v3.26.1
Shareholder Report
 6 Months Ended
Jun. 30, 2026
USD ($)
Holding
Shareholder Report [Line Items]  
Document Type N-CSRS
Amendment Flag false
Registrant Name Vanguard Bond Index Funds
Entity Central Index Key 0000794105
Entity Investment Company Type N-1A
Document Period End Date Jun. 30, 2026
C000105308 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Intermediate-Term Bond Index Fund
Class Name Institutional Plus Shares
Trading Symbol VBIUX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Intermediate-Term Bond Index Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
Institutional Plus Shares $1 0.02%1
​1
Annualized.
Expenses Paid, Amount $ 1
Expense Ratio, Percent 0.02% [1]
Net Assets $ 52,656,000,000
Holdings Count | Holding 2,331
Investment Company Portfolio Turnover 27.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $52,656
Number of Portfolio Holdings 2,331
Portfolio Turnover Rate 27%
Holdings [Text Block]
Portfolio Composition % of Net Assets
(as of June 30, 2026)
Corporate Bonds 38.1%
Sovereign Bonds 4.6%
Taxable Municipal Bonds 0.3%
U.S. Government and Agency Obligations 55.8%
Other Assets and Liabilities—Net 1.2%
This table reflects the Fund’s investments, including short-term investments and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000024520 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Intermediate-Term Bond Index Fund
Class Name Institutional Shares
Trading Symbol VBIMX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Intermediate-Term Bond Index Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
Institutional Shares $1 0.03%1
​1
Annualized.
Expenses Paid, Amount $ 1
Expense Ratio, Percent 0.03% [2]
Net Assets $ 52,656,000,000
Holdings Count | Holding 2,331
Investment Company Portfolio Turnover 27.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $52,656
Number of Portfolio Holdings 2,331
Portfolio Turnover Rate 27%
Holdings [Text Block]
Portfolio Composition % of Net Assets
(as of June 30, 2026)
Corporate Bonds 38.1%
Sovereign Bonds 4.6%
Taxable Municipal Bonds 0.3%
U.S. Government and Agency Obligations 55.8%
Other Assets and Liabilities—Net 1.2%
This table reflects the Fund’s investments, including short-term investments and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000007058 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Intermediate-Term Bond Index Fund
Class Name Admiral™ Shares
Trading Symbol VBILX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Intermediate-Term Bond Index Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
Admiral Shares $3 0.06%1
​1
Annualized.
Expenses Paid, Amount $ 3
Expense Ratio, Percent 0.06% [3]
Net Assets $ 52,656,000,000
Holdings Count | Holding 2,331
Investment Company Portfolio Turnover 27.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $52,656
Number of Portfolio Holdings 2,331
Portfolio Turnover Rate 27%
Holdings [Text Block]
Portfolio Composition % of Net Assets
(as of June 30, 2026)
Corporate Bonds 38.1%
Sovereign Bonds 4.6%
Taxable Municipal Bonds 0.3%
U.S. Government and Agency Obligations 55.8%
Other Assets and Liabilities—Net 1.2%
This table reflects the Fund’s investments, including short-term investments and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000046841 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Intermediate-Term Bond Index Fund
Class Name ETF Shares
Trading Symbol BIV
Security Exchange Name NYSEArca
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Intermediate-Term Bond Index Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
ETF Shares $1 0.03%1
​1
Annualized.
Expenses Paid, Amount $ 1
Expense Ratio, Percent 0.03% [4]
Net Assets $ 52,656,000,000
Holdings Count | Holding 2,331
Investment Company Portfolio Turnover 27.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $52,656
Number of Portfolio Holdings 2,331
Portfolio Turnover Rate 27%
Holdings [Text Block]
Portfolio Composition % of Net Assets
(as of June 30, 2026)
Corporate Bonds 38.1%
Sovereign Bonds 4.6%
Taxable Municipal Bonds 0.3%
U.S. Government and Agency Obligations 55.8%
Other Assets and Liabilities—Net 1.2%
This table reflects the Fund’s investments, including short-term investments and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000007057 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Intermediate-Term Bond Index Fund
Class Name Investor Shares
Trading Symbol VBIIX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Intermediate-Term Bond Index Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
Investor Shares $7 0.15%1
​1
Annualized.
