Vanguard Mortgage-Backed Securities Index Fund Annual Fund Operating Expenses - Admiral Prospectus [Member] - Vanguard Mortgage-Backed Securities Index Fund - Admiral Shares |
Aug. 31, 2025 |
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|---|---|---|---|---|
| Prospectus [Line Items] | ||||
| Management Fees (as a percentage of Assets) | 0.03% | |||
| Distribution and Service (12b-1) Fees | 0.00% | |||
| Other Expenses (as a percentage of Assets): | 0.01% | |||
| Expenses (as a percentage of Assets) | 0.04% | [1] | ||
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