| Form N-CSR Cover | 6 Months Ended |
| Jun. 30, 2024 | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSRS |
| Amendment Flag | false |
| Registrant Name | Fidelity Summer Street Trust |
| Entity Central Index Key | 0000225322 |
| Entity Investment Company Type | N-1A |
| Document Period End Date | Jun. 30, 2024 |
| Shareholder Report | 6 Months Ended |
| Jun. 30, 2024 USD ($) shares | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSRS |
| Amendment Flag | false |
| Registrant Name | Fidelity Summer Street Trust |
| Entity Central Index Key | 0000225322 |
| Entity Investment Company Type | N-1A |
| Document Period End Date | Jun. 30, 2024 |
| Fidelity Advisor New Markets Income Fund - Class M | |
| Shareholder Report [Line Items] | |
| Fund Name | Fidelity® New Markets Income Fund |
| Class Name | Fidelity Advisor® New Markets Income Fund Class M |
| Trading Symbol | FGWMX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains information about Fidelity® New Markets Income Fund for the period January 1, 2024 to June 30, 2024. |
| Shareholder Report Annual or Semi-Annual | semi-annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the Fund at fundresearch.fidelity.com/prospectus/sec. You can also request this information by contacting us at 1-877-208-0098 or by sending an e-mail to fidfunddocuments@fidelity.com. |
| Additional Information Phone Number | 1-877-208-0098 |
| Additional Information Email | fidfunddocuments@fidelity.com |
| Additional Information Website | fundresearch.fidelity.com/prospectus/sec |
| Expenses [Text Block] | What were your Fund costs for the last six months? (based on hypothetical $10,000 investment) Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class M $ 1.10 % |
| Expenses Paid, Amount | $ 55 |
| Expense Ratio, Percent | 1.10% |
| Net Assets | $ 4,074,947,550 |
| Holdings Count | shares | 422 |
| Investment Company Portfolio Turnover | 12% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics (as of June 30, 2024) KEY FACTS Fund Size $ Number of Holdings 422 Portfolio Turnover 12 % |
| Holdings [Text Block] | U.S. Government and U.S. Government Agency Obligations 2.9 AA 6.4 A 7.1 BBB 20.4 BB 22.2 B 17.1 CCC,CC,C 16.0 D 0.5 Not Rated 4.6 Short-Term Investments and Net Other Assets (Liabilities) 2.8 QUALITY DIVERSIFICATION (% of Fund's net assets) We have used ratings from Moody's Investors Service, Inc. Where Moody's® ratings are not available, we have used S&P® ratings. All ratings are as of the date indicated and do not reflect subsequent changes. Foreign Government and Government Agency Obligations 62.3 Corporate Bonds 31.0 U.S. Treasury Obligations 2.9 Preferred Securities 1.0 Short-Term Investments and Net Other Assets (Liabilities) 2.8 ASSET ALLOCATION (% of Fund's net assets) Mexico 6.8 United States 5.7 Saudi Arabia 4.5 Brazil 4.4 Venezuela 4.0 Turkey 4.0 United Arab Emirates 3.9 Colombia 3.9 Dominican Republic 3.9 Others 58.9 GEOGRAPHIC DIVERSIFICATION (% of Fund's net assets) |
| Largest Holdings [Text Block] | TOP HOLDINGS (% of Fund's net assets) Dominican Republic 3.9 Republic of Turkiye/The 3.7 Petroleos Mexicanos 3.6 Colombian Republic 2.9 Arab Republic of Egypt 2.8 US Treasury Bonds 2.7 Republic of Nigeria 2.5 Indonesia Government 2.4 Panamanian Republic 2.2 Petroleos de Venezuela SA 2.2 28.9 |
| Fidelity New Markets Income Fund | |
| Shareholder Report [Line Items] | |
| Fund Name | Fidelity® New Markets Income Fund |
| Class Name | Fidelity® New Markets Income Fund |
| Trading Symbol | FNMIX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains information about Fidelity® New Markets Income Fund for the period January 1, 2024 to June 30, 2024. |
| Shareholder Report Annual or Semi-Annual | semi-annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the Fund at fundresearch.fidelity.com/prospectus/sec. You can also request this information by contacting us at 1-800-544-8544 or by sending an e-mail to fidfunddocuments@fidelity.com. |
| Additional Information Phone Number | 1-800-544-8544 |
| Additional Information Email | fidfunddocuments@fidelity.com |
| Additional Information Website | fundresearch.fidelity.com/prospectus/sec |
| Expenses [Text Block] | What were your Fund costs for the last six months? (based on hypothetical $10,000 investment) Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Fidelity® New Markets Income Fund $ 0.80 % |
| Expenses Paid, Amount | $ 40 |
| Expense Ratio, Percent | 0.80% |
| Net Assets | $ 4,074,947,550 |
| Holdings Count | shares | 422 |
| Investment Company Portfolio Turnover | 12% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics (as of June 30, 2024) KEY FACTS Fund Size $ Number of Holdings 422 Portfolio Turnover 12 % |
| Holdings [Text Block] | U.S. Government and U.S. Government Agency Obligations 2.9 AA 6.4 A 7.1 BBB 20.4 BB 22.2 B 17.1 CCC,CC,C 16.0 D 0.5 Not Rated 4.6 Short-Term Investments and Net Other Assets (Liabilities) 2.8 QUALITY DIVERSIFICATION (% of Fund's net assets) We have used ratings from Moody's Investors Service, Inc. Where Moody's® ratings are not available, we have used S&P® ratings. All ratings are as of the date indicated and do not reflect subsequent changes. Foreign Government and Government Agency Obligations 62.3 Corporate Bonds 31.0 U.S. Treasury Obligations 2.9 Preferred Securities 1.0 Short-Term Investments and Net Other Assets (Liabilities) 2.8 ASSET ALLOCATION (% of Fund's net assets) Mexico 6.8 United States 5.7 Saudi Arabia 4.5 Brazil 4.4 Venezuela 4.0 Turkey 4.0 United Arab Emirates 3.9 Colombia 3.9 Dominican Republic 3.9 Others 58.9 GEOGRAPHIC DIVERSIFICATION (% of Fund's net assets) |