Expenses Paid, Amount $ 7
Expense Ratio, Percent 0.15% [5]
Net Assets $ 52,656,000,000
Holdings Count | Holding 2,331
Investment Company Portfolio Turnover 27.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $52,656
Number of Portfolio Holdings 2,331
Portfolio Turnover Rate 27%
Holdings [Text Block]
Portfolio Composition % of Net Assets
(as of June 30, 2026)
Corporate Bonds 38.1%
Sovereign Bonds 4.6%
Taxable Municipal Bonds 0.3%
U.S. Government and Agency Obligations 55.8%
Other Assets and Liabilities—Net 1.2%
This table reflects the Fund’s investments, including short-term investments and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000046842 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Long-Term Bond Index Fund
Class Name ETF Shares
Trading Symbol BLV
Security Exchange Name NYSEArca
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Long-Term Bond Index Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
ETF Shares $1 0.03%1
​1
Annualized.
Expenses Paid, Amount $ 1
Expense Ratio, Percent 0.03% [6]
Net Assets $ 8,673,000,000
Holdings Count | Holding 2,970
Investment Company Portfolio Turnover 13.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $8,673
Number of Portfolio Holdings 2,970
Portfolio Turnover Rate 13%
Holdings [Text Block]
Portfolio Composition % of Net Assets
(as of June 30, 2026)
Corporate Bonds 41.2%
Sovereign Bonds 2.8%
Taxable Municipal Bonds 1.7%
U.S. Government and Agency Obligations 52.8%
Other Assets and Liabilities—Net 1.5%
This table reflects the Fund’s investments, including short-term investments, derivatives and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000209800 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Long-Term Bond Index Fund
Class Name Admiral™ Shares
Trading Symbol VBLAX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Long-Term Bond Index Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
Admiral Shares $3 0.06%1
​1
Annualized.
Expenses Paid, Amount $ 3
Expense Ratio, Percent 0.06% [7]
Net Assets $ 8,673,000,000
Holdings Count | Holding 2,970
Investment Company Portfolio Turnover 13.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $8,673
Number of Portfolio Holdings 2,970
Portfolio Turnover Rate 13%
Holdings [Text Block]
Portfolio Composition % of Net Assets
(as of June 30, 2026)
Corporate Bonds 41.2%
Sovereign Bonds 2.8%
Taxable Municipal Bonds 1.7%
U.S. Government and Agency Obligations 52.8%
Other Assets and Liabilities—Net 1.5%
This table reflects the Fund’s investments, including short-term investments, derivatives and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000024522 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Long-Term Bond Index Fund
Class Name Institutional Shares
Trading Symbol VBLLX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Long-Term Bond Index Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
Institutional Shares $1 0.03%1
​1
Annualized.
Expenses Paid, Amount $ 1
Expense Ratio, Percent 0.03% [8]
Net Assets $ 8,673,000,000
Holdings Count | Holding 2,970
Investment Company Portfolio Turnover 13.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $8,673
Number of Portfolio Holdings 2,970
Portfolio Turnover Rate 13%
Holdings [Text Block]
Portfolio Composition % of Net Assets
(as of June 30, 2026)
Corporate Bonds 41.2%
Sovereign Bonds 2.8%
Taxable Municipal Bonds 1.7%
U.S. Government and Agency Obligations 52.8%
Other Assets and Liabilities—Net 1.5%
This table reflects the Fund’s investments, including short-term investments, derivatives and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000105309 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Long-Term Bond Index Fund
Class Name Institutional Plus Shares
Trading Symbol VBLIX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Long-Term Bond Index Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
Institutional Plus Shares $1 0.02%1
​1
Annualized.
