Prospectus: Series [Axis] Series S000005203 Member Eaton Vance VT Floating-Rate Income Fund Eaton Vance VT Floating Rate Income Fund. S000013808 Member Eaton Vance VT Large-Cap Value Fund Eaton Vance VT Large Cap Value Fund. Risk/Return: Risk/Return [Heading] Objective [Heading] Objective, Primary [Text Block] Expense [Heading] Expense Narrative [Text Block] Operating Expenses Caption [Text] Annual Fund Operating Expenses [Table] Expense Example [Heading] Expense Example Narrative [Text Block] Expense Example, With Redemption [Table] Portfolio Turnover [Heading] Portfolio Turnover [Text Block] Strategy [Heading] Strategy Narrative [Text Block] Risk [Heading] Risk Narrative [Text Block] Bar Chart and Performance Table [Heading] Performance Narrative [Text Block] Bar Chart [Table] Bar Chart Closing [Text Block] Caption Performance [Table] Market Index Performance [Table] Annual Fund Operating Expenses Operating Expenses: Management Fees Management Fees (as a percentage of Assets) Distribution (12b-1) Fees Distribution and Service (12b-1) Fees Service Fees Distribution or Similar (Non 12b-1) Fees Other Expenses Other Expenses Other Expenses (as a percentage of Assets): Total Annual Fund Operating Expenses Total Expenses Expenses (as a percentage of Assets) Expense Reimbursement Expense Reimbursement Fee Waiver or Reimbursement Fee Waiver or Reimbursement Total Annual Fund Operating Expenses After Expense Reimbursement Net Expenses Net Expenses (as a percentage of Assets) Example Expense Example: Fund Shares Column Expense Example, By Year, Column [Text] 1 Year 1 Year Expense Example, with Redemption, 1 Year 3 Years 3 Years Expense Example, with Redemption, 3 Years 5 Years 5 Years Expense Example, with Redemption, 5 Years 10 Years 10 Years Expense Example, with Redemption, 10 Years Annual Total Returns Bar Chart Table: 2002 Annual Return 2002 2003 Annual Return 2003 2004 Annual Return 2004 2005 Annual Return 2005 2006 Annual Return 2006 2007 Annual Return 2007 2008 Annual Return 2008 2009 Annual Return 2009 2010 Annual Return 2010 2011 Annual Return 2011 Performance Measure [Axis] Performance Measure S And P Lsta Leveraged Loan Index Member S&P/LSTA Leveraged Loan Index S And P Lsta Leveraged Loan Index. Average Annual Total Return Average Annual Return: Label Index No Deduction for Fees, Expenses, Taxes [Text] One Year 1 Year Five Years 5 Years Ten Years 10 Years Russell Thousand Value Index Member Russell 1000 Value Index Russell Thousand Value Index. Life of Fund Since Inception Document Type Document Period End Date Registrant Name Central Index Key Amendment Flag Document Creation Date Document Effective Date Prospectus Date Fund Fees And Expenses Abstract Fees and Expenses of the Fund Fund Fees And Expenses. Fee Waiver or Reimbursement over Assets, Date of Termination Portfolio Turnover Alt Abstract Portfolio Turnover Portfolio Turnover Alt. Portfolio Turnover, Rate Strategy Portfolio Concentration [Text] Risk Lose Money [Text] Risk Not Insured Depository Institution [Text] Fund Past Performance Abstract Performance Fund Past Performance. Performance Information Illustrates Variability of Returns [Text] Bar Chart Does Not Reflect Sales Loads [Text] Performance Past Does Not Indicate Future [Text] Highest Quarterly Return, Label Highest Quarterly Return, Date Highest Quarterly Return Lowest Quarterly Return, Label Lowest Quarterly Return, Date Lowest Quarterly Return Performance Additional Market Index [Text]