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Performance Management - The Merger Fund
Dec. 31, 2025
Prospectus [Line Items]  
Bar Chart and Performance Table [Heading] Performance Information
Performance Narrative [Text Block]

The bar chart and table below provide some indication of the potential risks of investing in the fund. The fund’s past performance, before and after taxes, is not necessarily an indication of how the fund will perform in the future.

The bar chart shows changes in the fund’s performance from year to year over a 10-year period. The table shows how the fund’s average annual returns compare to those of a broad-based securities market index and the ICE BofA US Treasury Bill 3 Month Index. Updated performance information is available at virtus.com or by calling 800-243-1574.
Performance Past Does Not Indicate Future [Text] The fund’s past performance, before and after taxes, is not necessarily an indication of how the fund will perform in the future.
Performance Information Illustrates Variability of Returns [Text] The bar chart and table below provide some indication of the potential risks of investing in the fund.
Performance Additional Market Index [Text] ICE BofA US Treasury Bill 3 Month Index (reflects no deduction for fees, expenses or taxes) 4.18% 3.17% 2.18%     The Bloomberg U.S. Aggregate Bond Index measures the U.S. investment grade fixed rate bond market. The index is calculated on a total return basis. The index is unmanaged and not available for direct investment.
Bar Chart Does Not Reflect Sales Loads [Text] Returns do not reflect sales charges applicable to other share classes and would be lower if they did.
Bar Chart [Heading] Calendar year total returns for Class I Shares 
Bar Chart Closing [Text Block]
        

Best Quarter:

2023, Q3:

3.51%

Worst Quarter:

2020, Q1:

-2.34%

Year to Date (3/31/2026):

0.82%
Performance Table Heading Average Annual Total Returns (for the periods ended 12/31/25)
Performance Table Uses Highest Federal Rate After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. After-tax returns are shown only for Class I Shares; after-tax returns for other classes will vary. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold fund shares in tax-deferred accounts or to shares held by non-taxable entities. In certain cases, the Return After Taxes on Distributions and Sale of Fund Shares for a period may be higher than other return figures for the same period. This will occur when a capital loss is realized upon the sale of fund shares and provides an assumed tax benefit that increases the return.
Performance Table Not Relevant to Tax Deferred Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold fund shares in tax-deferred accounts or to shares held by non-taxable entities.
Performance Table Explanation after Tax Higher In certain cases, the Return After Taxes on Distributions and Sale of Fund Shares for a period may be higher than other return figures for the same period. This will occur when a capital loss is realized upon the sale of fund shares and provides an assumed tax benefit that increases the return.
Performance [Table]
Average Annual Total Returns - The Merger Fund
 12 Months Ended 60 Months Ended 120 Months Ended
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Bloomberg U.S. Aggregate Bond Index | Average Annual Return, Label [Optional Text] Bloomberg U.S. Aggregate Bond Index      
Bloomberg U.S. Aggregate Bond Index | Average Annual Return, Percent   7.30% (0.36%) 2.01%
ICE BofA US Treasury Bill 3 Month Index | Average Annual Return, Label [Optional Text] ICE BofA US Treasury Bill 3 Month Index      
ICE BofA US Treasury Bill 3 Month Index | Average Annual Return, Percent   4.18% 3.17% 2.18%
Class A Shares | Average Annual Return, Label [Optional Text] Return Before Taxes      
Class A Shares | Average Annual Return, Percent   2.17% 2.01% 3.34%
Class I Shares | Average Annual Return, Label [Optional Text] Return Before Taxes      
Class I Shares | Average Annual Return, Percent   8.41% 3.47% 4.24%
Class I Shares | After Taxes on Distributions | Average Annual Return, Label [Optional Text] Return After Taxes on Distributions      
Class I Shares | After Taxes on Distributions | Average Annual Return, Percent   5.32% 2.01% 3.11%
Class I Shares | After Taxes on Distributions and Sales | Average Annual Return, Label [Optional Text] Return After Taxes on Distributions and Sale of Fund Shares      
Class I Shares | After Taxes on Distributions and Sales | Average Annual Return, Percent   5.12% 2.10% 2.89%
Performance Table One Class of after Tax Shown [Text] After-tax returns are shown only for Class I Shares; after-tax returns for other classes will vary.
Index No Deduction for Fees, Expenses, or Taxes [Text] (reflects no deduction for fees, expenses or taxes)
Performance Table Closing [Text Block]

The Bloomberg U.S. Aggregate Bond Index measures the U.S. investment grade fixed rate bond market. The index is calculated on a total return basis. The index is unmanaged and not available for direct investment.

ICE BofA US Treasury Bill 3 Month Index measures performance of the three-month Treasury bill, based on monthly average auction rates. The index is calculated on a total-return basis, is unmanaged and not available for direct investment.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. After-tax returns are shown only for Class I Shares; after-tax returns for other classes will vary. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold fund shares in tax-deferred accounts or to shares held by non-taxable entities. In certain cases, the Return After Taxes on Distributions and Sale of Fund Shares for a period may be higher than other return figures for the same period. This will occur when a capital loss is realized upon the sale of fund shares and provides an assumed tax benefit that increases the return.
Performance Availability Website Address [Text] virtus.com
Performance Availability Phone [Text] 800-243-1574
Class I Shares  
Prospectus [Line Items]  
Year to Date Return, Label [Optional Text] Year to Date
Bar Chart, Year to Date Return 0.82%
Bar Chart, Year to Date Return, Date Mar. 31, 2026
Highest Quarterly Return, Label [Optional Text] Best Quarter
Highest Quarterly Return 3.51%
Highest Quarterly Return, Date Sep. 30, 2023
Lowest Quarterly Return, Label [Optional Text] Worst Quarter
Lowest Quarterly Return (2.34%)
Lowest Quarterly Return, Date Mar. 31, 2020