Expenses Paid, Amount $ 1
Expense Ratio, Percent 0.02% [9]
Net Assets $ 8,673,000,000
Holdings Count | Holding 2,970
Investment Company Portfolio Turnover 13.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $8,673
Number of Portfolio Holdings 2,970
Portfolio Turnover Rate 13%
Holdings [Text Block]
Portfolio Composition % of Net Assets
(as of June 30, 2026)
Corporate Bonds 41.2%
Sovereign Bonds 2.8%
Taxable Municipal Bonds 1.7%
U.S. Government and Agency Obligations 52.8%
Other Assets and Liabilities—Net 1.5%
This table reflects the Fund’s investments, including short-term investments, derivatives and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000105311 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Short-Term Bond Index Fund
Class Name Institutional Plus Shares
Trading Symbol VBIPX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Short-Term Bond Index Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
Institutional Plus Shares $1 0.02%1
​1
Annualized.
Expenses Paid, Amount $ 1
Expense Ratio, Percent 0.02% [10]
Net Assets $ 69,937,000,000
Holdings Count | Holding 3,200
Investment Company Portfolio Turnover 29.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $69,937
Number of Portfolio Holdings 3,200
Portfolio Turnover Rate 29%
Holdings [Text Block]
Portfolio Composition % of Net Assets
(as of June 30, 2026)
Corporate Bonds 24.5%
Sovereign Bonds 5.0%
Taxable Municipal Bonds 0.0%
U.S. Government and Agency Obligations 69.3%
Other Assets and Liabilities—Net 1.2%
This table reflects the Fund’s investments, including short-term investments and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000105310 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Short-Term Bond Index Fund
Class Name Institutional Shares
Trading Symbol VBITX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Short-Term Bond Index Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
Institutional Shares $1 0.03%1
​1
Annualized.
Expenses Paid, Amount $ 1
Expense Ratio, Percent 0.03% [11]
Net Assets $ 69,937,000,000
Holdings Count | Holding 3,200
Investment Company Portfolio Turnover 29.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $69,937
Number of Portfolio Holdings 3,200
Portfolio Turnover Rate 29%
Holdings [Text Block]
Portfolio Composition % of Net Assets
(as of June 30, 2026)
Corporate Bonds 24.5%
Sovereign Bonds 5.0%
Taxable Municipal Bonds 0.0%
U.S. Government and Agency Obligations 69.3%
Other Assets and Liabilities—Net 1.2%
This table reflects the Fund’s investments, including short-term investments and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000007061 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Short-Term Bond Index Fund
Class Name Admiral™ Shares
Trading Symbol VBIRX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Short-Term Bond Index Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
Admiral Shares $3 0.06%1
​1
Annualized.
Expenses Paid, Amount $ 3
Expense Ratio, Percent 0.06% [12]
Net Assets $ 69,937,000,000
Holdings Count | Holding 3,200
Investment Company Portfolio Turnover 29.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $69,937
Number of Portfolio Holdings 3,200
Portfolio Turnover Rate 29%
Holdings [Text Block]
Portfolio Composition % of Net Assets
(as of June 30, 2026)
Corporate Bonds 24.5%
Sovereign Bonds 5.0%
Taxable Municipal Bonds 0.0%
U.S. Government and Agency Obligations 69.3%
Other Assets and Liabilities—Net 1.2%
This table reflects the Fund’s investments, including short-term investments and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000046843 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Short-Term Bond Index Fund
Class Name ETF Shares
Trading Symbol BSV
Security Exchange Name NYSEArca
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Short-Term Bond Index Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
ETF Shares $1 0.03%1
​1
Annualized.
Expenses Paid, Amount $ 1
Expense Ratio, Percent 0.03% [13]
Net Assets $ 69,937,000,000
Holdings Count | Holding 3,200
Investment Company Portfolio Turnover 29.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $69,937
Number of Portfolio Holdings 3,200
Portfolio Turnover Rate 29%
Holdings [Text Block]
Portfolio Composition % of Net Assets
(as of June 30, 2026)
Corporate Bonds 24.5%
Sovereign Bonds 5.0%
Taxable Municipal Bonds 0.0%
U.S. Government and Agency Obligations 69.3%
Other Assets and Liabilities—Net 1.2%
This table reflects the Fund’s investments, including short-term investments and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000007060 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Short-Term Bond Index Fund
Class Name Investor Shares
Trading Symbol VBISX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Short-Term Bond Index Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
Investor Shares $7 0.15%1
​1
Annualized.