| Largest Holdings [Text Block] | TOP HOLDINGS (% of Fund's net assets) Dominican Republic 3.9 Republic of Turkiye/The 3.7 Petroleos Mexicanos 3.6 Colombian Republic 2.9 Arab Republic of Egypt 2.8 US Treasury Bonds 2.7 Republic of Nigeria 2.5 Indonesia Government 2.4 Panamanian Republic 2.2 Petroleos de Venezuela SA 2.2 28.9 |
| Fidelity Advisor New Markets Income Fund - Class Z | |
| Shareholder Report [Line Items] | |
| Fund Name | Fidelity® New Markets Income Fund |
| Class Name | Fidelity Advisor® New Markets Income Fund Class Z |
| Trading Symbol | FGBMX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains information about Fidelity® New Markets Income Fund for the period January 1, 2024 to June 30, 2024. |
| Shareholder Report Annual or Semi-Annual | semi-annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the Fund at fundresearch.fidelity.com/prospectus/sec. You can also request this information by contacting us at 1-877-208-0098 or by sending an e-mail to fidfunddocuments@fidelity.com. |
| Additional Information Phone Number | 1-877-208-0098 |
| Additional Information Email | fidfunddocuments@fidelity.com |
| Additional Information Website | fundresearch.fidelity.com/prospectus/sec |
| Expenses [Text Block] | What were your Fund costs for the last six months? (based on hypothetical $10,000 investment) Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class Z $ 0.73 % |
| Expenses Paid, Amount | $ 37 |
| Expense Ratio, Percent | 0.73% |
| Net Assets | $ 4,074,947,550 |
| Holdings Count | shares | 422 |
| Investment Company Portfolio Turnover | 12% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics (as of June 30, 2024) KEY FACTS Fund Size $ Number of Holdings 422 Portfolio Turnover 12 % |
| Holdings [Text Block] | U.S. Government and U.S. Government Agency Obligations 2.9 AA 6.4 A 7.1 BBB 20.4 BB 22.2 B 17.1 CCC,CC,C 16.0 D 0.5 Not Rated 4.6 Short-Term Investments and Net Other Assets (Liabilities) 2.8 QUALITY DIVERSIFICATION (% of Fund's net assets) We have used ratings from Moody's Investors Service, Inc. Where Moody's® ratings are not available, we have used S&P® ratings. All ratings are as of the date indicated and do not reflect subsequent changes. Foreign Government and Government Agency Obligations 62.3 Corporate Bonds 31.0 U.S. Treasury Obligations 2.9 Preferred Securities 1.0 Short-Term Investments and Net Other Assets (Liabilities) 2.8 ASSET ALLOCATION (% of Fund's net assets) Mexico 6.8 United States 5.7 Saudi Arabia 4.5 Brazil 4.4 Venezuela 4.0 Turkey 4.0 United Arab Emirates 3.9 Colombia 3.9 Dominican Republic 3.9 Others 58.9 GEOGRAPHIC DIVERSIFICATION (% of Fund's net assets) |
| Largest Holdings [Text Block] | TOP HOLDINGS (% of Fund's net assets) Dominican Republic 3.9 Republic of Turkiye/The 3.7 Petroleos Mexicanos 3.6 Colombian Republic 2.9 Arab Republic of Egypt 2.8 US Treasury Bonds 2.7 Republic of Nigeria 2.5 Indonesia Government 2.4 Panamanian Republic 2.2 Petroleos de Venezuela SA 2.2 28.9 |
| Fidelity Advisor New Markets Income Fund - Class C | |
| Shareholder Report [Line Items] | |
| Fund Name | Fidelity® New Markets Income Fund |
| Class Name | Fidelity Advisor® New Markets Income Fund Class C |
| Trading Symbol | FGYMX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains information about Fidelity® New Markets Income Fund for the period January 1, 2024 to June 30, 2024. |
| Shareholder Report Annual or Semi-Annual | semi-annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the Fund at fundresearch.fidelity.com/prospectus/sec. You can also request this information by contacting us at 1-877-208-0098 or by sending an e-mail to fidfunddocuments@fidelity.com. |
| Additional Information Phone Number | 1-877-208-0098 |
| Additional Information Email | fidfunddocuments@fidelity.com |
| Additional Information Website | fundresearch.fidelity.com/prospectus/sec |
| Expenses [Text Block] | What were your Fund costs for the last six months? (based on hypothetical $10,000 investment) Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class C $ 1.83 % |
| Expenses Paid, Amount | $ 92 |
| Expense Ratio, Percent | 1.83% |
| Net Assets | $ 4,074,947,550 |
| Holdings Count | shares | 422 |
| Investment Company Portfolio Turnover | 12% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics (as of June 30, 2024) KEY FACTS Fund Size $ Number of Holdings 422 Portfolio Turnover 12 % |
