| Form N-CSR Cover | 6 Months Ended |
| Jun. 30, 2024 | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSRS |
| Amendment Flag | false |
| Registrant Name | Vanguard Variable Insurance Funds |
| Entity Central Index Key | 0000857490 |
| Entity Investment Company Type | N-1A |
| Document Period End Date | Jun. 30, 2024 |
| Shareholder Report | 6 Months Ended | |
| Jun. 30, 2024 USD ($) Holding | ||
| Shareholder Report [Line Items] | ||
| Document Type | N-CSRS | |
| Amendment Flag | false | |
| Registrant Name | Vanguard Variable Insurance Funds | |
| Entity Central Index Key | 0000857490 | |
| Entity Investment Company Type | N-1A | |
| Document Period End Date | Jun. 30, 2024 | |
| C000012156 [Member] | ||
| Shareholder Report [Line Items] | ||
| Fund Name | Equity Index Portfolio | |
| Class Name | Equity Index Portfolio | |
| No Trading Symbol Flag | true | |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about Equity Index Portfolio (the "Fund") for the period of January 1, 2024, to June 30, 2024. | |
| 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. | |
| 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 Vanguard Variable Insurance Funds - $ 0.14 % 1 1 Annualized. | |
| Expenses Paid, Amount | $ 7 | |
| Expense Ratio, Percent | 0.14% | [1] |
| Net Assets | $ 10,543,000,000 | |
| Holdings Count | Holding | 506 | |
| Investment Company Portfolio Turnover | 2% | |
| Additional Fund Statistics [Text Block] | Fund Statistics Fund Net Assets $ % Number of Portfolio Holdings $ % Portfolio Turnover Rate $ % | |
| Holdings [Text Block] | This table reflects the Fund’s investments, including short-term investments, derivatives and other assets and liabilities. Portfolio Composition % of Net Assets Communication Services 9.3 % Consumer Discretionary 9.9 % Consumer Staples 5.7 % Energy 3.6 % Financials 12.4 % Health Care 11.7 % Industrials 8.1 % Information Technology 32.3 % Materials 2.2 % Real Estate 2.1 % Utilities 2.3 % Other Assets and Liabilities—Net 0.4 % | |
| C000102906 [Member] | ||
| Shareholder Report [Line Items] | ||
| Fund Name | Moderate Allocation Portfolio | |
| Class Name | Moderate Allocation Portfolio | |
| No Trading Symbol Flag | true | |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about Moderate Allocation Portfolio (the "Fund") for the period of January 1, 2024, to June 30, 2024. | |
| 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. | |
| 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 Vanguard Variable Insurance Funds - $ 0.13 % 1 1 Annualized. | |
| Expenses Paid, Amount | $ 7 | |
| Expense Ratio, Percent | 0.13% | [2] |
| Net Assets | $ 663,000,000 | |
| Holdings Count | Holding | 6 | |
| Investment Company Portfolio Turnover | 5% | |
| Additional Fund Statistics [Text Block] | Fund Statistics Fund Net Assets $ % Number of Portfolio Holdings $ % Portfolio Turnover Rate $ % | |
| Holdings [Text Block] | This table reflects the Fund’s investments, including short-term investments and other assets and liabilities. Portfolio Composition % of Net Assets (as of June 30, 2024) Vanguard Variable Insurance Funds—Equity Index Portfolio 31.6 % Vanguard Variable Insurance Funds—Total Bond Market Index Portfolio 27.9 % Vanguard Total International Stock Index Fund Admiral Shares 24.1 % Vanguard Total International Bond Index Fund Admiral Shares 12.0 % Vanguard Extended Market Index Fund Admiral Shares 4.5 % Other Assets and Liabilities—Net (0.1%) | |
| C000012152 [Member] | ||
| Shareholder Report [Line Items] | ||
| Fund Name | Total Stock Market Index Portfolio | |
| Class Name | Total Stock Market Index Portfolio | |
| No Trading Symbol Flag | true | |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about Total Stock Market Index Portfolio (the "Fund") for the period of January 1, 2024, to June 30, 2024. | |
| 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. | |
| 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 Vanguard Variable Insurance Funds - $ 0.13 % 1 1 Annualized. | |
| Expenses Paid, Amount | $ 7 | |
| Expense Ratio, Percent | 0.13% | [3] |
| Net Assets | $ 5,008,000,000 | |
| Holdings Count | Holding | 3 | |
| Investment Company Portfolio Turnover | 3% | |
| Additional Fund Statistics [Text Block] | Fund Statistics Fund Net Assets $ % Number of Portfolio Holdings $ % Portfolio Turnover Rate $ % | |
| Largest Holdings [Text Block] | This table reflects the Fund’s investments, including short-term investments and other assets and liabilities. Portfolio Composition % of Net Assets (as of June 30, 2024) Vanguard Variable Insurance Funds—Equity Index Portfolio 87.4 % Vanguard Extended Market Index Fund Admiral Shares 12.5 % Other Assets and Liabilities—Net 0.1 % | |
| C000102905 [Member] | ||
| Shareholder Report [Line Items] | ||