Expenses Paid, Amount $ 7
Expense Ratio, Percent 0.15% [14]
Net Assets $ 69,937,000,000
Holdings Count | Holding 3,200
Investment Company Portfolio Turnover 29.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $69,937
Number of Portfolio Holdings 3,200
Portfolio Turnover Rate 29%
Holdings [Text Block]
Portfolio Composition % of Net Assets
(as of June 30, 2026)
Corporate Bonds 24.5%
Sovereign Bonds 5.0%
Taxable Municipal Bonds 0.0%
U.S. Government and Agency Obligations 69.3%
Other Assets and Liabilities—Net 1.2%
This table reflects the Fund’s investments, including short-term investments and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000007062 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Total Bond Market Index Fund
Class Name Investor Shares
Trading Symbol VBMFX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Total Bond Market Index Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
Investor Shares $7 0.15%1
​1
Annualized.
Expenses Paid, Amount $ 7
Expense Ratio, Percent 0.15% [15]
Net Assets $ 398,069,000,000
Holdings Count | Holding 17,408
Investment Company Portfolio Turnover 21.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $398,069
Number of Portfolio Holdings 17,408
Portfolio Turnover Rate 21%
Holdings [Text Block]
Portfolio Composition % of Net Assets
(as of June 30, 2026)
Asset-Backed/Commercial Mortgage-Backed Securities 1.9%
Corporate Bonds 25.4%
Sovereign Bonds 3.4%
Taxable Municipal Bonds 0.4%
U.S. Government and Agency Obligations 67.9%
Other Assets and Liabilities—Net 1.0%
This table reflects the Fund’s investments, including short-term investments and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000046844 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Total Bond Market Index Fund
Class Name ETF Shares
Trading Symbol BND
Security Exchange Name NASDAQ
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Total Bond Market Index Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
ETF Shares $1 0.03%1
​1
Annualized.
Expenses Paid, Amount $ 1
Expense Ratio, Percent 0.03% [16]
Net Assets $ 398,069,000,000
Holdings Count | Holding 17,408
Investment Company Portfolio Turnover 21.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $398,069
Number of Portfolio Holdings 17,408
Portfolio Turnover Rate 21%
Holdings [Text Block]
Portfolio Composition % of Net Assets
(as of June 30, 2026)
Asset-Backed/Commercial Mortgage-Backed Securities 1.9%
Corporate Bonds 25.4%
Sovereign Bonds 3.4%
Taxable Municipal Bonds 0.4%
U.S. Government and Agency Obligations 67.9%
Other Assets and Liabilities—Net 1.0%
This table reflects the Fund’s investments, including short-term investments and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000007063 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Total Bond Market Index Fund
Class Name Admiral™ Shares
Trading Symbol VBTLX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Total Bond Market Index Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
Admiral Shares $2 0.04%1
​1
Annualized.
Expenses Paid, Amount $ 2
Expense Ratio, Percent 0.04% [17]
Net Assets $ 398,069,000,000
Holdings Count | Holding 17,408
Investment Company Portfolio Turnover 21.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $398,069
Number of Portfolio Holdings 17,408
Portfolio Turnover Rate 21%
Holdings [Text Block]
Portfolio Composition % of Net Assets
(as of June 30, 2026)
Asset-Backed/Commercial Mortgage-Backed Securities 1.9%
Corporate Bonds 25.4%
Sovereign Bonds 3.4%
Taxable Municipal Bonds 0.4%
U.S. Government and Agency Obligations 67.9%
Other Assets and Liabilities—Net 1.0%
This table reflects the Fund’s investments, including short-term investments and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000007064 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Total Bond Market Index Fund
Class Name Institutional Shares
Trading Symbol VBTIX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Total Bond Market Index Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
Institutional Shares $1 0.025%1
​1
Annualized.