| Holdings [Text Block] | U.S. Government and U.S. Government Agency Obligations 2.9 AA 6.4 A 7.1 BBB 20.4 BB 22.2 B 17.1 CCC,CC,C 16.0 D 0.5 Not Rated 4.6 Short-Term Investments and Net Other Assets (Liabilities) 2.8 QUALITY DIVERSIFICATION (% of Fund's net assets) We have used ratings from Moody's Investors Service, Inc. Where Moody's® ratings are not available, we have used S&P® ratings. All ratings are as of the date indicated and do not reflect subsequent changes. Foreign Government and Government Agency Obligations 62.3 Corporate Bonds 31.0 U.S. Treasury Obligations 2.9 Preferred Securities 1.0 Short-Term Investments and Net Other Assets (Liabilities) 2.8 ASSET ALLOCATION (% of Fund's net assets) Mexico 6.8 United States 5.7 Saudi Arabia 4.5 Brazil 4.4 Venezuela 4.0 Turkey 4.0 United Arab Emirates 3.9 Colombia 3.9 Dominican Republic 3.9 Others 58.9 GEOGRAPHIC DIVERSIFICATION (% of Fund's net assets) |
| Largest Holdings [Text Block] | TOP HOLDINGS (% of Fund's net assets) Dominican Republic 3.9 Republic of Turkiye/The 3.7 Petroleos Mexicanos 3.6 Colombian Republic 2.9 Arab Republic of Egypt 2.8 US Treasury Bonds 2.7 Republic of Nigeria 2.5 Indonesia Government 2.4 Panamanian Republic 2.2 Petroleos de Venezuela SA 2.2 28.9 |
| Fidelity Advisor New Markets Income Fund - Class A | |
| Shareholder Report [Line Items] | |
| Fund Name | Fidelity® New Markets Income Fund |
| Class Name | Fidelity Advisor® New Markets Income Fund Class A |
| Trading Symbol | FGVMX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains information about Fidelity® New Markets Income Fund for the period January 1, 2024 to June 30, 2024. |
| Shareholder Report Annual or Semi-Annual | semi-annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the Fund at fundresearch.fidelity.com/prospectus/sec. You can also request this information by contacting us at 1-877-208-0098 or by sending an e-mail to fidfunddocuments@fidelity.com. |
| Additional Information Phone Number | 1-877-208-0098 |
| Additional Information Email | fidfunddocuments@fidelity.com |
| Additional Information Website | fundresearch.fidelity.com/prospectus/sec |
| Expenses [Text Block] | What were your Fund costs for the last six months? (based on hypothetical $10,000 investment) Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class A $ 1.09 % |
| Expenses Paid, Amount | $ 55 |
| Expense Ratio, Percent | 1.09% |
| Net Assets | $ 4,074,947,550 |
| Holdings Count | shares | 422 |
| Investment Company Portfolio Turnover | 12% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics (as of June 30, 2024) KEY FACTS Fund Size $ Number of Holdings 422 Portfolio Turnover 12 % |
| Holdings [Text Block] | U.S. Government and U.S. Government Agency Obligations 2.9 AA 6.4 A 7.1 BBB 20.4 BB 22.2 B 17.1 CCC,CC,C 16.0 D 0.5 Not Rated 4.6 Short-Term Investments and Net Other Assets (Liabilities) 2.8 QUALITY DIVERSIFICATION (% of Fund's net assets) We have used ratings from Moody's Investors Service, Inc. Where Moody's® ratings are not available, we have used S&P® ratings. All ratings are as of the date indicated and do not reflect subsequent changes. Foreign Government and Government Agency Obligations 62.3 Corporate Bonds 31.0 U.S. Treasury Obligations 2.9 Preferred Securities 1.0 Short-Term Investments and Net Other Assets (Liabilities) 2.8 ASSET ALLOCATION (% of Fund's net assets) Mexico 6.8 United States 5.7 Saudi Arabia 4.5 Brazil 4.4 Venezuela 4.0 Turkey 4.0 United Arab Emirates 3.9 Colombia 3.9 Dominican Republic 3.9 Others 58.9 GEOGRAPHIC DIVERSIFICATION (% of Fund's net assets) |
| Largest Holdings [Text Block] | TOP HOLDINGS (% of Fund's net assets) Dominican Republic 3.9 Republic of Turkiye/The 3.7 Petroleos Mexicanos 3.6 Colombian Republic 2.9 Arab Republic of Egypt 2.8 US Treasury Bonds 2.7 Republic of Nigeria 2.5 Indonesia Government 2.4 Panamanian Republic 2.2 Petroleos de Venezuela SA 2.2 28.9 |
| Fidelity Advisor New Markets Income Fund - Class I | |
| Shareholder Report [Line Items] | |
| Fund Name | Fidelity® New Markets Income Fund |
| Class Name | Fidelity Advisor® New Markets Income Fund Class I |
| Trading Symbol | FGZMX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains information about Fidelity® New Markets Income Fund for the period January 1, 2024 to June 30, 2024. |
| Shareholder Report Annual or Semi-Annual | semi-annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the Fund at fundresearch.fidelity.com/prospectus/sec. You can also request this information by contacting us at 1-877-208-0098 or by sending an e-mail to fidfunddocuments@fidelity.com. |
| Additional Information Phone Number | 1-877-208-0098 |
| Additional Information Email | fidfunddocuments@fidelity.com |
| Additional Information Website | fundresearch.fidelity.com/prospectus/sec |
| Expenses [Text Block] | What were your Fund costs for the last six months? (based on hypothetical $10,000 investment) Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class I $ 0.83 % |
| Expenses Paid, Amount | $ 42 |
| Expense Ratio, Percent | 0.83% |
| Net Assets | $ 4,074,947,550 |
| Holdings Count | shares | 422 |
| Investment Company Portfolio Turnover | 12% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics (as of June 30, 2024) KEY FACTS Fund Size $ Number of Holdings 422 Portfolio Turnover 12 % |
