Transamerica Intermediate Muni Investment Strategy - Retail Class [Member] - Transamerica Intermediate Muni	Oct. 31, 2025
Prospectus [Line Items]
Strategy [Heading]	<span style="color:#000000;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’s sub-adviser, Belle Haven Investments, L.P. (the “sub-adviser”), invests at least 80% of the fund’s net assets (plus the amount of borrowings, if any, for investment purposes) in municipal fixed-income securities the interest from which is exempt from federal income tax and the federal alternative minimum tax (“AMT”) applicable to individuals. The fund invests primarily in general obligation and revenue bonds issued by U.S. municipal issuers, as well as issuers in U.S. territories and possessions. The fund is an actively managed, total return strategy that seeks to identify inefficiencies in the municipal bond market. The sub-adviser will invest utilizing a process that seeks to maximize total return, while adhering to longer term strategic risk management through a disciplined commitment to the diversification benefits of investment in a number of security types within the municipal bond market. The sub-adviser does this by taking a flexible approach to where it identifies value opportunities regardless of the par value. The sub-adviser also has the flexibility to invest in a broad array of issuers across the credit spectrum, although the fund is expected to have an investment grade bias. Under normal conditions, the fund’s dollar-weighted duration is more than 3 years and less than 10 years. Duration is a measure used to determine the sensitivity of a security’s price to changes in interest rates. The longer a security’s duration, the more sensitive it will be to changes in interest rates. A fixed-income security’s maturity is the date at which the security’s issuer legally agrees to repay the principal. The fund may invest no more than 25% of its net assets in securities of issuers in the same state, political subdivision or U.S. territory. The fund may invest up to 20% of its net assets in taxable investments, including U.S. high yield fixed-income securities (commonly known as “junk bonds”) rated B or higher by Standard & Poor’s. Junk bonds are those securities rated below investment grade by at least one nationally recognized statistical rating organization, or, if unrated, determined by the sub-adviser to be of comparable quality. The fund may, but is not required to, invest in derivative instruments such as options and futures for speculative, hedging, or duration management purposes. The fund may also invest in exchange-traded funds (“ETFs”).

Transamerica Intermediate Muni Investment Strategy - Retail Class [Member] - Transamerica Intermediate Muni

Oct. 31, 2025

<span style="color:#000000;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’s sub-adviser, Belle Haven Investments, L.P. (the “sub-adviser”), invests at least 80% of the fund’s net assets (plus the amount of borrowings, if any, for investment purposes) in municipal fixed-income securities the interest from which is exempt from federal income tax and the federal alternative minimum tax (“AMT”) applicable to individuals. The fund invests primarily in general obligation and revenue bonds issued by U.S. municipal issuers, as well as issuers in U.S. territories and possessions. The fund is an actively managed, total return strategy that seeks to identify inefficiencies in the municipal bond market. The sub-adviser will invest utilizing a process that seeks to maximize total return, while adhering to longer term strategic risk management through a disciplined commitment to the diversification benefits of investment in a number of security types within the municipal bond market. The sub-adviser does this by taking a flexible approach to where it identifies value opportunities regardless of the par value. The sub-adviser also has the flexibility to invest in a broad array of issuers across the credit spectrum, although the fund is expected to have an investment grade bias. Under normal conditions, the fund’s dollar-weighted duration is more than 3 years and less than 10 years. Duration is a measure used to determine the sensitivity of a security’s price to changes in interest rates. The longer a security’s duration, the more sensitive it will be to changes in interest rates. A fixed-income security’s maturity is the date at which the security’s issuer legally agrees to repay the principal. The fund may invest no more than 25% of its net assets in securities of issuers in the same state, political subdivision or U.S. territory. The fund may invest up to 20% of its net assets in taxable investments, including U.S. high yield fixed-income securities (commonly known as “junk bonds”) rated B or higher by Standard & Poor’s. Junk bonds are those securities rated below investment grade by at least one nationally recognized statistical rating organization, or, if unrated, determined by the sub-adviser to be of comparable quality. The fund may, but is not required to, invest in derivative instruments such as options and futures for speculative, hedging, or duration management purposes. The fund may also invest in exchange-traded funds (“ETFs”).