnInceptionDate May 03, 2004
(John Hancock Variable Insurance Trust) | (Fundamental Large Cap Value Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.62%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.66%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 67
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 211
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 368
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 822
1 Year rr_AverageAnnualReturnYear01 (1.06%)
5 Years rr_AverageAnnualReturnYear05 12.97%
10 Years rr_AverageAnnualReturnYear10 5.83%
Date of Inception rr_AverageAnnualReturnInceptionDate Feb. 28, 2005
(John Hancock Variable Insurance Trust) | (Global 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 and hold 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 medium 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, 2017
Expenses Restated to Reflect Current [Text] rr_ExpensesRestatedToReflectCurrent "Other expenses" have been restated from fiscal year amounts to reflect current 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 medium 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 primarily in the equity securities of companies located throughout the world, including emerging markets. Although the fund seeks investments across a number of countries and sectors, from time to time, based on economic conditions, the Fund may have significant positions in particular countries or sectors. The fund may invest in companies of any size, including small and medium capitalization companies.

Depending upon current market conditions, the fund may invest up to 25% of its total assets in debt securities of companies and governments located anywhere in the world. Debt securities represent the obligation of the issuer to repay a loan of money to it, and generally pay interest to the holder. Bonds, notes and debentures are examples of debt securities. The fund may invest in depositary receipts. Equity securities may include, among other things, common stocks, preferred stocks and convertible securities. The fund may lend certain of its portfolio securities to qualified banks and broker dealers. The fund may invest in equity-linked notes, the value of which is tied to a single stock or a basket of 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 entering into option transactions.

When choosing equity investments for the fund, the subadvisor applies a "bottom up," value-oriented, long-term approach, focusing on the market price of a company's securities relative to the subadvisor's evaluation of the company's long-term earnings, asset value and cash flow potential. The subadvisor also considers a company's price/earnings ratio, price/cash flow ratio, profit margins and liquidation value.
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 principal risks of investing in the fund include:

Convertible securities risk. 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.

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.

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, 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. 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.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, options, credit default swaps, swaps, and 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). 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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q3 '09, 19.16%

Worst quarter: Q3 '11, –20.19%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Global Trust) | MSCI World Index (gross of foreign withholding taxes on dividends) (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (0.32%)
5 Years rr_AverageAnnualReturnYear05 8.19%
10 Years rr_AverageAnnualReturnYear10 5.56%
Date of Inception rr_AverageAnnualReturnInceptionDate Mar. 18, 1988
(John Hancock Variable Insurance Trust) | (Global Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.81%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.06% [6]
Total annual fund operating expenses rr_ExpensesOverAssets 0.92%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [10]
Total annual fund operating expenses after expense reimbursements 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 2006 rr_AnnualReturn2006 20.32%
Annual Return 2007 rr_AnnualReturn2007 1.28%
Annual Return 2008 rr_AnnualReturn2008 (39.51%)
Annual Return 2009 rr_AnnualReturn2009 31.37%
Annual Return 2010 rr_AnnualReturn2010 7.76%
Annual Return 2011 rr_AnnualReturn2011 (6.00%)
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%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q3 '09, 19.16%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 19.16%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q3 '11, –20.19%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (20.19%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2011
1 Year rr_AverageAnnualReturnYear01 (6.42%)
5 Years rr_AverageAnnualReturnYear05 6.46%
10 Years rr_AverageAnnualReturnYear10 3.62%
Date of Inception rr_AverageAnnualReturnInceptionDate Mar. 18, 1988
(John Hancock Variable Insurance Trust) | (Global Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.81%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.06% [6]
Total annual fund operating expenses rr_ExpensesOverAssets 1.12%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [10]
Total annual fund operating expenses after expense reimbursements 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 (6.61%)
5 Years rr_AverageAnnualReturnYear05 6.24%
10 Years rr_AverageAnnualReturnYear10 3.41%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Global Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.81%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.06% [6]
Total annual fund operating expenses rr_ExpensesOverAssets 0.87%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [10]
Total annual fund operating expenses after expense reimbursements 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 (6.34%)
5 Years rr_AverageAnnualReturnYear05 6.51%
10 Years rr_AverageAnnualReturnYear10 3.68%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Global Bond 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 and hold 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 medium 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)

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 medium 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 81% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 81.00%
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 that are economically tied to at least three countries (one of which may be the United States). These fixed-income instruments may be denominated in foreign currencies or in U.S. dollars, and may be represented by forwards or derivatives, such as options, futures contracts, or swap agreements.

In selecting securities for the fund, the subadvisor utilizes economic forecasting, interest rate anticipation, credit and call risk analysis, foreign currency exchange rate forecasting, and other security selection techniques. The proportion of the fund's assets committed to investment in securities with particular characteristics (such as maturity, type and coupon rate) will vary based on the subadvisor's outlook for the U.S. and foreign economies, the financial markets, and other factors.

The types of fixed-income securities in which the fund may invest include the following securities which, unless otherwise noted, may be issued by domestic or foreign issuers and may be denominated in U.S. dollars or foreign currencies:

  • securities issued or guaranteed by the U.S. government, its agencies or government-sponsored enterprises;

  • corporate debt securities of U.S. and foreign issuers, including convertible securities and corporate commercial paper;

  • mortgage-backed and other asset-backed securities;

  • inflation-indexed bonds issued by both governments and corporations;

  • bank capital and trust preferred securities;

  • structured notes, including hybrid or "indexed" securities and event-linked bonds;

  • loan participations and assignments;

  • delayed funding loans and revolving credit facilities;

  • bank certificates of deposit, fixed time deposits and bankers' acceptances;

  • debt securities issued by states or local governments and their agencies, authorities and other government-sponsored enterprises;

  • repurchase agreements and reverse repurchase agreements;

  • obligations of foreign governments or their subdivisions, agencies and government-sponsored enterprises; and

  • obligations of international agencies or supranational entities.

Fixed-income securities may have fixed, variable, or floating rates of interest, including rates of interest that vary inversely at a multiple of a designated or floating rate, or that vary according to change in relative values of currencies.

Depending on the subadvisor's current opinion as to the proper allocation of assets among domestic and foreign issuers, investments that are economically tied to foreign (non-U.S.) countries will normally be at least 25% of the fund's net assets. The fund may invest, without limitation, in securities and instruments that are economically tied to emerging countries. The fund may invest up to 10% of its total assets in fixed-income securities that are rated below investment grade but rated B or higher by Moody's or equivalently rated by S&P or Fitch, or, if unrated, determined by the subadvisor to be of comparable quality (except that within such limitations, the fund may invest in mortgage-related securities and variable rate master demand notes rated below B). The fund's investment policies are based on credit ratings at the time of purchase. The fund may invest in baskets of foreign currencies (such as the euro) and directly in currencies. The average portfolio duration of the fund normally varies within three years (plus or minus) of the duration of the benchmark index, as calculated by the subadvisor.

The fund's investment process may, at times, result in a higher than average portfolio turnover ratio and increased trading expenses.

The fund may make short sales of a security including short sales "against the box."

The fund is non-diversified, which means that it may invest its assets in a smaller number of issuers than a diversified fund.

The fund may:

  • purchase and sell options on domestic and foreign securities, securities indexes and currencies,

  • purchase and sell futures and options on futures,

  • purchase and sell currency or securities on a forward basis, and

  • enter into interest rate, index, equity, total return, currency, and credit default swap agreements.
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 principal risks of investing in the fund include:

Changing distribution levels risk. The distribution amounts paid by the fund generally depend on the amount of income and/or dividends received by the fund's investments. As a result of market, interest rate and other circumstances, the amount of cash available for distribution by the fund and the fund's distribution rate may vary or decline. The risk of such variability is accentuated in currently prevailing market and interest rate circumstances.

Convertible securities risk. 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.

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.

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. 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.

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, inverse floating-rate securities, 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.

High portfolio turnover risk. Actively trading securities can increase transaction costs (thus lowering performance).

Hybrid instrument risk. 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.
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.
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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q3 '09, 11.03%

Worst quarter: Q3 '08, –9.49%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

Performance Table Narrative rr_PerformanceTableNarrativeTextBlock

Prior to April 1, 2016, the fund compared its performance to the J.P. Morgan Global Government Bond Unhedged Index. After this date, the fund replaced the J.P. Morgan Global Government Bond Unhedged Index with the Barclays Global Aggregate Index, which better reflects its investment strategy.
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.
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.
(John Hancock Variable Insurance Trust) | (Global Bond Trust) | Barclays Global Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (3.15%)
5 Years rr_AverageAnnualReturnYear05 0.90%
10 Years rr_AverageAnnualReturnYear10 3.74%
Date of Inception rr_AverageAnnualReturnInceptionDate Mar. 19, 1988
(John Hancock Variable Insurance Trust) | (Global Bond Trust) | JP Morgan Global Government Bond Unhedged Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (2.61%)
5 Years rr_AverageAnnualReturnYear05 0.34%
10 Years rr_AverageAnnualReturnYear10 3.79%
Date of Inception rr_AverageAnnualReturnInceptionDate Mar. 19, 1988
(John Hancock Variable Insurance Trust) | (Global Bond Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.70%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.08% [11]
Total annual fund operating expenses rr_ExpensesOverAssets 0.83%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 85
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 265
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 460
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,025
Annual Return 2006 rr_AnnualReturn2006 5.27%
Annual Return 2007 rr_AnnualReturn2007 9.63%
Annual Return 2008 rr_AnnualReturn2008 (4.48%)
Annual Return 2009 rr_AnnualReturn2009 15.39%
Annual Return 2010 rr_AnnualReturn2010 10.30%
Annual Return 2011 rr_AnnualReturn2011 9.08%
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%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q3 '09, 11.03%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 11.03%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q3 '08, –9.49%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (9.49%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2008
1 Year rr_AverageAnnualReturnYear01 (3.50%)
5 Years rr_AverageAnnualReturnYear05 1.74%
10 Years rr_AverageAnnualReturnYear10 4.34%
Date of Inception rr_AverageAnnualReturnInceptionDate Mar. 19, 1988
(John Hancock Variable Insurance Trust) | (Global Bond Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.70%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.08% [11]
Total annual fund operating expenses rr_ExpensesOverAssets 1.03%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 105
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 328
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 569
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,259
1 Year rr_AverageAnnualReturnYear01 (3.73%)
5 Years rr_AverageAnnualReturnYear05 1.52%
10 Years rr_AverageAnnualReturnYear10 4.12%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Global Bond Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.70%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.08% [11]
Total annual fund operating expenses rr_ExpensesOverAssets 0.78%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 80
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 249
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 433
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 966
1 Year rr_AverageAnnualReturnYear01 (3.50%)
5 Years rr_AverageAnnualReturnYear05 1.76%
10 Years rr_AverageAnnualReturnYear10 4.37%
Date of Inception rr_AverageAnnualReturnInceptionDate Feb. 28, 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 and hold 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 medium 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 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 medium 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 43% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 43.00%
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").

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: pharmaceuticals, 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 such as to secure 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 principal risks of investing in the fund include:

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.

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.

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. 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.

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: options. Options generally are subject to counterparty risk.

Industry or sector investing risk. The performance of a fund that focuses on a single industry or sector of the economy depends in large part on the performance of that industry or sector. As a result, the value of an investment may fluctuate more widely than it would in a fund that is diversified across industries or sectors. Health sciences companies may be subject to additional risks, such as increased competition within the sector, changes in legislation or government regulations affecting the sector and product liabilities.

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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q1 '12, 18.02%

Worst quarter: Q4 '08, –19.64%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(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 1.38%
5 Years rr_AverageAnnualReturnYear05 12.57%
10 Years rr_AverageAnnualReturnYear10 7.31%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 30, 2001
(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 8.55%
5 Years rr_AverageAnnualReturnYear05 23.78%
10 Years rr_AverageAnnualReturnYear10 13.51%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 30, 2001
(John Hancock Variable Insurance Trust) | (Health Sciences Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.97%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.05%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.08% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 110
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 343
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 595
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,317
Annual Return 2006 rr_AnnualReturn2006 8.51%
Annual Return 2007 rr_AnnualReturn2007 17.67%
Annual Return 2008 rr_AnnualReturn2008 (29.90%)
Annual Return 2009 rr_AnnualReturn2009 31.81%
Annual Return 2010 rr_AnnualReturn2010 15.70%
Annual Return 2011 rr_AnnualReturn2011 10.57%
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%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q1 '12, 18.02%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 18.02%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2012
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –19.64%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (19.64%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 12.69%
5 Years rr_AverageAnnualReturnYear05 26.77%
10 Years rr_AverageAnnualReturnYear10 16.15%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 30, 2001
(John Hancock Variable Insurance Trust) | (Health Sciences Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.97%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.05%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.28% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 130
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 406
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 702
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,545
1 Year rr_AverageAnnualReturnYear01 12.49%
5 Years rr_AverageAnnualReturnYear05 26.53%
10 Years rr_AverageAnnualReturnYear10 15.92%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Health Sciences Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.97%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.05%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.03% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 105
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 328
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 569
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,259
1 Year rr_AverageAnnualReturnYear01 12.76%
5 Years rr_AverageAnnualReturnYear05 26.84%
10 Years rr_AverageAnnualReturnYear10 16.21%
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 and hold 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 medium 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)

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 medium 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 borrowings for investment purposes) at the time of investment in high yield securities. 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

Standard & Poor's Ratings. . . . . . . . . . . . . . . . . . . . . . . . . . . BB through D

Non-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 principal risks of investing in the fund include:

Changing distribution levels risk. The distribution amounts paid by the fund generally depend on the amount of income and/or dividends received by the fund's investments. As a result of market, interest rate and other circumstances, the amount of cash available for distribution by the fund and the fund's distribution rate may vary or decline. The risk of such variability is accentuated in currently prevailing market and interest rate circumstances.

Convertible securities risk. 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.

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.

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. 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.

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, along with specific additional associated risks, if any, 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.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.
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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 24.28%

Worst quarter: Q4 '08, –20.68%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (High Yield Trust) | Citigroup High Yield Market Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (5.55%)
5 Years rr_AverageAnnualReturnYear05 4.62%
10 Years rr_AverageAnnualReturnYear10 6.50%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 02, 1997
(John Hancock Variable Insurance Trust) | (High Yield Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.68%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.07%
Total annual fund operating expenses rr_ExpensesOverAssets 0.80%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 82
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 255
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 444
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 990
Annual Return 2006 rr_AnnualReturn2006 10.37%
Annual Return 2007 rr_AnnualReturn2007 1.64%
Annual Return 2008 rr_AnnualReturn2008 (29.52%)
Annual Return 2009 rr_AnnualReturn2009 54.51%
Annual Return 2010 rr_AnnualReturn2010 13.78%
Annual Return 2011 rr_AnnualReturn2011 0.90%
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%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 24.28%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 24.28%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –20.68%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (20.68%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (8.32%)
5 Years rr_AverageAnnualReturnYear05 3.64%
10 Years rr_AverageAnnualReturnYear10 5.21%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 02, 1997
(John Hancock Variable Insurance Trust) | (High Yield Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.68%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.07%
Total annual fund operating expenses rr_ExpensesOverAssets 1.00%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 102
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 318
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 552
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,225
1 Year rr_AverageAnnualReturnYear01 (8.55%)
5 Years rr_AverageAnnualReturnYear05 3.42%
10 Years rr_AverageAnnualReturnYear10 5.00%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (High Yield Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.68%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.07%
Total annual fund operating expenses rr_ExpensesOverAssets 0.75%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 77
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 240
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 417
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 930
1 Year rr_AverageAnnualReturnYear01 (8.38%)
5 Years rr_AverageAnnualReturnYear05 3.69%
10 Years rr_AverageAnnualReturnYear10 5.25%
Date of Inception rr_AverageAnnualReturnInceptionDate Feb. 28, 2005
(John Hancock Variable Insurance Trust) | (Income Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

To seek to maximize income while maintaining prospects for 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 and hold 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 medium 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)

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 medium 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 27% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 27.00%
Strategy [Heading] rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Under normal market conditions, the fund invests in a diversified portfolio of debt securities, such as bonds, notes and debentures, and equity securities, such as common stocks, preferred stocks and convertible securities. The fund may shift its investments from one asset class to another based on the subadvisor's analysis of the best opportunities for the fund's portfolio in a given market.

The fund seeks income by selecting investments such as corporate and foreign debt securities and U.S. Treasury bonds, as well as stocks with attractive dividend yields. In its search for growth opportunities, the fund maintains the flexibility to invest in common stocks of companies from a variety of industries such as energy and utilities. From time to time, based on economic conditions, the fund may have significant investments in particular sectors.

The fund may invest up to 100% of total assets in debt securities that are rated below investment grade (sometimes referred to as "junk bonds"). Securities rated in the top four rating categories by independent rating organizations such as Standard & Poor's Ratings Services ("S&P") or Moody's Investors Service ("Moody's") are considered investment grade. Below-investment-grade securities, such as those rated BB or lower by S&P, or Ba or lower by Moody's, or unrated, but deemed by the subadvisor to be of comparable quality, generally pay higher yields but involve greater risks than investment-grade securities. The fund may invest in equity-linked notes, the value of which is tied to a single stock or a basket of stocks. The fund may also invest up to 25% of its assets in foreign securities, either directly or through depositary receipts. The fund may invest in convertible securities without regard to the ratings assigned by rating services.

The fund may, from time to time, seek to hedge (protect) against currency risks, using principally forward foreign currency exchange contracts and currency futures contracts when, in the subadvisor's opinion, it would be advantageous to the fund to do so. The fund may also, from time to time, seek to hedge against market risk or generate income, using a variety of derivative instruments, which may include purchasing or selling call and put options on equity securities and equity security indices.

The fund's subadvisor searches for undervalued or out-of-favor securities it believes offer opportunities for income today and significant growth tomorrow. It generally performs independent analysis of the debt securities being considered for the fund's portfolio, rather than relying principally on the ratings assigned by rating organizations. In analyzing both debt and equity securities, the subadvisor considers a variety of factors, including:

  • a security's relative value based on such factors as anticipated cash flow, interest or dividend coverage, asset coverage, and earnings prospects;

  • the experience and strength of the company's management;

  • the company's changing financial condition and market recognition of the change;

  • the company's sensitivity to changes in interest rates and business conditions; and

  • the company's debt maturity schedules and borrowing requirements.

With respect to debt and equity securities in the utilities industry, the subadvisor considers the effects of the regulatory environment on utilities companies. When choosing equity investments for the fund, the subadvisor applies a "bottom-up," value oriented, long-term approach, focusing on the market price of a company's securities relative to the subadvisor's evaluation of the company's long-term earnings, asset value and cash flow potential. The subadvisor also considers a company's price/earnings ratio, profit margins and liquidation value.
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 principal risks of investing in the fund include:

Changing distribution levels risk. The distribution amounts paid by the fund generally depend on the amount of income and/or dividends received by the fund's investments. As a result of market, interest rate and other circumstances, the amount of cash available for distribution by the fund and the fund's distribution rate may vary or decline. The risk of such variability is accentuated in currently prevailing market and interest rate circumstances.

Convertible securities risk. 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.

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.

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, 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. 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.

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, along with specific additional associated risks, if any, 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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Interest-rate risk. Fixed-income securities are affected by changes in interest rates. When interest rates decline, the market value of fixed-income securities generally can be expected to rise. Conversely, when interest rates rise, the market value of fixed-income securities generally can be expected to decline. The longer the duration or maturity of a fixed-income security, the more susceptible it is to interest-rate risk.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Utilities sector risk. Utilities companies' performance may be volatile due to variable fuel, service, and financing costs, conservation efforts, government regulation, and other factors.
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. Unless all share classes shown in the table have the same inception date, 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 medium. 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 50% of the S&P 500 Index and 50% of the Barclays U.S. Aggregate Bond Index.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series NAV (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 16.59%

Worst quarter: Q3 '08, –14.27%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Income Trust) | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.55%
5 Years rr_AverageAnnualReturnYear05 3.25%
Inception rr_AverageAnnualReturnSinceInception 4.47%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (Income Trust) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.38%
5 Years rr_AverageAnnualReturnYear05 12.57%
Inception rr_AverageAnnualReturnSinceInception 6.04%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (Income Trust) | Combined Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.21%
5 Years rr_AverageAnnualReturnYear05 8.02%
Inception rr_AverageAnnualReturnSinceInception 5.60%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (Income Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.80%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.05% [12]
Total annual fund operating expenses rr_ExpensesOverAssets 0.90%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 92
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 287
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 498
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,108
(John Hancock Variable Insurance Trust) | (Income Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.80%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.05% [12]
Total annual fund operating expenses rr_ExpensesOverAssets 1.10%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 112
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 350
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 606
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,340
(John Hancock Variable Insurance Trust) | (Income Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.80%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.05%
Total annual fund operating expenses rr_ExpensesOverAssets 0.85%
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 2008 rr_AnnualReturn2008 (28.64%)
Annual Return 2009 rr_AnnualReturn2009 35.07%
Annual Return 2010 rr_AnnualReturn2010 12.71%
Annual Return 2011 rr_AnnualReturn2011 2.72%
Annual Return 2012 rr_AnnualReturn2012 13.23%
Annual Return 2013 rr_AnnualReturn2013 14.75%
Annual Return 2014 rr_AnnualReturn2014 4.65%
Annual Return 2015 rr_AnnualReturn2015 (6.22%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 16.59%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 16.59%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q3 '08, –14.27%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (14.27%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2008
1 Year rr_AverageAnnualReturnYear01 (6.22%)
5 Years rr_AverageAnnualReturnYear05 5.55%
Inception rr_AverageAnnualReturnSinceInception 3.93%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (International Core Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

To seek high total return.
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 and hold 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 medium 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 Restated to Reflect Current [Text] rr_ExpensesRestatedToReflectCurrent "Other expenses" have been restated from fiscal year amounts to reflect current 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 medium 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 67% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 67.00%
Strategy [Heading] rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

The subadvisor seeks to achieve the fund's investment objective by investing the fund's portfolio primarily in non-U.S. developed market equities that the subadvisor believes will provide a higher return than the MSCI EAFE Index.

Under normal market conditions, the fund invests at least 80% of its total assets in equity investments. The terms "equities" and "equity investments" refer to direct and indirect investments in common stocks and other stock-related securities, such as preferred stocks, convertible securities, depositary receipts, and exchange-traded equity real estate investment trusts (REITs) and income trusts.

The subadvisor determines which securities the fund should buy or sell based on its evaluation of companies' published financial information and corporate behavior, securities' prices, equity and bond markets, and the overall economy.

In selecting securities for the fund, the subadvisor uses a combination of investment methods to identify securities that the subadvisor believes have positive return potential relative to other securities in the fund's investment universe. Some of these methods evaluate individual securities or groups of securities based on the ratio of their price to historical financial information and forecasted financial information, such as book value, cash flow and earnings, and a comparison of these ratios to industry or market averages or to their own history. Other methods focus on patterns of information, such as price movement or volatility of a security or groups of securities relative to the fund's investment universe or corporate behavior of an issuer. The subadvisor also uses multi-year return forecasts for asset classes and other groups of securities as an input to the investment process and may adjust the fund's portfolio for factors such as position size, market capitalization, and exposure to factors such as industry, sector, country, or currency. The factors considered and investment methods used by the subadvisor can change over time. The subadvisor does not manage the fund to, or control the fund's risk relative to, any securities index or securities benchmark.

As a substitute for direct investments in equities, the subadvisor may use exchange-traded and over-the-counter derivatives. The subadvisor also may use derivatives and exchange-traded funds: (i) in an attempt to reduce investment exposures (which may result in a reduction below zero); and (ii) in an attempt to adjust elements of the fund's investment exposure. Derivatives used may include futures, options, foreign currency forward contracts, and swap contracts.
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 principal risks of investing in the fund include:

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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. A fund bears ETF fees and expenses indirectly.

Foreign securities risk. Less information may be publicly available regarding foreign 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.

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, along with specific additional associated risks, if any, 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.

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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.

Real estate investment trust 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 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 20.53%

Worst quarter: Q3 '11, –19.42%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (International Core Trust) | MSCI EAFE Index (gross of foreign withholding taxes on dividends) (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (0.39%)
5 Years rr_AverageAnnualReturnYear05 4.07%
10 Years rr_AverageAnnualReturnYear10 3.50%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 02, 1997
(John Hancock Variable Insurance Trust) | (International Core Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.87% [13]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.07% [14]
Total annual fund operating expenses rr_ExpensesOverAssets 0.99%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 101
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 315
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 547
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,213
Annual Return 2006 rr_AnnualReturn2006 24.69%
Annual Return 2007 rr_AnnualReturn2007 11.49%
Annual Return 2008 rr_AnnualReturn2008 (38.62%)
Annual Return 2009 rr_AnnualReturn2009 18.64%
Annual Return 2010 rr_AnnualReturn2010 9.58%
Annual Return 2011 rr_AnnualReturn2011 (9.57%)
Annual Return 2012 rr_AnnualReturn2012 15.05%
Annual Return 2013 rr_AnnualReturn2013 24.99%
Annual Return 2014 rr_AnnualReturn2014 (6.70%)
Annual Return 2015 rr_AnnualReturn2015 (5.45%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 20.53%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 20.53%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q3 '11, –19.42%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (19.42%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2011
1 Year rr_AverageAnnualReturnYear01 (5.45%)
5 Years rr_AverageAnnualReturnYear05 2.78%
10 Years rr_AverageAnnualReturnYear10 2.44%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 02, 1997
(John Hancock Variable Insurance Trust) | (International Core Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.87% [13]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.07% [14]
Total annual fund operating expenses rr_ExpensesOverAssets 1.19%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 121
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 378
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 654
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,443
1 Year rr_AverageAnnualReturnYear01 (5.62%)
5 Years rr_AverageAnnualReturnYear05 2.57%
10 Years rr_AverageAnnualReturnYear10 2.24%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (International Core Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.87% [13]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.07% [14]
Total annual fund operating expenses rr_ExpensesOverAssets 0.94%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 96
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 300
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 520
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,155
1 Year rr_AverageAnnualReturnYear01 (5.32%)
5 Years rr_AverageAnnualReturnYear05 2.84%
10 Years rr_AverageAnnualReturnYear10 2.49%
Date of Inception rr_AverageAnnualReturnInceptionDate Feb. 28, 2005
(John Hancock Variable Insurance Trust) | (International Equity Index Trust B)  
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 and hold 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 medium 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, 2017
Expenses Restated to Reflect Current [Text] rr_ExpensesRestatedToReflectCurrent Other expenses" have been restated from fiscal year amounts to reflect current 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 medium 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 4% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 4.00%
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. As of February 29, 2016, the market capitalization range of the Index was $336 million to $224 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 mirror the risk and return profile of market indices, 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. 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 fund uses "sampling" methodology to track the total return performance of the Index. This means that the fund does not intend 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 is 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, ADRs, GDRs, 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 principal risks of investing in the fund include:

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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. A fund bears ETF fees and expenses indirectly.

Foreign securities risk. Less information may be publicly available regarding foreign 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.