| Holdings [Text Block] | U.S. Government and U.S. Government Agency Obligations 2.9 AA 6.4 A 7.1 BBB 20.4 BB 22.2 B 17.1 CCC,CC,C 16.0 D 0.5 Not Rated 4.6 Short-Term Investments and Net Other Assets (Liabilities) 2.8 QUALITY DIVERSIFICATION (% of Fund's net assets) We have used ratings from Moody's Investors Service, Inc. Where Moody's® ratings are not available, we have used S&P® ratings. All ratings are as of the date indicated and do not reflect subsequent changes. Foreign Government and Government Agency Obligations 62.3 Corporate Bonds 31.0 U.S. Treasury Obligations 2.9 Preferred Securities 1.0 Short-Term Investments and Net Other Assets (Liabilities) 2.8 ASSET ALLOCATION (% of Fund's net assets) Mexico 6.8 United States 5.7 Saudi Arabia 4.5 Brazil 4.4 Venezuela 4.0 Turkey 4.0 United Arab Emirates 3.9 Colombia 3.9 Dominican Republic 3.9 Others 58.9 GEOGRAPHIC DIVERSIFICATION (% of Fund's net assets) |
| Largest Holdings [Text Block] | TOP HOLDINGS (% of Fund's net assets) Dominican Republic 3.9 Republic of Turkiye/The 3.7 Petroleos Mexicanos 3.6 Colombian Republic 2.9 Arab Republic of Egypt 2.8 US Treasury Bonds 2.7 Republic of Nigeria 2.5 Indonesia Government 2.4 Panamanian Republic 2.2 Petroleos de Venezuela SA 2.2 28.9 |
| Shareholder Report, Holdings (Details) | Jun. 30, 2024 |
| Fidelity Advisor New Markets Income Fund - Class M | TH0Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Fidelity Advisor New Markets Income Fund - Class M | TH1Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.70% |
| Fidelity Advisor New Markets Income Fund - Class M | TH2Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.60% |
| Fidelity Advisor New Markets Income Fund - Class M | TH3Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.90% |
| Fidelity Advisor New Markets Income Fund - Class M | TH4Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| Fidelity Advisor New Markets Income Fund - Class M | TH5Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.70% |
| Fidelity Advisor New Markets Income Fund - Class M | TH6Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.50% |
| Fidelity Advisor New Markets Income Fund - Class M | TH7Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.40% |
| Fidelity Advisor New Markets Income Fund - Class M | TH8Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.20% |
| Fidelity Advisor New Markets Income Fund - Class M | TH9Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.20% |
| Fidelity Advisor New Markets Income Fund - Class M | QDUSGovernmentandUSGovernmentAgencyObligationsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.90% |
| Fidelity Advisor New Markets Income Fund - Class M | QDAMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 7.10% |
| Fidelity Advisor New Markets Income Fund - Class M | QDBBBMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 20.40% |
| Fidelity Advisor New Markets Income Fund - Class M | QDBBMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 22.20% |
| Fidelity Advisor New Markets Income Fund - Class M | QDBMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 17.10% |
| Fidelity Advisor New Markets Income Fund - Class M | QDCCCCCCMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 16% |
| Fidelity Advisor New Markets Income Fund - Class M | QDDMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.50% |
| Fidelity Advisor New Markets Income Fund - Class M | QDNotRatedMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.60% |
| Fidelity Advisor New Markets Income Fund - Class M | QDShortTermInvestmentsandNetOtherAssetsLiabilitiesMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| Fidelity Advisor New Markets Income Fund - Class M | Mexico | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.80% |
| Fidelity Advisor New Markets Income Fund - Class M | United States | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.70% |
| Fidelity Advisor New Markets Income Fund - Class M | Saudi Arabia | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.50% |
| Fidelity Advisor New Markets Income Fund - Class M | Brazil | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.40% |
| Fidelity Advisor New Markets Income Fund - Class M | Venezuela | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4% |
| Fidelity Advisor New Markets Income Fund - Class M | Turkey | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4% |
| Fidelity Advisor New Markets Income Fund - Class M | United Arab Emirates | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Fidelity Advisor New Markets Income Fund - Class M | Colombia | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Fidelity Advisor New Markets Income Fund - Class M | Dominican Republic | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Fidelity Advisor New Markets Income Fund - Class M | OtherMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 58.90% |
| Fidelity Advisor New Markets Income Fund - Class M | AAForeignGovernmentandGovernmentAgencyObligationsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 62.30% |
| Fidelity Advisor New Markets Income Fund - Class M | AACorporateBondsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 31% |
| Fidelity Advisor New Markets Income Fund - Class M | AAUSTreasuryObligationsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.90% |
| Fidelity Advisor New Markets Income Fund - Class M | AAPreferredSecuritiesMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1% |
| Fidelity Advisor New Markets Income Fund - Class M | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| Fidelity New Markets Income Fund | TH0Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Fidelity New Markets Income Fund | TH1Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.70% |
