Shareholder Report, Holdings (Details)	Aug. 31, 2025
Fidelity California Municipal Money Market Fund \| EMD0Member
Holdings [Line Items]
Percent of Net Asset Value	67.30%
Fidelity California Municipal Money Market Fund \| EMD1Member
Holdings [Line Items]
Percent of Net Asset Value	7.30%
Fidelity California Municipal Money Market Fund \| EMD2Member
Holdings [Line Items]
Percent of Net Asset Value	13.20%
Fidelity California Municipal Money Market Fund \| EMD3Member
Holdings [Line Items]
Percent of Net Asset Value	4.40%
Fidelity California Municipal Money Market Fund \| EMD4Member
Holdings [Line Items]
Percent of Net Asset Value	0.10%
Fidelity California Municipal Money Market Fund \| EMD5Member
Holdings [Line Items]
Percent of Net Asset Value	5.00%
Fidelity California Municipal Money Market Fund \| AATenderOptionBondMember
Holdings [Line Items]
Percent of Net Asset Value	33.50%
Fidelity California Municipal Money Market Fund \| AAVariableRateDemandNotesVRDNsMember
Holdings [Line Items]
Percent of Net Asset Value	23.30%
Fidelity California Municipal Money Market Fund \| AACommercialPaperMember
Holdings [Line Items]
Percent of Net Asset Value	19.40%
Fidelity California Municipal Money Market Fund \| AAMunicipalSecuritiesMember
Holdings [Line Items]
Percent of Net Asset Value	9.40%
Fidelity California Municipal Money Market Fund \| AANetOtherAssetsLiabilitiesMember
Holdings [Line Items]
Percent of Net Asset Value	14.40%
Fidelity California Municipal Money Market Fund - Premium Class \| EMD0Member
Holdings [Line Items]
Percent of Net Asset Value	67.30%
Fidelity California Municipal Money Market Fund - Premium Class \| EMD1Member
Holdings [Line Items]
Percent of Net Asset Value	7.30%
Fidelity California Municipal Money Market Fund - Premium Class \| EMD2Member
Holdings [Line Items]
Percent of Net Asset Value	13.20%
Fidelity California Municipal Money Market Fund - Premium Class \| EMD3Member
Holdings [Line Items]
Percent of Net Asset Value	4.40%
Fidelity California Municipal Money Market Fund - Premium Class \| EMD4Member
Holdings [Line Items]
Percent of Net Asset Value	0.10%
Fidelity California Municipal Money Market Fund - Premium Class \| EMD5Member
Holdings [Line Items]
Percent of Net Asset Value	5.00%
Fidelity California Municipal Money Market Fund - Premium Class \| AATenderOptionBondMember
Holdings [Line Items]
Percent of Net Asset Value	33.50%
Fidelity California Municipal Money Market Fund - Premium Class \| AAVariableRateDemandNotesVRDNsMember
Holdings [Line Items]
Percent of Net Asset Value	23.30%
Fidelity California Municipal Money Market Fund - Premium Class \| AACommercialPaperMember
Holdings [Line Items]
Percent of Net Asset Value	19.40%
Fidelity California Municipal Money Market Fund - Premium Class \| AAMunicipalSecuritiesMember
Holdings [Line Items]
Percent of Net Asset Value	9.40%
Fidelity California Municipal Money Market Fund - Premium Class \| AANetOtherAssetsLiabilitiesMember
Holdings [Line Items]
Percent of Net Asset Value	14.40%
Fidelity California Municipal Money Market Fund - Institutional Class \| EMD0Member
Holdings [Line Items]
Percent of Net Asset Value	67.30%
Fidelity California Municipal Money Market Fund - Institutional Class \| EMD1Member
Holdings [Line Items]
Percent of Net Asset Value	7.30%
Fidelity California Municipal Money Market Fund - Institutional Class \| EMD2Member
Holdings [Line Items]
Percent of Net Asset Value	13.20%
Fidelity California Municipal Money Market Fund - Institutional Class \| EMD3Member
Holdings [Line Items]
Percent of Net Asset Value	4.40%
Fidelity California Municipal Money Market Fund - Institutional Class \| EMD4Member
Holdings [Line Items]
Percent of Net Asset Value	0.10%
Fidelity California Municipal Money Market Fund - Institutional Class \| EMD5Member
Holdings [Line Items]
Percent of Net Asset Value	5.00%
Fidelity California Municipal Money Market Fund - Institutional Class \| AATenderOptionBondMember
Holdings [Line Items]
Percent of Net Asset Value	33.50%
Fidelity California Municipal Money Market Fund - Institutional Class \| AAVariableRateDemandNotesVRDNsMember
Holdings [Line Items]
Percent of Net Asset Value	23.30%
Fidelity California Municipal Money Market Fund - Institutional Class \| AACommercialPaperMember
Holdings [Line Items]
Percent of Net Asset Value	19.40%
Fidelity California Municipal Money Market Fund - Institutional Class \| AAMunicipalSecuritiesMember
Holdings [Line Items]
Percent of Net Asset Value	9.40%
Fidelity California Municipal Money Market Fund - Institutional Class \| AANetOtherAssetsLiabilitiesMember
Holdings [Line Items]
Percent of Net Asset Value	14.40%

Shareholder Report, Holdings (Details)

Aug. 31, 2025