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, along with specific additional associated risks, if any, 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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. For periods prior to the inception date of the fund, performance shown is the actual performance of the sole share class of the fund's predecessor fund and has not been adjusted to reflect the Rule 12b-1 fees of any class of shares. As a result, pre-inception performance of the fund may be higher than 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series NAV (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 27.40%

Worst quarter: Q4 '08, –22.28%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (International Equity Index Trust B) | MSCI All Country World Ex US Index (gross of foreign withholding taxes on dividends) (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (5.25%)
5 Years rr_AverageAnnualReturnYear05 1.51%
10 Years rr_AverageAnnualReturnYear10 3.38%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (International Equity Index Trust B) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.53%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.08%
Total annual fund operating expenses rr_ExpensesOverAssets 0.66%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.27%) [15]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.39%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 40
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 184
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 341
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 797
1 Year rr_AverageAnnualReturnYear01 (5.91%)
5 Years rr_AverageAnnualReturnYear05 0.80%
10 Years rr_AverageAnnualReturnYear10 2.82%
Date of Inception rr_AverageAnnualReturnInceptionDate Nov. 05, 2012
(John Hancock Variable Insurance Trust) | (International Equity Index Trust B) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.53%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.08%
Total annual fund operating expenses rr_ExpensesOverAssets 0.86%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.27%) [15]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.59%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 60
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 247
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 450
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,036
1 Year rr_AverageAnnualReturnYear01 (6.11%)
5 Years rr_AverageAnnualReturnYear05 0.68%
10 Years rr_AverageAnnualReturnYear10 2.76%
Date of Inception rr_AverageAnnualReturnInceptionDate Nov. 05, 2012
(John Hancock Variable Insurance Trust) | (International Equity Index Trust B) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.53%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.08%
Total annual fund operating expenses rr_ExpensesOverAssets 0.61%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.27%) [15]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.34%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 35
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 168
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 313
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 736
Annual Return 2006 rr_AnnualReturn2006 27.41%
Annual Return 2007 rr_AnnualReturn2007 15.76%
Annual Return 2008 rr_AnnualReturn2008 (44.36%)
Annual Return 2009 rr_AnnualReturn2009 38.80%
Annual Return 2010 rr_AnnualReturn2010 11.44%
Annual Return 2011 rr_AnnualReturn2011 (13.99%)
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%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 27.40%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 27.40%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –22.28%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (22.28%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (5.80%)
5 Years rr_AverageAnnualReturnYear05 0.84%
10 Years rr_AverageAnnualReturnYear10 2.84%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (International Growth Stock Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

The fund seeks to achieve 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 and hold 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 medium 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 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 medium 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 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 invests primarily in a diversified portfolio of international securities whose issuers are considered by the fund's subadvisor to have potential for earnings or revenue growth. The fund will, under normal circumstances, invest at least 80% of its net assets (plus any borrowings for investment purposes) in stocks of any market capitalization.

The fund invests significantly in foreign issuers. The fund focuses its investments in equity securities of foreign issuers that are listed on a recognized foreign or U.S. securities exchange or traded in a foreign or U.S. over-the-counter market. The fund invests, under normal circumstances, in issuers located in at least three countries outside of the U.S. The fund may invest in issuers located in developing countries (emerging markets). Under normal circumstances, the maximum percentage of the fund's net assets that may be invested in these issuers is 1.25 times of the emerging market weight of the MSCI All Country World ex U.S. Growth Index.

The fund invests primarily in the securities of large-capitalization issuers; however, the fund may invest a significant amount of its net assets in the securities of mid-capitalization issuers. The fund can invest in derivative instruments including forward foreign currency contracts and futures. The fund can utilize forward foreign currency contracts to hedge against adverse movements in the foreign currencies in which portfolio securities are denominated. Historically the fund has not hedged the currency exposure created by its investments in foreign securities but has the ability do so if deemed appropriate by the fund's portfolio managers.The fund can also invest in futures contracts to gain exposure to the broad market in connection with managing cash balances or to hedge against downside risk.

The portfolio managers employ a disciplined investment strategy that emphasizes fundamental research. The fundamental research primarily focuses on identifying quality growth companies and is supported by quantitative analysis, portfolio construction and risk management. Investments for the portfolio are selected bottom-up on a security-by-security basis. The focus is on the strengths of individual issuers, rather than sector or country trends. The portfolio managers' strategy primarily focuses on identifying issuers that they believe have sustainable earnings growth, efficient capital allocation, and attractive prices.

Use of Hedging and Other Strategic Transactions. The fund is authorized to use various hedging, derivatives and other strategic transactions, including, but not limited to, U.S. Treasury futures and options, index derivatives, credit default swaps and currency forwards, described under "Additional Information about the Funds' Principal Risks – Hedging, derivatives and other strategic transactions risk."
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 principal risks of investing in the fund include:

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.

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.

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.

Foreign securities risk. Less information may be publicly available regarding foreign 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.

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, along with specific additional associated risks, if any, 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.

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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, performance shown for periods prior to theinception 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series NAV (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q3 '13, 10.86%

Worst quarter: Q3 '11, –18.11%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (International Growth Stock Trust) | MSCI All Country World ex U.S. Growth Index (gross of foreign withholding taxes on dividends) (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (0.91%)
5 Years rr_AverageAnnualReturnYear05 2.48%
Inception rr_AverageAnnualReturnSinceInception 4.44%
Date of Inception rr_AverageAnnualReturnInceptionDate Sep. 16, 2010
(John Hancock Variable Insurance Trust) | (International Growth Stock Trust) | MSCI EAFE Growth Index (gross of foreign withholding taxes on dividends)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 4.47%
5 Years rr_AverageAnnualReturnYear05 4.97%
Inception rr_AverageAnnualReturnSinceInception 6.72%
Date of Inception rr_AverageAnnualReturnInceptionDate Sep. 16, 2010
(John Hancock Variable Insurance Trust) | (International Growth Stock Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.79%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.08%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.93% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 95
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 296
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 515
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,143
1 Year rr_AverageAnnualReturnYear01 (2.27%)
5 Years rr_AverageAnnualReturnYear05 4.60%
Inception rr_AverageAnnualReturnSinceInception 6.07%
Date of Inception rr_AverageAnnualReturnInceptionDate Nov. 05, 2012
(John Hancock Variable Insurance Trust) | (International Growth Stock Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.79%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.08%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.13% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 115
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 359
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 622
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,375
1 Year rr_AverageAnnualReturnYear01 (2.53%)
5 Years rr_AverageAnnualReturnYear05 4.46%
Inception rr_AverageAnnualReturnSinceInception 5.94%
Date of Inception rr_AverageAnnualReturnInceptionDate Nov. 05, 2012
(John Hancock Variable Insurance Trust) | (International Growth Stock Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.79%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.08%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.88% [5]
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 2011 rr_AnnualReturn2011 (7.12%)
Annual Return 2012 rr_AnnualReturn2012 15.64%
Annual Return 2013 rr_AnnualReturn2013 19.19%
Annual Return 2014 rr_AnnualReturn2014 0.19%
Annual Return 2015 rr_AnnualReturn2015 (2.24%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q3 '13, 10.86%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 10.86%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2013
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q3 '11, –18.11%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (18.11%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2011
1 Year rr_AverageAnnualReturnYear01 (2.24%)
5 Years rr_AverageAnnualReturnYear05 4.63%
Inception rr_AverageAnnualReturnSinceInception 6.10%
Date of Inception rr_AverageAnnualReturnInceptionDate Sep. 16, 2010
(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 and hold 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 medium 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 Restated to Reflect Current [Text] rr_ExpensesRestatedToReflectCurrent "Other expenses" have been restated from fiscal year amounts to reflect current 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 medium 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) in securities of small cap companies in the particular markets in which the fund invests. As of February 29, 2016, the maximum market capitalization range of eligible companies for purchase was approximately $1,465 million to approximately $6,262 million, depending on the country. 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 or traded on the over-the-counter markets, including securities listed or traded in the form of International Depositary Receipts (IDRs), American Depositary Receipts (ADRs), European Depositary Receipts (EDRs), Global Depositary Receipts (GDRs), Non-Voting Depositary Receipts (NVDRs) and other similar securities, including dual-listed securities. Each of these securities may be traded within or outside the issuer's domicile country.

The subadvisor measures 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, MSCI or Citigroup.

The fund also may use derivatives such as futures contracts and options on futures contracts, to adjust market exposure based on expected cash inflows to or outflows from the fund. The fund does not intend to use derivatives for purposes of speculation or leveraging investment returns. 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.

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 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 adjusted by the subadvisor for a variety of reasons. The subadvisor may consider such factors as free float, momentum, trading strategies, liquidity management, and profitability, as well as other factors determined to be appropriate by the subadvisor given market conditions. In assessing profitability, the subadvisor may consider different ratios, such as that of earnings or profits from operations relative to book value or assets. 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 security is inappropriate in light of other conditions. 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 market capitalization 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 adjust the exposure to a particular country or region to a maximum proportion of the assets of that vehicle. Country weights may also deviate from target weights due to general day-to-day trading patterns and price movements. The weighting of countries will likely vary from their weighting in published international indices. Also, deviation from target weights may result from holding securities from countries that are no longer authorized for future 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 principal risks of investing in the fund include:

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.

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.

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.

Foreign securities risk. Less information may be publicly available regarding foreign 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.

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.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series NAV (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 31.13%

Worst quarter: Q3 '08, –22.53%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (International Small Company Trust) | MSCI World ex-U.S. Small Cap Index (gross of foreign withholding taxes on dividends) (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 5.83%
5 Years rr_AverageAnnualReturnYear05 4.77%
Inception rr_AverageAnnualReturnSinceInception 3.02%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 28, 2006
(John Hancock Variable Insurance Trust) | (International Small Company Trust) | MSCI EAFE Small Cap Index (gross of foreign withholding taxes on dividends) (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 9.94%
5 Years rr_AverageAnnualReturnYear05 6.67%
Inception rr_AverageAnnualReturnSinceInception 3.52%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 28, 2006
(John Hancock Variable Insurance Trust) | (International Small Company Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.95%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.19% [6]
Total annual fund operating expenses rr_ExpensesOverAssets 1.19%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 121
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 378
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 654
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,443
1 Year rr_AverageAnnualReturnYear01 6.54%
5 Years rr_AverageAnnualReturnYear05 4.59%
Inception rr_AverageAnnualReturnSinceInception 2.79%
Date of Inception rr_AverageAnnualReturnInceptionDate Nov. 16, 2009
(John Hancock Variable Insurance Trust) | (International Small Company Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.95%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.19% [6]
Total annual fund operating expenses rr_ExpensesOverAssets 1.39%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 142
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 440
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 761
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,669
1 Year rr_AverageAnnualReturnYear01 6.39%
5 Years rr_AverageAnnualReturnYear05 4.38%
Inception rr_AverageAnnualReturnSinceInception 2.66%
Date of Inception rr_AverageAnnualReturnInceptionDate Nov. 16, 2009
(John Hancock Variable Insurance Trust) | (International Small Company Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.95%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.19% [6]
Total annual fund operating expenses rr_ExpensesOverAssets 1.14%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 116
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 362
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 628
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,386
Annual Return 2007 rr_AnnualReturn2007 5.43%
Annual Return 2008 rr_AnnualReturn2008 (45.35%)
Annual Return 2009 rr_AnnualReturn2009 39.44%
Annual Return 2010 rr_AnnualReturn2010 22.63%
Annual Return 2011 rr_AnnualReturn2011 (16.18%)
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%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 31.13%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 31.13%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q3 '08, –22.53%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (22.53%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2008
1 Year rr_AverageAnnualReturnYear01 6.68%
5 Years rr_AverageAnnualReturnYear05 4.64%
Inception rr_AverageAnnualReturnSinceInception 2.82%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 28, 2006
(John Hancock Variable Insurance Trust) | (International 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 and hold 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 medium 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 Restated to Reflect Current [Text] rr_ExpensesRestatedToReflectCurrent "Other expenses" have been restated from fiscal year amounts to reflect current 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 medium 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 16% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 16.00%
Strategy [Heading] rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Under normal market conditions, the fund invests primarily in equity securities of companies located outside the U.S., including in emerging markets. The fund may invest in securities of any size company, across the entire market capitalization spectrum, including smaller and midsize companies. From time to time, based on economic conditions, the fund may have significant investments in one or more countries and/or in particular sectors.

Equity securities generally entitle the holder to participate in a company's general operating results. These include common stocks, preferred stocks, and convertible securities. The fund also invests in American Depositary Receipts (ADRs), European Depositary Receipts (EDRs), and Global Depositary Receipts (GDRs), which are certificates typically issued by a bank or trust company that give their holders the right to receive securities issued by a foreign or domestic company. The fund may invest in all types of equity-linked notes, which are hybrid derivative-type instruments that are specially designed to combine the characteristics of one or more reference securities (usually a single stock, a stock index or a basket of stocks (underlying securities)) and a related equity derivative, such as a put or call option, in a single note form.

The subadvisor's investment philosophy is "bottom-up," value-oriented, and long-term. In choosing equity investments, the subadvisor will focus on the market price of a company's securities relative to its evaluation of the company's long-term earnings, asset value, and cash flow potential. A company's historical value measure, including price/earnings ratio, profit margins and liquidation value, will also be considered.

The fund may invest in equity-linked notes, the value of which is tied to a single stock or a basket of stocks.
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 principal risks of investing in the fund include:

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.

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.

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, 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. 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.

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: 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).

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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.

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 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. Unless all share classes shown in the table have the same inception date, 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 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q3 '09, 24.09%

Worst quarter: Q4 '08, –21.66%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (International Value Trust) | MSCI EAFE Index (gross of foreign withholding taxes on dividends) (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (0.39%)
5 Years rr_AverageAnnualReturnYear05 4.07%
10 Years rr_AverageAnnualReturnYear10 3.50%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 1999
(John Hancock Variable Insurance Trust) | (International Value Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.80%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.06% [6]
Total annual fund operating expenses rr_ExpensesOverAssets 0.91%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 93
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 290
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 504
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,120
Annual Return 2006 rr_AnnualReturn2006 29.59%
Annual Return 2007 rr_AnnualReturn2007 9.53%
Annual Return 2008 rr_AnnualReturn2008 (42.67%)
Annual Return 2009 rr_AnnualReturn2009 35.77%
Annual Return 2010 rr_AnnualReturn2010 7.98%
Annual Return 2011 rr_AnnualReturn2011 (12.85%)
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%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q3 '09, 24.09%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 24.09%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –21.66%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (21.66%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (7.81%)
5 Years rr_AverageAnnualReturnYear05 1.14%
10 Years rr_AverageAnnualReturnYear10 2.36%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 1999
(John Hancock Variable Insurance Trust) | (International Value Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.80%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.06% [6]
Total annual fund operating expenses rr_ExpensesOverAssets 1.11%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 113
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 353
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 612
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,352
1 Year rr_AverageAnnualReturnYear01 (7.95%)
5 Years rr_AverageAnnualReturnYear05 0.96%
10 Years rr_AverageAnnualReturnYear10 2.17%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (International Value Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.80%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.06% [6]
Total annual fund operating expenses rr_ExpensesOverAssets 0.86%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 88
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 274
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 477
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,061
1 Year rr_AverageAnnualReturnYear01 (7.72%)
5 Years rr_AverageAnnualReturnYear05 1.19%
10 Years rr_AverageAnnualReturnYear10 2.41%
Date of Inception rr_AverageAnnualReturnInceptionDate Feb. 28, 2005
(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 and hold 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 medium 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)

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 medium 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 97% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 97.00%
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 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 at the time of investment, 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 principal risks of investing in the fund include:

Changing distribution levels risk. The distribution amounts paid by the fund generally depend on the amount of income and/or dividends received by the fund's investments. As a result of market, interest rate and other circumstances, the amount of cash available for distribution by the fund and the fund's distribution rate may vary or decline. The risk of such variability is accentuated in currently prevailing market and interest rate circumstances.

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.

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.

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. 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.

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.

High portfolio turnover risk. Actively trading securities can increase transaction costs (thus lowering performance).

Hybrid instrument risk. 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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 50% of the Barclays U.S. Credit Index and 50% of the Barclays U.S. Government Bond Index.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q3 '09, 6.55%

Worst quarter: Q2 '13, –3.48%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Investment Quality Bond Trust) | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.55%
5 Years rr_AverageAnnualReturnYear05 3.25%
10 Years rr_AverageAnnualReturnYear10 4.51%
Date of Inception rr_AverageAnnualReturnInceptionDate Jun. 19, 1985
(John Hancock Variable Insurance Trust) | (Investment Quality Bond Trust) | Barclays Credit Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (0.77%)
5 Years rr_AverageAnnualReturnYear05 4.38%
10 Years rr_AverageAnnualReturnYear10 5.18%
Date of Inception rr_AverageAnnualReturnInceptionDate Jun. 19, 1985
(John Hancock Variable Insurance Trust) | (Investment Quality Bond Trust) | Barclays U.S. Government Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.86%
5 Years rr_AverageAnnualReturnYear05 2.77%
10 Years rr_AverageAnnualReturnYear10 4.10%
Date of Inception rr_AverageAnnualReturnInceptionDate Jun. 19, 1985
(John Hancock Variable Insurance Trust) | (Investment Quality Bond Trust) | Combined Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.04%
5 Years rr_AverageAnnualReturnYear05 3.58%
10 Years rr_AverageAnnualReturnYear10 4.67%
Date of Inception rr_AverageAnnualReturnInceptionDate Jun. 19, 1985
(John Hancock Variable Insurance Trust) | (Investment Quality Bond Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.58%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.06%
Total annual fund operating expenses rr_ExpensesOverAssets 0.69%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 70
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 221
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 384
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 859
Annual Return 2006 rr_AnnualReturn2006 3.57%
Annual Return 2007 rr_AnnualReturn2007 6.21%
Annual Return 2008 rr_AnnualReturn2008 (1.67%)
Annual Return 2009 rr_AnnualReturn2009 12.45%
Annual Return 2010 rr_AnnualReturn2010 7.45%
Annual Return 2011 rr_AnnualReturn2011 8.07%
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%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q3 '09, 6.55%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 6.55%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q2 '13, –3.48%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (3.48%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2013
1 Year rr_AverageAnnualReturnYear01 (0.82%)
5 Years rr_AverageAnnualReturnYear05 3.59%
10 Years rr_AverageAnnualReturnYear10 4.54%
Date of Inception rr_AverageAnnualReturnInceptionDate Jun. 19, 1985
(John Hancock Variable Insurance Trust) | (Investment Quality Bond Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.58%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.06%
Total annual fund operating expenses rr_ExpensesOverAssets 0.89%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 91
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 284
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 493
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,096
1 Year rr_AverageAnnualReturnYear01 (1.02%)
5 Years rr_AverageAnnualReturnYear05 3.38%
10 Years rr_AverageAnnualReturnYear10 4.33%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Investment Quality Bond Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.58%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.06%
Total annual fund operating expenses rr_ExpensesOverAssets 0.64%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 65
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 205
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 357
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 798
1 Year rr_AverageAnnualReturnYear01 (0.68%)
5 Years rr_AverageAnnualReturnYear05 3.65%
10 Years rr_AverageAnnualReturnYear10 4.59%
Date of Inception rr_AverageAnnualReturnInceptionDate Feb. 28, 2005
(John Hancock Variable Insurance Trust) | (Lifecycle 2010 Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

To seek high total return until the fund's target retirement date.
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 and hold 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 medium 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)

Other Expenses, New Fund, Based on Estimates [Text] rr_OtherExpensesNewFundBasedOnEstimates For funds and classes that have not commenced operations or have an inception date of less than six months as of December 31,2015, expenses are estimated.
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 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 medium 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. Because the fund had not commenced operations as of the date of this prospectus, there is no portfolio turnover to report.
Strategy [Heading] rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Under normal market conditions, the fund invests substantially all of its assets in underlying funds using an asset allocation strategy designed for investors expected to retire around the year 2010. Over time, the asset allocation strategy will change according to a predetermined glide path as set forth below.

After December 31st of the designated retirement year of the fund, the fund will, under normal market conditions, continue to invest its assets in accordance with the predetermined "glide path" set forth below although the subadvisors may at times determine in light of prevailing market or economic conditions that the fund's asset allocations should vary from those indicated by the "glide path" in order to preserve the fund's assets or to help it achieve its objective.

Within the prescribed percentage allocation, the subadvisors select the percentage level to be maintained in specific underlying funds. The subadvisors may, from time to time, change the allocation in specific underlying funds or rebalance the underlying funds. To maintain target allocation in the underlying funds, daily cash flows for the fund will be directed to its underlying funds that most deviate from target.

The allocations reflected in the glide path are also referred to as "neutral" allocations because they do not reflect active decisions made by the subadvisors to produce an overweight or an underweight position in a particular asset class based on the subadvisors' market outlook. The fund has a target allocation for the broad asset classes of equities and fixed income but may invest outside these target allocations to protect the fund or help it achieve its objective.

The investment performance of the fund will reflect both its subadvisors' allocation decisions with respect to underlying funds and investments and the investment decisions made by the underlying funds' subadvisors.

In addition to investing in exchange-traded funds (ETFs), the fund may also invest in the securities of other investment companies and may make direct investments in other types of investments, such as equity and fixed-income securities, including U.S. government securities, closed-end funds and partnerships. See "Other Permitted Investments by the Funds of Funds." The fund may also engage in short selling of securities.

The fund may invest in various underlying funds that as a group hold a wide range of equity-type securities in their portfolios. 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 the underlying funds has its own investment strategy that, 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. Certain of the 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, government issued, domestic and international securities.

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 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, without limitation, investing in credit default swaps, foreign currency forward contracts, futures contracts, interest rate swaps and options.

glidepath chart

Fund Combination after Designated Retirement Date

The Board of Trustees may, in its discretion, determine to combine the fund with another fund if the target allocation of the fund matches the target allocation of the other fund. In such event, the fund's shareholders will become shareholders of the other fund. To the extent permitted by applicable regulatory requirements, such a combination would be implemented without seeking the approval of shareholders. There is no assurance that the Board of Trustees at any point will determine to implement such a combination.
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 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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. A fund bears ETF fees and expenses indirectly.

Exchange-traded notes 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 is subject to risks related to: (i) the underlying funds' performance, expenses, and ability to meet their investment objectives; (ii) properly rebalancing assets among underlying funds and different asset classes; (iii) layering of fees of the underlying funds; and (iv) conflicts of interest associated with the subadvisor's ability to allocate fund assets without limit to underlying funds advised by the subadvisor and/or other affiliated subadvisors.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, options, credit default swaps, 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.

Investment company securities risk. A fund bears underlying fund fees and expenses indirectly.

Lifecycle risk. Managers might not correctly predict market or economic conditions, and you could lose money even close to, during, or after the fund's designated retirement year.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Target allocation risk. Relatively large redemptions from or investments in an underlying fund due to reallocation or rebalancing of portfolio assets could affect the performance of the underlying fund and the fund.

Principal risks of investing in the underlying funds

The principal risks of investing in the Underlying Funds include:

Convertible securities risk. 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 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.

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.

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. 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. 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.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, options, credit default swaps, 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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Initial public offerings risk. IPO share prices are frequently volatile and may significantly impact fund performance.

Investment company securities risk. A fund bears underlying fund fees and expenses indirectly.

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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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

This section normally shows how the fund's total returns have varied from year to year, along with a broad-based market index for reference. Because the fund has not commenced operations as of the date of this Prospectus, there is no past performance to report.
(John Hancock Variable Insurance Trust) | (Lifecycle 2010 Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05% [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.73% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 0.93% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 95
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 296
(John Hancock Variable Insurance Trust) | (Lifecycle 2010 Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25% [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.73% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 1.13% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 115
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 359
(John Hancock Variable Insurance Trust) | (Lifecycle 2010 Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.73% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 0.88% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 90
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 281
(John Hancock Variable Insurance Trust) | (Lifecycle 2015 Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

To seek high total return until the fund's target retirement date.
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 and hold 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 medium 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)

Other Expenses, New Fund, Based on Estimates [Text] rr_OtherExpensesNewFundBasedOnEstimates For funds and classes that have not commenced operations or have an inception date of less than six months as of December 31,2015, expenses are estimated.
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 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 medium 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. Because the fund had not commenced operations as of the date of this prospectus, there is no portfolio turnover to report.
Strategy [Heading] rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Under normal market conditions, the fund invests substantially all of its assets in underlying funds using an asset allocation strategy designed for investors expected to retire around the year 2015. Over time, the asset allocation strategy will change according to a predetermined glide path as set forth below.

After December 31st of the designated retirement year of the fund, the fund will, under normal market conditions, continue to invest its assets in accordance with the predetermined "glide path" set forth below although the subadvisors may at times determine in light of prevailing market or economic conditions that the fund's asset allocations should vary from those indicated by the "glide path" in order to preserve the fund's assets or to help it achieve its objective.

Within the prescribed percentage allocation, the subadvisors select the percentage level to be maintained in specific underlying funds. The subadvisors may, from time to time, change the allocation in specific underlying funds or rebalance the underlying funds. To maintain target allocation in the underlying funds, daily cash flows for the fund will be directed to its underlying funds that most deviate from target.

The allocations reflected in the glide path are also referred to as "neutral" allocations because they do not reflect active decisions made by the subadvisors to produce an overweight or an underweight position in a particular asset class based on the subadvisors' market outlook. The fund has a target allocation for the broad asset classes of equities and fixed income but may invest outside these target allocations to protect the fund or help it achieve its objective.

The investment performance of the fund will reflect both its subadvisors' allocation decisions with respect to underlying funds and investments and the investment decisions made by the underlying funds' subadvisors.

In addition to investing in exchange-traded funds (ETFs), the fund may also invest in the securities of other investment companies and may make direct investments in other types of investments, such as equity and fixed-income securities, including U.S. government securities, closed-end funds and partnerships. See "Other Permitted Investments by the Funds of Funds." The fund may also engage in short selling of securities.

The fund may invest in various underlying funds that as a group hold a wide range of equity type securities in their portfolios. 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 the underlying funds has its own investment strategy that, 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. Certain of the 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, government issued, domestic and international securities.

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 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, without limitation, investing in credit default swaps, foreign currency forward contracts, futures contracts, interest rate swaps and options.

glidepath chart

Fund Combination after Designated Retirement Date

The Board of Trustees may, in its discretion, determine to combine the fund with another fund if the target allocation of the fund matches the target allocation of the other fund. In such event, the fund's shareholders will become shareholders of the other fund. To the extent permitted by applicable regulatory requirements, such a combination would be implemented without seeking the approval of shareholders. There is no assurance that the Board of Trustees at any point will determine to implement such a combination.
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 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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. A fund bears ETF fees and expenses indirectly.

Exchange-traded notes 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 is subject to risks related to: (i) the underlying funds' performance, expenses, and ability to meet their investment objectives; (ii) properly rebalancing assets among underlying funds and different asset classes; (iii) layering of fees of the underlying funds; and (iv) conflicts of interest associated with the subadvisor's ability to allocate fund assets without limit to underlying funds advised by the subadvisor and/or other affiliated subadvisors.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, options, credit default swaps, 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.

Investment company securities risk. A fund bears underlying fund fees and expenses indirectly.

Lifecycle risk. Managers might not correctly predict market or economic conditions, and you could lose money even close to, during, or after the fund's designated retirement year.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Target allocation risk. Relatively large redemptions from or investments in an underlying fund due to reallocation or rebalancing of portfolio assets could affect the performance of the underlying fund and the fund.

