Investment Strategy	Dec. 31, 2025
CVT S&P 500 Index Portfolio
Prospectus [Line Items]
Strategy Narrative [Text Block]	The Fund intends to be diversified in approximately the same proportion as the Index is diversified. The Fund may become “non-diversified,” as defined in the Investment Company Act of 1940 (the “1940 Act”), solely as a result of a change in relative market capitalization or index weighting of one or more constituents of the Index. Shareholder approval will not be sought if the Fund becomes “non-diversified” due solely to a change in the relative market capitalization or index weighting of one or more constituents of the Index.
CVT S&P MidCap 400 Index Portfolio
Prospectus [Line Items]
Strategy Narrative [Text Block]	The Fund intends to be diversified in approximately the same proportion as the Index is diversified. The Fund may become “non-diversified,” as defined in the Investment Company Act of 1940 (the “1940 Act”), solely as a result of a change in relative market capitalization or index weighting of one or more constituents of the Index. Shareholder approval will not be sought if the Fund becomes “non-diversified” due solely to a change in the relative market capitalization or index weighting of one or more constituents of the Index.
CVT Russell 2000 Small Cap Index Portfolio
Prospectus [Line Items]
Strategy Narrative [Text Block]	The Fund intends to be diversified in approximately the same proportion as the Index is diversified. The Fund may become “non-diversified,” as defined in the Investment Company Act of 1940 (the “1940 Act”), solely as a result of a change in relative market capitalization or index weighting of one or more constituents of the Index. Shareholder approval will not be sought if the Fund becomes “non-diversified” due solely to a change in the relative market capitalization or index weighting of one or more constituents of the Index.
CVT EAFE International Index Portfolio
Prospectus [Line Items]
Strategy Narrative [Text Block]	The Fund intends to be diversified in approximately the same proportion as the Index is diversified. The Fund may become “non-diversified,” as defined in the Investment Company Act of 1940 (the “1940 Act”), solely as a result of a change in relative market capitalization or index weighting of one or more constituents of the Index. Shareholder approval will not be sought if the Fund becomes “non-diversified” due solely to a change in the relative market capitalization or index weighting of one or more constituents of the Index.
CVT Investment Grade Bond Index Portfolio
Prospectus [Line Items]
Strategy Narrative [Text Block]	The Fund intends to be diversified in approximately the same proportion as the Index is diversified. The Fund may become “non-diversified,” as defined in the Investment Company Act of 1940 (the “1940 Act”), solely as a result of a change in relative market capitalization or index weighting of one or more constituents of the Index. Shareholder approval will not be sought if the Fund becomes “non-diversified” due solely to a change in the relative market capitalization or index weighting of one or more constituents of the Index.

The Fund intends to be diversified in approximately the same proportion as the Index is diversified. The Fund may become “non-diversified,” as defined in the Investment Company Act of 1940 (the “1940 Act”), solely as a result of a change in relative market capitalization or index weighting of one or more constituents of the Index. Shareholder approval will not be sought if the Fund becomes “non-diversified” due solely to a change in the relative market capitalization or index weighting of one or more constituents of the Index.

Prospectus [Line Items]

Strategy Narrative [Text Block]

The Fund intends to be diversified in approximately the same proportion as the Index is diversified. The Fund may become “non-diversified,” as defined in the Investment Company Act of 1940 (the “1940 Act”), solely as a result of a change in relative market capitalization or index weighting of one or more constituents of the Index. Shareholder approval will not be sought if the Fund becomes “non-diversified” due solely to a change in the relative market capitalization or index weighting of one or more constituents of the Index.