Vanguard Long-Term Treasury Fund Investment Strategy - Retail Prospectus [Member] - Vanguard Long-Term Treasury Fund |
Jan. 31, 2026 |
|---|---|
| Prospectus [Line Items] | |
| Strategy [Heading] | <span style="color:#000000;font-family:Arial;font-size:10pt;font-weight:bold;">Principal Investment Strategies</span> |
| Strategy Narrative [Text Block] | The Fund employs an active management approach. Under normal circumstances, the Fund invests at least 80% of its net assets, plus the amount of any borrowings for investment purposes, in U.S. Treasury securities, which include bills, bonds, and notes issued by the U.S. Treasury. The Fund expects to maintain a dollar-weighted average maturity of 15 to 30 years.In addition to U.S. Treasury securities, the Fund may invest in other types of fixed income securities. These may include bonds issued by agencies and instrumentalities of the U.S. government or mortgage-backed securities. The Fund also may invest in derivatives such as options, futures contracts, or swap agreements, or may enter into To Be Announced (“TBA”) transactions. The Fund may take short positions in certain derivatives or in TBA mortgage-backed securities. |