Principal risks of investing in the underlying funds

The principal risks of investing in the Underlying Funds include:

Convertible securities risk. 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 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.

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.

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. 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. 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.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, options, credit default swaps, 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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Initial public offerings 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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

This section normally shows how the fund's total returns have varied from year to year, along with a broad-based market index for reference. Because the fund has not commenced operations as of the date of this Prospectus, there is no past performance to report.
(John Hancock Variable Insurance Trust) | (Lifecycle 2015 Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05% [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.74% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 0.94% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 96
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 300
(John Hancock Variable Insurance Trust) | (Lifecycle 2015 Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25% [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.74% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 1.14% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 116
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 362
(John Hancock Variable Insurance Trust) | (Lifecycle 2015 Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.74% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 0.89% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 91
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 284
(John Hancock Variable Insurance Trust) | (Lifecycle 2020 Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

To seek high total return until the fund's target retirement date.
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 and hold 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 medium 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)

Other Expenses, New Fund, Based on Estimates [Text] rr_OtherExpensesNewFundBasedOnEstimates For funds and classes that have not commenced operations or have an inception date of less than six months as of December 31,2015, expenses are estimated.
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 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 medium 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. Because the fund had not commenced operations as of the date of this prospectus, there is no portfolio turnover to report.
Strategy [Heading] rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Under normal market conditions, the fund invests substantially all of its assets in underlying funds using an asset allocation strategy designed for investors expected to retire around the year 2020. Over time, the asset allocation strategy will change according to a predetermined glide path as set forth below.

After December 31st of the designated retirement year of the fund, the fund will, under normal market conditions, continue to invest its assets in accordance with the predetermined "glide path" set forth below although the subadvisors may at times determine in light of prevailing market or economic conditions that the fund's asset allocations should vary from those indicated by the "glide path" in order to preserve the fund's assets or to help it achieve its objective.

Within the prescribed percentage allocation, the subadvisors select the percentage level to be maintained in specific underlying funds. The subadvisors may, from time to time, change the allocation in specific underlying funds or rebalance the underlying funds. To maintain target allocation in the underlying funds, daily cash flows for the fund will be directed to its underlying funds that most deviate from target.

The allocations reflected in the glide path are also referred to as "neutral" allocations because they do not reflect active decisions made by the subadvisors to produce an overweight or an underweight position in a particular asset class based on the subadvisors' market outlook. The fund has a target allocation for the broad asset classes of equities and fixed income but may invest outside these target allocations to protect the fund or help it achieve its objective.

The investment performance of the fund will reflect both its subadvisors' allocation decisions with respect to underlying funds and investments and the investment decisions made by the underlying funds' subadvisors.

In addition to investing in exchange-traded funds (ETFs), the fund may also invest in the securities of other investment companies and may make direct investments in other types of investments, such as equity and fixed-income securities, including U.S. government securities, closed-end funds and partnerships. See "Other Permitted Investments by the Funds of Funds." The fund may also engage in short selling of securities.

The fund may invest in various underlying funds that as a group hold a wide range of equity type securities in their portfolios. 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 the underlying funds has its own investment strategy that, 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. Certain of the 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, government issued, domestic and international securities.

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 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, without limitation, investing in credit default swaps, foreign currency forward contracts, futures contracts, interest rate swaps and options.

glidepath chart

Fund Combination after Designated Retirement Date

The Board of Trustees may, in its discretion, determine to combine the fund with another fund if the target allocation of the fund matches the target allocation of the other fund. In such event, the fund's shareholders will become shareholders of the other fund. To the extent permitted by applicable regulatory requirements, such a combination would be implemented without seeking the approval of shareholders. There is no assurance that the Board of Trustees at any point will determine to implement such a combination.
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 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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. A fund bears ETF fees and expenses indirectly.

Exchange-traded notes 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 is subject to risks related to: (i) the underlying funds' performance, expenses, and ability to meet their investment objectives; (ii) properly rebalancing assets among underlying funds and different asset classes; (iii) layering of fees of the underlying funds; and (iv) conflicts of interest associated with the subadvisor's ability to allocate fund assets without limit to underlying funds advised by the subadvisor and/or other affiliated subadvisors.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, options, credit default swaps, 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.

Investment company securities risk. A fund bears underlying fund fees and expenses indirectly.

Lifecycle risk. Managers might not correctly predict market or economic conditions, and you could lose money even close to, during, or after the fund's designated retirement year.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Target allocation risk. Relatively large redemptions from or investments in an underlying fund due to reallocation or rebalancing of portfolio assets could affect the performance of the underlying fund and the fund.

Principal risks of investing in the underlying funds

The principal risks of investing in the Underlying Funds include:

Convertible securities risk. 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 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.

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.

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. 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. 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.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, options, credit default swaps, 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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Initial public offerings 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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

This section normally shows how the fund's total returns have varied from year to year, along with a broad-based market index for reference. Because the fund has not commenced operations as of the date of this Prospectus, there is no past performance to report.
(John Hancock Variable Insurance Trust) | (Lifecycle 2020 Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05% [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.74% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 0.94% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 96
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 300
(John Hancock Variable Insurance Trust) | (Lifecycle 2020 Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25% [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.74% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 1.14% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 116
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 362
(John Hancock Variable Insurance Trust) | (Lifecycle 2020 Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.74% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 0.89% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 91
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 284
(John Hancock Variable Insurance Trust) | (Lifecycle 2025 Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

To seek high total return until the fund's target retirement date.
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 and hold 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 medium 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)

Other Expenses, New Fund, Based on Estimates [Text] rr_OtherExpensesNewFundBasedOnEstimates For funds and classes that have not commenced operations or have an inception date of less than six months as of December 31,2015, expenses are estimated.
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 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 medium 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. Because the fund had not commenced operations as of the date of this prospectus, there is no portfolio turnover to report.
Strategy [Heading] rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Under normal market conditions, the fund invests substantially all of its assets in underlying funds using an asset allocation strategy designed for investors expected to retire around the year 2025. Over time, the asset allocation strategy will change according to a predetermined glide path as set forth below.

After December 31st of the designated retirement year of the fund, the fund will, under normal market conditions, continue to invest its assets in accordance with the predetermined "glide path" set forth below although the subadvisors may at times determine in light of prevailing market or economic conditions that the fund's asset allocations should vary from those indicated by the "glide path" in order to preserve the fund's assets or to help it achieve its objective.

Within the prescribed percentage allocation, the subadvisors select the percentage level to be maintained in specific underlying funds. The subadvisors may, from time to time, change the allocation in specific underlying funds or rebalance the underlying funds. To maintain target allocation in the underlying funds, daily cash flows for the fund will be directed to its underlying funds that most deviate from target.

The allocations reflected in the glide path are also referred to as "neutral" allocations because they do not reflect active decisions made by the subadvisors to produce an overweight or an underweight position in a particular asset class based on the subadvisors' market outlook. The fund has a target allocation for the broad asset classes of equities and fixed income but may invest outside these target allocations to protect the fund or help it achieve its objective.

The investment performance of the fund will reflect both its subadvisors' allocation decisions with respect to underlying funds and investments and the investment decisions made by the underlying funds' subadvisors.

In addition to investing in exchange-traded funds (ETFs), the fund may also invest in the securities of other investment companies and may make direct investments in other types of investments, such as equity and fixed-income securities, including U.S. government securities, closed-end funds and partnerships. See "Other Permitted Investments by the Funds of Funds." The fund may also engage in short selling of securities.

The fund may invest in various underlying funds that as a group hold a wide range of equity type securities in their portfolios. 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 the underlying funds has its own investment strategy that, 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. Certain of the 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, government issued, domestic and international securities.

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 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, without limitation, investing in credit default swaps, foreign currency forward contracts, futures contracts, interest rate swaps and options.

glidepath chart

Fund Combination after Designated Retirement Date

The Board of Trustees may, in its discretion, determine to combine the fund with another fund if the target allocation of the fund matches the target allocation of the other fund. In such event, the fund's shareholders will become shareholders of the other fund. To the extent permitted by applicable regulatory requirements, such a combination would be implemented without seeking the approval of shareholders. There is no assurance that the Board of Trustees at any point will determine to implement such a combination.
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 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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. A fund bears ETF fees and expenses indirectly.

Exchange-traded notes 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 is subject to risks related to: (i) the underlying funds' performance, expenses, and ability to meet their investment objectives; (ii) properly rebalancing assets among underlying funds and different asset classes; (iii) layering of fees of the underlying funds; and (iv) conflicts of interest associated with the subadvisor's ability to allocate fund assets without limit to underlying funds advised by the subadvisor and/or other affiliated subadvisors.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, options, credit default swaps, 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.

Investment company securities risk. A fund bears underlying fund fees and expenses indirectly.

Lifecycle risk. Managers might not correctly predict market or economic conditions, and you could lose money even close to, during, or after the fund's designated retirement year.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Target allocation risk. Relatively large redemptions from or investments in an underlying fund due to reallocation or rebalancing of portfolio assets could affect the performance of the underlying fund and the fund.

Principal risks of investing in the underlying funds

The principal risks of investing in the Underlying Funds include:

Convertible securities risk. 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 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.

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.

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. 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. 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.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, options, credit default swaps, 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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Initial public offerings 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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

This section normally shows how the fund's total returns have varied from year to year, along with a broad-based market index for reference. Because the fund has not commenced operations as of the date of this Prospectus, there is no past performance to report.
(John Hancock Variable Insurance Trust) | (Lifecycle 2025 Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05% [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.75% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 0.95% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 97
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 303
(John Hancock Variable Insurance Trust) | (Lifecycle 2025 Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25% [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.75% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 1.15% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 117
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 365
(John Hancock Variable Insurance Trust) | (Lifecycle 2025 Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.75% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 0.90% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 92
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 287
(John Hancock Variable Insurance Trust) | (Lifecycle 2030 Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

To seek high total return until the fund's target retirement date.
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 and hold 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 medium 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)

Other Expenses, New Fund, Based on Estimates [Text] rr_OtherExpensesNewFundBasedOnEstimates For funds and classes that have not commenced operations or have an inception date of less than six months as of December 31,2015, expenses are estimated.
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 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 medium 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. Because the fund had not commenced operations as of the date of this prospectus, there is no portfolio turnover to report.
Strategy [Heading] rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Under normal market conditions, the fund invests substantially all of its assets in underlying funds using an asset allocation strategy designed for investors expected to retire around the year 2030. Over time, the asset allocation strategy will change according to a predetermined glide path as set forth below.

After December 31st of the designated retirement year of the fund, the fund will, under normal market conditions, continue to invest its assets in accordance with the predetermined "glide path" set forth below although the subadvisors may at times determine in light of prevailing market or economic conditions that the fund's asset allocations should vary from those indicated by the "glide path" in order to preserve the fund's assets or to help it achieve its objective.

Within the prescribed percentage allocation, the subadvisors select the percentage level to be maintained in specific underlying funds. The subadvisors may, from time to time, change the allocation in specific underlying funds or rebalance the underlying funds. To maintain target allocation in the underlying funds, daily cash flows for the fund will be directed to its underlying funds that most deviate from target.

The allocations reflected in the glide path are also referred to as "neutral" allocations because they do not reflect active decisions made by the subadvisors to produce an overweight or an underweight position in a particular asset class based on the subadvisors' market outlook. The fund has a target allocation for the broad asset classes of equities and fixed income but may invest outside these target allocations to protect the fund or help it achieve its objective.

The investment performance of the fund will reflect both its subadvisors' allocation decisions with respect to underlying funds and investments and the investment decisions made by the underlying funds' subadvisors.

In addition to investing in exchange-traded funds (ETFs), the fund may also invest in the securities of other investment companies and may make direct investments in other types of investments, such as equity and fixed-income securities, including U.S. government securities, closed-end funds and partnerships. See "Other Permitted Investments by the Funds of Funds." The fund may also engage in short selling of securities.

The fund may invest in various underlying funds that as a group hold a wide range of equity type securities in their portfolios. 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 the underlying funds has its own investment strategy that, 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. Certain of the 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, government issued, domestic and international securities.

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 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, without limitation, investing in credit default swaps, foreign currency forward contracts, futures contracts, interest rate swaps and options.

glidepath chart

Fund Combination after Designated Retirement Date

The Board of Trustees may, in its discretion, determine to combine the fund with another fund if the target allocation of the fund matches the target allocation of the other fund. In such event, the fund's shareholders will become shareholders of the other fund. To the extent permitted by applicable regulatory requirements, such a combination would be implemented without seeking the approval of shareholders. There is no assurance that the Board of Trustees at any point will determine to implement such a combination.
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 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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. A fund bears ETF fees and expenses indirectly.

Exchange-traded notes 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 is subject to risks related to: (i) the underlying funds' performance, expenses, and ability to meet their investment objectives; (ii) properly rebalancing assets among underlying funds and different asset classes; (iii) layering of fees of the underlying funds; and (iv) conflicts of interest associated with the subadvisor's ability to allocate fund assets without limit to underlying funds advised by the subadvisor and/or other affiliated subadvisors.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, options, credit default swaps, 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.

Investment company securities risk. A fund bears underlying fund fees and expenses indirectly.

Lifecycle risk. Managers might not correctly predict market or economic conditions, and you could lose money even close to, during, or after the fund's designated retirement year.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Target allocation risk. Relatively large redemptions from or investments in an underlying fund due to reallocation or rebalancing of portfolio assets could affect the performance of the underlying fund and the fund.

Principal risks of investing in the underlying funds

The principal risks of investing in the Underlying Funds include:

Convertible securities risk. 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 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.

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.

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. 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. 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.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, options, credit default swaps, 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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Initial public offerings 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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

This section normally shows how the fund's total returns have varied from year to year, along with a broad-based market index for reference. Because the fund has not commenced operations as of the date of this Prospectus, there is no past performance to report.
(John Hancock Variable Insurance Trust) | (Lifecycle 2030 Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05% [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.76% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 0.96% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 98
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 306
(John Hancock Variable Insurance Trust) | (Lifecycle 2030 Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25% [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.76% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 1.16% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 118
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 368
(John Hancock Variable Insurance Trust) | (Lifecycle 2030 Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.76% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 0.91% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 93
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 290
(John Hancock Variable Insurance Trust) | (Lifecycle 2035 Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

To seek high total return until the fund's target retirement date.
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 and hold 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 medium 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)

Other Expenses, New Fund, Based on Estimates [Text] rr_OtherExpensesNewFundBasedOnEstimates For funds and classes that have not commenced operations or have an inception date of less than six months as of December 31,2015, expenses are estimated.
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 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 medium 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. Because the fund had not commenced operations as of the date of this prospectus, there is no portfolio turnover to report.
Strategy [Heading] rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Under normal market conditions, the fund invests substantially all of its assets in underlying funds using an asset allocation strategy designed for investors expected to retire around the year 2035. Over time, the asset allocation strategy will change according to a predetermined glide path as set forth below.

After December 31st of the designated retirement year of the fund, the fund will, under normal market conditions, continue to invest its assets in accordance with the predetermined "glide path" set forth below although the subadvisors may at times determine in light of prevailing market or economic conditions that the fund's asset allocations should vary from those indicated by the "glide path" in order to preserve the fund's assets or to help it achieve its objective.

Within the prescribed percentage allocation, the subadvisors select the percentage level to be maintained in specific underlying funds. The subadvisors may, from time to time, change the allocation in specific underlying funds or rebalance the underlying funds. To maintain target allocation in the underlying funds, daily cash flows for the fund will be directed to its underlying funds that most deviate from target.

The allocations reflected in the glide path are also referred to as "neutral" allocations because they do not reflect active decisions made by the subadvisors to produce an overweight or an underweight position in a particular asset class based on the subadvisors' market outlook. The fund has a target allocation for the broad asset classes of equities and fixed income but may invest outside these target allocations to protect the fund or help it achieve its objective.

The investment performance of the fund will reflect both its subadvisors' allocation decisions with respect to underlying funds and investments and the investment decisions made by the underlying funds' subadvisors.

In addition to investing in exchange-traded funds (ETFs), the fund may also invest in the securities of other investment companies and may make direct investments in other types of investments, such as equity and fixed-income securities, including U.S. government securities, closed-end funds and partnerships. See "Other Permitted Investments by the Funds of Funds." The fund may also engage in short selling of securities.

The fund may invest in various underlying funds that as a group hold a wide range of equity type securities in their portfolios. 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 the underlying funds has its own investment strategy that, 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. Certain of the 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, government issued, domestic and international securities.

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 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, without limitation, investing in credit default swaps, foreign currency forward contracts, futures contracts, interest rate swaps and options.

glidepath chart

Fund Combination after Designated Retirement Date

The Board of Trustees may, in its discretion, determine to combine the fund with another fund if the target allocation of the fund matches the target allocation of the other fund. In such event, the fund's shareholders will become shareholders of the other fund. To the extent permitted by applicable regulatory requirements, such a combination would be implemented without seeking the approval of shareholders. There is no assurance that the Board of Trustees at any point will determine to implement such a combination.
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 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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. A fund bears ETF fees and expenses indirectly.

Exchange-traded notes 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 is subject to risks related to: (i) the underlying funds' performance, expenses, and ability to meet their investment objectives; (ii) properly rebalancing assets among underlying funds and different asset classes; (iii) layering of fees of the underlying funds; and (iv) conflicts of interest associated with the subadvisor's ability to allocate fund assets without limit to underlying funds advised by the subadvisor and/or other affiliated subadvisors.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, options, credit default swaps, 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.

Investment company securities risk. A fund bears underlying fund fees and expenses indirectly.

Lifecycle risk. Managers might not correctly predict market or economic conditions, and you could lose money even close to, during, or after the fund's designated retirement year.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Target allocation risk. Relatively large redemptions from or investments in an underlying fund due to reallocation or rebalancing of portfolio assets could affect the performance of the underlying fund and the fund.

Principal risks of investing in the underlying funds

The principal risks of investing in the Underlying Funds include:

Convertible securities risk. 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 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.

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.

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. 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. 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.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, options, credit default swaps, 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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Initial public offerings 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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

This section normally shows how the fund's total returns have varied from year to year, along with a broad-based market index for reference. Because the fund has not commenced operations as of the date of this Prospectus, there is no past performance to report.
(John Hancock Variable Insurance Trust) | (Lifecycle 2035 Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05% [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.77% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 0.97% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 99
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 309
(John Hancock Variable Insurance Trust) | (Lifecycle 2035 Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25% [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.77% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 1.17% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 119
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 372
(John Hancock Variable Insurance Trust) | (Lifecycle 2035 Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.77% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 0.92% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 94
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 293
(John Hancock Variable Insurance Trust) | (Lifecycle 2040 Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

To seek high total return until the fund's target retirement date.
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 and hold 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 medium 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)

Other Expenses, New Fund, Based on Estimates [Text] rr_OtherExpensesNewFundBasedOnEstimates For funds and classes that have not commenced operations or have an inception date of less than six months as of December 31,2015, expenses are estimated.
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 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 medium 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. Because the fund had not commenced operations as of the date of this prospectus, there is no portfolio turnover to report.
Strategy [Heading] rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Under normal market conditions, the fund invests substantially all of its assets in underlying funds using an asset allocation strategy designed for investors expected to retire around the year 2040. Over time, the asset allocation strategy will change according to a predetermined glide path as set forth below.

After December 31st of the designated retirement year of the fund, the fund will, under normal market conditions, continue to invest its assets in accordance with the predetermined "glide path" set forth below although the subadvisors may at times determine in light of prevailing market or economic conditions that the fund's asset allocations should vary from those indicated by the "glide path" in order to preserve the fund's assets or to help it achieve its objective.

Within the prescribed percentage allocation, the subadvisors select the percentage level to be maintained in specific underlying funds. The subadvisors may, from time to time, change the allocation in specific underlying funds or rebalance the underlying funds. To maintain target allocation in the underlying funds, daily cash flows for the fund will be directed to its underlying funds that most deviate from target.

The allocations reflected in the glide path are also referred to as "neutral" allocations because they do not reflect active decisions made by the subadvisors to produce an overweight or an underweight position in a particular asset class based on the subadvisors' market outlook. The fund has a target allocation for the broad asset classes of equities and fixed income but may invest outside these target allocations to protect the fund or help it achieve its objective.

The investment performance of the fund will reflect both its subadvisors' allocation decisions with respect to underlying funds and investments and the investment decisions made by the underlying funds' subadvisors.

In addition to investing in exchange-traded funds (ETFs), the fund may also invest in the securities of other investment companies and may make direct investments in other types of investments, such as equity and fixed-income securities, including U.S. government securities, closed-end funds and partnerships. See "Other Permitted Investments by the Funds of Funds." The fund may also engage in short selling of securities.

The fund may invest in various underlying funds that as a group hold a wide range of equity type securities in their portfolios. 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 the underlying funds has its own investment strategy that, 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. Certain of the 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, government issued, domestic and international securities.

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 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, without limitation, investing in credit default swaps, foreign currency forward contracts, futures contracts, interest rate swaps and options.

glidepath chart

Fund Combination after Designated Retirement Date

The Board of Trustees may, in its discretion, determine to combine the fund with another fund if the target allocation of the fund matches the target allocation of the other fund. In such event, the fund's shareholders will become shareholders of the other fund. To the extent permitted by applicable regulatory requirements, such a combination would be implemented without seeking the approval of shareholders. There is no assurance that the Board of Trustees at any point will determine to implement such a combination.
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 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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. A fund bears ETF fees and expenses indirectly.

Exchange-traded notes 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 is subject to risks related to: (i) the underlying funds' performance, expenses, and ability to meet their investment objectives; (ii) properly rebalancing assets among underlying funds and different asset classes; (iii) layering of fees of the underlying funds; and (iv) conflicts of interest associated with the subadvisor's ability to allocate fund assets without limit to underlying funds advised by the subadvisor and/or other affiliated subadvisors.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, options, credit default swaps, 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.

Investment company securities risk. A fund bears underlying fund fees and expenses indirectly.

Lifecycle risk. Managers might not correctly predict market or economic conditions, and you could lose money even close to, during, or after the fund's designated retirement year.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Target allocation risk. Relatively large redemptions from or investments in an underlying fund due to reallocation or rebalancing of portfolio assets could affect the performance of the underlying fund and the fund.

Principal risks of investing in the underlying funds

The principal risks of investing in the Underlying Funds include:

Convertible securities risk. 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 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.

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.

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. 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. 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.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, options, credit default swaps, 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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Initial public offerings 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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

This section normally shows how the fund's total returns have varied from year to year, along with a broad-based market index for reference. Because the fund has not commenced operations as of the date of this Prospectus, there is no past performance to report.
(John Hancock Variable Insurance Trust) | (Lifecycle 2040 Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05% [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.78% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 0.98% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 100
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 312
(John Hancock Variable Insurance Trust) | (Lifecycle 2040 Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25% [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.78% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 1.18% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 120
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 375
(John Hancock Variable Insurance Trust) | (Lifecycle 2040 Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.78% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 0.93% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 95
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 296
(John Hancock Variable Insurance Trust) | (Lifecycle 2045 Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

To seek high total return until the fund's target retirement date.
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 and hold 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 medium 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)

Other Expenses, New Fund, Based on Estimates [Text] rr_OtherExpensesNewFundBasedOnEstimates For funds and classes that have not commenced operations or have an inception date of less than six months as of December 31,2015, expenses are estimated.
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 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 medium 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. Because the fund had not commenced operations as of the date of this prospectus, there is no portfolio turnover to report.
Strategy [Heading] rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Under normal market conditions, the fund invests substantially all of its assets in underlying funds using an asset allocation strategy designed for investors expected to retire around the year 2045. Over time, the asset allocation strategy will change according to a predetermined glide path as set forth below.

After December 31st of the designated retirement year of the fund, the fund will, under normal market conditions, continue to invest its assets in accordance with the predetermined "glide path" set forth below although the subadvisors may at times determine in light of prevailing market or economic conditions that the fund's asset allocations should vary from those indicated by the "glide path" in order to preserve the fund's assets or to help it achieve its objective.

Within the prescribed percentage allocation, the subadvisors select the percentage level to be maintained in specific underlying funds. The subadvisors may, from time to time, change the allocation in specific underlying funds or rebalance the underlying funds. To maintain target allocation in the underlying funds, daily cash flows for the fund will be directed to its underlying funds that most deviate from target.

The allocations reflected in the glide path are also referred to as "neutral" allocations because they do not reflect active decisions made by the subadvisors to produce an overweight or an underweight position in a particular asset class based on the subadvisors' market outlook. The fund has a target allocation for the broad asset classes of equities and fixed-income but may invest outside these target allocations to protect the fund or help it achieve its objective.

The investment performance of the fund will reflect both its subadvisors' allocation decisions with respect to underlying funds and investments and the investment decisions made by the underlying funds' subadvisors.

In addition to investing in exchange-traded funds (ETFs), the fund may also invest in the securities of other investment companies and may make direct investments in other types of investments, such as equity and fixed-income securities, including U.S. government securities, closed-end funds and partnerships. See "Other Permitted Investments by the Funds of Funds." The fund may also engage in short selling of securities.

The fund may invest in various underlying funds that as a group hold a wide range of equity type securities in their portfolios. 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 the underlying funds has its own investment strategy that, 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. Certain of the 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, government issued, domestic and international securities.

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 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, without limitation, investing in credit default swaps, foreign currency forward contracts, futures contracts, interest rate swaps and options.

glidepath chart

Fund Combination after Designated Retirement Date

The Board of Trustees may, in its discretion, determine to combine the fund with another fund if the target allocation of the fund matches the target allocation of the other fund. In such event, the fund's shareholders will become shareholders of the other fund. To the extent permitted by applicable regulatory requirements, such a combination would be implemented without seeking the approval of shareholders. There is no assurance that the Board of Trustees at any point will determine to implement such a combination.
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 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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. A fund bears ETF fees and expenses indirectly.

Exchange-traded notes 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 is subject to risks related to: (i) the underlying funds' performance, expenses, and ability to meet their investment objectives; (ii) properly rebalancing assets among underlying funds and different asset classes; (iii) layering of fees of the underlying funds; and (iv) conflicts of interest associated with the subadvisor's ability to allocate fund assets without limit to underlying funds advised by the subadvisor and/or other affiliated subadvisors.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, options, credit default swaps, 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.

Investment company securities risk. A fund bears underlying fund fees and expenses indirectly.

Lifecycle risk. Managers might not correctly predict market or economic conditions, and you could lose money even close to, during, or after the fund's designated retirement year.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Target allocation risk. Relatively large redemptions from or investments in an underlying fund due to reallocation or rebalancing of portfolio assets could affect the performance of the underlying fund and the fund.

Principal risks of investing in the underlying funds

The principal risks of investing in the Underlying Funds include:

Convertible securities risk. 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 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.

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.

