Transamerica Mid Cap Value Opportunities Investment Strategy - Retail Class [Member] - Transamerica Mid Cap Value Opportunities	Oct. 31, 2025
Prospectus [Line Items]
Strategy [Heading]	<span style="font-family:Times New Roman;font-size:10pt;font-weight:bold;margin-left:0%;">Principal Investment Strategies:</span>
Strategy Narrative [Text Block]	Under normal circumstances, the fund invests at least 80% of its net assets (plus the amount of borrowings, if any, for investment purposes) in equity securities of mid cap companies. The fund's sub-adviser, Thompson, Siegel & Walmsley LLC (the “sub-adviser”), considers mid cap companies to be those companies, at the time of purchase, with market capitalizations within the range of companies included in the Russell Midcap® Value Index1, a benchmark of the fund, (between approximately $7 billion and $59 billion as of June 30, 2025, the date of the last reconstitution). The size of the companies in the Russell Midcap® Value Index will change with market conditions. The fund invests primarily in common stocks. The fund may invest in other equity and non-equity securities, including preferred stocks, convertible securities and foreign securities which may take the form of depositary receipts. The fund typically invests in a relatively small number of companies. The sub-adviser seeks to invest in companies it believes present a value or potential worth that is not recognized by prevailing market prices or that have experienced some fundamental changes and are intrinsically undervalued by the investment community. The sub-adviser's mid cap value process uses a combination of quantitative and qualitative methods and is based on a four-factor valuation screen. Parts one and two of the screen attempt to assess a company's discount to private market value relative to other mid cap stocks. The third factor considers the relative earnings prospects of the company. The fourth factor involves looking at the company's recent price action. Value stocks as a group may be out of favor and underperform the overall equity market for a long period of time, for example, while the market favors “growth” stocks. The sub-adviser's analysts also explore numerous factors that might affect the outlook for a company. They evaluate publicly available information including, but not limited to, sell-side research, company filings, and trade periodicals. The analysts may speak with company management to hear their perspectives and outlook on pertinent business issues. They apply a consistent and disciplined review in a team environment that encourages critical thinking and analysis for each company considered for investment. The sub-adviser generally considers selling a security when the catalyst for the investment is no longer valid, when the sub-adviser believes that another stock will have a higher expected return, or for portfolio risk management. The fund generally engages in active and frequent trading of portfolio securities as part of its principal investment strategy.1 “Russell®” and other service marks and trademarks related to the Russell indexes are trademarks of the London Stock Exchange Group companies.

Transamerica Mid Cap Value Opportunities Investment Strategy - Retail Class [Member] - Transamerica Mid Cap Value Opportunities

Oct. 31, 2025

<span style="font-family:Times New Roman;font-size:10pt;font-weight:bold;margin-left:0%;">Principal Investment Strategies:</span>

Strategy Narrative [Text Block]

Under normal circumstances, the fund invests at least 80% of its net assets (plus the amount of borrowings, if any, for investment purposes) in equity securities of mid cap companies. The fund's sub-adviser, Thompson, Siegel & Walmsley LLC (the “sub-adviser”), considers mid cap companies to be those companies, at the time of purchase, with market capitalizations within the range of companies included in the Russell Midcap® Value Index1, a benchmark of the fund, (between approximately $7 billion and $59 billion as of June 30, 2025, the date of the last reconstitution). The size of the companies in the Russell Midcap® Value Index will change with market conditions. The fund invests primarily in common stocks. The fund may invest in other equity and non-equity securities, including preferred stocks, convertible securities and foreign securities which may take the form of depositary receipts. The fund typically invests in a relatively small number of companies. The sub-adviser seeks to invest in companies it believes present a value or potential worth that is not recognized by prevailing market prices or that have experienced some fundamental changes and are intrinsically undervalued by the investment community. The sub-adviser's mid cap value process uses a combination of quantitative and qualitative methods and is based on a four-factor valuation screen. Parts one and two of the screen attempt to assess a company's discount to private market value relative to other mid cap stocks. The third factor considers the relative earnings prospects of the company. The fourth factor involves looking at the company's recent price action. Value stocks as a group may be out of favor and underperform the overall equity market for a long period of time, for example, while the market favors “growth” stocks. The sub-adviser's analysts also explore numerous factors that might affect the outlook for a company. They evaluate publicly available information including, but not limited to, sell-side research, company filings, and trade periodicals. The analysts may speak with company management to hear their perspectives and outlook on pertinent business issues. They apply a consistent and disciplined review in a team environment that encourages critical thinking and analysis for each company considered for investment. The sub-adviser generally considers selling a security when the catalyst for the investment is no longer valid, when the sub-adviser believes that another stock will have a higher expected return, or for portfolio risk management. The fund generally engages in active and frequent trading of portfolio securities as part of its principal investment strategy.1 “Russell®” and other service marks and trademarks related to the Russell indexes are trademarks of the London Stock Exchange Group companies.