Expenses Paid, Amount $ 1
Expense Ratio, Percent 0.025% [18]
Net Assets $ 398,069,000,000
Holdings Count | Holding 17,408
Investment Company Portfolio Turnover 21.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $398,069
Number of Portfolio Holdings 17,408
Portfolio Turnover Rate 21%
Holdings [Text Block]
Portfolio Composition % of Net Assets
(as of June 30, 2026)
Asset-Backed/Commercial Mortgage-Backed Securities 1.9%
Corporate Bonds 25.4%
Sovereign Bonds 3.4%
Taxable Municipal Bonds 0.4%
U.S. Government and Agency Obligations 67.9%
Other Assets and Liabilities—Net 1.0%
This table reflects the Fund’s investments, including short-term investments and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000081425 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Total Bond Market Index Fund
Class Name Institutional Plus Shares
Trading Symbol VBMPX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Total Bond Market Index Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
Institutional Plus Shares $1 0.02%1
​1
Annualized.
Expenses Paid, Amount $ 1
Expense Ratio, Percent 0.02% [19]
Net Assets $ 398,069,000,000
Holdings Count | Holding 17,408
Investment Company Portfolio Turnover 21.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $398,069
Number of Portfolio Holdings 17,408
Portfolio Turnover Rate 21%
Holdings [Text Block]
Portfolio Composition % of Net Assets
(as of June 30, 2026)
Asset-Backed/Commercial Mortgage-Backed Securities 1.9%
Corporate Bonds 25.4%
Sovereign Bonds 3.4%
Taxable Municipal Bonds 0.4%
U.S. Government and Agency Obligations 67.9%
Other Assets and Liabilities—Net 1.0%
This table reflects the Fund’s investments, including short-term investments and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000170279 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Total Bond Market Index Fund
Class Name Institutional Select Shares
Trading Symbol VTBSX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Total Bond Market Index Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
Institutional Select Shares $0 0.01%1
​1
Annualized.
Expenses Paid, Amount $ 0
Expense Ratio, Percent 0.01% [20]
Net Assets $ 398,069,000,000
Holdings Count | Holding 17,408
Investment Company Portfolio Turnover 21.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $398,069
Number of Portfolio Holdings 17,408
Portfolio Turnover Rate 21%
Holdings [Text Block]
Portfolio Composition % of Net Assets
(as of June 30, 2026)
Asset-Backed/Commercial Mortgage-Backed Securities 1.9%
Corporate Bonds 25.4%
Sovereign Bonds 3.4%
Taxable Municipal Bonds 0.4%
U.S. Government and Agency Obligations 67.9%
Other Assets and Liabilities—Net 1.0%
This table reflects the Fund’s investments, including short-term investments and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000054351 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Inflation-Protected Securities Fund
Class Name Institutional Shares
Trading Symbol VIPIX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Inflation-Protected Securities Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
Institutional Shares $3 0.07%1
​1
Annualized.
Expenses Paid, Amount $ 3
Expense Ratio, Percent 0.07% [21]
Net Assets $ 28,202,000,000
Holdings Count | Holding 130
Investment Company Portfolio Turnover 27.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $28,202
Number of Portfolio Holdings 130
Portfolio Turnover Rate 27%
Holdings [Text Block]
Distribution by Stated Maturity % of Net Asset
(as of June 30, 2026)
0 - 5 Years 48.9%
5 - 10 Years 36.6%
10 - 15 Years 1.4%
15 - 20 Years 5.0%
20 - 25 Years 3.0%
Over 25 Years 4.3%
Other Assets and Liabilities—Net 0.8%
This table reflects the Fund’s investments, including short-term investments, derivatives and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000054350 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Inflation-Protected Securities Fund
Class Name Admiral™ Shares
Trading Symbol VAIPX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Inflation-Protected Securities Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
Admiral Shares $5 0.10%1
​1
Annualized.
Expenses Paid, Amount $ 5
Expense Ratio, Percent 0.10% [22]
Net Assets $ 28,202,000,000
Holdings Count | Holding 130
Investment Company Portfolio Turnover 27.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $28,202
Number of Portfolio Holdings 130
Portfolio Turnover Rate 27%
Holdings [Text Block]
Distribution by Stated Maturity % of Net Asset
(as of June 30, 2026)
0 - 5 Years 48.9%
5 - 10 Years 36.6%
10 - 15 Years 1.4%
15 - 20 Years 5.0%
20 - 25 Years 3.0%
Over 25 Years 4.3%
Other Assets and Liabilities—Net 0.8%
This table reflects the Fund’s investments, including short-term investments, derivatives and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000054349 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Inflation-Protected Securities Fund
Class Name Investor Shares
Trading Symbol VIPSX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Inflation-Protected Securities Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
Investor Shares $10 0.20%1
​1
Annualized.