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. 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. 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.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, options, credit default swaps, 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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Initial public offerings 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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

This section normally shows how the fund's total returns have varied from year to year, along with a broad-based market index for reference. Because the fund has not commenced operations as of the date of this Prospectus, there is no past performance to report.
(John Hancock Variable Insurance Trust) | (Lifecycle 2045 Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05% [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.78% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 0.98% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 100
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 312
(John Hancock Variable Insurance Trust) | (Lifecycle 2045 Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25% [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.78% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 1.18% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 120
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 375
(John Hancock Variable Insurance Trust) | (Lifecycle 2045 Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.78% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 0.93% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 95
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 296
(John Hancock Variable Insurance Trust) | (Lifecycle 2050 Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

To seek high total return until the fund's target retirement date.
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 and hold 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 medium 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)

Other Expenses, New Fund, Based on Estimates [Text] rr_OtherExpensesNewFundBasedOnEstimates For funds and classes that have not commenced operations or have an inception date of less than six months as of December 31,2015, expenses are estimated.
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 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 medium 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. Because the fund had not commenced operations as of the date of this prospectus, there is no portfolio turnover to report.
Strategy [Heading] rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Under normal market conditions, the fund invests substantially all of its assets in underlying funds using an asset allocation strategy designed for investors expected to retire around the year 2050. Over time, the asset allocation strategy will change according to a predetermined glide path as set forth below.

After December 31st of the designated retirement year of the fund, the fund will, under normal market conditions, continue to invest its assets in accordance with the predetermined "glide path" set forth below although the subadvisors may at times determine in light of prevailing market or economic conditions that the fund's asset allocations should vary from those indicated by the "glide path" in order to preserve the fund's assets or to help it achieve its objective.

Within the prescribed percentage allocation, the subadvisors select the percentage level to be maintained in specific underlying funds. The subadvisors may, from time to time, change the allocation in specific underlying funds or rebalance the underlying funds. To maintain target allocation in the underlying funds, daily cash flows for the fund will be directed to its underlying funds that most deviate from target.

The allocations reflected in the glide path are also referred to as "neutral" allocations because they do not reflect active decisions made by the subadvisors to produce an overweight or an underweight position in a particular asset class based on the subadvisors' market outlook. The fund has a target allocation for the broad asset classes of equities and fixed income but may invest outside these target allocations to protect the fund or help it achieve its objective.

The investment performance of the fund will reflect both its subadvisors' allocation decisions with respect to underlying funds and investments and the investment decisions made by the underlying funds' subadvisors.

In addition to investing in exchange-traded funds (ETFs), the fund may also invest in the securities of other investment companies and may make direct investments in other types of investments, such as equity and fixed-income securities, including U.S. government securities, closed-end funds and partnerships. See "Other Permitted Investments by the Funds of Funds." The fund may also engage in short selling of securities.

The fund may invest in various underlying funds that as a group hold a wide range of equity type securities in their portfolios. 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 the underlying funds has its own investment strategy that, 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. Certain of the 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, government issued, domestic and international securities.

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 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, without limitation, investing in credit default swaps, foreign currency forward contracts, futures contracts, interest rate swaps and options.

glidepath chart

Fund Combination after Designated Retirement Date

The Board of Trustees may, in its discretion, determine to combine the fund with another fund if the target allocation of the fund matches the target allocation of the other fund. In such event, the fund's shareholders will become shareholders of the other fund. To the extent permitted by applicable regulatory requirements, such a combination would be implemented without seeking the approval of shareholders. There is no assurance that the Board of Trustees at any point will determine to implement such a combination.
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 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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. A fund bears ETF fees and expenses indirectly.

Exchange-traded notes 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 is subject to risks related to: (i) the underlying funds' performance, expenses, and ability to meet their investment objectives; (ii) properly rebalancing assets among underlying funds and different asset classes; (iii) layering of fees of the underlying funds; and (iv) conflicts of interest associated with the subadvisor's ability to allocate fund assets without limit to underlying funds advised by the subadvisor and/or other affiliated subadvisors.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, options, credit default swaps, 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.

Investment company securities risk. A fund bears underlying fund fees and expenses indirectly.

Lifecycle risk. Managers might not correctly predict market or economic conditions, and you could lose money even close to, during, or after the fund's designated retirement year.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Target allocation risk. Relatively large redemptions from or investments in an underlying fund due to reallocation or rebalancing of portfolio assets could affect the performance of the underlying fund and the fund.

Principal risks of investing in the underlying funds

The principal risks of investing in the Underlying Funds include:

Convertible securities risk. 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 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.

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.

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. 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. 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.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, options, credit default swaps, 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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Initial public offerings 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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

This section normally shows how the fund's total returns have varied from year to year, along with a broad-based market index for reference. Because the fund has not commenced operations as of the date of this Prospectus, there is no past performance to report.
(John Hancock Variable Insurance Trust) | (Lifecycle 2050 Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05% [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.78% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 0.98% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 100
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 312
(John Hancock Variable Insurance Trust) | (Lifecycle 2050 Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25% [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.78% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 1.18% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 120
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 375
(John Hancock Variable Insurance Trust) | (Lifecycle 2050 Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.06% [16]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none [16]
Other expenses rr_OtherExpensesOverAssets 0.09% [16]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.78% [5],[16]
Total annual fund operating expenses rr_ExpensesOverAssets 0.93% [16]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 95
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 $ 296
(John Hancock Variable Insurance Trust) | (Lifestyle Aggressive MVP)  
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 and hold 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 medium 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, 2017
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 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 medium 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 16% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 16.00%
Strategy [Heading] rr_StrategyHeading

Principal investment strategies

Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

The Lifestyle Aggressive MVP (MVP refers to managed volatility portfolio), except as otherwise described below, normally invests primarily in underlying funds that invest primarily in equity securities ("Equity 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 also directly hold derivative instruments and collateral for these derivative instruments. The fund's economic exposure to equities 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 equity securities could be reduced to 0% and its economic exposure to cash and cash equivalents or fixed-income securities 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 100% 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 15% to 18.5% (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.

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 among the underlying Equity Funds, fixed-income securities, and cash and cash equivalents. 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 "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 securities, 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 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, 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, fixed-income securities, and cash and cash equivalents and may from time to time change the allocation to these investments or rebalance these holdings. To maintain a target allocation, daily cash flows for the fund may be directed to underlying funds or other investments 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 that, 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. Equity 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 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.

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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. A fund bears ETF fees and expenses indirectly.

Exchange-traded notes 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.

Foreign securities risk. Less information may be publicly available regarding foreign 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.

Fund of funds risk. The fund is subject to risks related to: (i) the underlying funds' performance, expenses, and ability to meet their investment objectives; (ii) properly rebalancing assets among underlying funds and different asset classes; (iii) layering of fees of the underlying funds; and (iv) conflicts of interest associated with the subadvisor's ability to allocate fund assets without limit to underlying funds advised by the subadvisor and/or other affiliated subadvisors.

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.

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. A fund bears underlying fund fees and expenses indirectly.

Leverage. 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.

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.

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. 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 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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. 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. 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.

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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Initial public offerings 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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 100% of its assets in underlying funds that invest primarily in equity securities and could invest up to 10% 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 70% of the Russell 3000 Index and 30% of the MSCI EAFE Index.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 20.25%

Worst quarter: Q4 '08, –24.12%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Lifestyle Aggressive MVP) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.38%
5 Years rr_AverageAnnualReturnYear05 12.57%
10 Years rr_AverageAnnualReturnYear10 7.31%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Lifestyle Aggressive MVP) | Combined Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.26%
5 Years rr_AverageAnnualReturnYear05 9.75%
10 Years rr_AverageAnnualReturnYear10 6.27%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Lifestyle Aggressive MVP) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.05%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.03%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.79% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.92% [5]
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.03%) [17]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.89%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 91
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 290
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 506
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,129
Annual Return 2006 rr_AnnualReturn2006 15.46%
Annual Return 2007 rr_AnnualReturn2007 8.55%
Annual Return 2008 rr_AnnualReturn2008 (41.99%)
Annual Return 2009 rr_AnnualReturn2009 35.63%
Annual Return 2010 rr_AnnualReturn2010 16.44%
Annual Return 2011 rr_AnnualReturn2011 (6.50%)
Annual Return 2012 rr_AnnualReturn2012 16.61%
Annual Return 2013 rr_AnnualReturn2013 26.72%
Annual Return 2014 rr_AnnualReturn2014 1.40%
Annual Return 2015 rr_AnnualReturn2015 (5.85%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 20.25%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 20.25%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –24.12%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (24.12%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (5.85%)
5 Years rr_AverageAnnualReturnYear05 5.69%
10 Years rr_AverageAnnualReturnYear10 4.24%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Lifestyle Aggressive MVP) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.05%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.03%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.79% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.12% [5]
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.03%) [17]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 1.09%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 111
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 353
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 614
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,360
1 Year rr_AverageAnnualReturnYear01 (6.05%)
5 Years rr_AverageAnnualReturnYear05 5.50%
10 Years rr_AverageAnnualReturnYear10 4.03%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Lifestyle Aggressive MVP) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.05%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.03%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.79% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.87% [5]
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.03%) [17]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.84%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 86
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 275
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 479
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,070
1 Year rr_AverageAnnualReturnYear01 (5.79%)
5 Years rr_AverageAnnualReturnYear05 5.77%
10 Years rr_AverageAnnualReturnYear10 4.29%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Lifestyle Aggressive PS Series)  
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 and hold 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 medium 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, 2017
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 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 medium 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 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

The fund, except as otherwise described below, operates as a fund of funds and normally invests approximately 100% of its assets in underlying funds that invest primarily in equity securities or in futures contracts on equity markets (the "Equity Allocation") and up to 10% 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 include exchange-traded funds ("ETFs") and the fund may invest a significant portion of its assets in ETFs. At the discretion of the subadvisors, 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 subadvisors 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 subadvisors select 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 subadvisors.

The fund may invest in various underlying funds that as a group hold a wide range of equity type securities. 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 ("junk bonds") with maturities that range from short to longer term.

The fund may invest in derivatives, including futures contracts and options. The fund may use derivatives for hedging and non-hedging 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;

  • 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 by the Fund of Funds."
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 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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. A fund bears ETF fees and expenses indirectly.

Exchange-traded notes 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.

Fund of funds risk. The fund is subject to risks related to: (i) the underlying funds' performance, expenses, and ability to meet their investment objectives; (ii) properly rebalancing assets among underlying funds and different asset classes; (iii) layering of fees of the underlying funds; and (iv) conflicts of interest associated with the subadvisor's ability to allocate fund assets without limit to underlying funds advised by the subadvisor and/or other affiliated subadvisors.

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: futures contracts and options. Futures contracts and options generally are subject to counterparty risk.

Investment company securities risk. A fund bears underlying fund fees and expenses indirectly.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.

Principal risks of investing in the underlying funds

The principal risks of investing in the Underlying Funds include:

Convertible securities risk. 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 a fund's securities may be unable or unwilling to make timely principal, interest or settlement payments, or otherwise honor its obligations. Funds that invest in fixed-income securities are subject to varying degrees of risk that the issuers of the securities will have their credit rating downgraded or will default, potentially reducing a fund's share price and income level.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. 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. 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.

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: 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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Initial public offerings 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small capitalization securities may underperform the market as a whole.
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.
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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series II (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q4 '15, 5.04%

Worst quarter: Q3 '15, –8.75%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Lifestyle Aggressive PS Series) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.38%
Inception rr_AverageAnnualReturnSinceInception 9.32%
Date of Inception rr_AverageAnnualReturnInceptionDate Oct. 31, 2013
(John Hancock Variable Insurance Trust) | (Lifestyle Aggressive PS Series) | Combined Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.26%
Inception rr_AverageAnnualReturnSinceInception 5.32%
Date of Inception rr_AverageAnnualReturnInceptionDate Oct. 31, 2013
(John Hancock Variable Insurance Trust) | (Lifestyle Aggressive PS Series) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.13%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.27%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.45% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.90% [5]
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.23%) [18]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.67%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 68
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 264
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 476
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,087
1 Year rr_AverageAnnualReturnYear01 (1.56%)
Inception rr_AverageAnnualReturnSinceInception 3.54%
Date of Inception rr_AverageAnnualReturnInceptionDate Oct. 31, 2013
(John Hancock Variable Insurance Trust) | (Lifestyle Aggressive PS Series) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.13%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.27%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.45% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.10% [5]
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.23%) [18]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.87%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 89
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 327
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 584
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,320
Annual Return 2014 rr_AnnualReturn2014 5.21%
Annual Return 2015 rr_AnnualReturn2015 (1.75%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q4 '15, 5.04%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 5.04%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2015
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q3 '15, –8.75%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (8.75%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2015
1 Year rr_AverageAnnualReturnYear01 (1.75%)
Inception rr_AverageAnnualReturnSinceInception 3.32%
Date of Inception rr_AverageAnnualReturnInceptionDate Oct. 31, 2013
(John Hancock Variable Insurance Trust) | (Lifestyle Aggressive PS Series) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.13%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.27%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.45% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.85% [5]
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.23%) [18]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.62%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 63
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 248
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 449
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,028
1 Year rr_AverageAnnualReturnYear01 (1.51%)
Inception rr_AverageAnnualReturnSinceInception 3.59%
Date of Inception rr_AverageAnnualReturnInceptionDate Oct. 31, 2013
(John Hancock Variable Insurance Trust) | (Lifestyle Balanced MVP)  
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 and hold 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 medium 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, 2017
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 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 medium 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 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 Lifestyle Balanced MVP (MVP refers to managed volatility 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 "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 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.

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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. A fund bears ETF fees and expenses indirectly.

Exchange-traded notes 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 is subject to risks related to: (i) the underlying funds' performance, expenses, and ability to meet their investment objectives; (ii) properly rebalancing assets among underlying funds and different asset classes; (iii) layering of fees of the underlying funds; and (iv) conflicts of interest associated with the subadvisor's ability to allocate fund assets without limit to underlying funds advised by the subadvisor and/or other affiliated subadvisors.

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.

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. A fund bears underlying fund fees and expenses indirectly.

Leverage. 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

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.

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. 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 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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. 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. 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.

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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Initial public offerings 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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 1 represents 50% of the S&P 500 Index and 50% of the Barclays U.S. Aggregate Bond Index.

The Combined Index 2 represents 35% of the Russell 3000 Index, 15% of the MSCI EAFE Index, and 50% of the Barclays U.S. Aggregate Bond Index.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 15.83%

Worst quarter: Q4 '08, –17.72%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Lifestyle Balanced MVP) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.38%
5 Years rr_AverageAnnualReturnYear05 12.57%
10 Years rr_AverageAnnualReturnYear10 7.31%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Lifestyle Balanced MVP) | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.55%
5 Years rr_AverageAnnualReturnYear05 3.25%
10 Years rr_AverageAnnualReturnYear10 4.51%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Lifestyle Balanced MVP) | Combined Index 1 (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.21%
5 Years rr_AverageAnnualReturnYear05 8.02%
10 Years rr_AverageAnnualReturnYear10 6.22%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Lifestyle Balanced MVP) | Combined Index 2 (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.64%
5 Years rr_AverageAnnualReturnYear05 6.68%
10 Years rr_AverageAnnualReturnYear10 5.74%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Lifestyle Balanced MVP) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.05%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.02%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.66% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.78% [5]
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [17]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.76%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 78
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 247
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 431
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 964
Annual Return 2006 rr_AnnualReturn2006 12.73%
Annual Return 2007 rr_AnnualReturn2007 6.47%
Annual Return 2008 rr_AnnualReturn2008 (31.30%)
Annual Return 2009 rr_AnnualReturn2009 30.75%
Annual Return 2010 rr_AnnualReturn2010 11.75%
Annual Return 2011 rr_AnnualReturn2011 0.62%
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%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 15.83%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 15.83%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –17.72%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (17.72%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (2.25%)
5 Years rr_AverageAnnualReturnYear05 5.29%
10 Years rr_AverageAnnualReturnYear10 4.54%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Lifestyle Balanced MVP) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.05%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.02%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.66% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.98% [5]
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [17]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.96%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 98
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 310
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 540
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,200
1 Year rr_AverageAnnualReturnYear01 (2.39%)
5 Years rr_AverageAnnualReturnYear05 5.09%
10 Years rr_AverageAnnualReturnYear10 4.33%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Lifestyle Balanced MVP) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.05%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.02%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.66% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.73% [5]
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [17]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.71%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 73
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 231
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 404
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 905
1 Year rr_AverageAnnualReturnYear01 (2.20%)
5 Years rr_AverageAnnualReturnYear05 5.34%
10 Years rr_AverageAnnualReturnYear10 4.59%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Lifestyle Balanced PS Series)  
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 and hold 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 medium 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 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 medium 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 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, 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 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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. A fund bears ETF fees and expenses indirectly.

Exchange-traded notes 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.

Fund of funds risk. The fund is subject to risks related to: (i) the underlying funds' performance, expenses, and ability to meet their investment objectives; (ii) properly rebalancing assets among underlying funds and different asset classes; (iii) layering of fees of the underlying funds; and (iv) conflicts of interest associated with the subadvisor's ability to allocate fund assets without limit to underlying funds advised by the subadvisor and/or other affiliated subadvisors.

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: futures contracts and options. Futures contracts and options generally are subject to counterparty risk.

Investment company securities risk. A fund bears underlying fund fees and expenses indirectly.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

PS Series Asset Transfer Risk. The Lifestyle Growth PS Series, Lifestyle Moderate PS Series, Lifestyle Balanced PS Series and Lifestyle Conservative PS Series (collectively, the "JHVIT Lifestyle PS Series") are 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 Lifestyle PS Series and the 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 PS Series, the more likely that contract value will be reallocated from the JHVIT Lifestyle PS Series to the Bond Trust when equity markets fall. These asset flows may negatively affect the performance of an underlying fund in which the JHVIT Lifestyle PS Series 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 PS Series 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 PS Series.

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 PS Series 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 PS Series' 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 PS Series' 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 PS Series' 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 PS Series 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 PS Series 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 PS shares, there can be no assurance that the prices paid by the JHVIT Lifestyle PS Series will be better than if the JHVIT Lifestyle PS Series 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 PS Series 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 PS Series are less than estimated, the JHVIT Lifestyle PS Series could be forced to liquidate positions it had purchased. Conversely, if cash flows out of the JHVIT Lifestyle PS Series are less than estimated, the JHVIT Lifestyle PS Series 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 PS Series 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 PS Series' 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 PS Series expenses and adversely affect the performance of the JHVIT Lifestyle PS Series.

Convertible securities risk. 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 a fund's securities may be unable or unwilling to make timely principal, interest or settlement payments, or otherwise honor its obligations. Funds that invest in fixed-income securities are subject to varying degrees of risk that the issuers of the securities will have their credit rating downgraded or will default, potentially reducing a fund's share price and income level.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. 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. 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.

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: 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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Initial public offerings 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small capitalization securities may underperform the market as a whole.
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.
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. Unless all share classes shown in the table have the same inception date, 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 medium. 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 1 represents 50% of the S&P 500 Index and 50% of the Barclays U.S. Aggregate Bond Index.

The Combined Index 2 represents 35% of the Russell 3000 Index, 15% of the MSCI EAFE Index, and 50% of the Barclays U.S. Aggregate Bond Index.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series II (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q1 '12, 7.12%

Worst quarter: Q3 '15, –3.69%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Lifestyle Balanced PS Series) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.38%
Inception rr_AverageAnnualReturnSinceInception 11.46%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Balanced PS Series) | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.55%
Inception rr_AverageAnnualReturnSinceInception 3.13%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Balanced PS Series) | Combined Index 1 (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.28%
Inception rr_AverageAnnualReturnSinceInception 8.26%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Balanced PS Series) | Combined Index 2 (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.64%
Inception rr_AverageAnnualReturnSinceInception 5.96%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Balanced PS Series) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.04%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.03%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.56% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.68% [5]
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 0.05%
Inception rr_AverageAnnualReturnSinceInception 5.06%
Date of Inception rr_AverageAnnualReturnInceptionDate Oct. 31, 2013
(John Hancock Variable Insurance Trust) | (Lifestyle Balanced PS Series) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.04%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.03%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.56% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.88% [5]
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 10.54%
Annual Return 2013 rr_AnnualReturn2013 12.68%
Annual Return 2014 rr_AnnualReturn2014 5.74%
Annual Return 2015 rr_AnnualReturn2015 (0.22%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q1 '12, 7.12%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 7.12%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2012
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q3 '15, –3.69%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (3.69%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2015
1 Year rr_AverageAnnualReturnYear01 (0.22%)
Inception rr_AverageAnnualReturnSinceInception 4.96%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Balanced PS Series) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.04%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.03%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.56% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.63% [5]
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 0.10%
Inception rr_AverageAnnualReturnSinceInception 5.08%
Date of Inception rr_AverageAnnualReturnInceptionDate Oct. 31, 2013
(John Hancock Variable Insurance Trust) | (Lifestyle Conservative MVP)  
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 and hold 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 medium 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, 2017
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 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 medium 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 Lifestyle Conservative MVP (MVP refers to managed volatility 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 "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 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.

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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. A fund bears ETF fees and expenses indirectly.

Exchange-traded notes 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 is subject to risks related to: (i) the underlying funds' performance, expenses, and ability to meet their investment objectives; (ii) properly rebalancing assets among underlying funds and different asset classes; (iii) layering of fees of the underlying funds; and (iv) conflicts of interest associated with the subadvisor's ability to allocate fund assets without limit to underlying funds advised by the subadvisor and/or other affiliated subadvisors.

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.

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. A fund bears underlying fund fees and expenses indirectly.

Leverage. 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

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.

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. 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 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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. 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. 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.

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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Initial public offerings 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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 1 represents 20% of the S&P 500 Index and 80% of the Barclays U.S. Aggregate Bond Index.

The Combined Index 2 represents 14% of the Russell 3000 Index, 6% of the MSCI EAFE Index, and 80% of the Barclays U.S. Aggregate Bond Index.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 10.58%

Worst quarter: Q4 '08, –8.32%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Lifestyle Conservative MVP) | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.55%
5 Years rr_AverageAnnualReturnYear05 3.25%
10 Years rr_AverageAnnualReturnYear10 4.51%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Lifestyle Conservative MVP) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.38%
5 Years rr_AverageAnnualReturnYear05 12.57%
10 Years rr_AverageAnnualReturnYear10 7.31%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Lifestyle Conservative MVP) | Combined Index 1 (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.87%
5 Years rr_AverageAnnualReturnYear05 5.18%
10 Years rr_AverageAnnualReturnYear10 5.27%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Lifestyle Conservative MVP) | Combined Index 2 (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.64%
5 Years rr_AverageAnnualReturnYear05 4.66%
10 Years rr_AverageAnnualReturnYear10 5.08%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Lifestyle Conservative MVP) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.05%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.02%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.62% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.74% [5]
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [17]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.72%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 74
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 235
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 410
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 917
Annual Return 2006 rr_AnnualReturn2006 8.44%
Annual Return 2007 rr_AnnualReturn2007 5.38%
Annual Return 2008 rr_AnnualReturn2008 (15.57%)
Annual Return 2009 rr_AnnualReturn2009 21.71%
Annual Return 2010 rr_AnnualReturn2010 9.12%
Annual Return 2011 rr_AnnualReturn2011 4.23%
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%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 10.58%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 10.58%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –8.32%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (8.32%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 0.05%
5 Years rr_AverageAnnualReturnYear05 4.30%
10 Years rr_AverageAnnualReturnYear10 4.69%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Lifestyle Conservative MVP) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.05%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.02%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.62% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.94% [5]
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [17]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.92%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 94
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 298
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 518
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,153
1 Year rr_AverageAnnualReturnYear01 (0.15%)
5 Years rr_AverageAnnualReturnYear05 4.10%
10 Years rr_AverageAnnualReturnYear10 4.48%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Lifestyle Conservative MVP) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.05%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.02%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.62% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.69% [5]
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [17]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.67%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 68
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 219
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 382
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 857
1 Year rr_AverageAnnualReturnYear01 0.18%
5 Years rr_AverageAnnualReturnYear05 4.36%
10 Years rr_AverageAnnualReturnYear10 4.74%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Lifestyle Conservative PS Series)  
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 and hold 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 medium 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, 2017
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 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 medium 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 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

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 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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. A fund bears ETF fees and expenses indirectly.

Exchange-traded notes 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.

Fund of funds risk. The fund is subject to risks related to: (i) the underlying funds' performance, expenses, and ability to meet their investment objectives; (ii) properly rebalancing assets among underlying funds and different asset classes; (iii) layering of fees of the underlying funds; and (iv) conflicts of interest associated with the subadvisor's ability to allocate fund assets without limit to underlying funds advised by the subadvisor and/or other affiliated subadvisors.

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: futures contracts and options. Futures contracts and options generally are subject to counterparty risk.

Investment company securities risk. A fund bears underlying fund fees and expenses indirectly.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

PS Series Asset Transfer Risk. The Lifestyle Growth PS Series, Lifestyle Moderate PS Series, Lifestyle Balanced PS Series and Lifestyle Conservative PS Series (collectively, the "JHVIT Lifestyle PS Series") are 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 Lifestyle PS Series and the 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 PS Series, the more likely that contract value will be reallocated from the JHVIT Lifestyle PS Series to the Bond Trust when equity markets fall. These asset flows may negatively affect the performance of an underlying fund in which the JHVIT Lifestyle PS Series 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 PS Series 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 PS Series.

Principal risks of investing in the underlying funds

The fund is subject to risks, and you could lose money by investing in the fund. The principal risks of investing in the fund include:

Advance trade estimate risk. The JHVIT Lifestyle PS Series 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 PS Series' 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 PS Series' 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 PS Series' 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 PS Series 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 PS Series 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 PS shares, there can be no assurance that the prices paid by the JHVIT Lifestyle PS Series will be better than if the JHVIT Lifestyle PS Series 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 PS Series 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 PS Series are less than estimated, the JHVIT Lifestyle PS Series could be forced to liquidate positions it had purchased. Conversely, if cash flows out of the JHVIT Lifestyle PS Series are less than estimated, the JHVIT Lifestyle PS Series 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 PS Series 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 PS Series' 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 PS Series expenses and adversely affect the performance of the JHVIT Lifestyle PS Series.

Convertible securities risk. 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 a fund's securities may be unable or unwilling to make timely principal, interest or settlement payments, or otherwise honor its obligations. Funds that invest in fixed-income securities are subject to varying degrees of risk that the issuers of the securities will have their credit rating downgraded or will default, potentially reducing a fund's share price and income level.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. 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. 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.

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: 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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Initial public offerings 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small capitalization securities may underperform the market as a whole.
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.
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. Unless all share classes shown in the table have the same inception date, 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 medium. 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 1 represents 20% of the S&P 500 Index and 80% of the Barclays U.S. Aggregate Bond Index.

