| Label | Element | Value |
|---|---|---|
| Risk Return Abstract | rr_RiskReturnAbstract | |
| Registrant Name | dei_EntityRegistrantName | Vanguard Fixed Income Securities Funds |
| Prospectus Date | rr_ProspectusDate | May 24, 2024 |
| Document Creation Date | dei_DocumentCreationDate | May 23, 2024 |