Expenses Paid, Amount $ 10
Expense Ratio, Percent 0.20% [23]
Net Assets $ 28,202,000,000
Holdings Count | Holding 130
Investment Company Portfolio Turnover 27.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $28,202
Number of Portfolio Holdings 130
Portfolio Turnover Rate 27%
Holdings [Text Block]
Distribution by Stated Maturity % of Net Asset
(as of June 30, 2026)
0 - 5 Years 48.9%
5 - 10 Years 36.6%
10 - 15 Years 1.4%
15 - 20 Years 5.0%
20 - 25 Years 3.0%
Over 25 Years 4.3%
Other Assets and Liabilities—Net 0.8%
This table reflects the Fund’s investments, including short-term investments, derivatives and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000075027 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Total Bond Market II Index Fund
Class Name Investor Shares
Trading Symbol VTBIX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Total Bond Market II Index Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
Investor Shares $4 0.09%1
​1
Annualized.
Expenses Paid, Amount $ 4
Expense Ratio, Percent 0.09% [24]
Net Assets $ 386,563,000,000
Holdings Count | Holding 15,862
Investment Company Portfolio Turnover 62.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $386,563
Number of Portfolio Holdings 15,862
Portfolio Turnover Rate 62%
Holdings [Text Block]
Portfolio Composition % of Net Assets
(as of June 30, 2026)
Asset-Backed/Commercial Mortgage-Backed Securities 1.9%
Corporate Bonds 24.4%
Sovereign Bonds 3.3%
Taxable Municipal Bonds 0.4%
U.S. Government and Agency Obligations 69.0%
Other Assets and Liabilities—Net 1.0%
This table reflects the Fund’s investments, including short-term investments, derivatives and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000075028 [Member]  
Shareholder Report [Line Items]  
Fund Name Vanguard Total Bond Market II Index Fund
Class Name Institutional Shares
Trading Symbol VTBNX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Vanguard Total Bond Market II Index Fund (the "Fund") for the period of January 1, 2026, to June 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature. You can also request this information by contacting us at 800-662-7447.
Material Fund Change Notice [Text Block] The report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 800-662-7447
Additional Information Website https://personal1.vanguard.com/ngf‑next‑gen‑form‑webapp/fund‑literature
Expenses [Text Block]
What were the Fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
Institutional Shares $1 0.02%1
​1
Annualized.
Expenses Paid, Amount $ 1
Expense Ratio, Percent 0.02% [25]
Net Assets $ 386,563,000,000
Holdings Count | Holding 15,862
Investment Company Portfolio Turnover 62.00%
Additional Fund Statistics [Text Block]
Fund Statistics
(as of June 30, 2026)
Fund Net Assets
(in millions)		 $386,563
Number of Portfolio Holdings 15,862
Portfolio Turnover Rate 62%
Holdings [Text Block]
Portfolio Composition % of Net Assets
(as of June 30, 2026)
Asset-Backed/Commercial Mortgage-Backed Securities 1.9%
Corporate Bonds 24.4%
Sovereign Bonds 3.3%
Taxable Municipal Bonds 0.4%
U.S. Government and Agency Obligations 69.0%
Other Assets and Liabilities—Net 1.0%
This table reflects the Fund’s investments, including short-term investments, derivatives and other assets and liabilities.
Material Fund Change [Text Block]
How has the Fund changed?
Effective January 12, 2026, The Vanguard Group, Inc. exercises portfolio management responsibilities for the fund through its wholly-owned subsidiary, Vanguard Capital Management, LLC.
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Summary of Change Legend [Text Block]
This is a summary of certain changes to the Fund since December 31, 2025. For more complete information, you may review the Fund’s prospectus at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature or upon request at 800-662-7447.
Updated Prospectus Phone Number 800-662-7447
Updated Prospectus Web Address https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
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