The Combined Index 2 represents 14% of the Russell 3000 Index, 6% of the MSCI EAFE Index, and 80% of the Barclays U.S. Aggregate Bond Index.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series II (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q1 '12, 3.48%

Worst quarter: Q2 '13, –1.64%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Lifestyle Conservative PS Series) | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.55%
Inception rr_AverageAnnualReturnSinceInception 3.13%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Conservative PS Series) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.38%
Inception rr_AverageAnnualReturnSinceInception 11.46%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Conservative PS Series) | Combined Index 1 (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.87%
Inception rr_AverageAnnualReturnSinceInception 4.88%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Conservative PS Series) | Combined Index 2 (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.64%
Inception rr_AverageAnnualReturnSinceInception 4.31%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Conservative PS Series) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.04%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.05%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.58% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.72% [5]
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [19]
Total annual fund operating expenses after expense reimbursements 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 0.17%
Inception rr_AverageAnnualReturnSinceInception 3.70%
Date of Inception rr_AverageAnnualReturnInceptionDate Oct. 31, 2013
(John Hancock Variable Insurance Trust) | (Lifestyle Conservative PS Series) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.04%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.05%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.58% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.92% [5]
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [19]
Total annual fund operating expenses after expense reimbursements 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 7.53%
Annual Return 2013 rr_AnnualReturn2013 3.86%
Annual Return 2014 rr_AnnualReturn2014 5.41%
Annual Return 2015 rr_AnnualReturn2015 (0.03%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q1 '12, 3.48%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 3.48%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2012
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q2 '13, –1.64%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (1.64%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2013
1 Year rr_AverageAnnualReturnYear01 (0.03%)
Inception rr_AverageAnnualReturnSinceInception 3.60%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Conservative PS Series) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.04%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.05%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.58% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.67% [5]
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [19]
Total annual fund operating expenses after expense reimbursements 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
1 Year rr_AverageAnnualReturnYear01 0.22%
Inception rr_AverageAnnualReturnSinceInception 3.74%
Date of Inception rr_AverageAnnualReturnInceptionDate Oct. 31, 2013
(John Hancock Variable Insurance Trust) | (Lifestyle Growth MVP)  
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 and hold 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 medium 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, 2017
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 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 medium 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 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 Lifestyle Growth MVP (MVP refers to managed volatility 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 "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 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.

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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. A fund bears ETF fees and expenses indirectly.

Exchange-traded notes 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 is subject to risks related to: (i) the underlying funds' performance, expenses, and ability to meet their investment objectives; (ii) properly rebalancing assets among underlying funds and different asset classes; (iii) layering of fees of the underlying funds; and (iv) conflicts of interest associated with the subadvisor's ability to allocate fund assets without limit to underlying funds advised by the subadvisor and/or other affiliated subadvisors.

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.

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. A fund bears underlying fund fees and expenses indirectly.

Leverage. 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

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.

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. 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 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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. 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. 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.

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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Initial public offerings 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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 1 represents 70% of the S&P 500 Index and 30% of the Barclays U.S. Aggregate Bond Index.

The Combined Index 2 represents 49% of the Russell 3000 Index, 21% of the MSCI EAFE Index and 30% of the Barclays U.S. Aggregate Bond Index.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 17.89%

Worst quarter: Q4 '08, –20.75%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Lifestyle Growth MVP) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.38%
5 Years rr_AverageAnnualReturnYear05 12.57%
10 Years rr_AverageAnnualReturnYear10 7.31%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Lifestyle Growth MVP) | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.55%
5 Years rr_AverageAnnualReturnYear05 3.25%
10 Years rr_AverageAnnualReturnYear10 4.51%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Lifestyle Growth MVP) | Combined Index 1 (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.34%
5 Years rr_AverageAnnualReturnYear05 9.87%
10 Years rr_AverageAnnualReturnYear10 6.73%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Lifestyle Growth MVP) | Combined Index 2 (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.55%
5 Years rr_AverageAnnualReturnYear05 7.95%
10 Years rr_AverageAnnualReturnYear10 6.03%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Lifestyle Growth MVP) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.05%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.02%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.68% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.80% [5]
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [17]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.78%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 80
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 253
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 442
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 988
Annual Return 2006 rr_AnnualReturn2006 13.50%
Annual Return 2007 rr_AnnualReturn2007 7.44%
Annual Return 2008 rr_AnnualReturn2008 (36.56%)
Annual Return 2009 rr_AnnualReturn2009 33.30%
Annual Return 2010 rr_AnnualReturn2010 13.02%
Annual Return 2011 rr_AnnualReturn2011 (1.60%)
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%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 17.89%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 17.89%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –20.75%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (20.75%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (4.53%)
5 Years rr_AverageAnnualReturnYear05 5.45%
10 Years rr_AverageAnnualReturnYear10 4.28%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Lifestyle Growth MVP) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.05%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.02%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.68% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.00% [5]
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [17]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.98%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 100
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 316
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 551
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,223
1 Year rr_AverageAnnualReturnYear01 (4.81%)
5 Years rr_AverageAnnualReturnYear05 5.23%
10 Years rr_AverageAnnualReturnYear10 4.06%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Lifestyle Growth MVP) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.05%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.02%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.68% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.75% [5]
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [17]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.73%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 75
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 238
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 415
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 928
1 Year rr_AverageAnnualReturnYear01 (4.55%)
5 Years rr_AverageAnnualReturnYear05 5.50%
10 Years rr_AverageAnnualReturnYear10 4.33%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Lifestyle Growth PS Series)  
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 and hold 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 medium 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 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 medium 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 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, 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 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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. A fund bears ETF fees and expenses indirectly.

Exchange-traded notes 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.

Fund of funds risk. The fund is subject to risks related to: (i) the underlying funds' performance, expenses, and ability to meet their investment objectives; (ii) properly rebalancing assets among underlying funds and different asset classes; (iii) layering of fees of the underlying funds; and (iv) conflicts of interest associated with the subadvisor's ability to allocate fund assets without limit to underlying funds advised by the subadvisor and/or other affiliated subadvisors.

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: futures contracts and options. Futures contracts and options generally are subject to counterparty risk.

Investment company securities risk. A fund bears underlying fund fees and expenses indirectly.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

PS Series Asset Transfer Risk. The Lifestyle Growth PS Series, Lifestyle Moderate PS Series, Lifestyle Balanced PS Series and Lifestyle Conservative PS Series (collectively, the "JHVIT Lifestyle PS Series") are 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 Lifestyle PS Series and the 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 PS Series, the more likely that contract value will be reallocated from the JHVIT Lifestyle PS Series to the Bond Trust when equity markets fall. These asset flows may negatively affect the performance of an underlying fund in which the JHVIT Lifestyle PS Series 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 PS Series 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 PS Series.

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 PS Series 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 PS Series' 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 PS Series' 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 PS Series' 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 PS Series 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 PS Series 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 PS shares, there can be no assurance that the prices paid by the JHVIT Lifestyle PS Series will be better than if the JHVIT Lifestyle PS Series 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 PS Series 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 PS Series are less than estimated, the JHVIT Lifestyle PS Series could be forced to liquidate positions it had purchased. Conversely, if cash flows out of the JHVIT Lifestyle PS Series are less than estimated, the JHVIT Lifestyle PS Series 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 PS Series 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 PS Series' 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 PS Series expenses and adversely affect the performance of the JHVIT Lifestyle PS Series.

Convertible securities risk. 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 a fund's securities may be unable or unwilling to make timely principal, interest or settlement payments, or otherwise honor its obligations. Funds that invest in fixed-income securities are subject to varying degrees of risk that the issuers of the securities will have their credit rating downgraded or will default, potentially reducing a fund's share price and income level.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. 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. 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.

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: 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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Initial public offerings 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small capitalization securities may underperform the market as a whole.
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.
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. Unless all share classes shown in the table have the same inception date, 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 medium. 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 1 represents 70% of the S&P 500 Index and 30% of the Barclays U.S. Aggregate Bond Index.

The Combined Index 2 represents 49% of the Russell 3000 Index, 21% of the MSCI EAFE Index and 30% of the Barclays U.S. Aggregate Bond Index.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series II (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q1 '12, 9.44%

Worst quarter: Q3 '15, –5.45%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Lifestyle Growth PS Series) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.38%
Inception rr_AverageAnnualReturnSinceInception 11.46%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Growth PS Series) | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.55%
Inception rr_AverageAnnualReturnSinceInception 3.13%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Growth PS Series) | Combined Index 1 (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.37%
Inception rr_AverageAnnualReturnSinceInception 9.89%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Growth PS Series) | Combined Index 2 (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.55%
Inception rr_AverageAnnualReturnSinceInception 6.98%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Growth PS Series) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.04%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.02%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.55% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.66% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 67
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 211
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 368
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 822
1 Year rr_AverageAnnualReturnYear01 (0.12%)
Inception rr_AverageAnnualReturnSinceInception 5.94%
Date of Inception rr_AverageAnnualReturnInceptionDate Oct. 31, 2013
(John Hancock Variable Insurance Trust) | (Lifestyle Growth PS Series) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.04%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.02%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.55% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.86% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 88
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 274
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 477
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,061
Annual Return 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%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q1 '12, 9.44%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 9.44%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2012
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q3 '15, –5.45%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (5.45%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2015
1 Year rr_AverageAnnualReturnYear01 (0.25%)
Inception rr_AverageAnnualReturnSinceInception 5.83%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Growth PS Series) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.04%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.02%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.55% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.61% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 62
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 195
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 340
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 762
1 Year rr_AverageAnnualReturnYear01 none
Inception rr_AverageAnnualReturnSinceInception 5.97%
Date of Inception rr_AverageAnnualReturnInceptionDate Oct. 31, 2013
(John Hancock Variable Insurance Trust) | (Lifestyle Moderate MVP)  
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 and hold 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 medium 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, 2017
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 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 medium 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 Lifestyle Moderate MVP (MVP refers to managed volatility 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 "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 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.

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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. A fund bears ETF fees and expenses indirectly.

Exchange-traded notes 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 is subject to risks related to: (i) the underlying funds' performance, expenses, and ability to meet their investment objectives; (ii) properly rebalancing assets among underlying funds and different asset classes; (iii) layering of fees of the underlying funds; and (iv) conflicts of interest associated with the subadvisor's ability to allocate fund assets without limit to underlying funds advised by the subadvisor and/or other affiliated subadvisors.

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.

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. A fund bears underlying fund fees and expenses indirectly.

Leverage. 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.

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.

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. 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 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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. 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. 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.

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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Initial public offerings 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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 1 represents 40% of the S&P 500 Index and 60% of the Barclays U.S. Aggregate Bond Index.

The Combined Index 2 represents 28% of the Russell 3000 Index, 12% of the MSCI EAFE Index, and 60% of the Barclays U.S. Aggregate Bond Index.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 13.89%

Worst quarter: Q4 '08, –13.28%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Lifestyle Moderate MVP) | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.55%
5 Years rr_AverageAnnualReturnYear05 3.25%
10 Years rr_AverageAnnualReturnYear10 4.51%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Lifestyle Moderate MVP) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.38%
5 Years rr_AverageAnnualReturnYear05 12.57%
10 Years rr_AverageAnnualReturnYear10 7.31%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Lifestyle Moderate MVP) | Combined Index 1 (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.12%
5 Years rr_AverageAnnualReturnYear05 7.08%
10 Years rr_AverageAnnualReturnYear10 5.92%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Lifestyle Moderate MVP) | Combined Index 2 (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.66%
5 Years rr_AverageAnnualReturnYear05 6.02%
10 Years rr_AverageAnnualReturnYear10 5.55%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Lifestyle Moderate MVP) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.05%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.02%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.65% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.77% [5]
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [17]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.75%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 77
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 244
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 426
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 952
Annual Return 2006 rr_AnnualReturn2006 10.42%
Annual Return 2007 rr_AnnualReturn2007 5.29%
Annual Return 2008 rr_AnnualReturn2008 (24.23%)
Annual Return 2009 rr_AnnualReturn2009 27.26%
Annual Return 2010 rr_AnnualReturn2010 10.55%
Annual Return 2011 rr_AnnualReturn2011 2.33%
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%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 13.89%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 13.89%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –13.28%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (13.28%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (0.91%)
5 Years rr_AverageAnnualReturnYear05 5.35%
10 Years rr_AverageAnnualReturnYear10 4.87%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 08, 1997
(John Hancock Variable Insurance Trust) | (Lifestyle Moderate MVP) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.05%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.02%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.65% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.97% [5]
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [17]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.95%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 97
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 307
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 534
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,188
1 Year rr_AverageAnnualReturnYear01 (1.12%)
5 Years rr_AverageAnnualReturnYear05 5.14%
10 Years rr_AverageAnnualReturnYear10 4.65%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Lifestyle Moderate MVP) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.05%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.02%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.65% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.72% [5]
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [17]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.70%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 72
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 228
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 399
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 893
1 Year rr_AverageAnnualReturnYear01 (0.86%)
5 Years rr_AverageAnnualReturnYear05 5.40%
10 Years rr_AverageAnnualReturnYear10 4.92%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Lifestyle Moderate PS Series)  
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 and hold 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 medium 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 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 medium 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 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 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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. A fund bears ETF fees and expenses indirectly.

Exchange-traded notes 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.

Fund of funds risk. The fund is subject to risks related to: (i) the underlying funds' performance, expenses, and ability to meet their investment objectives; (ii) properly rebalancing assets among underlying funds and different asset classes; (iii) layering of fees of the underlying funds; and (iv) conflicts of interest associated with the subadvisor's ability to allocate fund assets without limit to underlying funds advised by the subadvisor and/or other affiliated subadvisors.

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: futures contracts and options. Futures contracts and options generally are subject to counterparty risk.

Investment company securities risk. A fund bears underlying fund fees and expenses indirectly.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.

PS Series Asset Transfer Risk. The Lifestyle Growth PS Series, Lifestyle Moderate PS Series, Lifestyle Balanced PS Series and Lifestyle Conservative PS Series (collectively, the "JHVIT Lifestyle PS Series") are 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 Lifestyle PS Series and the 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 PS Series, the more likely that contract value will be reallocated from the JHVIT Lifestyle PS Series to the Bond Trust when equity markets fall. These asset flows may negatively affect the performance of an underlying fund in which the JHVIT Lifestyle PS Series 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 PS Series 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 PS Series.

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 PS Series 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 PS Series' 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 PS Series' 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 PS Series' 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 PS Series 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 PS Series 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 PS shares, there can be no assurance that the prices paid by the JHVIT Lifestyle PS Series will be better than if the JHVIT Lifestyle PS Series 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 PS Series 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 PS Series are less than estimated, the JHVIT Lifestyle PS Series could be forced to liquidate positions it had purchased. Conversely, if cash flows out of the JHVIT Lifestyle PS Series are less than estimated, the JHVIT Lifestyle PS Series 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 PS Series 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 PS Series' 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 PS Series expenses and adversely affect the performance of the JHVIT Lifestyle PS Series.

Convertible securities risk. 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 a fund's securities may be unable or unwilling to make timely principal, interest or settlement payments, or otherwise honor its obligations. Funds that invest in fixed-income securities are subject to varying degrees of risk that the issuers of the securities will have their credit rating downgraded or will default, potentially reducing a fund's share price and income level.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. 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. 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.

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: 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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Initial public offerings 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small capitalization securities may underperform the market as a whole.
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.
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. Unless all share classes shown in the table have the same inception date, 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 medium. 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 1 represents 40% of the S&P 500 Index and 60% of the Barclays U.S. Aggregate Bond Index.

The Combined Index 2 represents 28% of the Russell 3000 Index, 12% of the MSCI EAFE Index, and 60% of the Barclays U.S. Aggregate Bond Index.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series II (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q1 '12, 5.90%

Worst quarter: Q3 '15, –2.82%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Lifestyle Moderate PS Series) | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.55%
Inception rr_AverageAnnualReturnSinceInception 3.13%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Moderate PS Series) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.38%
Inception rr_AverageAnnualReturnSinceInception 11.46%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Moderate PS Series) | Combined Index 1 (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.12%
Inception rr_AverageAnnualReturnSinceInception 6.59%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Moderate PS Series) | Combined Index 2 (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.66%
Inception rr_AverageAnnualReturnSinceInception 5.42%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Moderate PS Series) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.04%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.04%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.56% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.69% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 70
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 221
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 384
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 859
1 Year rr_AverageAnnualReturnYear01 0.10%
Inception rr_AverageAnnualReturnSinceInception 4.82%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Moderate PS Series) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.04%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.56% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.89% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 91
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 284
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 493
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,096
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%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q1 '12, 5.90%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 5.90%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2012
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q3 '15, –2.82%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (2.82%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2015
1 Year rr_AverageAnnualReturnYear01 (0.10%)
Inception rr_AverageAnnualReturnSinceInception 4.71%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(John Hancock Variable Insurance Trust) | (Lifestyle Moderate PS Series) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.04%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.04%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.56% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.64% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 65
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 205
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 357
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 798
1 Year rr_AverageAnnualReturnYear01 0.15%
Inception rr_AverageAnnualReturnSinceInception 4.84%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2011
(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 and hold 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 medium 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, 2017
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 medium 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) 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. As of February 29, 2016, the market capitalizations of companies included in the S&P MidCap 400 Index ranged from $450 million to $11.7 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 principal risks of investing in the fund include:

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.

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.

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, along with specific additional associated risks, if any, include: futures contracts. 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q3 '09, 19.86%

Worst quarter: Q4 '08, –25.65%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(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 (2.18%)
5 Years rr_AverageAnnualReturnYear05 10.68%
10 Years rr_AverageAnnualReturnYear10 8.18%
Date of Inception rr_AverageAnnualReturnInceptionDate May 02, 2000
(John Hancock Variable Insurance Trust) | (Mid Cap Index Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.47%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.56%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.10%) [20]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.46%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 47
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 169
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 303
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 692
Annual Return 2006 rr_AnnualReturn2006 9.72%
Annual Return 2007 rr_AnnualReturn2007 7.57%
Annual Return 2008 rr_AnnualReturn2008 (36.45%)
Annual Return 2009 rr_AnnualReturn2009 36.76%
Annual Return 2010 rr_AnnualReturn2010 25.98%
Annual Return 2011 rr_AnnualReturn2011 (2.25%)
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%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q3 '09, 19.86%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 19.86%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –25.65%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (25.65%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (2.59%)
5 Years rr_AverageAnnualReturnYear05 10.23%
10 Years rr_AverageAnnualReturnYear10 7.72%
Date of Inception rr_AverageAnnualReturnInceptionDate May 02, 2000
(John Hancock Variable Insurance Trust) | (Mid Cap Index Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.47%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.76%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.10%) [20]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.66%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 67
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 233
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 413
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 933
1 Year rr_AverageAnnualReturnYear01 (2.80%)
5 Years rr_AverageAnnualReturnYear05 10.01%
10 Years rr_AverageAnnualReturnYear10 7.50%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Mid Cap Index Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.47%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.51%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.10%) [20]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.41%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 42
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 153
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 275
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 631
1 Year rr_AverageAnnualReturnYear01 (2.54%)
5 Years rr_AverageAnnualReturnYear05 10.29%
10 Years rr_AverageAnnualReturnYear10 7.77%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Mid Cap Stock 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 and hold 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 medium 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)

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 medium 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 78% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 78.00%
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. 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 ($217.8 million to $28.4 billion as of February 29, 2016) or the S&P MidCap 400 Index ($450 million to $11.7 billion as of February 29, 2016).

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 principal risks of investing in the fund include:

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.

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. 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.

High portfolio turnover risk. Actively trading securities can increase transaction costs (thus lowering performance).

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q3 '09, 20.00%

Worst quarter: Q4 '08, –25.36%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Mid Cap Stock Trust) | Russell Midcap Growth Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (0.20%)
5 Years rr_AverageAnnualReturnYear05 11.54%
10 Years rr_AverageAnnualReturnYear10 8.16%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 1999
(John Hancock Variable Insurance Trust) | (Mid Cap Stock Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.83%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.92%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 94
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 293
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 509
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,131
Annual Return 2006 rr_AnnualReturn2006 13.55%
Annual Return 2007 rr_AnnualReturn2007 23.57%
Annual Return 2008 rr_AnnualReturn2008 (43.76%)
Annual Return 2009 rr_AnnualReturn2009 31.35%
Annual Return 2010 rr_AnnualReturn2010 23.08%
Annual Return 2011 rr_AnnualReturn2011 (9.20%)
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%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q3 '09, 20.00%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 20.00%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –25.36%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (25.36%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 3.00%
5 Years rr_AverageAnnualReturnYear05 11.05%
10 Years rr_AverageAnnualReturnYear10 7.98%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 1999
(John Hancock Variable Insurance Trust) | (Mid Cap Stock Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.83%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 1.12%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 114
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 356
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 617
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,363
1 Year rr_AverageAnnualReturnYear01 2.75%
5 Years rr_AverageAnnualReturnYear05 10.83%
10 Years rr_AverageAnnualReturnYear10 7.76%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Mid Cap Stock Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.83%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.87%
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
1 Year rr_AverageAnnualReturnYear01 3.04%
5 Years rr_AverageAnnualReturnYear05 11.12%
10 Years rr_AverageAnnualReturnYear10 8.03%
Date of Inception rr_AverageAnnualReturnInceptionDate Feb. 28, 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 and hold 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 medium 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 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 medium 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 93% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 93.00%
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 ($217.8 million to $28.4 billion as of February 29, 2016). 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 indices 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, such as to secure 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 principal risks of investing in the fund include:

Convertible securities risk. 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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. A fund bears ETF fees and expenses indirectly.

Foreign securities risk. Less information may be publicly available regarding foreign 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.

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 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 risk. IPO share prices are frequently volatile and may significantly impact fund performance.

Sector investing risk. Because the fund may focus on a single sector of the economy, its performance depends in large part on the performance of that sector. As a result, the value of your investment may fluctuate more widely than it would in a fund that is diversified 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 capitalization securities may underperform the market as a whole.

Value investing style risk. The fund emphasizes a value style of investing, which focuses on undervalued companies with characteristics for improved valuations. This style of investing is subject to the risk that the valuations never improve or that the returns on value equity securities are less than returns on other styles of investing or the overall stock market. Value stocks also may decline in price, even though in theory they are already underpriced.
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. Unless all share classes shown in the table have the same inception date, 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. For periods prior to the inception date of the fund, performance shown is the actual performance of the sole share class of the fund's predecessor fund and has not been adjusted to reflect the Rule 12b-1 fees of any class of shares. As a result, pre-inception performance of the fund may be higher than 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series NAV (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 23.21%

Worst quarter: Q4 '08, –23.60%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(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 (4.78%)
5 Years rr_AverageAnnualReturnYear05 11.25%
10 Years rr_AverageAnnualReturnYear10 7.61%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 1998
(John Hancock Variable Insurance Trust) | (Mid Value Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.95%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.04%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.06% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 108
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 337
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 585
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,294
1 Year rr_AverageAnnualReturnYear01 (3.43%)
5 Years rr_AverageAnnualReturnYear05 9.79%
10 Years rr_AverageAnnualReturnYear10 7.90%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Mid Value Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.95%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.26% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 128
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 400
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 692
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,523
1 Year rr_AverageAnnualReturnYear01 (3.64%)
5 Years rr_AverageAnnualReturnYear05 9.58%
10 Years rr_AverageAnnualReturnYear10 7.68%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Mid Value Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.95%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.04%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.01% [5]
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
Annual Return 2006 rr_AnnualReturn2006 20.34%
Annual Return 2007 rr_AnnualReturn2007 0.60%
Annual Return 2008 rr_AnnualReturn2008 (34.74%)
Annual Return 2009 rr_AnnualReturn2009 46.27%
Annual Return 2010 rr_AnnualReturn2010 16.16%
Annual Return 2011 rr_AnnualReturn2011 (4.71%)
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%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 23.21%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 23.21%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –23.60%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (23.60%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (3.40%)
5 Years rr_AverageAnnualReturnYear05 9.85%
10 Years rr_AverageAnnualReturnYear10 7.94%
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 and hold 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 medium 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, 2018
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 NAV 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 medium 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 and is managed in the following manner:

  • 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;

  • the fund invests only in U.S. dollar-denominated securities;

  • the fund buys securities that have remaining maturities of 397 days or less (as calculated pursuant to Rule 2a-7);

  • 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;

  • the fund must meet certain other criteria, including those relating to maturity, liquidity and credit quality; and

  • 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 "Multiclass Pricing; Rule 12b-1 Plans" in the prospectus.

From time to time, the Advisor and its affiliates may reimburse or otherwise voluntarily reduce the fund's expenses or the Advisor may waive a portion of its management fee in an effort to maintain a net asset value of $1.00 per share, for the purpose of avoiding a negative yield or for the purpose of increasing the fund's yield during the period of the limitation. Any such expense reimbursements, reductions or waivers are voluntary and temporary and may be terminated by the Advisor at any time without notice.
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 principal risks of investing in the fund include:

Changing distribution levels risk. The distribution amounts paid by the fund generally depend on the amount of income and/or dividends received by the fund's investments. As a result of market, interest rate and other circumstances, the amount of cash available for distribution by the fund and the fund's distribution rate may vary or decline. The risk of such variability is accentuated in currently prevailing market and interest rate circumstances.

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.

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.

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. An impairment of a fund's ability to sell securities at advantageous prices exposes the fund to liquidity risk. Liquidity risk may result from 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.

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.

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 (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 Code (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. See "Tax Matters" for more information.

U.S. Government agency obligations risk. The fund invests in obligations issued by agencies and instrumentalities of the U.S. government. Government-sponsored entities such as Federal National Mortgage Association (Fannie Mae), Federal Home Loan Mortgage Corporation (Freddie Mac) and the Federal Home Loan Banks, although chartered or sponsored by Congress, are not funded by congressional appropriations and the debt securities that they issue are neither guaranteed nor issued by the U.S. government. Such debt securities are subject to the risk of default on the payment of interest and/or principal, similar to the debt securities of private issuers. The maximum potential liability of the issuers of some U.S. government obligations may greatly exceed their current resources, including any legal right to support from the U.S. government. Although the U.S. government has provided financial support to Fannie Mae and Freddie Mac in the past, there can be no assurance that it will support these or other government-sponsored entities in the future.

U.S. 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.
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 April 29, 2016, performance shown for Series NAV 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.

Performance shown for periods prior to the inception date of Series II is the performance of the fund's oldest share class, Series I. This pre-inception performance has not been adjusted to reflect the higher Rule 12b-1 fee of Series II and would be lower if it did. The performance information below does not reflect fees and expenses of any variable insurance contract that may use JHVIT as its underlying investment medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q3 '06, 1.18%

Worst quarter: Q4 '15, 0.00%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Money Market Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.36% [21]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.03%
Total annual fund operating expenses rr_ExpensesOverAssets 0.44%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.11%) [22]
Total annual fund operating expenses after expense reimbursements 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 2006 rr_AnnualReturn2006 4.44%
Annual Return 2007 rr_AnnualReturn2007 4.56%
Annual Return 2008 rr_AnnualReturn2008 1.76%
Annual Return 2009 rr_AnnualReturn2009 0.20%
Annual Return 2010 rr_AnnualReturn2010 none
Annual Return 2011 rr_AnnualReturn2011 0.07%
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
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q3 '06, 1.18%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 1.18%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2006
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '15, 0.00%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn none
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2015
1 Year rr_AverageAnnualReturnYear01 none
5 Years rr_AverageAnnualReturnYear05 0.02%
10 Years rr_AverageAnnualReturnYear10 1.09%
Date of Inception rr_AverageAnnualReturnInceptionDate Jun. 15, 1985
(John Hancock Variable Insurance Trust) | (Money Market Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.36% [21]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.03%
Total annual fund operating expenses rr_ExpensesOverAssets 0.64%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.11%) [22]
Total annual fund operating expenses after expense reimbursements 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 0.02%
10 Years rr_AverageAnnualReturnYear10 1.02%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Money Market Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.36% [21]
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.03% [23]
Total annual fund operating expenses rr_ExpensesOverAssets 0.39%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.11%) [22]
Total annual fund operating expenses after expense reimbursements 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 0.02%
10 Years rr_AverageAnnualReturnYear10 1.09%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2016
(John Hancock Variable Insurance Trust) | (Money Market Trust B)  
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 and hold 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 medium 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, 2017
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 medium 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 and is managed in the following manner:

  • 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;

  • the fund invests only in U.S. dollar-denominated securities;

  • the fund buys securities that have remaining maturities of 397 days or less (as calculated pursuant to Rule 2a-7);

  • 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;

  • the fund must meet certain other criteria, including those relating to maturity, liquidity and credit quality; and

  • 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 "Multiclass Pricing; Rule 12b-1 Plans" in the prospectus.

