DWS RREEF Real Estate Securities Fund Investment Strategy - DWS RREEF Real Estate Securities Fund	Apr. 29, 2026
Prospectus [Line Items]
Strategy [Heading]	<span style="color:#000000;font-family:Arial;font-size:10pt;font-weight:bold;text-transform:uppercase;">Principal Investment Strategies</span>
Strategy Narrative [Text Block]	Main investments. Under normal circumstances, the fund will invest at least 80% of its net assets, plus the amount of any borrowing for investment purposes (calculated at the time of any investment), in equity securities of real estate investment trusts (REITs) and real estate companies. A company is considered to be a real estate company if, in the opinion of portfolio management, at least 50% of its revenues or 50% of the market value of its assets at the time of purchase are attributed to the ownership, construction, management or sale of real estate. The fund may invest without limitation in securities of companies engaged principally in the real estate industry.The fund may also invest a portion of its assets in other types of securities. These securities may include short-term securities, bonds, notes, securities of companies not principally engaged in the real estate industry and other similar securities.Due to regulatory changes, effective June 11, 2026, the fund will replace the 80% investment policy and related disclosures set forth in this prospectus. Specifically, effective June 11, 2026, under normal circumstances, the fund invests at least 80% of net assets, plus the amount of any borrowings for investment purposes, in equity securities of real estate investment trusts (REITs) and real estate companies.Management process. In choosing securities, portfolio management uses a combination of two analytical disciplines:Top-down research. Portfolio management analyzes market-wide investment conditions to arrive at the fund’s weighting across investment sectors, such as office, industrial, retail, hospitality and residential apartment real estate sectors.Bottom-up research. Portfolio management analyzes characteristics and investment prospects of a particular security relative to others to actively manage the fund’s exposure to individual securities within each sector. Disciplined valuation analysis drives this decision-making process, guiding portfolio management to invest in securities they believe can provide superior returns over the long-term, and to sell those that they believe no longer represent the strongest prospects. In its analysis, portfolio management primarily considers a company's balance sheet, the quality and geography of the property, the management team, liquidity, and a number of environmental, social and governance (ESG) considerations, each of which can impact an investment's risks and expected returns.Securities lending. The fund may lend securities (up to one-third of total assets) to approved institutions, such as registered broker-dealers, pooled investment vehicles, banks and other financial institutions. In connection with such loans, the fund receives liquid collateral in an amount that is based on the type and value of the securities being lent, with riskier securities generally requiring higher levels of collateral.Active trading. The fund may trade securities actively and this may lead to high portfolio turnover.
Strategy Portfolio Concentration [Text]	<span style="color:#000000;font-family:Arial;font-size:10pt;">The fund </span><span style="color:#000000;font-family:Arial;font-size:10pt;">may invest without limitation in securities of companies engaged principally in the real estate industry.</span>

DWS RREEF Real Estate Securities Fund Investment Strategy - DWS RREEF Real Estate Securities Fund

Apr. 29, 2026

Principal Investment Strategies

Strategy Narrative [Text Block]

Main investments. Under normal circumstances, the fund will invest at least 80% of its net assets, plus the amount of any borrowing for investment purposes (calculated at the time of any investment), in equity securities of real estate investment trusts (REITs) and real estate companies. A company is considered to be a real estate company if, in the opinion of portfolio management, at least 50% of its revenues or 50% of the market value of its assets at the time of purchase are attributed to the ownership, construction, management or sale of real estate. The fund may invest without limitation in securities of companies engaged principally in the real estate industry.The fund may also invest a portion of its assets in other types of securities. These securities may include short-term securities, bonds, notes, securities of companies not principally engaged in the real estate industry and other similar securities.Due to regulatory changes, effective June 11, 2026, the fund will replace the 80% investment policy and related disclosures set forth in this prospectus. Specifically, effective June 11, 2026, under normal circumstances, the fund invests at least 80% of net assets, plus the amount of any borrowings for investment purposes, in equity securities of real estate investment trusts (REITs) and real estate companies.Management process. In choosing securities, portfolio management uses a combination of two analytical disciplines:Top-down research. Portfolio management analyzes market-wide investment conditions to arrive at the fund’s weighting across investment sectors, such as office, industrial, retail, hospitality and residential apartment real estate sectors.Bottom-up research. Portfolio management analyzes characteristics and investment prospects of a particular security relative to others to actively manage the fund’s exposure to individual securities within each sector. Disciplined valuation analysis drives this decision-making process, guiding portfolio management to invest in securities they believe can provide superior returns over the long-term, and to sell those that they believe no longer represent the strongest prospects. In its analysis, portfolio management primarily considers a company's balance sheet, the quality and geography of the property, the management team, liquidity, and a number of environmental, social and governance (ESG) considerations, each of which can impact an investment's risks and expected returns.Securities lending. The fund may lend securities (up to one-third of total assets) to approved institutions, such as registered broker-dealers, pooled investment vehicles, banks and other financial institutions. In connection with such loans, the fund receives liquid collateral in an amount that is based on the type and value of the securities being lent, with riskier securities generally requiring higher levels of collateral.Active trading. The fund may trade securities actively and this may lead to high portfolio turnover.

Strategy Portfolio Concentration [Text]

The fund may invest without limitation in securities of companies engaged principally in the real estate industry.