Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JOHN HANCOCK VARIABLE INSURANCE TRUST
Prospectus Date	rr_ProspectusDate	Aug. 27, 2012
International Equity Index Trust B | Prospectus Series I, Series II and Series NAV Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	INTERNATIONAL EQUITY INDEX TRUST B
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 for the variable insurance contracts and would be higher if they did. For more information on the fees of the variable insurance contracts see the contract prospectus.
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, 2014
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 3% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	3.00%
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, 2011, expenses are estimated.
Expense Example [Heading]	rr_ExpenseExampleHeading	Examples.
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 examples do not reflect fees and expenses for the variable insurance contracts 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	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 May 31, 2012, the market capitalization range of the Index was $26 million to $249 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 their 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 subadviser 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 subadviser invests in stock index futures to maintain market exposure and manage cash flow. Although it 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). As an example of how derivatives may be used, the fund may invest in stock index futures to manage cash flow. 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 adviser or sub-adviser).
Risk [Heading]	rr_RiskHeading	Principal Risks of Investing in the Fund
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: Depositary receipt risk The value of depositary receipts, such as ADRs, GDRs and EDRs, will fluctuate with the value of the underlying securities and will reflect any changes in exchange rates against the U.S. dollar. Because GDRs and EDRs may not be denominated in the same currencies as those of the underlying securities, the fund also may be subject to changes in exchange rates between different foreign currencies. An investment in depositary receipts involves the same risks associated with investing in foreign securities. Economic and market events risk Events in the financial markets have resulted, and may continue to result, in an unusually high degree of volatility in the financial markets, both domestic and foreign. In addition, reduced liquidity in credit and fixed-income markets may adversely affect issuers worldwide. Equity securities risk The value of a company’s equity securities is subject to changes in the company’s financial condition, and overall market and economic conditions. Exchange-traded funds risk Owning an ETF generally reflects the risks of owning the underlying securities it is designed to track. Foreign securities risk As compared to U.S. companies, there may be less publicly available information relating to foreign companies. Foreign securities may be subject to foreign taxes. The value of foreign securities is subject to currency fluctuations and adverse political and economic developments. Investments in emerging-market countries are subject to greater levels of foreign investment risk. Hedging, derivatives and other strategic transactions risk Hedging and other strategic transactions may increase the volatility of a fund and, if the transaction is not successful, could result in a significant loss to a fund. The use of derivative instruments could produce disproportionate gains or losses, more than the principal amount invested. Investing in derivative instruments involves risks different from, or possibly greater than, the risks associated with investing directly in securities and other traditional investments and, in a down market, could become harder to value or sell at a fair price. The following is a list of certain derivatives and other strategic transactions in which the fund may invest and the main risks associated with each of them: Currency options Counterparty risk, liquidity risk (i.e., the inability to enter into closing transactions) and risk of disproportionate loss are the principal risks of engaging in transactions involving options. Futures contracts Counterparty risk, liquidity risk (i.e., the inability to enter into closing transactions) and risk of disproportionate loss are the principal risks of engaging in transactions involving futures contracts. Options Counterparty risk, liquidity risk (i.e., the inability to enter into closing transactions) and risk of disproportionate loss are the principal risks of engaging in transactions involving options. Counterparty risk does not apply to exchange-traded options. 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. Index management risk Certain factors may cause a fund that is an index fund to track its target index less closely. For example, a subadviser 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. Issuer risk An issuer of a security may perform poorly and, therefore, the value of its stocks and bonds may decline. An issuer of securities held by the fund could default or have its credit rating downgraded. Large company risk Large-capitalization stocks as a group could fall out of favor with the market, causing the fund to underperform investments that focus on small- or medium-capitalization stocks. Larger, more established companies may be slow to respond to challenges and may grow more slowly than smaller companies. For purposes of the fund’s investment policies, the market capitalization of a company is based on its market capitalization at the time the fund purchases the company’s securities. Market capitalizations of companies change over time. Medium and smaller company risk The prices of medium and smaller company stocks can change more frequently and dramatically than those of large company stocks. For purposes of the fund’s investment policies, the market capitalization of a company is based on its market capitalization at the time the fund purchases the company’s securities. Market capitalizations of companies change over time.
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 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 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, THE International Equity Index Fund, a series of John Hancock Variable Series Trust I. 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.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the fund by showing changes in performance from year to year and by showing how average annual returns for specified periods compare with those of a broad measure of market performance.