From time to time, the Advisor and its affiliates may reimburse or otherwise voluntarily reduce the fund's expenses or the Advisor may waive a portion of its management fee in an effort to maintain a net asset value of $1.00 per share, for the purpose of avoiding a negative yield or for the purpose of increasing the fund's yield during the period of the limitation. Any such expense reimbursements, reductions or waivers are voluntary and temporary and may be terminated by the Advisor at any time without notice.
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 principal risks of investing in the fund include:

Changing distribution levels risk. The distribution amounts paid by the fund generally depend on the amount of income and/or dividends received by the fund's investments. As a result of market, interest rate and other circumstances, the amount of cash available for distribution by the fund and the fund's distribution rate may vary or decline. The risk of such variability is accentuated in currently prevailing market and interest rate circumstances.

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.

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.

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. An impairment of a fund's ability to sell securities at advantageous prices exposes the fund to liquidity risk. Liquidity risk may result from 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.

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.

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 (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 Code (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. See "Tax Matters" for more information.

U.S. Government agency obligations risk. The fund invests in obligations issued by agencies and instrumentalities of the U.S. government. Government-sponsored entities such as Federal National Mortgage Association (Fannie Mae), Federal Home Loan Mortgage Corporation (Freddie Mac) and the Federal Home Loan Banks, although chartered or sponsored by Congress, are not funded by congressional appropriations and the debt securities that they issue are neither guaranteed nor issued by the U.S. government. Such debt securities are subject to the risk of default on the payment of interest and/or principal, similar to the debt securities of private issuers. The maximum potential liability of the issuers of some U.S. government obligations may greatly exceed their current resources, including any legal right to support from the U.S. government. Although the U.S. government has provided financial support to Fannie Mae and Freddie Mac in the past, there can be no assurance that it will support these or other government-sponsored entities in the future.

U.S. 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.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading

Past performance

Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The performance information below does not reflect fees and expenses of any variable insurance contract that may use JHVIT as its underlying investment medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series NAV (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q3 '06, 1.25%

Worst quarter: Q2 '15, 0.00%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
(John Hancock Variable Insurance Trust) | (Money Market Trust B) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.36% [21]
Other expenses rr_OtherExpensesOverAssets 0.08%
Total annual fund operating expenses rr_ExpensesOverAssets 0.44%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.16%) [24]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.28%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 29
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 125
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 230
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 539
Annual Return 2006 rr_AnnualReturn2006 4.71%
Annual Return 2007 rr_AnnualReturn2007 4.82%
Annual Return 2008 rr_AnnualReturn2008 2.11%
Annual Return 2009 rr_AnnualReturn2009 0.48%
Annual Return 2010 rr_AnnualReturn2010 0.05%
Annual Return 2011 rr_AnnualReturn2011 0.08%
Annual Return 2012 rr_AnnualReturn2012 0.05%
Annual Return 2013 rr_AnnualReturn2013 0.01%
Annual Return 2014 rr_AnnualReturn2014 none
Annual Return 2015 rr_AnnualReturn2015 none
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q3 '06, 1.25%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 1.25%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2006
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q2 '15, 0.00%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn none
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2015
1 Year rr_AverageAnnualReturnYear01 none
5 Years rr_AverageAnnualReturnYear05 0.03%
10 Years rr_AverageAnnualReturnYear10 1.21%
Date of Inception rr_AverageAnnualReturnInceptionDate Mar. 28, 1986
(John Hancock Variable Insurance Trust) | (Mutual Shares Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

To seek capital appreciation, which may occasionally be short-term. 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 and hold 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 medium 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)

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 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 medium 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 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

Under normal market conditions, the fund invests primarily in equity securities (including convertible securities or securities the subadvisor expects to be exchanged for common or preferred stock) of companies of any nation that the subadvisor believes are available at market prices less than their value based on certain recognized or objective criteria (intrinsic value).

Following this value-oriented strategy, the fund invests primarily in:

• Undervalued Securities. Securities the subadvisor believes are trading at a discount to intrinsic value.

And, to a lesser extent, the fund also invests in:

• Merger Arbitrage Securities and Distressed Companies. A merger or other restructuring, or a tender or exchange offer, proposed or pending at the time the fund invests in merger arbitrage securities may not be completed on the terms or within the time frame contemplated, which may result in losses to the fund. Debt obligations of distressed companies typically are unrated, lower-rated, in default or close to default and are generally more likely to become worthless than the securities of more financially stable companies.

In pursuit of its value-oriented strategy, the fund is not limited to pre-set maximums or minimums governing the size of the companies in which it may invest. However, as a general rule, the fund invests the equity portion of its portfolio primarily to predominantly in companies with market capitalizations (share price multiplied by the number of shares of common stock outstanding) greater than $5 billion, with a portion to significant amount in smaller companies. The fund may invest up to 35% of its assets in foreign securities including sovereign debt and participations in foreign government debt.

The fund's investments in distressed companies typically involve the purchase of bank debt, lower-rated or defaulted debt securities, comparable unrated debt securities or other indebtedness (or participations in the indebtedness) of such companies. Such other indebtedness generally represents a specific commercial loan or portion of a loan made to a company by a financial institution such as a bank. Loan participations represent fractional interests in a company's indebtedness and are generally made available by banks or other institutional investors. By purchasing all or a part of a company's direct indebtedness, the fund, in effect, steps into the shoes of the lender. If the loan is secured, the fund will have a priority claim to the assets of the company ahead of unsecured creditors and stockholders. The fund generally makes such investments to achieve capital appreciation rather than to seek income. The fund may also engage from time to time in an "arbitrage" strategy. When engaging in an arbitrage strategy, a fund typically buys one security while at the same time selling short another security. Such fund generally buys the security that the manager believes is either cheap relative to the price of the other security or otherwise undervalued, and sell short the security that the manager believes is either expensive relative to the price of the other security or otherwise overvalued. In doing so, a fund attempts to profit from a perceived relationship between the values of the two securities. The fund generally engages in an arbitrage strategy in connection with an announced corporate restructuring, such as a merger, acquisition or tender offer, or other corporate action or event.

The fund regularly attempts to hedge (protect) against currency risks using currency forward contracts when, in the investment manager's opinion, it would be advantageous to the fund to do so. The fund may also, from time to time, attempt to hedge against market risk using a variety of derivatives including put and call options on equity securities and swap agreements (which may include total return and credit default swaps). The use of these derivative transactions may allow the fund to obtain net long or net negative (short) exposures to selected countries, currencies or issues.

The subadvisor employs a research driven, fundamental value strategy for the fund. In choosing equity investments, the subadvisor focuses on the market price of a company's securities relative to the subadvisor's own evaluation of the company's asset value, including an analysis of book value, cash flow potential, long-term earnings and multiples of earnings. Similarly, debt securities and other indebtedness, including loan participations, are generally selected based on the subadvisor's own analysis of the security's intrinsic value rather than the coupon rate or rating of the security. The subadvisor examines each investment separately and there are no set criteria as to specific value parameters, asset size, earnings or industry type.
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 principal risks of investing in the fund include:

Arbitrage securities and distressed companies risk. A merger or other restructuring, tender offer, or exchange offer proposed or pending at the time of investment in risk arbitrage securities may not be completed on the terms contemplated, resulting in losses.

Convertible securities risk. 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.

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.

Distressed investments risk. Distressed investments, including loans, mortgages, bonds, and notes, may not be publicly traded and may involve substantial risk. A fund may 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. Securities the manager believes are undervalued may never realize their full potential, 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. 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.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, and credit default swaps. Foreign currency forward contracts, 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. Derivatives associated with foreign currency transactions are subject to currency 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.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series NAV (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 17.31%

Worst quarter: Q4 '08, –21.42%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Mutual Shares Trust) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.38%
5 Years rr_AverageAnnualReturnYear05 12.57%
Inception rr_AverageAnnualReturnSinceInception 6.04%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (Mutual Shares Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.96%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.05%
Total annual fund operating expenses rr_ExpensesOverAssets 1.06%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 108
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 337
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 585
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,294
1 Year rr_AverageAnnualReturnYear01 (4.68%)
5 Years rr_AverageAnnualReturnYear05 8.19%
Inception rr_AverageAnnualReturnSinceInception 2.59%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2008
(John Hancock Variable Insurance Trust) | (Mutual Shares Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.96%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.05% [25]
Total annual fund operating expenses rr_ExpensesOverAssets 1.26%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 128
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 400
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 692
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,523
(John Hancock Variable Insurance Trust) | (Mutual Shares Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.96%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.05%
Total annual fund operating expenses rr_ExpensesOverAssets 1.01%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 103
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 322
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 558
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,236
Annual Return 2008 rr_AnnualReturn2008 (37.86%)
Annual Return 2009 rr_AnnualReturn2009 27.31%
Annual Return 2010 rr_AnnualReturn2010 11.49%
Annual Return 2011 rr_AnnualReturn2011 (0.89%)
Annual Return 2012 rr_AnnualReturn2012 14.08%
Annual Return 2013 rr_AnnualReturn2013 28.40%
Annual Return 2014 rr_AnnualReturn2014 7.34%
Annual Return 2015 rr_AnnualReturn2015 (4.63%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 17.31%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 17.31%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –21.42%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (21.42%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (4.63%)
5 Years rr_AverageAnnualReturnYear05 8.25%
Inception rr_AverageAnnualReturnSinceInception 2.64%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 2007
(John Hancock Variable Insurance Trust) | (New 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 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 and hold 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 medium 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)

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.
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 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 medium 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

The fund will invest at least 80% of its total assets in income-producing securities, which may include, but not limited to, U.S. government and agency obligations, mortgage- and asset-backed securities, corporate bonds, foreign securities (up to 10% of total assets) including emerging markets, collateralized mortgage obligations (CMOs), Treasury inflation protected securities, and other securities, including, on occasion, equities.

Eighty percent (80%) of the debt securities purchased by the fund will be rated investment grade (AAA, AA, A, BBB, or equivalent) by each of the major credit rating agencies (Standard & Poor's, Moody's, and Fitch) that have assigned a rating to the security or if the security is unrated, be deemed to be of investment-grade quality by T. Rowe Price. Up to 15% of the fund's total assets may be invested in "split-rated securities," or those rated investment grade by at least one rating agency but below investment grade by others. The fund's investment policies are based on credit ratings at the time of purchase.

In addition, the fund may invest up to 5% of its total assets in below investment grade securities (commonly known as "junk bonds"). The fund has considerable flexibility in seeking high yield securities. There are no maturity restrictions, so the fund can purchase longer-term bonds, which tend to have higher yields than shorter-term issues. However, the portfolio's weighted average maturity is expected to be between four and fifteen years. In addition, when there is a large yield difference between the various quality levels, the fund may move down the credit scale and purchase lower-rated bonds with higher yields. When the difference is small or the outlook warrants, the fund may concentrate investments in higher-rated issues.

In keeping with the fund's investment objective, it may also invest in other securities, and use futures, options, swaps and foreign currency forward contracts.

The fund may sell holdings for a variety of reasons, such as to adjust the portfolio's average maturity, duration, or credit quality or to shift assets into and out of higher yielding or lower yielding securities or different sectors.

Active management of the portfolio can result in bonds being sold at gains or losses. However, over the long term, the fund seeks to achieve its investment objective by investing primarily in income-producing securities that possess what the subadvisor believes are favorable total return (income plus changes in principal) characteristics.

In pursuing its investment strategy, the subadvisor has the discretion to purchase some securities that do not meet the fund's normal investment criteria, as described above, when it perceives an unusual opportunity for gain. These situations might arise when the subadvisor believes a security could increase in value for a variety of reasons, including a change in management, a debt restructuring or other extraordinary corporate event, or a temporary imbalance in the supply of or demand for the 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 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.

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, without limitation, investing in foreign currency forward contracts, foreign currency swaps, futures contracts 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 principal risks of investing in the fund include:

Changing distribution levels risk. The distribution amounts paid by the fund generally depend on the amount of income and/or dividends received by the fund's investments. As a result of market, interest rate and other circumstances, the amount of cash available for distribution by the fund and the fund's distribution rate may vary or decline. The risk of such variability is accentuated in currently prevailing market and interest rate circumstances.

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.

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.

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. 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.

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, along with specific additional associated risks, if any, include: foreign currency forward contracts, futures contracts, options, and foreign currency 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 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.

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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.
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. Unless all share classes shown in the table have the same inception date, 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 medium. 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. Effective May 3, 2010, the fund changed its investment polices to reduce exposure to equities, high yield and foreign bonds.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series NAV (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 9.13%

Worst quarter: Q4 '08, –5.13%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (New Income Trust) | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.55%
5 Years rr_AverageAnnualReturnYear05 3.25%
10 Years rr_AverageAnnualReturnYear10 4.51%
Date of Inception rr_AverageAnnualReturnInceptionDate Oct. 24, 2005
(John Hancock Variable Insurance Trust) | (New Income Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.55%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.04% [26]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [8]
Total annual fund operating expenses rr_ExpensesOverAssets 0.65% [9]
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
(John Hancock Variable Insurance Trust) | (New Income Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.55%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04% [26]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [8]
Total annual fund operating expenses rr_ExpensesOverAssets 0.85% [9]
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
(John Hancock Variable Insurance Trust) | (New Income Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.55%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.04%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [8]
Total annual fund operating expenses rr_ExpensesOverAssets 0.60% [9]
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
Annual Return 2006 rr_AnnualReturn2006 7.90%
Annual Return 2007 rr_AnnualReturn2007 5.88%
Annual Return 2008 rr_AnnualReturn2008 (9.30%)
Annual Return 2009 rr_AnnualReturn2009 18.09%
Annual Return 2010 rr_AnnualReturn2010 6.96%
Annual Return 2011 rr_AnnualReturn2011 5.91%
Annual Return 2012 rr_AnnualReturn2012 5.91%
Annual Return 2013 rr_AnnualReturn2013 (2.12%)
Annual Return 2014 rr_AnnualReturn2014 5.83%
Annual Return 2015 rr_AnnualReturn2015 0.22%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 9.13%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 9.13%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –5.13%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (5.13%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 0.22%
5 Years rr_AverageAnnualReturnYear05 3.09%
10 Years rr_AverageAnnualReturnYear10 4.30%
Date of Inception rr_AverageAnnualReturnInceptionDate Oct. 24, 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 and hold 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 medium 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)

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 medium 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 152% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 152.00%
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, in the opinion of the subadvisor, at least 50% of its revenues or 50% of the market value of its assets at the time its securities are purchased by the fund are attributed to the ownership, construction, management or sale of real estate.

The subadvisor 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.

To find these issuers, the subadvisor tracks economic conditions and real estate market performance in major metropolitan areas and analyzes performance of various property types within those regions. To perform this analysis, it uses information from a nationwide network of real estate professionals to evaluate the holdings of real estate companies and REITs in which the fund may invest. Its analysis also includes the companies' management structure, financial structure and business strategy. The goal of these analyses is to determine which of the issuers the subadvisor believes will be the most profitable to the fund. The subadvisor also considers the effect of the real estate securities markets in general when making investment decisions. The subadvisor does not attempt to time the market.

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 subadvisor 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 subadvisor 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 subadvisor 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 non-diversified, which means that it may invest its assets in a smaller number of issuers than a diversified fund. 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 principal risks of investing in the fund include:

Convertible securities risk. 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.

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.

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. 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.

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. Actively trading securities can increase transaction costs (thus lowering performance).

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

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.

Real estate investment trust 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 capitalization securities may underperform the market as a whole.
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.
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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q3 '09, 32.43%

Worst quarter: Q4 '08, –39.92%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Real Estate Securities Trust) | MSCI U.S. REIT Index (gross of foreign withholding taxes on dividends) (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 2.52%
5 Years rr_AverageAnnualReturnYear05 11.88%
10 Years rr_AverageAnnualReturnYear10 7.35%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 30, 1987
(John Hancock Variable Insurance Trust) | (Real Estate Securities Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.70%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.79%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 81
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 252
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 439
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 978
Annual Return 2006 rr_AnnualReturn2006 38.10%
Annual Return 2007 rr_AnnualReturn2007 (15.61%)
Annual Return 2008 rr_AnnualReturn2008 (39.42%)
Annual Return 2009 rr_AnnualReturn2009 30.17%
Annual Return 2010 rr_AnnualReturn2010 29.19%
Annual Return 2011 rr_AnnualReturn2011 9.46%
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%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q3 '09, 32.43%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 32.43%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –39.92%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (39.92%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 2.68%
5 Years rr_AverageAnnualReturnYear05 11.64%
10 Years rr_AverageAnnualReturnYear10 7.49%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 30, 1987
(John Hancock Variable Insurance Trust) | (Real Estate Securities Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.70%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.99%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 101
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 315
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 547
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,213
1 Year rr_AverageAnnualReturnYear01 2.46%
5 Years rr_AverageAnnualReturnYear05 11.42%
10 Years rr_AverageAnnualReturnYear10 7.28%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Real Estate Securities Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.70%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.74%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 76
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 237
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 411
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 918
1 Year rr_AverageAnnualReturnYear01 2.80%
5 Years rr_AverageAnnualReturnYear05 11.72%
10 Years rr_AverageAnnualReturnYear10 7.55%
Date of Inception rr_AverageAnnualReturnInceptionDate Feb. 28, 2005
(John Hancock Variable Insurance Trust) | (Real Return Bond Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

To seek maximum real return, consistent with preservation of real 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 and hold 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 medium 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)

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 medium 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

Under normal market conditions, the fund invests at least 80% of its net assets (plus borrowings for investment purposes) in inflation-indexed bonds of varying maturities issued by the U.S. and foreign governments, their agencies or instrumentalities and corporations, which may be represented by forwards or derivatives such as options, futures contracts, or swap agreements.

Inflation-indexed bonds are fixed-income securities that are structured to provide protection against inflation. The value of the bond's principal or the interest income paid on the bond is adjusted to track changes in an official inflation measure. The U.S. Treasury uses the Consumer Price Index for Urban Consumers as the inflation measure. Inflation-indexed bonds issued by a foreign government are generally adjusted to reflect a comparable inflation index, calculated by that government. "Real return" equals total return less the estimated cost of inflation, which is typically measured by the change in an official inflation measure.

The types of fixed-income securities in which the fund may invest include the following securities which, unless otherwise noted, may be issued by domestic or foreign issuers and may be denominated in U.S. dollars or foreign currencies:

  • securities issued or guaranteed by the U.S. government, its agencies or government-sponsored enterprises;

  • corporate debt securities of U.S. and foreign issuers, including convertible securities and corporate commercial paper;

  • mortgage-backed and other asset-backed securities;

  • inflation-indexed bonds issued by both governments and corporations;

  • structured notes, including hybrid or "indexed" securities and event-linked bonds;

  • bank capital and trust preferred securities;

  • loan participations and assignments;

  • delayed funding loans and revolving credit facilities;

  • bank certificates of deposit, fixed time deposits and bankers' acceptances;

  • debt securities issued by states or local governments and their agencies, authorities and other government-sponsored enterprises;

  • repurchase agreements and reverse repurchase agreements;

  • obligations of foreign governments or their subdivisions, agencies and government-sponsored enterprises; and

  • obligations of international agencies or supranational entities.

Fixed-income securities may have fixed, variable, or floating rates of interest, including rates of interest that vary inversely at a multiple of a designated or floating rate, or that vary according to change in relative values of currencies.

The fund invests primarily in investment-grade securities, but may invest up to 10% of its total assets in high yield securities ("junk bonds") rated B or higher by Moody's or equivalently rated by S&P or Fitch, or, if unrated, determined by the subadvisor to be of comparable quality. The fund may also invest up to 30% of its total assets in securities denominated in foreign currencies, and may invest beyond this limit in U.S. dollar-denominated securities of foreign issuers. The fund may invest in baskets of foreign currencies (such as the Euro) and direct currency. The fund will normally limit its foreign currency exposure (from foreign dollardenominated securities or foreign currencies) to 20% of its total assets. The fund may invest up to 10% of its total assets in securities and instruments that are economically tied to emerging market countries (this limitation does not apply to investment grade sovereign debt denominated in the local currency with less than 1 year remaining to maturity). The effective duration of this fund normally varies within three years (plus or minus) of the duration of the benchmark, as calculated by the subadvisor.

The fund may invest up to 10% of its total assets in preferred stocks.

The fund may also lend its portfolio securities to brokers, dealers and other financial institutions to earn income. The fund may, without limitation, seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as buy backs or dollar rolls).

The fund's investment process may, at times, result in a higher than average portfolio turnover ratio and increased trading expenses.

The fund may make short sales of a security including short sales "against the box."

The fund may:

  • purchase and sell options on domestic and foreign securities, securities indexes and currencies,

  • purchase and sell futures and options on futures,

  • purchase and sell currency or securities on a forward basis, and

  • enter into interest rate, index, equity, total return, currency, and credit default swap agreements.
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 principal risks of investing in the fund include:

Changing distribution levels risk. The distribution amounts paid by the fund generally depend on the amount of income and/or dividends received by the fund's investments. As a result of market, interest rate and other circumstances, the amount of cash available for distribution by the fund and the fund's distribution rate may vary or decline. The risk of such variability is accentuated in currently prevailing market and interest rate circumstances.

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.

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.

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. 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.

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, inverse floating-rate securities, 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.

Hybrid instrument risk. 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q1 '09, 6.26%

Worst quarter: Q2 '13, –8.36%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Real Return Bond Trust) | Barclays U.S. TIPS Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.44%)
5 Years rr_AverageAnnualReturnYear05 2.55%
10 Years rr_AverageAnnualReturnYear10 3.93%
Date of Inception rr_AverageAnnualReturnInceptionDate May 05, 2003
(John Hancock Variable Insurance Trust) | (Real Return Bond Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.70%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.52% [27]
Total annual fund operating expenses rr_ExpensesOverAssets 1.27%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 129
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 403
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 697
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,534
Annual Return 2006 rr_AnnualReturn2006 0.23%
Annual Return 2007 rr_AnnualReturn2007 11.49%
Annual Return 2008 rr_AnnualReturn2008 (11.28%)
Annual Return 2009 rr_AnnualReturn2009 19.47%
Annual Return 2010 rr_AnnualReturn2010 8.83%
Annual Return 2011 rr_AnnualReturn2011 12.02%
Annual Return 2012 rr_AnnualReturn2012 8.86%
Annual Return 2013 rr_AnnualReturn2013 (9.28%)
Annual Return 2014 rr_AnnualReturn2014 4.77%
Annual Return 2015 rr_AnnualReturn2015 (2.95%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q1 '09, 6.26%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 6.26%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q2 '13, –8.36%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (8.36%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2013
1 Year rr_AverageAnnualReturnYear01 (2.95%)
5 Years rr_AverageAnnualReturnYear05 2.38%
10 Years rr_AverageAnnualReturnYear10 3.79%
Date of Inception rr_AverageAnnualReturnInceptionDate May 05, 2003
(John Hancock Variable Insurance Trust) | (Real Return Bond Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.70%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.52% [27]
Total annual fund operating expenses rr_ExpensesOverAssets 1.47%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 150
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 465
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 803
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,757
1 Year rr_AverageAnnualReturnYear01 (3.10%)
5 Years rr_AverageAnnualReturnYear05 2.19%
10 Years rr_AverageAnnualReturnYear10 3.58%
Date of Inception rr_AverageAnnualReturnInceptionDate May 05, 2003
(John Hancock Variable Insurance Trust) | (Real Return Bond Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.70%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.52% [27]
Total annual fund operating expenses rr_ExpensesOverAssets 1.22%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 124
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 387
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 670
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,477
1 Year rr_AverageAnnualReturnYear01 (2.94%)
5 Years rr_AverageAnnualReturnYear05 2.44%
10 Years rr_AverageAnnualReturnYear10 3.82%
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 and hold 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 medium 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 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 medium 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 118% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 118.00%
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. 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 sell securities for a variety of reasons such as to secure 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 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, such as to secure 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 principal risks of investing in the fund include:

Convertible securities risk. 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.

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.

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. 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.

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.

High portfolio turnover risk. Actively trading securities can increase transaction costs (thus lowering performance).

Hybrid instrument risk. 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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Initial public offerings 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement date.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 23.51%

Worst quarter: Q4 '08, –25.14%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(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 1.38%
5 Years rr_AverageAnnualReturnYear05 12.57%
10 Years rr_AverageAnnualReturnYear10 7.31%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 01, 1997
(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 4.78%
5 Years rr_AverageAnnualReturnYear05 11.66%
10 Years rr_AverageAnnualReturnYear10 8.45%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 01, 1997
(John Hancock Variable Insurance Trust) | (Science & Technology Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 1.02%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.05%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.13% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 115
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 359
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 622
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,375
Annual Return 2006 rr_AnnualReturn2006 5.52%
Annual Return 2007 rr_AnnualReturn2007 19.57%
Annual Return 2008 rr_AnnualReturn2008 (44.44%)
Annual Return 2009 rr_AnnualReturn2009 64.48%
Annual Return 2010 rr_AnnualReturn2010 24.61%
Annual Return 2011 rr_AnnualReturn2011 (7.75%)
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%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 23.51%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 23.51%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –25.14%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (25.14%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 6.69%
5 Years rr_AverageAnnualReturnYear05 11.99%
10 Years rr_AverageAnnualReturnYear10 9.73%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 01, 1997
(John Hancock Variable Insurance Trust) | (Science & Technology Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 1.02%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.05%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.33% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 135
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 421
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 729
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,601
1 Year rr_AverageAnnualReturnYear01 6.49%
5 Years rr_AverageAnnualReturnYear05 11.77%
10 Years rr_AverageAnnualReturnYear10 9.52%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Science & Technology Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 1.02%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.05%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.08% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 110
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 343
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 595
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,317
1 Year rr_AverageAnnualReturnYear01 6.77%
5 Years rr_AverageAnnualReturnYear05 12.05%
10 Years rr_AverageAnnualReturnYear10 9.79%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(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 and hold 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 medium 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)

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 medium 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 43% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 43.00%
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 assetbacked 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 principal risks of investing in the fund include:

Changing distribution levels risk. The distribution amounts paid by the fund generally depend on the amount of income and/or dividends received by the fund's investments. As a result of market, interest rate and other circumstances, the amount of cash available for distribution by the fund and the fund's distribution rate may vary or decline. The risk of such variability is accentuated in currently prevailing market and interest rate circumstances.

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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. 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. 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.

High portfolio turnover risk. Actively trading securities can increase transaction costs (thus lowering performance).