| Fidelity New Markets Income Fund | TH2Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.60% |
| Fidelity New Markets Income Fund | TH3Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.90% |
| Fidelity New Markets Income Fund | TH4Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| Fidelity New Markets Income Fund | TH5Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.70% |
| Fidelity New Markets Income Fund | TH6Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.50% |
| Fidelity New Markets Income Fund | TH7Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.40% |
| Fidelity New Markets Income Fund | TH8Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.20% |
| Fidelity New Markets Income Fund | TH9Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.20% |
| Fidelity New Markets Income Fund | QDUSGovernmentandUSGovernmentAgencyObligationsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.90% |
| Fidelity New Markets Income Fund | QDAMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 7.10% |
| Fidelity New Markets Income Fund | QDBBBMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 20.40% |
| Fidelity New Markets Income Fund | QDBBMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 22.20% |
| Fidelity New Markets Income Fund | QDBMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 17.10% |
| Fidelity New Markets Income Fund | QDCCCCCCMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 16% |
| Fidelity New Markets Income Fund | QDDMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.50% |
| Fidelity New Markets Income Fund | QDNotRatedMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.60% |
| Fidelity New Markets Income Fund | QDShortTermInvestmentsandNetOtherAssetsLiabilitiesMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| Fidelity New Markets Income Fund | Mexico | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.80% |
| Fidelity New Markets Income Fund | United States | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.70% |
| Fidelity New Markets Income Fund | Saudi Arabia | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.50% |
| Fidelity New Markets Income Fund | Brazil | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.40% |
| Fidelity New Markets Income Fund | Venezuela | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4% |
| Fidelity New Markets Income Fund | Turkey | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4% |
| Fidelity New Markets Income Fund | United Arab Emirates | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Fidelity New Markets Income Fund | Colombia | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Fidelity New Markets Income Fund | Dominican Republic | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Fidelity New Markets Income Fund | OtherMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 58.90% |
| Fidelity New Markets Income Fund | AAForeignGovernmentandGovernmentAgencyObligationsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 62.30% |
| Fidelity New Markets Income Fund | AACorporateBondsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 31% |
| Fidelity New Markets Income Fund | AAUSTreasuryObligationsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.90% |
| Fidelity New Markets Income Fund | AAPreferredSecuritiesMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1% |
| Fidelity New Markets Income Fund | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| Fidelity Advisor New Markets Income Fund - Class Z | TH0Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Fidelity Advisor New Markets Income Fund - Class Z | TH1Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.70% |
| Fidelity Advisor New Markets Income Fund - Class Z | TH2Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.60% |
| Fidelity Advisor New Markets Income Fund - Class Z | TH3Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.90% |
| Fidelity Advisor New Markets Income Fund - Class Z | TH4Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| Fidelity Advisor New Markets Income Fund - Class Z | TH5Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.70% |
| Fidelity Advisor New Markets Income Fund - Class Z | TH6Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.50% |
| Fidelity Advisor New Markets Income Fund - Class Z | TH7Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.40% |
| Fidelity Advisor New Markets Income Fund - Class Z | TH8Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.20% |
| Fidelity Advisor New Markets Income Fund - Class Z | TH9Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.20% |
| Fidelity Advisor New Markets Income Fund - Class Z | QDUSGovernmentandUSGovernmentAgencyObligationsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.90% |
| Fidelity Advisor New Markets Income Fund - Class Z | QDAMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 7.10% |
| Fidelity Advisor New Markets Income Fund - Class Z | QDBBBMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 20.40% |
| Fidelity Advisor New Markets Income Fund - Class Z | QDBBMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 22.20% |