| Fund Name | Conservative Allocation Portfolio | |
| Class Name | Conservative Allocation Portfolio | |
| No Trading Symbol Flag | true | |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about Conservative Allocation Portfolio (the "Fund") for the period of January 1, 2024, to June 30, 2024. | |
| 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. | |
| 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 Vanguard Variable Insurance Funds - $ 0.13 % 1 1 Annualized. | |
| Expenses Paid, Amount | $ 7 | |
| Expense Ratio, Percent | 0.13% | [4] |
| Net Assets | $ 462,000,000 | |
| Holdings Count | Holding | 6 | |
| Investment Company Portfolio Turnover | 5% | |
| Additional Fund Statistics [Text Block] | Fund Statistics Fund Net Assets $ % Number of Portfolio Holdings $ % Portfolio Turnover Rate $ % | |
| Holdings [Text Block] | This table reflects the Fund’s investments, including short-term investments and other assets and liabilities. Portfolio Composition % of Net Assets (as of June 30, 2024) Vanguard Variable Insurance Funds—Total Bond Market Index Portfolio 41.9 % Vanguard Variable Insurance Funds—Equity Index Portfolio 21.0 % Vanguard Total International Bond Index Fund Admiral Shares 18.0 % Vanguard Total International Stock Index Fund Admiral Shares 16.0 % Vanguard Extended Market Index Fund Admiral Shares 3.1 % Other Assets and Liabilities—Net 0.0 % | |
| C000192543 [Member] | ||
| Shareholder Report [Line Items] | ||
| Fund Name | Total International Stock Market Index Portfolio | |
| Class Name | Total International Stock Market Index Portfolio | |
| No Trading Symbol Flag | true | |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about Total International Stock Market Index Portfolio (the "Fund") for the period of January 1, 2024, to June 30, 2024. | |
| 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. | |
| 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 Vanguard Variable Insurance Funds - $ 0.10 % 1 1 Annualized. | |
| Expenses Paid, Amount | $ 5 | |
| Expense Ratio, Percent | 0.10% | [5] |
| Net Assets | $ 1,550,000,000 | |
| Holdings Count | Holding | 8 | |
| Investment Company Portfolio Turnover | 3% | |
| Additional Fund Statistics [Text Block] | Fund Statistics Fund Net Assets $ % Number of Portfolio Holdings $ % Portfolio Turnover Rate $ % | |
| Holdings [Text Block] | This table reflects the Fund’s investments, including short-term investments and other assets and liabilities. Portfolio Composition % of Net Assets (as of June 30, 2024) Vanguard Developed Markets Index Fund Admiral Shares 28.0 % Vanguard FTSE All-World ex-US Index Fund Admiral Shares 28.0 % Vanguard Emerging Markets Stock Index Fund Admiral Shares 18.5 % Vanguard European Stock Index Fund Admiral Shares 12.3 % Vanguard Pacific Stock Index Fund Admiral Shares 8.1 % Vanguard FTSE All-World ex-US Small-Cap Index Fund Admiral Shares 3.2 % Vanguard FTSE Canada All Cap Index ETF 1.9 % Other Assets and Liabilities—Net 0.0 % | |
| C000012148 [Member] | ||
| Shareholder Report [Line Items] | ||
| Fund Name | Real Estate Index Portfolio | |
| Class Name | Real Estate Index Portfolio | |
| No Trading Symbol Flag | true | |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about Real Estate Index Portfolio (the "Fund") for the period of January 1, 2024, to June 30, 2024. | |
| 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. | |
| 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 Vanguard Variable Insurance Funds - $ 0.26 % 1 1 Annualized. | |
| Expenses Paid, Amount | $ 13 | |
| Expense Ratio, Percent | 0.26% | [6] |
| Net Assets | $ 1,054,000,000 | |
| Holdings Count | Holding | 156 | |
| Investment Company Portfolio Turnover | 4% | |
| Additional Fund Statistics [Text Block] | Fund Statistics Fund Net Assets $ % Number of Portfolio Holdings $ % Portfolio Turnover Rate $ % | |
| Holdings [Text Block] | This table reflects the Fund’s investments, including short-term investments, derivatives and other assets and liabilities. Portfolio Composition % of Net Assets (as of June 30, 2024) Data Center REITs 8.0 % Health Care REITs 10.7 % Industrial REITs 11.5 % Multi-Family Residential REITs 9.1 % Office REITs 3.1 % Other Specialized REITs 6.6 % Real Estate Services 6.4 % Retail REITs 13.2 % Self-Storage REITs 6.9 % Single-Family Residential REITs 4.6 % Telecom Tower REITs 11.6 % Other Assets and Liabilities—Net 8.3 % | |
| C000012160 [Member] | ||
| Shareholder Report [Line Items] | ||
| Fund Name | Mid-Cap Index Portfolio | |
| Class Name | Mid-Cap Index Portfolio | |
| No Trading Symbol Flag | true | |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about Mid-Cap Index Portfolio (the "Fund") for the period of January 1, 2024, to June 30, 2024. | |
| 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. | |
