v3.25.3
Shareholder Report, Holdings (Details)
Aug. 31, 2025
Fidelity Specialized High Income Central Fund | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.80%
Fidelity Specialized High Income Central Fund | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.50%
Fidelity Specialized High Income Central Fund | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Specialized High Income Central Fund | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Specialized High Income Central Fund | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Specialized High Income Central Fund | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Specialized High Income Central Fund | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Specialized High Income Central Fund | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Specialized High Income Central Fund | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Specialized High Income Central Fund | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Specialized High Income Central Fund | QDUSGovernmentandUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
Fidelity Specialized High Income Central Fund | QDBBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.00%
Fidelity Specialized High Income Central Fund | QDBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 65.40%
Fidelity Specialized High Income Central Fund | QDBMember  
Holdings [Line Items]  
Percent of Net Asset Value 23.40%
Fidelity Specialized High Income Central Fund | QDCCCCCCMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.30%
Fidelity Specialized High Income Central Fund | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Specialized High Income Central Fund | QDEquitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Specialized High Income Central Fund | QDShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 3.70%
Fidelity Specialized High Income Central Fund | United States  
Holdings [Line Items]  
Percent of Net Asset Value 86.90%
Fidelity Specialized High Income Central Fund | Canada  
Holdings [Line Items]  
Percent of Net Asset Value 3.00%
Fidelity Specialized High Income Central Fund | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Specialized High Income Central Fund | Ireland  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Specialized High Income Central Fund | Australia  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Specialized High Income Central Fund | France  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Fidelity Specialized High Income Central Fund | Israel  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Fidelity Specialized High Income Central Fund | GrandCaymanUKOverseasTerMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Specialized High Income Central Fund | Panama  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Specialized High Income Central Fund | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.60%
Fidelity Specialized High Income Central Fund | AACorporateBondsMember  
Holdings [Line Items]  
Percent of Net Asset Value 86.90%
Fidelity Specialized High Income Central Fund | AABankLoanObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.60%
Fidelity Specialized High Income Central Fund | AAPreferredSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 3.90%
Fidelity Specialized High Income Central Fund | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
Fidelity Specialized High Income Central Fund | AAAssetBackedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Specialized High Income Central Fund | AACommonStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Specialized High Income Central Fund | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 3.70%
Fidelity High Income Central Fund | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.70%
Fidelity High Income Central Fund | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.60%
Fidelity High Income Central Fund | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity High Income Central Fund | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity High Income Central Fund | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.00%
Fidelity High Income Central Fund | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.50%
Fidelity High Income Central Fund | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity High Income Central Fund | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity High Income Central Fund | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity High Income Central Fund | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity High Income Central Fund | QDBBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.60%
Fidelity High Income Central Fund | QDBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 27.00%
Fidelity High Income Central Fund | QDBMember  
Holdings [Line Items]  
Percent of Net Asset Value 34.20%
Fidelity High Income Central Fund | QDCCCCCCMember  
Holdings [Line Items]  
Percent of Net Asset Value 19.60%
Fidelity High Income Central Fund | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 3.40%
Fidelity High Income Central Fund | QDEquitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 6.60%
Fidelity High Income Central Fund | QDShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.60%
Fidelity High Income Central Fund | United States  
Holdings [Line Items]  
Percent of Net Asset Value 89.00%
Fidelity High Income Central Fund | Canada  
Holdings [Line Items]  
Percent of Net Asset Value 2.10%
Fidelity High Income Central Fund | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity High Income Central Fund | Australia  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
Fidelity High Income Central Fund | France  
Holdings [Line Items]  
Percent of Net Asset Value 3.10%
Fidelity High Income Central Fund | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity High Income Central Fund | Switzerland  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity High Income Central Fund | Brazil  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
Fidelity High Income Central Fund | Luxembourg  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity High Income Central Fund | Japan  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Fidelity High Income Central Fund | AACorporateBondsMember  
Holdings [Line Items]  
Percent of Net Asset Value 78.40%
Fidelity High Income Central Fund | AABankLoanObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 8.70%
Fidelity High Income Central Fund | AAPreferredSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity High Income Central Fund | AAAssetBackedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Fidelity High Income Central Fund | AACommonStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 3.50%
Fidelity High Income Central Fund | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.60%
Fidelity High Income Central Fund | AAAlternativeFundsMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.00%
Fidelity High Income Central Fund | AAPreferredStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%