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The past performance of the fund is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Calendar year total returns for Series NAV:
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	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.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter: 27.40% (Quarter ended 6/30/2009) Worst Quarter: -22.28% (Quarter ended 12/31/2008)
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns for period ended 12/31/2011
International Equity Index Trust B | Prospectus Series I, Series II and Series NAV Shares | Series I
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.54%	[1]
Distribution and service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.05%	[1]
Other Expenses	rr_OtherExpensesOverAssets	0.04%	[1]
Total fund operating Expenses	rr_ExpensesOverAssets	0.63%	[1]
Contractual expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.24%)	[1],[2]
Net fund operating expenses	rr_NetExpensesOverAssets	0.39%	[1]
Year 1	rr_ExpenseExampleYear01	40
Year 3	rr_ExpenseExampleYear03	178
Year 5	rr_ExpenseExampleYear05	327
Year 10	rr_ExpenseExampleYear10	763
One Year	rr_AverageAnnualReturnYear01	(13.99%)
Five Year	rr_AverageAnnualReturnYear05	(3.04%)
Ten Year	rr_AverageAnnualReturnYear10	6.31%
Date of Inception	rr_AverageAnnualReturnInceptionDate	Aug. 27, 2012
International Equity Index Trust B | Prospectus Series I, Series II and Series NAV Shares | Series II
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.54%	[1]
Distribution and service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.25%	[1]
Other Expenses	rr_OtherExpensesOverAssets	0.04%	[1]
Total fund operating Expenses	rr_ExpensesOverAssets	0.83%	[1]
Contractual expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.24%)	[1],[2]
Net fund operating expenses	rr_NetExpensesOverAssets	0.59%	[1]
Year 1	rr_ExpenseExampleYear01	60
Year 3	rr_ExpenseExampleYear03	241
Year 5	rr_ExpenseExampleYear05	437
Year 10	rr_ExpenseExampleYear10	1,003
One Year	rr_AverageAnnualReturnYear01	(13.99%)
Five Year	rr_AverageAnnualReturnYear05	(3.04%)
Ten Year	rr_AverageAnnualReturnYear10	6.31%
Date of Inception	rr_AverageAnnualReturnInceptionDate	Aug. 27, 2012
International Equity Index Trust B | Prospectus Series I, Series II and Series NAV Shares | Series NAV
Risk/Return:	rr_RiskReturnAbstract
Management fee	rr_ManagementFeesOverAssets	0.54%
Distribution and service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.04%
Total fund operating Expenses	rr_ExpensesOverAssets	0.58%
Contractual expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.24%)	[2]
Net fund operating expenses	rr_NetExpensesOverAssets	0.34%
Year 1	rr_ExpenseExampleYear01	35
Year 3	rr_ExpenseExampleYear03	162
Year 5	rr_ExpenseExampleYear05	300
Year 10	rr_ExpenseExampleYear10	703
2002	rr_AnnualReturn2002	(15.18%)
2003	rr_AnnualReturn2003	41.99%
2004	rr_AnnualReturn2004	20.24%
2005	rr_AnnualReturn2005	16.58%
2006	rr_AnnualReturn2006	27.41%
2007	rr_AnnualReturn2007	15.76%
2008	rr_AnnualReturn2008	(44.36%)
2009	rr_AnnualReturn2009	38.80%
2010	rr_AnnualReturn2010	11.44%
2011	rr_AnnualReturn2011	(13.99%)
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	27.40%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(22.28%)
One Year	rr_AverageAnnualReturnYear01	(13.99%)
Five Year	rr_AverageAnnualReturnYear05	(3.04%)
Ten Year	rr_AverageAnnualReturnYear10	6.31%
Date of Inception	rr_AverageAnnualReturnInceptionDate	Apr. 29, 2005
International Equity Index Trust B | Prospectus Series I, Series II and Series NAV Shares | MSCI AC World Ex US Index (gross of foreign withholding taxes on dividends)
Risk/Return:	rr_RiskReturnAbstract
One Year	rr_AverageAnnualReturnYear01	(13.33%)
Five Year	rr_AverageAnnualReturnYear05	(2.48%)
Ten Year	rr_AverageAnnualReturnYear10	6.76%
Date of Inception	rr_AverageAnnualReturnInceptionDate	Apr. 29, 2005

[1] For funds and classes that have not commenced operations or have an inception date of less than six months as of December 31, 2011, expenses are estimated.

[2] Adviser contractually agrees until April 30, 2014 to waive certain fund expenses.