Shareholder Report, Holdings (Details)	Aug. 31, 2026
Fidelity California Municipal Money Market Fund \| EMD0Member
Holdings [Line Items]
Percent of Net Asset Value	43.10%
Fidelity California Municipal Money Market Fund \| EMD1Member
Holdings [Line Items]
Percent of Net Asset Value	35.90%
Fidelity California Municipal Money Market Fund \| EMD2Member
Holdings [Line Items]
Percent of Net Asset Value	9.40%
Fidelity California Municipal Money Market Fund \| EMD3Member
Holdings [Line Items]
Percent of Net Asset Value	3.20%
Fidelity California Municipal Money Market Fund \| EMD4Member
Holdings [Line Items]
Percent of Net Asset Value	4.90%
Fidelity California Municipal Money Market Fund \| EMD5Member
Holdings [Line Items]
Percent of Net Asset Value	4.00%
Fidelity California Municipal Money Market Fund \| AATenderOptionBondMember
Holdings [Line Items]
Percent of Net Asset Value	36.60%
Fidelity California Municipal Money Market Fund \| AAVariableRateDemandNotesVRDNsMember
Holdings [Line Items]
Percent of Net Asset Value	23.90%
Fidelity California Municipal Money Market Fund \| AACommercialPaperMember
Holdings [Line Items]
Percent of Net Asset Value	18.10%
Fidelity California Municipal Money Market Fund \| AAMunicipalSecuritiesMember
Holdings [Line Items]
Percent of Net Asset Value	8.10%
Fidelity California Municipal Money Market Fund \| AANetOtherAssetsLiabilitiesMember
Holdings [Line Items]
Percent of Net Asset Value	13.30%
Fidelity California Municipal Money Market Fund - Premium Class \| EMD0Member
Holdings [Line Items]
Percent of Net Asset Value	43.10%
Fidelity California Municipal Money Market Fund - Premium Class \| EMD1Member
Holdings [Line Items]
Percent of Net Asset Value	35.90%
Fidelity California Municipal Money Market Fund - Premium Class \| EMD2Member
Holdings [Line Items]
Percent of Net Asset Value	9.40%
Fidelity California Municipal Money Market Fund - Premium Class \| EMD3Member
Holdings [Line Items]
Percent of Net Asset Value	3.20%
Fidelity California Municipal Money Market Fund - Premium Class \| EMD4Member
Holdings [Line Items]
Percent of Net Asset Value	4.90%
Fidelity California Municipal Money Market Fund - Premium Class \| EMD5Member
Holdings [Line Items]
Percent of Net Asset Value	4.00%
Fidelity California Municipal Money Market Fund - Premium Class \| AATenderOptionBondMember
Holdings [Line Items]
Percent of Net Asset Value	36.60%
Fidelity California Municipal Money Market Fund - Premium Class \| AAVariableRateDemandNotesVRDNsMember
Holdings [Line Items]
Percent of Net Asset Value	23.90%
Fidelity California Municipal Money Market Fund - Premium Class \| AACommercialPaperMember
Holdings [Line Items]
Percent of Net Asset Value	18.10%
Fidelity California Municipal Money Market Fund - Premium Class \| AAMunicipalSecuritiesMember
Holdings [Line Items]
Percent of Net Asset Value	8.10%
Fidelity California Municipal Money Market Fund - Premium Class \| AANetOtherAssetsLiabilitiesMember
Holdings [Line Items]
Percent of Net Asset Value	13.30%
Fidelity California Municipal Money Market Fund - Institutional Class \| EMD0Member
Holdings [Line Items]
Percent of Net Asset Value	43.10%
Fidelity California Municipal Money Market Fund - Institutional Class \| EMD1Member
Holdings [Line Items]
Percent of Net Asset Value	35.90%
Fidelity California Municipal Money Market Fund - Institutional Class \| EMD2Member
Holdings [Line Items]
Percent of Net Asset Value	9.40%
Fidelity California Municipal Money Market Fund - Institutional Class \| EMD3Member
Holdings [Line Items]
Percent of Net Asset Value	3.20%
Fidelity California Municipal Money Market Fund - Institutional Class \| EMD4Member
Holdings [Line Items]
Percent of Net Asset Value	4.90%
Fidelity California Municipal Money Market Fund - Institutional Class \| EMD5Member
Holdings [Line Items]
Percent of Net Asset Value	4.00%
Fidelity California Municipal Money Market Fund - Institutional Class \| AATenderOptionBondMember
Holdings [Line Items]
Percent of Net Asset Value	36.60%
Fidelity California Municipal Money Market Fund - Institutional Class \| AAVariableRateDemandNotesVRDNsMember
Holdings [Line Items]
Percent of Net Asset Value	23.90%
Fidelity California Municipal Money Market Fund - Institutional Class \| AACommercialPaperMember
Holdings [Line Items]
Percent of Net Asset Value	18.10%
Fidelity California Municipal Money Market Fund - Institutional Class \| AAMunicipalSecuritiesMember
Holdings [Line Items]
Percent of Net Asset Value	8.10%
Fidelity California Municipal Money Market Fund - Institutional Class \| AANetOtherAssetsLiabilitiesMember
Holdings [Line Items]
Percent of Net Asset Value	13.30%

Shareholder Report, Holdings (Details)

Aug. 31, 2026