| Fidelity Advisor New Markets Income Fund - Class Z | QDBMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 17.10% |
| Fidelity Advisor New Markets Income Fund - Class Z | QDCCCCCCMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 16% |
| Fidelity Advisor New Markets Income Fund - Class Z | QDDMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.50% |
| Fidelity Advisor New Markets Income Fund - Class Z | QDNotRatedMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.60% |
| Fidelity Advisor New Markets Income Fund - Class Z | QDShortTermInvestmentsandNetOtherAssetsLiabilitiesMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| Fidelity Advisor New Markets Income Fund - Class Z | Mexico | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.80% |
| Fidelity Advisor New Markets Income Fund - Class Z | United States | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.70% |
| Fidelity Advisor New Markets Income Fund - Class Z | Saudi Arabia | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.50% |
| Fidelity Advisor New Markets Income Fund - Class Z | Brazil | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.40% |
| Fidelity Advisor New Markets Income Fund - Class Z | Venezuela | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4% |
| Fidelity Advisor New Markets Income Fund - Class Z | Turkey | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4% |
| Fidelity Advisor New Markets Income Fund - Class Z | United Arab Emirates | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Fidelity Advisor New Markets Income Fund - Class Z | Colombia | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Fidelity Advisor New Markets Income Fund - Class Z | Dominican Republic | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Fidelity Advisor New Markets Income Fund - Class Z | OtherMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 58.90% |
| Fidelity Advisor New Markets Income Fund - Class Z | AAForeignGovernmentandGovernmentAgencyObligationsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 62.30% |
| Fidelity Advisor New Markets Income Fund - Class Z | AACorporateBondsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 31% |
| Fidelity Advisor New Markets Income Fund - Class Z | AAUSTreasuryObligationsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.90% |
| Fidelity Advisor New Markets Income Fund - Class Z | AAPreferredSecuritiesMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1% |
| Fidelity Advisor New Markets Income Fund - Class Z | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| Fidelity Advisor New Markets Income Fund - Class C | TH0Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Fidelity Advisor New Markets Income Fund - Class C | TH1Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.70% |
| Fidelity Advisor New Markets Income Fund - Class C | TH2Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.60% |
| Fidelity Advisor New Markets Income Fund - Class C | TH3Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.90% |
| Fidelity Advisor New Markets Income Fund - Class C | TH4Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| Fidelity Advisor New Markets Income Fund - Class C | TH5Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.70% |
| Fidelity Advisor New Markets Income Fund - Class C | TH6Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.50% |
| Fidelity Advisor New Markets Income Fund - Class C | TH7Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.40% |
| Fidelity Advisor New Markets Income Fund - Class C | TH8Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.20% |
| Fidelity Advisor New Markets Income Fund - Class C | TH9Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.20% |
| Fidelity Advisor New Markets Income Fund - Class C | QDUSGovernmentandUSGovernmentAgencyObligationsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.90% |
| Fidelity Advisor New Markets Income Fund - Class C | QDAMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 7.10% |
| Fidelity Advisor New Markets Income Fund - Class C | QDBBBMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 20.40% |
| Fidelity Advisor New Markets Income Fund - Class C | QDBBMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 22.20% |
| Fidelity Advisor New Markets Income Fund - Class C | QDBMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 17.10% |
| Fidelity Advisor New Markets Income Fund - Class C | QDCCCCCCMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 16% |
| Fidelity Advisor New Markets Income Fund - Class C | QDDMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.50% |
| Fidelity Advisor New Markets Income Fund - Class C | QDNotRatedMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.60% |
| Fidelity Advisor New Markets Income Fund - Class C | QDShortTermInvestmentsandNetOtherAssetsLiabilitiesMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| Fidelity Advisor New Markets Income Fund - Class C | Mexico | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.80% |
| Fidelity Advisor New Markets Income Fund - Class C | United States | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.70% |
