The fund invests mainly in bonds and securitized debt instruments (such as mortgage-backed investments) that are obligations of companies and governments worldwide; that are investment-grade in quality; and that have intermediate - to long-term maturities (three years or longer). The fund currently has significant investment exposure to residential and commercial mortgage-backed securities. Under normal circumstances, the fund invests at least 80% of its net assets in investment-grade securities. This policy may be changed only after 60 days’ notice to shareholders. The fund may also invest in bonds that are below investment-grade in quality (sometimes referred to as “junk bonds”).

The Investment Manager, as defined below, may consider, among other factors, credit, interest rate and prepayment risks, as well as general market conditions, when deciding whether to buy or sell investments. The fund typically uses, to a significant extent, derivatives, including credit default swaps, interest rate swaps, total return swaps, to‑be‑announced (TBA) commitments, futures, options and swaptions on mortgage-backed securities and indices, and certain foreign currency transactions, for both hedging and non‑hedging purposes, including to obtain or adjust exposure to mortgage-backed investments.

The fund is “non‑diversified,” which means it may invest a greater percentage of its assets in fewer issuers than a “diversified” fund. The fund expects to invest in a limited number of issuers.

Investment Strategy - PUTNAM GLOBAL INCOME TRUST	Oct. 31, 2025
Prospectus [Line Items]
Strategy [Heading]	Investments, risks, and performance Investments
Strategy Narrative [Text Block]	The fund invests mainly in bonds and securitized debt instruments (such as mortgage-backed investments) that are obligations of companies and governments worldwide; that are investment-grade in quality; and that have intermediate - to long-term maturities (three years or longer). The fund currently has significant investment exposure to residential and commercial mortgage-backed securities. Under normal circumstances, the fund invests at least 80% of its net assets in investment-grade securities. This policy may be changed only after 60 days’ notice to shareholders. The fund may also invest in bonds that are below investment-grade in quality (sometimes referred to as “junk bonds”). The Investment Manager, as defined below, may consider, among other factors, credit, interest rate and prepayment risks, as well as general market conditions, when deciding whether to buy or sell investments. The fund typically uses, to a significant extent, derivatives, including credit default swaps, interest rate swaps, total return swaps, to‑be‑announced (TBA) commitments, futures, options and swaptions on mortgage-backed securities and indices, and certain foreign currency transactions, for both hedging and non‑hedging purposes, including to obtain or adjust exposure to mortgage-backed investments. The fund is “non‑diversified,” which means it may invest a greater percentage of its assets in fewer issuers than a “diversified” fund. The fund expects to invest in a limited number of issuers.