Managed Volatility Moderate Portfolio Performance Management - Managed Volatility Moderate Portfolio	Dec. 31, 2024
Prospectus [Line Items]
Performance Narrative [Text Block]	The following information illustrates the variability of the fund’s returns and provides some indication of the risks of investing in the fund by showing changes in the fund’s performance from year to year and by showing how the fund’s average annual returns compared with a broad-based securities market index. Past performance does not indicate future results. The Morningstar U.S. Moderately Conservative Target Allocation Index and the fund’s custom blended benchmark, the “John Hancock Lifestyle Moderate Index,” show how the fund’s performance compares against the returns of similar investments. All figures assume dividend reinvestment. The performance information below does not reflect fees and expenses of any variable insurance contract which may use JHVIT as its underlying investment option. If such fees and expenses had been reflected, performance would be lower.
Performance Past Does Not Indicate Future [Text]	<span style="color:#000000;font-family:Arial Narrow;font-size:9pt;">Past performance does not indicate future results.</span>
Performance Information Illustrates Variability of Returns [Text]	<span style="color:#000000;font-family:Arial Narrow;font-size:9pt;">The following information illustrates the variability of the fund’s returns and provides some indication of the risks of investing in the fund by showing changes in the fund’s performance from year to year and by showing how the fund’s average annual returns compared with a broad-based securities market index. </span>
Performance Additional Market Index [Text]	<span style="color:#000000;font-family:Arial Narrow;font-size:8pt;">Prior to July 1, 2026, the fund’s additional benchmark was the 28% Russell 3000 Index/12% MSCI EAFE Index/60% Bloomberg U.S. Aggregate Bond Index. Effective July 1, 2026, the fund’s additional benchmark is the John Hancock Lifestyle Moderate Index. The John Hancock Lifestyle Moderate Index better reflects the universe of investment opportunities based on the fund’s investment strategy. As of January 1, 2025, the John Hancock Lifestyle Moderate Index comprises 21.2% of the S&P 500 Index, 8.6% of the MSCI World ex-USA Index, 5.4% of the Russell 2500 Index, 2.9% of the MSCI Emerging Markets Index, 2.0% of the John Hancock Real Asset Blended Index, 4.5% of the ICE BofA U.S. High Yield Index, 4.5% of the JPMorgan EMBI Global Index, 4.5% of the S&P/LSTA Leveraged Loan Index, 38.5% of the Bloomberg U.S. Aggregate Bond Index, 2.0% of the ICE BofA Long U.S. STRIPS Index, and 6.0% of the Bloomberg 1-5 Year TIPS Index.</span>
Performance Table Heading	<span style="color:#000000;font-family:Arial Narrow;font-size:8pt;font-weight:bold;margin-left:0.0pt;">Average annual total returns (%)—as of 12/31/2024</span>
Performance Table Market Index Changed	<span style="color:#000000;font-family:Arial Narrow;font-size:8pt;">Prior to July 1, 2026, the fund’s additional benchmark was the 28% Russell 3000 Index/12% MSCI EAFE Index/60% Bloomberg U.S. Aggregate Bond Index. Effective July 1, 2026, the fund’s additional benchmark is the John Hancock Lifestyle Moderate Index. The John Hancock Lifestyle Moderate Index better reflects the universe of investment opportunities based on the fund’s investment strategy. As of January 1, 2025, the John Hancock Lifestyle Moderate Index comprises 21.2% of the S&P 500 Index, 8.6% of the MSCI World ex-USA Index, 5.4% of the Russell 2500 Index, 2.9% of the MSCI Emerging Markets Index, 2.0% of the John Hancock Real Asset Blended Index, 4.5% of the ICE BofA U.S. High Yield Index, 4.5% of the JPMorgan EMBI Global Index, 4.5% of the S&P/LSTA Leveraged Loan Index, 38.5% of the Bloomberg U.S. Aggregate Bond Index, 2.0% of the ICE BofA Long U.S. STRIPS Index, and 6.0% of the Bloomberg 1-5 Year TIPS Index.</span>