S000021579 [Member] Investment Strategy - S000021579 [Member]	Apr. 30, 2025
Prospectus [Line Items]
Strategy [Heading]	Principal Investment Strategies
Strategy Narrative [Text Block]	Under normal circumstances, the Fund invests at least 80% of its net assets (including the amount of any borrowings for investment purposes) in bonds and other debt securities. The Fund generally invests at least 65% of its assets in debt securities issued by the U.S. Government and its agencies and instrumentalities, debt securities issued by corporations, and mortgage- and other asset-backed securities that, at the time of purchase, are rated in at least one of the three highest rating categories or are unrated but determined to be of comparable quality. The Fund may invest up to 25% of its net assets in debt instruments that, at the time of purchase, are rated below investment grade or are unrated but determined to be of comparable quality (commonly referred to as “high yield” investments or “junk” bonds). The Fund may invest up to 25% of its assets in U.S. dollar-denominated foreign debt securities and instruments, including those of foreign governments, non-governmental issuers or other entities, and up to 20% of its assets in preferred stock. The Fund’s dollar-weighted average maturity and duration will vary over time depending on expectations for market and economic conditions. The Fund may invest in derivatives, such as futures (including interest rate futures) and swaps (including credit default swaps, credit default swap indexes, and interest rate swaps) for hedging and investment purposes, and to manage interest rate and/or credit exposure of the Fund. The Fund may purchase or sell securities on a when-issued, delayed delivery or forward commitment basis. Such securities may include mortgage-backed securities acquired or sold in the “to be announced” (TBA) market and those in a dollar roll transaction. The Fund may invest in privately placed and other securities or instruments that are purchased and sold pursuant to Rule 144A or other exemptions under the Securities Act of 1933, as amended, subject to certain regulatory restrictions. The Fund’s investment strategy may involve the frequent trading of portfolio securities.

Under normal circumstances, the Fund invests at least 80% of its net assets (including the amount of any borrowings for investment purposes) in bonds and other debt securities. The Fund generally invests at least 65% of its assets in debt securities issued by the U.S. Government and its agencies and instrumentalities, debt securities issued by corporations, and mortgage- and other asset-backed securities that, at the time of purchase, are rated in at least one of the three highest rating categories or are unrated but determined to be of comparable quality. The Fund may invest up to 25% of its net assets in debt instruments that, at the time of purchase, are rated below investment grade or are unrated but determined to be of comparable quality (commonly referred to as “high yield” investments or “junk” bonds).

The Fund may invest up to 25% of its assets in U.S. dollar-denominated foreign debt securities and instruments, including those of foreign governments, non-governmental issuers or other entities, and up to 20% of its assets in preferred stock. The Fund’s dollar-weighted average maturity and duration will vary over time depending on expectations for market and economic conditions.

The Fund may invest in derivatives, such as futures (including interest rate futures) and swaps (including credit default swaps, credit default swap indexes, and interest rate swaps) for hedging and investment purposes, and to manage interest rate and/or credit exposure of the Fund.

The Fund may purchase or sell securities on a when-issued, delayed delivery or forward commitment basis. Such securities may include mortgage-backed securities acquired or sold in the “to be announced” (TBA) market and those in a dollar roll transaction.

The Fund may invest in privately placed and other securities or instruments that are purchased and sold pursuant to Rule 144A or other exemptions under the Securities Act of 1933, as amended, subject to certain regulatory restrictions.