v3.26.1
Vanguard Long-Term Treasury Index Fund Expense Example - ETF Prospectus [Member] - Vanguard Long-Term Treasury Index Fund - ETF Shares
Aug. 31, 2025
USD ($)
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year $ 3
Expense Example, with Redemption, 3 Years 10
Expense Example, with Redemption, 5 Years 17
Expense Example, with Redemption, 10 Years $ 39