| Fidelity Advisor New Markets Income Fund - Class C | Saudi Arabia | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.50% |
| Fidelity Advisor New Markets Income Fund - Class C | Brazil | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.40% |
| Fidelity Advisor New Markets Income Fund - Class C | Venezuela | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4% |
| Fidelity Advisor New Markets Income Fund - Class C | Turkey | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4% |
| Fidelity Advisor New Markets Income Fund - Class C | United Arab Emirates | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Fidelity Advisor New Markets Income Fund - Class C | Colombia | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Fidelity Advisor New Markets Income Fund - Class C | Dominican Republic | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Fidelity Advisor New Markets Income Fund - Class C | OtherMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 58.90% |
| Fidelity Advisor New Markets Income Fund - Class C | AAForeignGovernmentandGovernmentAgencyObligationsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 62.30% |
| Fidelity Advisor New Markets Income Fund - Class C | AACorporateBondsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 31% |
| Fidelity Advisor New Markets Income Fund - Class C | AAUSTreasuryObligationsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.90% |
| Fidelity Advisor New Markets Income Fund - Class C | AAPreferredSecuritiesMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1% |
| Fidelity Advisor New Markets Income Fund - Class C | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| Fidelity Advisor New Markets Income Fund - Class A | TH0Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Fidelity Advisor New Markets Income Fund - Class A | TH1Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.70% |
| Fidelity Advisor New Markets Income Fund - Class A | TH2Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.60% |
| Fidelity Advisor New Markets Income Fund - Class A | TH3Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.90% |
| Fidelity Advisor New Markets Income Fund - Class A | TH4Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| Fidelity Advisor New Markets Income Fund - Class A | TH5Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.70% |
| Fidelity Advisor New Markets Income Fund - Class A | TH6Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.50% |
| Fidelity Advisor New Markets Income Fund - Class A | TH7Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.40% |
| Fidelity Advisor New Markets Income Fund - Class A | TH8Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.20% |
| Fidelity Advisor New Markets Income Fund - Class A | TH9Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.20% |
| Fidelity Advisor New Markets Income Fund - Class A | QDUSGovernmentandUSGovernmentAgencyObligationsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.90% |
| Fidelity Advisor New Markets Income Fund - Class A | QDAMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 7.10% |
| Fidelity Advisor New Markets Income Fund - Class A | QDBBBMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 20.40% |
| Fidelity Advisor New Markets Income Fund - Class A | QDBBMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 22.20% |
| Fidelity Advisor New Markets Income Fund - Class A | QDBMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 17.10% |
| Fidelity Advisor New Markets Income Fund - Class A | QDCCCCCCMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 16% |
| Fidelity Advisor New Markets Income Fund - Class A | QDDMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.50% |
| Fidelity Advisor New Markets Income Fund - Class A | QDNotRatedMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.60% |
| Fidelity Advisor New Markets Income Fund - Class A | QDShortTermInvestmentsandNetOtherAssetsLiabilitiesMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| Fidelity Advisor New Markets Income Fund - Class A | Mexico | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.80% |
| Fidelity Advisor New Markets Income Fund - Class A | United States | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.70% |
| Fidelity Advisor New Markets Income Fund - Class A | Saudi Arabia | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.50% |
| Fidelity Advisor New Markets Income Fund - Class A | Brazil | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.40% |
| Fidelity Advisor New Markets Income Fund - Class A | Venezuela | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4% |
| Fidelity Advisor New Markets Income Fund - Class A | Turkey | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4% |
| Fidelity Advisor New Markets Income Fund - Class A | United Arab Emirates | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Fidelity Advisor New Markets Income Fund - Class A | Colombia | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Fidelity Advisor New Markets Income Fund - Class A | Dominican Republic | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Fidelity Advisor New Markets Income Fund - Class A | OtherMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 58.90% |