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Short sales risk. In a short sale, a fund pays interest on the borrowed security. The fund will lose money if the security price increases between the short sale and the replacement 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series NAV (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '10, 1.87%

Worst quarter: Q2 '13, –1.24%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Short Term Government Income Trust) | Barclays U.S. Government 1-5 Year Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.93%
5 Years rr_AverageAnnualReturnYear05 1.23%
Inception rr_AverageAnnualReturnSinceInception 1.52%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 02, 2009
(John Hancock Variable Insurance Trust) | (Short Term Government Income Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.56%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.05%
Total annual fund operating expenses rr_ExpensesOverAssets 0.66%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 67
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 211
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 368
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 822
1 Year rr_AverageAnnualReturnYear01 0.64%
5 Years rr_AverageAnnualReturnYear05 0.97%
Inception rr_AverageAnnualReturnSinceInception 1.43%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 30, 2010
(John Hancock Variable Insurance Trust) | (Short Term Government Income Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.56%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.05%
Total annual fund operating expenses rr_ExpensesOverAssets 0.86%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 88
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 274
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 477
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,061
1 Year rr_AverageAnnualReturnYear01 0.36%
5 Years rr_AverageAnnualReturnYear05 0.76%
Inception rr_AverageAnnualReturnSinceInception 1.26%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 30, 2010
(John Hancock Variable Insurance Trust) | (Short Term Government Income Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.56%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.05%
Total annual fund operating expenses rr_ExpensesOverAssets 0.61%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 62
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 195
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 340
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 762
Annual Return 2009 rr_AnnualReturn2009 1.96%
Annual Return 2010 rr_AnnualReturn2010 3.28%
Annual Return 2011 rr_AnnualReturn2011 2.82%
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%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '10, 1.87%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 1.87%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2010
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q2 '13, –1.24%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (1.24%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2013
1 Year rr_AverageAnnualReturnYear01 0.69%
5 Years rr_AverageAnnualReturnYear05 1.02%
Inception rr_AverageAnnualReturnSinceInception 1.48%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 02, 2009
(John Hancock Variable Insurance Trust) | (Small Cap Growth 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 and hold 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 medium 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)

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 medium 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 small-cap companies. 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 ($5.5 billion as of February 29, 2016) or the S&P SmallCap 600 Index ($4.7 billion as of February 29, 2016).

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 principal risks of investing in the fund include:

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. A fund bears ETF fees and expenses indirectly.

Foreign securities risk. Less information may be publicly available regarding foreign 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.

High portfolio turnover risk. Actively trading securities can increase transaction costs (thus lowering performance).

Information technology risk. Information technology companies can be significantly affected by rapid obsolescence, short product cycles, competition, and government regulation, among other factors.

Initial public offerings risk. IPO share prices are frequently volatile and may significantly impact fund performance.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. For periods prior to the inception of the fund, performance shown for each share class is the actual performance of the sole share class of the fund's predecessor fund. This pre-inception performance for each of the Series I and Series II share classes has not been adjusted to reflect the Rule 12b-1 fees of that class and would be lower if it did. The performance information below does not reflect fees and expenses of any variable insurance contract which may use JHVIT as its underlying investment medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 19.13%

Worst quarter: Q4 '08, –24.23%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Small Cap Growth Trust) | Russell 2000 Growth Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.38%)
5 Years rr_AverageAnnualReturnYear05 10.67%
10 Years rr_AverageAnnualReturnYear10 7.95%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Small Cap Growth Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 1.04%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.05%
Total annual fund operating expenses rr_ExpensesOverAssets 1.14%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 116
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 362
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 628
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,386
Annual Return 2006 rr_AnnualReturn2006 13.48%
Annual Return 2007 rr_AnnualReturn2007 13.99%
Annual Return 2008 rr_AnnualReturn2008 (39.68%)
Annual Return 2009 rr_AnnualReturn2009 34.58%
Annual Return 2010 rr_AnnualReturn2010 22.07%
Annual Return 2011 rr_AnnualReturn2011 (6.81%)
Annual Return 2012 rr_AnnualReturn2012 16.47%
Annual Return 2013 rr_AnnualReturn2013 44.08%
Annual Return 2014 rr_AnnualReturn2014 7.57%
Annual Return 2015 rr_AnnualReturn2015 (8.85%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 19.13%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 19.13%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –24.23%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (24.23%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (8.85%)
5 Years rr_AverageAnnualReturnYear05 8.92%
10 Years rr_AverageAnnualReturnYear10 6.99%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Small Cap Growth Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 1.04%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.05%
Total annual fund operating expenses rr_ExpensesOverAssets 1.34%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 136
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 425
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 734
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,613
1 Year rr_AverageAnnualReturnYear01 (9.06%)
5 Years rr_AverageAnnualReturnYear05 8.70%
10 Years rr_AverageAnnualReturnYear10 6.77%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Small Cap Growth Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 1.04%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.05%
Total annual fund operating expenses rr_ExpensesOverAssets 1.09%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 111
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 347
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 601
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,329
1 Year rr_AverageAnnualReturnYear01 (8.78%)
5 Years rr_AverageAnnualReturnYear05 8.98%
10 Years rr_AverageAnnualReturnYear10 7.04%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(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 and hold 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 medium 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, 2017
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 medium 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 19% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 19.00%
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. As of February 29, 2016, the market capitalizations of companies included in the Russell 2000 Index ranged from $13 million to $5.5 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 principal risks of investing in the fund include:

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.

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.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 20.90%

Worst quarter: Q4 '08, –26.09%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(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 (4.41%)
5 Years rr_AverageAnnualReturnYear05 9.19%
10 Years rr_AverageAnnualReturnYear10 6.80%
Date of Inception rr_AverageAnnualReturnInceptionDate May 02, 2000
(John Hancock Variable Insurance Trust) | (Small Cap Index Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.49%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.58%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.05%) [28]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.53%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 54
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 181
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 319
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 721
Annual Return 2006 rr_AnnualReturn2006 17.61%
Annual Return 2007 rr_AnnualReturn2007 (2.16%)
Annual Return 2008 rr_AnnualReturn2008 (33.71%)
Annual Return 2009 rr_AnnualReturn2009 26.65%
Annual Return 2010 rr_AnnualReturn2010 26.36%
Annual Return 2011 rr_AnnualReturn2011 (4.50%)
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%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 20.90%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 20.90%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –26.09%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (26.09%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (4.58%)
5 Years rr_AverageAnnualReturnYear05 8.93%
10 Years rr_AverageAnnualReturnYear10 6.47%
Date of Inception rr_AverageAnnualReturnInceptionDate May 02, 2000
(John Hancock Variable Insurance Trust) | (Small Cap Index Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.49%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.78%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.05%) [28]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.73%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 75
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 244
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 428
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 961
1 Year rr_AverageAnnualReturnYear01 (4.79%)
5 Years rr_AverageAnnualReturnYear05 8.71%
10 Years rr_AverageAnnualReturnYear10 6.25%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Small Cap Index Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.49%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.53%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.05%) [28]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.48%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 49
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 165
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 291
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 660
1 Year rr_AverageAnnualReturnYear01 (4.59%)
5 Years rr_AverageAnnualReturnYear05 8.99%
10 Years rr_AverageAnnualReturnYear10 6.53%
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 and hold 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 medium 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, 2017
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 medium 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 25% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 25.00%
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 has two subadvisors: Invesco Advisers, Inc. ("Invesco") and Dimensional Fund Advisors LP ("Dimensional" or "DFA"). Each subadvisor's investment strategy is described below.

The fund will be rebalanced periodically so that the subadvisors manage the following portions of the fund:

50% Invesco

50% Dimensional

*Percentages are approximate. Since the fund is only rebalanced periodically, the actual portion of the fund managed by each subadvisor will vary.

Invesco

Invesco will manage its portion of the fund's assets (the "Invesco Subadvised Assets") as follows:

Under normal market conditions, Invesco invests at least 80% of the Invesco Subadvised Assets (plus any borrowings for investment purposes) in equity securities, including convertible securities, of small-capitalization companies. Invesco considers small-capitalization companies to be those companies with market capitalizations, at the time of investment, no larger than the largest capitalized company included in the Russell 2000 Index during the most recent 11-month period (based on month-end data) plus the most recent data during the current month. As of February 29, 2016, the capitalization of companies in the Russell 2000 Index range from less than $13 million to $5.5 billion.

The portfolio managers consider selling a security if the investment thesis for owning the security is no longer valid, the stock reaches its price target or timeliness factors indicate that the risk/return characteristics of the stock as viewed in the market are no longer attractive.

In selecting investments, Invesco utilizes a disciplined portfolio construction process that aligns the fund with the S&P SmallCap 600 Index, which Invesco believes represents the small cap core asset class. The security selection process is based on a three-step process that includes fundamental, valuation and timeliness analysis:

  • Fundamental analysis involves building a series of financial models (tools to analyze stock), as well as conducting in-depth interviews with company management. The goal is to find high quality, fundamentally sound companies operating in an attractive industry.

  • Valuation analysis focuses on identifying attractively valued securities given their growth potential over a one- to two-year horizon.

  • Timeliness analysis is used to help identify the "timeliness" of a purchase. In this step, relative price strength (the price of stock in comparison to the rest of the market), trading volume characteristics, and trend analysis (using past data to predict future movement of stock) are reviewed for signs of deterioration. If a stock shows signs of deterioration, it will not be considered as a candidate for the portfolio.

Invesco may invest up to 25% of the Invesco Subadvised Assets in foreign securities. The fund's investments in foreign securities may include direct investments in foreign currency-denominated securities traded outside of the U.S.

Dimensional

DFA will manage its portion of the fund's assets (the "DFA Subadvised Assets") as follows:

DFA generally will invest the DFA Subadvised Assets in a broad and diverse group of common stocks of small and mid cap companies traded on a U.S. national securities exchange or on the over-the counter market that DFA determines to be value stocks at the time of purchase. Securities are considered value stocks primarily because a company's shares have a high book value in relation to their market value. In assessing value, DFA may consider additional factors, such as price to cash flow or price-to-earnings ratios, as well as economic conditions and developments in the issuer's industry. The criteria DFA uses for assessing value are subject to change from time to time. As of the date of this Prospectus, DFA generally considers for investment companies whose market capitalizations are generally smaller than the 500th largest U.S. company. DFA uses a market capitalization weighted approach in weighing portfolio securities. See "Market Capitalization Weighted Approach" below. DFA 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.

DFA 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 DFA Subadvised Assets. In addition, DFA may sell portfolio securities when their book-to-market ratios fall below those of the security with the lowest such ratio that is then eligible for purchase by the DFA Subadvised Assets. However, DFA may retain securities of issuers with relatively smaller market capitalizations for longer periods, despite a decrease in the issuers' book-to-market ratios.

The total market capitalization ranges, and the value criteria used by DFA for the DFA Subadvised Assets, as described above, generally apply at the time of purchase. DFA 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. Similarly, DFA is not required to sell a security even if the decline in the market capitalization reflects a serious financial difficulty or potential or actual insolvency of the company. Securities that do meet the market capitalization and/or value criteria nevertheless may be sold at any time when, in DFA's judgment, circumstances warrant their sale.

DFA may use derivatives such as futures contracts and options on futures contracts, to adjust market exposure based on expected cash inflows to or outflows from the fund. The fund does not intend to use derivatives for purposes of speculation or leveraging investment returns. DFA may enter into futures contracts and options on futures contracts for U.S. equity securities and indices. DFA may also invest in ETFs and similarly structured pooled investments for the purpose of gaining exposure to the U.S. equity markets while maintaining liquidity.

Market Capitalization Weighted Approach

The strategy used by DFA in managing the DFA 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 adjusted by DFA for a variety of reasons. DFA may consider such factors as free float, momentum, liquidity management, and profitability, as well as other factors determined to be appropriate by DFA given market conditions. In assessing profitability, DFA may consider different ratios, such as that of earnings or profits from operations relative to book value or assets. DFA may deviate from market capitalization weighting to limit or fix the exposure of the DFA Subadvised Assets to a particular issuer to a maximum proportion of the assets of the DFA Subadvised Assets. DFA may exclude the stock of a company that meets applicable market capitalization criteria if DFA determines that the purchase of such security is inappropriate in light of other conditions. These adjustments will result in a deviation from traditional market capitalization weighting.
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 principal risks of investing in the fund include:

Convertible securities risk. 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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. A fund bears ETF fees and expenses indirectly.

Foreign securities risk. Less information may be publicly available regarding foreign 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.

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.

Investment company securities risk. A fund bears underlying fund fees and expenses indirectly.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 26.43%

Worst quarter: Q4 '08, –26.09%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(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 (4.41%)
5 Years rr_AverageAnnualReturnYear05 9.19%
10 Years rr_AverageAnnualReturnYear10 6.80%
Date of Inception rr_AverageAnnualReturnInceptionDate May 05, 2003
(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 (7.47%)
5 Years rr_AverageAnnualReturnYear05 7.67%
10 Years rr_AverageAnnualReturnYear10 5.57%
Date of Inception rr_AverageAnnualReturnInceptionDate May 05, 2003
(John Hancock Variable Insurance Trust) | (Small Cap Opportunities Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 1.00%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.05%
Total annual fund operating expenses rr_ExpensesOverAssets 1.10%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.09%) [29]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 1.01%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 103
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 341
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 597
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,332
Annual Return 2006 rr_AnnualReturn2006 10.45%
Annual Return 2007 rr_AnnualReturn2007 (7.66%)
Annual Return 2008 rr_AnnualReturn2008 (42.13%)
Annual Return 2009 rr_AnnualReturn2009 33.87%
Annual Return 2010 rr_AnnualReturn2010 29.67%
Annual Return 2011 rr_AnnualReturn2011 (3.16%)
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%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 26.43%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 26.43%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –26.09%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (26.09%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (5.17%)
5 Years rr_AverageAnnualReturnYear05 9.02%
10 Years rr_AverageAnnualReturnYear10 4.66%
Date of Inception rr_AverageAnnualReturnInceptionDate May 05, 2003
(John Hancock Variable Insurance Trust) | (Small Cap Opportunities Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 1.00%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.05%
Total annual fund operating expenses rr_ExpensesOverAssets 1.30%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.09%) [29]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 1.21%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 123
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 403
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 704
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,560
1 Year rr_AverageAnnualReturnYear01 (5.34%)
5 Years rr_AverageAnnualReturnYear05 8.81%
10 Years rr_AverageAnnualReturnYear10 4.45%
Date of Inception rr_AverageAnnualReturnInceptionDate May 05, 2003
(John Hancock Variable Insurance Trust) | (Small Cap Opportunities Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 1.00%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.05%
Total annual fund operating expenses rr_ExpensesOverAssets 1.05%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.09%) [29]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.96%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 98
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 325
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 571
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,274
1 Year rr_AverageAnnualReturnYear01 (5.12%)
5 Years rr_AverageAnnualReturnYear05 9.07%
10 Years rr_AverageAnnualReturnYear10 4.71%
Date of Inception rr_AverageAnnualReturnInceptionDate Feb. 28, 2005
(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 and hold 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 medium 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 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 medium 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 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

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. 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 ($5.5 billion as of February 29, 2016) or the S&P SmallCap 600 Index ($4.7 billion as of February 29, 2016).

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 estaterelated 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 principal risks of investing in the fund include:

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. 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. 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.

Initial public offerings risk. IPO share prices are frequently volatile and may significantly impact fund performance.

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 capitalization securities may underperform the market as a whole.

Value investing style risk. The fund emphasizes a value style of investing, which focuses on undervalued companies with characteristics for improved valuations. This style of investing is subject to the risk that the valuations never improve or that the returns on value equity securities are less than returns on other styles of investing or the overall stock market. Value stocks also may decline in price, even though in theory they are already underpriced.
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. For periods prior to the inception of the fund, performance shown for each share class is the actual performance of the sole share class of the fund's predecessor fund. This pre-inception performance for each of the Series I and Series II share classes has not been adjusted to reflect the Rule 12b-1 fees of that class and would be lower if it did. The performance information below does not reflect fees and expenses of any variable insurance contract which may use JHVIT as its underlying investment medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series NAV (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q3 '09, 20.61%

Worst quarter: Q4 '08, –23.35%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(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 (7.47%)
5 Years rr_AverageAnnualReturnYear05 7.67%
10 Years rr_AverageAnnualReturnYear10 5.57%
Date of Inception rr_AverageAnnualReturnInceptionDate Aug. 31, 1999
(John Hancock Variable Insurance Trust) | (Small Cap Value Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 1.03%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.04%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.05% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.17% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 119
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 372
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 644
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,420
1 Year rr_AverageAnnualReturnYear01 (1.36%)
5 Years rr_AverageAnnualReturnYear05 10.51%
10 Years rr_AverageAnnualReturnYear10 8.63%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Small Cap Value Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 1.03%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.05% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.37% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 139
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 434
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 750
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,646
1 Year rr_AverageAnnualReturnYear01 (1.57%)
5 Years rr_AverageAnnualReturnYear05 10.29%
10 Years rr_AverageAnnualReturnYear10 8.41%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Small Cap Value Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 1.03%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.04%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.05% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.12% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 114
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 356
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 617
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,363
Annual Return 2006 rr_AnnualReturn2006 19.32%
Annual Return 2007 rr_AnnualReturn2007 (2.86%)
Annual Return 2008 rr_AnnualReturn2008 (26.12%)
Annual Return 2009 rr_AnnualReturn2009 28.79%
Annual Return 2010 rr_AnnualReturn2010 26.15%
Annual Return 2011 rr_AnnualReturn2011 1.15%
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%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q3 '09, 20.61%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 20.61%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –23.35%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (23.35%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (1.31%)
5 Years rr_AverageAnnualReturnYear05 10.57%
10 Years rr_AverageAnnualReturnYear10 8.68%
Date of Inception rr_AverageAnnualReturnInceptionDate Aug. 31, 1999
(John Hancock Variable Insurance Trust) | (Small Company 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 and hold 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 medium 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)

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 medium 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 30% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 30.00%
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-capitalization companies. The fund invests primarily in equity securities. Common stock is the principal type of equity security in which the fund invests. The fund considers a company to be a small-capitalization company if it has a market capitalization, at the time of investment, no larger than the largest capitalized company included in the Russell 2000 Index during the most recent 11-month period (based on month-end data) plus the most recent data during the current month. As of February 29, 2016, the capitalizations of companies included in the Russell 2000 Index ranged from $13 million to $5.5 billion.

The fund may invest up to 25% of its total assets in foreign securities.

In selecting investments, the subadvisor utilizes a disciplined portfolio construction process that constrains the fund's industry group weightings within a specific range versus the industry group weightings of the Russell 2000 Growth Index which the subadvisor believes represents the small cap growth asset class. The security selection process is based on a three-step process that includes fundamental, valuation and timeliness analysis.

  • Fundamental analysis involves building a series of financial models, as well as conducting in-depth interviews with company management. The goal is to find high quality, fundamentally sound companies operating in an attractive industry.

  • Valuation analysis focuses on identifying attractively valued securities given their growth potential over a one- to two-year horizon.

  • Timeliness analysis is used to help identify the "timeliness" of a purchase. In this step, relative price strength, trading volume characteristics, and trend analysis are reviewed for signs of deterioration. If a stock shows signs of deterioration, it will not be considered as a candidate for the portfolio.

The portfolio managers consider selling a security if the investment thesis for owning the security is no longer valid, the stock reaches its price target or timeliness factors indicate that the risk/return characteristics of the stock as viewed in the market are no longer attractive.
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 principal risks of investing in the fund include:

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. 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. 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.

Information technology risk. Information technology companies can be significantly affected by rapid obsolescence, short product cycles, competition, and government regulation, among other factors.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series NAV (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 19.00%

Worst quarter: Q4 '08, –26.67%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Small Company Growth Trust) | Russell 2000 Growth Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (1.38%)
5 Years rr_AverageAnnualReturnYear05 10.67%
10 Years rr_AverageAnnualReturnYear10 7.95%
Date of Inception rr_AverageAnnualReturnInceptionDate Oct. 24, 2005
(John Hancock Variable Insurance Trust) | (Small Company Growth Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 1.00%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.07% [30]
Total annual fund operating expenses rr_ExpensesOverAssets 1.12%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 114
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 356
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 617
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,363
(John Hancock Variable Insurance Trust) | (Small Company Growth Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 1.00%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.07% [30]
Total annual fund operating expenses rr_ExpensesOverAssets 1.32%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 134
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 418
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 723
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,590
(John Hancock Variable Insurance Trust) | (Small Company Growth Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 1.00%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.07%
Total annual fund operating expenses rr_ExpensesOverAssets 1.07%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 109
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 340
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 590
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,306
Annual Return 2006 rr_AnnualReturn2006 13.83%
Annual Return 2007 rr_AnnualReturn2007 10.34%
Annual Return 2008 rr_AnnualReturn2008 (38.57%)
Annual Return 2009 rr_AnnualReturn2009 30.82%
Annual Return 2010 rr_AnnualReturn2010 26.44%
Annual Return 2011 rr_AnnualReturn2011 (1.77%)
Annual Return 2012 rr_AnnualReturn2012 18.32%
Annual Return 2013 rr_AnnualReturn2013 39.98%
Annual Return 2014 rr_AnnualReturn2014 7.85%
Annual Return 2015 rr_AnnualReturn2015 (1.75%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 19.00%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 19.00%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –26.67%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (26.67%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (1.75%)
5 Years rr_AverageAnnualReturnYear05 11.51%
10 Years rr_AverageAnnualReturnYear10 8.20%
Date of Inception rr_AverageAnnualReturnInceptionDate Oct. 24, 2005
(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 and hold 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 medium 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 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 medium 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 35% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 35.00%
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 ($13 million to $5.5 billion as of February 29, 2016). 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:

  • Low price/earnings, price/book value or price/cash flow ratios relative to the Russell 2000 Index, the company's peers or its own historic norm;

  • 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 non-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, such as to secure 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 principal risks of investing in the fund include:

Convertible securities risk. 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.

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.

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, 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. 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.

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 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Real estate investment trust 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 investing risk. Because the fund may focus on a single sector of the economy, its performance depends in large part on the performance of that sector. As a result, the value of your investment may fluctuate more widely than it would in a fund that is diversified 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 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 20.80%

Worst quarter: Q4 '08, –25.40%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(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 (7.47%)
5 Years rr_AverageAnnualReturnYear05 7.67%
10 Years rr_AverageAnnualReturnYear10 5.57%
Date of Inception rr_AverageAnnualReturnInceptionDate Oct. 01, 1997
(John Hancock Variable Insurance Trust) | (Small Company Value Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 1.04%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.04%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.14% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.27% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 129
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 403
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 697
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,534
Annual Return 2006 rr_AnnualReturn2006 15.42%
Annual Return 2007 rr_AnnualReturn2007 (1.20%)
Annual Return 2008 rr_AnnualReturn2008 (27.05%)
Annual Return 2009 rr_AnnualReturn2009 27.69%
Annual Return 2010 rr_AnnualReturn2010 21.36%
Annual Return 2011 rr_AnnualReturn2011 (0.93%)
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%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 20.80%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 20.80%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –25.40%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (25.40%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (5.60%)
5 Years rr_AverageAnnualReturnYear05 7.46%
10 Years rr_AverageAnnualReturnYear10 6.33%
Date of Inception rr_AverageAnnualReturnInceptionDate Oct. 01, 1997
(John Hancock Variable Insurance Trust) | (Small Company Value Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 1.04%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.14% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.47% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 150
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 465
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 803
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,757
1 Year rr_AverageAnnualReturnYear01 (5.79%)
5 Years rr_AverageAnnualReturnYear05 7.24%
10 Years rr_AverageAnnualReturnYear10 6.11%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Small Company Value Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 1.04%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.04%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.14% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.22% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 124
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 387
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 670
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,477
1 Year rr_AverageAnnualReturnYear01 (5.51%)
5 Years rr_AverageAnnualReturnYear05 7.52%
10 Years rr_AverageAnnualReturnYear10 6.39%
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 and hold 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 medium 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)

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 medium 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 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 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 principal risks of investing in the fund include:

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.

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.

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 risk. An ETF generally reflects the risks of the underlying securities it is designed to track. 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. 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.

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 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.

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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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 medium. 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 75% of the Russell 3000 Index and 25% of the MSCI EAFE Index.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series NAV (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q1 '13, 9.12%

Worst quarter: Q3 '15, –8.10%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(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 1.38%
Inception rr_AverageAnnualReturnSinceInception 13.36%
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)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.30%
Inception rr_AverageAnnualReturnSinceInception 11.60%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 16, 2012
(John Hancock Variable Insurance Trust) | (Strategic Equity Allocation Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.63%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.04% [31]
Total annual fund operating expenses rr_ExpensesOverAssets 0.72%
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
(John Hancock Variable Insurance Trust) | (Strategic Equity Allocation Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.63%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04% [31]
Total annual fund operating expenses rr_ExpensesOverAssets 0.92%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 94
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 293
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 509
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,131
(John Hancock Variable Insurance Trust) | (Strategic Equity Allocation Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.63%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.67%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 68
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 214
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 373
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 835
Annual Return 2013 rr_AnnualReturn2013 29.23%
Annual Return 2014 rr_AnnualReturn2014 6.40%
Annual Return 2015 rr_AnnualReturn2015 (0.35%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q1 '13, 9.12%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 9.12%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2013
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q3 '15, –8.10%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (8.10%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2015
1 Year rr_AverageAnnualReturnYear01 (0.35%)
Inception rr_AverageAnnualReturnSinceInception 10.91%
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 and hold 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 medium 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 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 medium 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 49% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 49.00%
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 Standard & Poor's Ratings Services ("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 principal risks of investing in the fund include:

Changing distribution levels risk. The distribution amounts paid by the fund generally depend on the amount of income and/or dividends received by the fund's investments. As a result of market, interest rate and other circumstances, the amount of cash available for distribution by the fund and the fund's distribution rate may vary or decline. The risk of such variability is accentuated in currently prevailing market and interest rate circumstances.

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.

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.

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. 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.

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 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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.
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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 9.61%

Worst quarter: Q3 '11, –8.83%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Strategic Income Opportunities Trust) | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.55%
5 Years rr_AverageAnnualReturnYear05 3.25%
10 Years rr_AverageAnnualReturnYear10 4.51%
Date of Inception rr_AverageAnnualReturnInceptionDate May 03, 2004
(John Hancock Variable Insurance Trust) | (Strategic Income Opportunities Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.63%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.06%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.75% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 77
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 240
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 417
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 930
Annual Return 2006 rr_AnnualReturn2006 4.13%
Annual Return 2007 rr_AnnualReturn2007 5.87%
Annual Return 2008 rr_AnnualReturn2008 (8.61%)
Annual Return 2009 rr_AnnualReturn2009 26.66%
Annual Return 2010 rr_AnnualReturn2010 15.89%
Annual Return 2011 rr_AnnualReturn2011 2.02%
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%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 9.61%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 9.61%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q3 '11, –8.83%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (8.83%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2011
1 Year rr_AverageAnnualReturnYear01 1.22%
5 Years rr_AverageAnnualReturnYear05 4.92%
10 Years rr_AverageAnnualReturnYear10 6.52%
Date of Inception rr_AverageAnnualReturnInceptionDate May 03, 2004
(John Hancock Variable Insurance Trust) | (Strategic Income Opportunities Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.63%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.06%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.95% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 97
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 303
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 525
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,166
1 Year rr_AverageAnnualReturnYear01 1.01%
5 Years rr_AverageAnnualReturnYear05 4.71%
10 Years rr_AverageAnnualReturnYear10 6.29%
Date of Inception rr_AverageAnnualReturnInceptionDate May 03, 2004
(John Hancock Variable Insurance Trust) | (Strategic Income Opportunities Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.63%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.06%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.70% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 72
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 224
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 390
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 871
1 Year rr_AverageAnnualReturnYear01 1.27%
5 Years rr_AverageAnnualReturnYear05 4.97%
10 Years rr_AverageAnnualReturnYear10 6.56%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Total Bond Market Trust B)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

To seek to track the performance of the Barclays U.S. Aggregate Bond Index (the "Barclays 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 and hold 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 medium 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, 2017
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 medium 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 67% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 67.00%
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 Barclays U.S. Aggregate Bond Index (the Barclays Index).

