Shareholder Report, Holdings (Details) - Fidelity Municipal Money Market Fund |
Aug. 31, 2026 |
|---|---|
| EMD0Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 20.50% |
| EMD1Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 57.10% |
| EMD2Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 7.30% |
| EMD3Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.20% |
| EMD4Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.50% |
| EMD5Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 10.30% |
| AAVariableRateDemandNotesVRDNsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 34.70% |
| AATenderOptionBondMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 30.70% |
| AAMunicipalSecuritiesMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 15.30% |
| AACommercialPaperMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 7.80% |
| AANetOtherAssetsLiabilitiesMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 11.50% |