DWS Government and Agency Securities Portfolio Investment Strategy - DWS Gov Cash Inst Shares [Member] - DWS Government and Agency Securities Portfolio	Apr. 30, 2025
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. The fund is a money market fund that is managed in accordance with federal regulations which govern the quality, maturity, diversity and liquidity of instruments in which a money market fund may invest.The fund operates as a “government money market fund,” as such term is defined under federal regulations. As a government money market fund, the fund is required to invest at least 99.5% of its total assets at the time of investment in cash, US government securities, and/or repurchase agreements that are collateralized by these instruments.Due to regulatory changes, effective June 11, 2026, the fund will adopt an 80% investment policy and related disclosures set forth in this prospectus. Specifically, effective June 11, 2026, under normal circumstances, the fund will invest at least 80% of net assets, plus the amount of any borrowings for investment purposes, in US government securities and/or repurchase agreements that are collateralized by US government securities. For purposes of the 80% investment policy, US government securities are obligations issued or guaranteed as to both principal and interest by the US government, its agencies, instrumentalities or sponsored enterprises which include: (a) direct obligations of the US Treasury; and (b) securities issued or guaranteed by US government agencies.The fund follows policies designed to maintain a stable $1.00 share price.The fund pursues its objective by investing exclusively in the following types of investments:■US Treasury bills, notes, bonds and other obligations issued or guaranteed by the US government, its agencies or instrumentalities. ■Repurchase agreements backed by these instruments. In a repurchase agreement, the fund buys securities at one price with a simultaneous agreement to sell back the securities at a future date at an agreed-upon price.The fund may invest in floating and variable rate instruments (obligations that do not bear interest at fixed rates).Management process. Working in consultation with portfolio management, a credit team screens potential securities and develops a list of those that the fund may buy. Portfolio management, looking for attractive yield and weighing considerations such as credit quality, economic outlooks and possible interest rate movements, then decides which securities on this list to buy.

DWS Government and Agency Securities Portfolio Investment Strategy - DWS Gov Cash Inst Shares [Member] - DWS Government and Agency Securities Portfolio

Apr. 30, 2025

<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. The fund is a money market fund that is managed in accordance with federal regulations which govern the quality, maturity, diversity and liquidity of instruments in which a money market fund may invest.The fund operates as a “government money market fund,” as such term is defined under federal regulations. As a government money market fund, the fund is required to invest at least 99.5% of its total assets at the time of investment in cash, US government securities, and/or repurchase agreements that are collateralized by these instruments.Due to regulatory changes, effective June 11, 2026, the fund will adopt an 80% investment policy and related disclosures set forth in this prospectus. Specifically, effective June 11, 2026, under normal circumstances, the fund will invest at least 80% of net assets, plus the amount of any borrowings for investment purposes, in US government securities and/or repurchase agreements that are collateralized by US government securities. For purposes of the 80% investment policy, US government securities are obligations issued or guaranteed as to both principal and interest by the US government, its agencies, instrumentalities or sponsored enterprises which include: (a) direct obligations of the US Treasury; and (b) securities issued or guaranteed by US government agencies.The fund follows policies designed to maintain a stable $1.00 share price.The fund pursues its objective by investing exclusively in the following types of investments:■US Treasury bills, notes, bonds and other obligations issued or guaranteed by the US government, its agencies or instrumentalities. ■Repurchase agreements backed by these instruments. In a repurchase agreement, the fund buys securities at one price with a simultaneous agreement to sell back the securities at a future date at an agreed-upon price.The fund may invest in floating and variable rate instruments (obligations that do not bear interest at fixed rates).Management process. Working in consultation with portfolio management, a credit team screens potential securities and develops a list of those that the fund may buy. Portfolio management, looking for attractive yield and weighing considerations such as credit quality, economic outlooks and possible interest rate movements, then decides which securities on this list to buy.