| 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 Vanguard Variable Insurance Funds - $ 0.17 % 1 1 Annualized. | |
| Expenses Paid, Amount | $ 9 | |
| Expense Ratio, Percent | 0.17% | [7] |
| Net Assets | $ 2,603,000,000 | |
| Holdings Count | Holding | 320 | |
| Investment Company Portfolio Turnover | 11% | |
| Additional Fund Statistics [Text Block] | Fund Statistics Fund Net Assets $ % Number of Portfolio Holdings $ % Portfolio Turnover Rate $ % | |
| Holdings [Text Block] | This table reflects the Fund’s investments, including short-term investments, derivatives and other assets and liabilities. Portfolio Composition % of Net Assets (as of June 30, 2024) Basic Materials 3.4 % Consumer Discretionary 12.3 % Consumer Staples 5.4 % Energy 5.1 % Financials 12.6 % Health Care 9.3 % Industrials 20.7 % Real Estate 7.5 % Technology 14.4 % Telecommunications 0.8 % Utilities 8.1 % Other Assets and Liabilities—Net 0.4 % | |
| C000192542 [Member] | ||
| Shareholder Report [Line Items] | ||
| Fund Name | Global Bond Index Portfolio | |
| Class Name | Global Bond Index Portfolio | |
| No Trading Symbol Flag | true | |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about Global Bond Index Portfolio (the "Fund") for the period of January 1, 2024, to June 30, 2024. | |
| 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. | |
| 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 Vanguard Variable Insurance Funds - $ 0.13 % 1 1 Annualized. | |
| Expenses Paid, Amount | $ 6 | |
| Expense Ratio, Percent | 0.13% | [8] |
| Net Assets | $ 469,000,000 | |
| Holdings Count | Holding | 3 | |
| Investment Company Portfolio Turnover | 4% | |
| Additional Fund Statistics [Text Block] | Fund Statistics Fund Net Assets $ % Number of Portfolio Holdings $ % Portfolio Turnover Rate $ % | |
| Holdings [Text Block] | This table reflects the Fund’s investments, including short-term investments and other assets and liabilities. Portfolio Composition % of Net Assets (as of June 30, 2024) Vanguard Variable Insurance Funds—Total Bond Market Index Portfolio 70.0 % Vanguard Total International Bond Index Fund Admiral Shares 30.0 % Other Assets and Liabilities—Net 0.0 % | |
| [1]Annualized.[2]Annualized.[3]Annualized.[4]Annualized.[5]Annualized.[6]Annualized.[7]Annualized.[8]Annualized. | ||
| Shareholder Report, Holdings (Details) | Jun. 30, 2024 |
| C000012156 [Member] | Energy Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.60% |
| C000012156 [Member] | Healthcare Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 11.70% |
| C000012156 [Member] | Real Estate Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.10% |
| C000012156 [Member] | Communications Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 9.30% |
| C000012156 [Member] | Consumer Discretionary Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 9.90% |
| C000012156 [Member] | Consumer Staples Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.70% |
| C000012156 [Member] | Industrial Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.10% |
| C000012156 [Member] | Information Technology Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 32.30% |
| C000012156 [Member] | Materials Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.20% |
| C000012156 [Member] | Utilities Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.30% |
| C000012156 [Member] | Financials [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.40% |
| C000012156 [Member] | Other Assets and Liabilities Net [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000102906 [Member] | Other Assets and Liabilities Net [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | (0.10%) |
| C000102906 [Member] | Vanguard Variable Insurance Funds Equity Index Portfolio [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 31.60% |
| C000102906 [Member] | Vanguard Variable Insurance Funds Total Bond Market Index Portfolio [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 27.90% |
| C000102906 [Member] | Vanguard Total International Stock Index Fund Admiral Shares [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 24.10% |
| C000102906 [Member] | Vanguard Total International Bond Index Fund Admiral Shares [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12% |
| C000102906 [Member] | Vanguard Extended Market Index Fund Admiral Shares [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.50% |
| C000012152 [Member] | Other Assets and Liabilities Net [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.10% |
| C000012152 [Member] | Vanguard Variable Insurance Funds Equity Index Portfolio [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 87.40% |
| C000012152 [Member] | Vanguard Extended Market Index Fund Admiral Shares [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.50% |