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 Barclays Index by holding a representative sample of the securities that comprise the Barclays 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 Barclays Index, which broadly represents the U.S. investment grade bond market.

The subadvisor employs a passive management strategy using quantitative techniques to select individual securities that provide a representative sample of the securities in the Barclays Index.

The Barclays 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 Barclays Index's duration, cash flow, sector, credit quality, callability and other key performance characteristics.

The Barclays 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 principal risks of investing in the fund include:

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.

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.

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. 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.

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, along with specific additional associated risks, if any, 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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

TBA mortgage contracts 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.

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. Unless all share classes shown in the table have the same inception date, 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. For periods prior to the inception date of the fund, performance shown is the actual performance of the sole share class of the fund's predecessor fund and has not been adjusted to reflect the Rule 12b-1 fees of any class of shares. As a result, pre-inception performance of the fund may be higher than 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series NAV (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q4 '08, 4.46%

Worst quarter: Q2 '13, –2.61%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Total Bond Market Trust B) | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.55%
5 Years rr_AverageAnnualReturnYear05 3.25%
10 Years rr_AverageAnnualReturnYear10 4.51%
Date of Inception rr_AverageAnnualReturnInceptionDate May 01, 1998
(John Hancock Variable Insurance Trust) | (Total Bond Market Trust B) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.47%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.56%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.26%) [1]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.30%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 31
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 153
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 287
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 677
1 Year rr_AverageAnnualReturnYear01 0.25%
5 Years rr_AverageAnnualReturnYear05 3.03%
10 Years rr_AverageAnnualReturnYear10 4.48%
Date of Inception rr_AverageAnnualReturnInceptionDate Nov. 05, 2012
(John Hancock Variable Insurance Trust) | (Total Bond Market Trust B) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.47%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.76%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.26%) [1]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.50%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 51
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 217
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 397
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 918
1 Year rr_AverageAnnualReturnYear01 0.05%
5 Years rr_AverageAnnualReturnYear05 2.90%
10 Years rr_AverageAnnualReturnYear10 4.41%
Date of Inception rr_AverageAnnualReturnInceptionDate Nov. 05, 2012
(John Hancock Variable Insurance Trust) | (Total Bond Market Trust B) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.47%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.51%
Contractual expense reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.26%) [1]
Total annual fund operating expenses after expense reimbursements rr_NetExpensesOverAssets 0.25%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 26
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 137
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 259
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 615
Annual Return 2006 rr_AnnualReturn2006 4.07%
Annual Return 2007 rr_AnnualReturn2007 7.13%
Annual Return 2008 rr_AnnualReturn2008 5.79%
Annual Return 2009 rr_AnnualReturn2009 6.29%
Annual Return 2010 rr_AnnualReturn2010 6.50%
Annual Return 2011 rr_AnnualReturn2011 7.60%
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%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q4 '08, 4.46%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 4.46%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2008
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q2 '13, –2.61%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (2.61%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2013
1 Year rr_AverageAnnualReturnYear01 0.30%
5 Years rr_AverageAnnualReturnYear05 3.05%
10 Years rr_AverageAnnualReturnYear10 4.49%
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 and hold 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 medium 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 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 medium 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 4% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 4.00%
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 Index and (b) securities (which may or may not be included in the Wilshire 5000 Total Market Index) that the subadvisor believes as a group will behave in a manner similar to the index. As of February 29, 2016, the market capitalizations of companies included in the Wilshire 5000 Total Market Index ranged from less than $28 million to $539.1 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 Wilshire 5000 Total Market 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 principal risks of investing in the fund include:

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.

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.

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.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 16.64%

Worst quarter: Q4 '08, –22.82%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Total Stock Market Index Trust) | Wilshire 5000 Total Market Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (0.24%)
5 Years rr_AverageAnnualReturnYear05 11.84%
10 Years rr_AverageAnnualReturnYear10 7.44%
Date of Inception rr_AverageAnnualReturnInceptionDate May 02, 2000
(John Hancock Variable Insurance Trust) | (Total Stock Market Index Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.48%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.04%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.58% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 59
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 186
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 324
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 726
Annual Return 2006 rr_AnnualReturn2006 15.29%
Annual Return 2007 rr_AnnualReturn2007 5.18%
Annual Return 2008 rr_AnnualReturn2008 (37.20%)
Annual Return 2009 rr_AnnualReturn2009 28.87%
Annual Return 2010 rr_AnnualReturn2010 17.20%
Annual Return 2011 rr_AnnualReturn2011 0.28%
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%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 16.64%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 16.64%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –22.82%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (22.82%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (0.64%)
5 Years rr_AverageAnnualReturnYear05 11.34%
10 Years rr_AverageAnnualReturnYear10 7.01%
Date of Inception rr_AverageAnnualReturnInceptionDate May 02, 2000
(John Hancock Variable Insurance Trust) | (Total Stock Market Index Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.48%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.78% [5]
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
1 Year rr_AverageAnnualReturnYear01 (0.83%)
5 Years rr_AverageAnnualReturnYear05 11.13%
10 Years rr_AverageAnnualReturnYear10 6.79%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Total Stock Market Index Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.48%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.04%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.53% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 54
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 170
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 296
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 665
1 Year rr_AverageAnnualReturnYear01 (0.53%)
5 Years rr_AverageAnnualReturnYear05 11.40%
10 Years rr_AverageAnnualReturnYear10 7.06%
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 and hold 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 medium 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)

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 medium 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 86% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 86.00%
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. 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. Bank loans may be illiquid. The fund may also invest in cash and cash equivalents.

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 Standard & Poor's Ratings Services ("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.
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 principal risks of investing in the fund include:

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.

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.

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. 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.

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, along with specific additional associated risks, if any, 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.

High portfolio turnover risk. Actively trading securities can increase transaction costs (thus lowering performance).

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.
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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q1 '12, 0.41%

Worst quarter: Q2 '13, –0.41%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Ultra Short Term Bond Trust) | Bank of America Merrill Lynch 6 Month Treasury Bill Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.22%
5 Years rr_AverageAnnualReturnYear05 0.19%
Inception rr_AverageAnnualReturnSinceInception 0.21%
Date of Inception rr_AverageAnnualReturnInceptionDate Jul. 29, 2010
(John Hancock Variable Insurance Trust) | (Ultra Short Term Bond Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.55%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.06%
Total annual fund operating expenses rr_ExpensesOverAssets 0.66%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 67
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 211
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 368
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 822
Annual Return 2011 rr_AnnualReturn2011 0.12%
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%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q1 '12, 0.41%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 0.41%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2012
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q2 '13, –0.41%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (0.41%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2013
1 Year rr_AverageAnnualReturnYear01 (0.04%)
5 Years rr_AverageAnnualReturnYear05 0.11%
Inception rr_AverageAnnualReturnSinceInception 0.07%
Date of Inception rr_AverageAnnualReturnInceptionDate Jul. 29, 2010
(John Hancock Variable Insurance Trust) | (Ultra Short Term Bond Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.55%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.06%
Total annual fund operating expenses rr_ExpensesOverAssets 0.86%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 88
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 274
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 477
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,061
1 Year rr_AverageAnnualReturnYear01 (0.15%)
5 Years rr_AverageAnnualReturnYear05 (0.09%)
Inception rr_AverageAnnualReturnSinceInception (0.12%)
Date of Inception rr_AverageAnnualReturnInceptionDate Jul. 29, 2010
(John Hancock Variable Insurance Trust) | (Ultra Short Term Bond Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.55%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.06%
Total annual fund operating expenses rr_ExpensesOverAssets 0.61%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 62
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 195
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 340
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 762
1 Year rr_AverageAnnualReturnYear01 0.01%
5 Years rr_AverageAnnualReturnYear05 0.15%
Inception rr_AverageAnnualReturnSinceInception 0.12%
Date of Inception rr_AverageAnnualReturnInceptionDate Jul. 29, 2010
(John Hancock Variable Insurance Trust) | (U.S. 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 and hold 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 medium 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)

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 medium 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 66% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 66.00%
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. The subadvisor seeks to achieve the fund's objective by investing in equity investments or groups of equity investments that the subadvisor believes will provide higher returns than the Russell 3000 Index. Investments in equity securities include common stocks and other stock-related securities, such as preferred stocks, convertible securities, depositary receipts, and exchange-traded equity REITs and equity income trusts.

The Russell 3000 Index is an independently maintained and published index which measures the performance of the 3,000 largest U.S. companies based on total market capitalization. This index represents approximately 98% of the investable U.S. equity market. As of February 29, 2016, the market capitalizations of companies included in the Russell 3000 Index ranged from $16 million to $536 billion.

The subadvisor employs an active investment management method, which means that securities are bought and sold according to the subadvisor's evaluations of companies' published financial information, securities prices, equity and bond markets and the overall economy. In selecting investments for the fund, the subadvisor may use a combination of investment methods to identify which stocks present positive relative return potential. Some of these methods evaluate individual stocks or a group of stocks based on the ratio of its price relative to historical financial information, including book value, cash flow and earnings, and to forecast financial information provided by industry analysts. These ratios can then be compared to industry or market averages to assess the relative attractiveness of the stock. Other methods focus on evaluating patterns of price movement or volatility of a stock or group of stocks relative to the investment universe. The subadvisor selects which methods to use, and in what combination, based on the subadvisor's assessment of what combination is best positioned to meet the fund's investment objective. The subadvisor may also adjust the portfolio for other factors such as position size, industry and sector weights, and market capitalization. The fund may make significant investments in certain sectors including the information technology and health care services sectors.
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 principal risks of investing in the fund include:

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.

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.

Healthcare risk. Health sciences industries may be affected by product obsolescence, thin capitalization, limited product lines, markets, and financial resources or personnel challenges, and legislative or regulatory activities affecting the sector, such as approval policies for drugs, medical devices, or procedures, and changes in governmental and private payment systems and product liabilities.

Information technology risk. Information technology companies can be significantly affected by rapid obsolescence, short product cycles, competition, and government regulation, 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.

Liquidity risk. The extent to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.

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 investing risk. Because the fund may at times focus on a single sector of the economy, its performance may depend in large part on the performance of that sector. As a result, the value of your investment may fluctuate more widely than it would if the fund diversified across sectors. Banks and financial services companies could suffer losses when interest rates fall or economic conditions deteriorate.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series NAV (%)

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q3 '10, 12.54%

Worst quarter: Q4 '08, –14.03%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (U.S. Equity Trust) | Russell 3000 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 0.48%
5 Years rr_AverageAnnualReturnYear05 12.18%
10 Years rr_AverageAnnualReturnYear10 7.35%
Date of Inception rr_AverageAnnualReturnInceptionDate Oct. 24, 2005
(John Hancock Variable Insurance Trust) | (U.S. Equity Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.76%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.03%
Total annual fund operating expenses rr_ExpensesOverAssets 0.84%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 86
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 268
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 466
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,037
1 Year rr_AverageAnnualReturnYear01 0.53%
5 Years rr_AverageAnnualReturnYear05 11.70%
10 Years rr_AverageAnnualReturnYear10 6.07%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 27, 2012
(John Hancock Variable Insurance Trust) | (U.S. Equity Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.76%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.03%
Total annual fund operating expenses rr_ExpensesOverAssets 1.04%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 106
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 331
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 574
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,271
1 Year rr_AverageAnnualReturnYear01 0.33%
5 Years rr_AverageAnnualReturnYear05 11.54%
10 Years rr_AverageAnnualReturnYear10 5.99%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 27, 2012
(John Hancock Variable Insurance Trust) | (U.S. Equity Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.76%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.03%
Total annual fund operating expenses rr_ExpensesOverAssets 0.79%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 81
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 252
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 439
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 978
Annual Return 2006 rr_AnnualReturn2006 7.63%
Annual Return 2007 rr_AnnualReturn2007 2.38%
Annual Return 2008 rr_AnnualReturn2008 (27.30%)
Annual Return 2009 rr_AnnualReturn2009 19.94%
Annual Return 2010 rr_AnnualReturn2010 7.92%
Annual Return 2011 rr_AnnualReturn2011 8.13%
Annual Return 2012 rr_AnnualReturn2012 12.56%
Annual Return 2013 rr_AnnualReturn2013 28.36%
Annual Return 2014 rr_AnnualReturn2014 11.07%
Annual Return 2015 rr_AnnualReturn2015 0.52%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q3 '10, 12.54%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 12.54%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2010
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –14.03%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (14.03%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 0.52%
5 Years rr_AverageAnnualReturnYear05 11.77%
10 Years rr_AverageAnnualReturnYear10 6.10%
Date of Inception rr_AverageAnnualReturnInceptionDate Oct. 24, 2005
(John Hancock Variable Insurance Trust) | (Utilities Trust)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading

Investment objective

Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

To seek capital growth and current income (income above that available from the fund invested entirely in equity securities).
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 and hold 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 medium 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)

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 medium 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 borrowing for investment purposes) in securities of companies in the utilities industry. The subadvisor considers a company to be in the utilities industry if, at the time of investment, the subadvisor determines that a substantial portion (i.e., at least 50%) of the company's assets or revenues are derived from one or more utilities.

Companies in the utilities industry include: (i) companies engaged in the manufacture, production, generation, transmission, sale or distribution of electric, gas or other types of energy, water or other sanitary services; and (ii) companies engaged in telecommunications, including telephone, cellular telephone, satellite, microwave, cable television and other communications media (but not engaged in public broadcasting).

The fund primarily invests in equity securities, including common stocks and related securities, such as preferred stocks, convertible securities and depositary receipts, but may also invest in corporate bonds and other debt instruments. The subadvisor may invest up to 20% of the fund's net assets in lower rated debt instruments (commonly known as "junk bonds"). The fund's investment policies are based on credit ratings at the time of purchase. The fund may invest in companies of any size.

The subadvisor uses a bottom-up investment approach to buying and selling investments for the fund. Investments are selected primarily based on fundamental analysis of individual issuers and/or instruments in light of issuers' financial condition and market, economic, political, and regulatory conditions. Factors considered for equity securities may include analysis of an issuer's earnings, cash flows, competitive position, and management ability. Factors considered for debt instruments may include the instrument's credit quality, collateral characteristics and indenture provisions and the issuer's management ability, capital structure, leverage, and ability to meet its current obligations. Quantitative models that systematically evaluate the valuation, price and earnings momentum, earnings quality, and other factors of the issuer of an equity security or the structure of a debt instrument may also be considered.

The subadvisor may invest the fund's assets in U.S. and foreign securities. The fund may invest up to 40% of its net assets in foreign securities (including emerging markets securities, Brady bonds and depositary receipts). The subadvisor may invest a large percentage of the fund's assets in issuers in a single country, a small number of countries, or a particular geographic region.

The fund may have exposure to foreign currencies through its investments in foreign 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.

While the fund may use derivatives for any investment purpose, to the extent the subadvisor uses derivatives, the subadvisor expects to use derivatives primarily to increase or decrease currency exposure.
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 principal risks of investing in the fund include:

Convertible securities risk. 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.

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.

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.

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.

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. 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.

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, along with specific additional associated risks, if any, 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.

Industry or sector risk. When a fund focuses on one or more industries or sectors of the economy, its performance may be largely driven by industry or sector performance and could fluctuate more widely than if the fund were invested more evenly across industries or sectors.

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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, 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.

Small and mid-sized company risk. Small and mid-sized companies are generally less established and may be more volatile than larger companies. Small capitalization securities may underperform the market as a whole.

Utilities sector risk. Utilities companies' performance may be volatile due to variable fuel, service, and financing costs, conservation efforts, government regulation, and other factors.
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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q2 '09, 21.12%

Worst quarter: Q3 '08, –24.50%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Utilities Trust) | S&P 500 Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 1.38%
5 Years rr_AverageAnnualReturnYear05 12.57%
10 Years rr_AverageAnnualReturnYear10 7.31%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 30, 2001
(John Hancock Variable Insurance Trust) | (Utilities Trust) | S&P 500 Utilities Sector Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (4.84%)
5 Years rr_AverageAnnualReturnYear05 11.03%
10 Years rr_AverageAnnualReturnYear10 7.41%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 30, 2001
(John Hancock Variable Insurance Trust) | (Utilities Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.83%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.92%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 94
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 293
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 509
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,131
Annual Return 2006 rr_AnnualReturn2006 31.00%
Annual Return 2007 rr_AnnualReturn2007 27.40%
Annual Return 2008 rr_AnnualReturn2008 (38.64%)
Annual Return 2009 rr_AnnualReturn2009 33.64%
Annual Return 2010 rr_AnnualReturn2010 14.03%
Annual Return 2011 rr_AnnualReturn2011 6.65%
Annual Return 2012 rr_AnnualReturn2012 13.65%
Annual Return 2013 rr_AnnualReturn2013 20.57%
Annual Return 2014 rr_AnnualReturn2014 12.59%
Annual Return 2015 rr_AnnualReturn2015 (14.76%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q2 '09, 21.12%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 21.12%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q3 '08, –24.50%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (24.50%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2008
1 Year rr_AverageAnnualReturnYear01 (14.76%)
5 Years rr_AverageAnnualReturnYear05 7.00%
10 Years rr_AverageAnnualReturnYear10 8.15%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 30, 2001
(John Hancock Variable Insurance Trust) | (Utilities Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.83%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 1.12%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 114
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 356
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 617
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,363
1 Year rr_AverageAnnualReturnYear01 (15.02%)
5 Years rr_AverageAnnualReturnYear05 6.79%
10 Years rr_AverageAnnualReturnYear10 7.93%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Utilities Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.83%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.04%
Total annual fund operating expenses rr_ExpensesOverAssets 0.87%
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
1 Year rr_AverageAnnualReturnYear01 (14.79%)
5 Years rr_AverageAnnualReturnYear05 7.06%
10 Years rr_AverageAnnualReturnYear10 8.20%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
(John Hancock Variable Insurance Trust) | (Value 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 and hold 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 medium 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 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 medium 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 in equity securities of companies with capitalizations, at the time of investment, similar to the market capitalization of companies in the Russell Midcap Value Index ($217.8 million to $28.4 billion as of February 29, 2016).

The fund invests at least 65% of its total assets in equity securities. These primarily include common stocks but may also include preferred stocks, convertible securities, rights, warrants and ADRs. The fund may invest without limit in ADRs and may invest up to 20% of its total assets in foreign equities (investments in ADRs are not foreign securities for the purposes of this limit and the fund may invest without limitation in ADRs). The fund may invest up to 15% of its net assets in real estate investment trusts, or REITs. The fund may hedge non-U.S. currency exposure through the use of forward foreign currency contracts.

The subadvisor's approach is to select equity securities which are believed to be undervalued relative to the stock market in general as measured by the Russell Midcap Value Index. Generally, medium market capitalization companies will consist primarily of those that the subadvisor believes are selling below their intrinsic value and offer the opportunity for growth of capital. The fund emphasizes a "value" style of investing focusing on those companies with strong fundamentals, consistent track records, growth prospects, and attractive valuations. The subadvisor may favor securities of companies that are in undervalued industries. The subadvisor may purchase stocks that do not pay dividends. The subadvisor may also invest the fund's assets in companies with smaller or larger market capitalizations.
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 principal risks of investing in the fund include:

Convertible securities risk. 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.

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.

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, 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. 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.

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.

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 to which a security may be sold or a derivative position closed without negatively impacting its market value, if at all, may be impaired by reduced market activity or participation, legal restrictions, or other economic and market impediments.

Real estate investment trust 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 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. Unless all share classes shown in the table have the same inception date, 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 medium. 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.
Bar Chart [Heading] rr_BarChartHeading

Calendar year total returns for Series I (%)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Best quarter: Q3 '09, 23.67%

Worst quarter: Q4 '08, –27.95%

Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns for Period Ended 12/31/2015

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.
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.
(John Hancock Variable Insurance Trust) | (Value Trust) | Russell Midcap Value Index (reflects no deduction for fees, expenses, or taxes)  
Prospectus: rr_ProspectusTable  
1 Year rr_AverageAnnualReturnYear01 (4.78%)
5 Years rr_AverageAnnualReturnYear05 11.25%
10 Years rr_AverageAnnualReturnYear10 7.61%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 01, 1997
(John Hancock Variable Insurance Trust) | (Value Trust) | Series I  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.69%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.05%
Other expenses rr_OtherExpensesOverAssets 0.04%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.11% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.89% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 91
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 284
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 493
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,096
Annual Return 2006 rr_AnnualReturn2006 21.05%
Annual Return 2007 rr_AnnualReturn2007 8.22%
Annual Return 2008 rr_AnnualReturn2008 (40.87%)
Annual Return 2009 rr_AnnualReturn2009 41.18%
Annual Return 2010 rr_AnnualReturn2010 22.22%
Annual Return 2011 rr_AnnualReturn2011 0.98%
Annual Return 2012 rr_AnnualReturn2012 17.42%
Annual Return 2013 rr_AnnualReturn2013 35.40%
Annual Return 2014 rr_AnnualReturn2014 9.82%
Annual Return 2015 rr_AnnualReturn2015 (8.89%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best quarter: Q3 '09, 23.67%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 23.67%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst quarter: Q4 '08, –27.95%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (27.95%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
1 Year rr_AverageAnnualReturnYear01 (8.89%)
5 Years rr_AverageAnnualReturnYear05 9.94%
10 Years rr_AverageAnnualReturnYear10 7.94%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 01, 1997
(John Hancock Variable Insurance Trust) | (Value Trust) | Series II  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.69%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.04%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.11% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 1.09% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 111
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 347
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 601
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,329
1 Year rr_AverageAnnualReturnYear01 (9.12%)
5 Years rr_AverageAnnualReturnYear05 9.72%
10 Years rr_AverageAnnualReturnYear10 7.72%
Date of Inception rr_AverageAnnualReturnInceptionDate Jan. 28, 2002
(John Hancock Variable Insurance Trust) | (Value Trust) | Series NAV  
Prospectus: rr_ProspectusTable  
Management fee rr_ManagementFeesOverAssets 0.69%
Distribution and service (Rule 12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.04%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.11% [4]
Total annual fund operating expenses rr_ExpensesOverAssets 0.84% [5]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 86
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 268
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 466
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,037
1 Year rr_AverageAnnualReturnYear01 (8.86%)
5 Years rr_AverageAnnualReturnYear05 10.00%
10 Years rr_AverageAnnualReturnYear10 7.98%
Date of Inception rr_AverageAnnualReturnInceptionDate Apr. 29, 2005
[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 annual net assets (on an annualized basis) 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) acquired fund fees and expenses paid indirectly, (g) borrowing costs, (h) prime brokerage fees, and (i) short dividend expense. This agreement expires on April 30, 2017, 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.
[2] "Other expenses" have been estimated for the first year of operations of the fund's Series II shares.
[3] The table reflects the combined fees of the feeder fund and the master fund.
[4] "Acquired fund fees and expenses" are based on indirect net expenses associated with the fund's investments in underlying investment companies.
[5] The "Total annual fund operating expenses" shown may not correlate to the fund's ratios of expenses to average net assets shown in the "Financial highlights" section of the fund's prospectus, which does not include "Acquired fund fees and expenses."
[6] "Other expenses" have been restated from fiscal year amounts to reflect current fees and expenses.
[7] "Management fee" has been restated to reflect the contractual management fee schedule effective January 1, 2016.
[8] "Acquired fund fees and expenses" are based on indirect net expenses associated with the fund's investments in underlying investment companies.
[9] The "Total annual fund operating expenses" shown may not correlate to the fund's ratios of expenses to average net assets shown in the "Financial highlights" section of the fund's prospectus, which does not include "Acquired fund fees and expenses."
[10] 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 net assets (on an annualized basis). The current expense limitation agreement expires on April 30, 2017, 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.
[11] "Other expenses" reflect interest expense resulting from the fund's use of certain investments such as reverse repurchase agreements or sale-buybacks. Such expense is required to be treated as a fund expense for accounting purposes. Any interest expense amount will vary based on the fund's use of those investments as an investment strategy. Had these expenses been excluded, "Other expenses" would have been 0.07%.
[12] "Other expenses" have been estimated for the first year of operations of the fund's Series I and Series II shares.
[13] "Management fee" has been restated to reflect the contractual management fee schedule effective July 1, 2015.
[14] "Other expenses" have been restated from fiscal year amounts to reflect current fees and expenses.
[15] 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 annual net assets (on an annualized basis) 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) acquired fund fees and expenses paid indirectly, (g) borrowing costs, (h) prime brokerage fees, and (i) short dividend expense. This agreement expires on April 30, 2017, 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.
[16] For funds and classes that have not commenced operations or have an inception date of less than six months as of December 31,2015, expenses are estimated.
[17] 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 0.00% of the averaged annual net assets (on an annualized basis) 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, 2017 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] 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 averaged annual net assets (on an annualized basis) 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, 2017 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] 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 averaged annual net assets (on an annualized basis) 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, 2017 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] 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, 2017, 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] "Management fee" has been restated to reflect the contractual management fee schedule effective April 6, 2016.
[22] 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 annual net assets (on an annualized basis) 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) acquired fund fees and expenses paid indirectly, (g) borrowing costs, (h) prime brokerage fees, and (i) short dividend expense. This agreement expires on April 30, 2018, 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.
[23] "Other expenses" have been estimated for the first year of operations of the fund's Series NAV shares.
[24] 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 annual net assets (on an annualized basis) 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) acquired fund fees and expenses paid indirectly, (g) borrowing costs, (h) prime brokerage fees, and (i) short dividend expense. This agreement expires on April 30, 2017, 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.
[25] "Other expenses" have been estimated for the first year of operations of the fund's Series II shares.
[26] "Other expenses" have been estimated for the first year of operations of the fund's Series I and Series II shares.
[27] "Other expenses" reflect interest expense resulting from the fund's use of certain investments such as reverse repurchase agreements or sale-buybacks. Such expense is required to be treated as a fund expense for accounting purposes. Any interest expense amount will vary based on the fund's use of those investments as an investment strategy. Had these expenses been excluded, "Other expenses" would have been 0.27%.
[28] 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, 2017, 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.
[29] 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 net assets (on an annualized basis). The current expense limitation agreement expires on April 30, 2017, 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] "Other expenses" have been estimated for the first year of operations of the fund's Series I and Series II shares.
[31] "Other expenses" have been estimated for the first year of operations of the fund's Series I and Series II shares.