| C000102905 [Member] | Other Assets and Liabilities Net [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0% |
| C000102905 [Member] | Vanguard Variable Insurance Funds Equity Index Portfolio [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 21% |
| C000102905 [Member] | Vanguard Variable Insurance Funds Total Bond Market Index Portfolio [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 41.90% |
| C000102905 [Member] | Vanguard Total International Stock Index Fund Admiral Shares [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 16% |
| C000102905 [Member] | Vanguard Total International Bond Index Fund Admiral Shares [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 18% |
| C000102905 [Member] | Vanguard Extended Market Index Fund Admiral Shares [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.10% |
| C000192543 [Member] | Other Assets and Liabilities Net [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0% |
| C000192543 [Member] | Vanguard Developed Markets Index Fund Admiral Shares [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 28% |
| C000192543 [Member] | Vanguard FTSE All World ex US Index Fund Admiral Shares [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 28% |
| C000192543 [Member] | Vanguard Emerging Markets Stock Index Fund Admiral Shares [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 18.50% |
| C000192543 [Member] | Vanguard European Stock Index Fund Admiral Shares [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.30% |
| C000192543 [Member] | Vanguard Pacific Stock Index Fund Admiral Shares [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.10% |
| C000192543 [Member] | Vanguard FTSE All World ex US Small Cap Index Fund Admiral Shares [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.20% |
| C000192543 [Member] | Vanguard FTSE Canada All Cap Index ETF [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.90% |
| C000012148 [Member] | Other Assets and Liabilities Net [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.30% |
| C000012148 [Member] | Data Center REITs [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8% |
| C000012148 [Member] | Health Care REITs [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 10.70% |
| C000012148 [Member] | Industrial REITs [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 11.50% |
| C000012148 [Member] | Multi Family Residential REITs [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 9.10% |
| C000012148 [Member] | Office REITs [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.10% |
| C000012148 [Member] | Other Specialized REITs [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.60% |
| C000012148 [Member] | Real Estate Services [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.40% |
| C000012148 [Member] | Retail REITs [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 13.20% |
| C000012148 [Member] | Self Storage REITs [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.90% |
| C000012148 [Member] | Single Family Residential REITs [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.60% |
| C000012148 [Member] | Telecom Tower REITs [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 11.60% |
| C000012160 [Member] | Energy Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.10% |
| C000012160 [Member] | Healthcare Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 9.30% |
| C000012160 [Member] | Real Estate Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 7.50% |
| C000012160 [Member] | Consumer Discretionary Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.30% |
| C000012160 [Member] | Consumer Staples Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.40% |
| C000012160 [Member] | Industrial Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 20.70% |
| C000012160 [Member] | Utilities Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.10% |
| C000012160 [Member] | Financials [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.60% |
| C000012160 [Member] | Technology Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 14.40% |
| C000012160 [Member] | Basic Materials [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.40% |
| C000012160 [Member] | Telecommunications [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.80% |
| C000012160 [Member] | Other Assets and Liabilities Net [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000192542 [Member] | Other Assets and Liabilities Net [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0% |
| C000192542 [Member] | Vanguard Variable Insurance Funds Total Bond Market Index Portfolio [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 70% |
| C000192542 [Member] | Vanguard Total International Bond Index Fund Admiral Shares [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 30% |