| Fidelity Advisor New Markets Income Fund - Class A | AAForeignGovernmentandGovernmentAgencyObligationsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 62.30% |
| Fidelity Advisor New Markets Income Fund - Class A | AACorporateBondsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 31% |
| Fidelity Advisor New Markets Income Fund - Class A | AAUSTreasuryObligationsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.90% |
| Fidelity Advisor New Markets Income Fund - Class A | AAPreferredSecuritiesMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1% |
| Fidelity Advisor New Markets Income Fund - Class A | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| Fidelity Advisor New Markets Income Fund - Class I | TH0Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Fidelity Advisor New Markets Income Fund - Class I | TH1Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.70% |
| Fidelity Advisor New Markets Income Fund - Class I | TH2Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.60% |
| Fidelity Advisor New Markets Income Fund - Class I | TH3Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.90% |
| Fidelity Advisor New Markets Income Fund - Class I | TH4Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| Fidelity Advisor New Markets Income Fund - Class I | TH5Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.70% |
| Fidelity Advisor New Markets Income Fund - Class I | TH6Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.50% |
| Fidelity Advisor New Markets Income Fund - Class I | TH7Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.40% |
| Fidelity Advisor New Markets Income Fund - Class I | TH8Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.20% |
| Fidelity Advisor New Markets Income Fund - Class I | TH9Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.20% |
| Fidelity Advisor New Markets Income Fund - Class I | QDUSGovernmentandUSGovernmentAgencyObligationsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.90% |
| Fidelity Advisor New Markets Income Fund - Class I | QDAMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 7.10% |
| Fidelity Advisor New Markets Income Fund - Class I | QDBBBMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 20.40% |
| Fidelity Advisor New Markets Income Fund - Class I | QDBBMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 22.20% |
| Fidelity Advisor New Markets Income Fund - Class I | QDBMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 17.10% |
| Fidelity Advisor New Markets Income Fund - Class I | QDCCCCCCMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 16% |
| Fidelity Advisor New Markets Income Fund - Class I | QDDMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.50% |
| Fidelity Advisor New Markets Income Fund - Class I | QDNotRatedMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.60% |
| Fidelity Advisor New Markets Income Fund - Class I | QDShortTermInvestmentsandNetOtherAssetsLiabilitiesMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| Fidelity Advisor New Markets Income Fund - Class I | Mexico | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.80% |
| Fidelity Advisor New Markets Income Fund - Class I | United States | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.70% |
| Fidelity Advisor New Markets Income Fund - Class I | Saudi Arabia | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.50% |
| Fidelity Advisor New Markets Income Fund - Class I | Brazil | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.40% |
| Fidelity Advisor New Markets Income Fund - Class I | Venezuela | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4% |
| Fidelity Advisor New Markets Income Fund - Class I | Turkey | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4% |
| Fidelity Advisor New Markets Income Fund - Class I | United Arab Emirates | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Fidelity Advisor New Markets Income Fund - Class I | Colombia | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Fidelity Advisor New Markets Income Fund - Class I | Dominican Republic | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.90% |
| Fidelity Advisor New Markets Income Fund - Class I | OtherMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 58.90% |
| Fidelity Advisor New Markets Income Fund - Class I | AAForeignGovernmentandGovernmentAgencyObligationsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 62.30% |
| Fidelity Advisor New Markets Income Fund - Class I | AACorporateBondsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 31% |
| Fidelity Advisor New Markets Income Fund - Class I | AAUSTreasuryObligationsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.90% |
| Fidelity Advisor New Markets Income Fund - Class I | AAPreferredSecuritiesMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1% |
| Fidelity Advisor New Markets Income Fund - Class I | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| Label | Element | Value |
| C000206229 [Member] | QDAAMember [Member] | ||
| Percent of Net Asset Value | oef_PctOfNav | 6.40% |
| C000206231 [Member] | QDAAMember [Member] | ||
| Percent of Net Asset Value | oef_PctOfNav | 6.40% |
| C000206230 [Member] | QDAAMember [Member] | ||
| Percent of Net Asset Value | oef_PctOfNav | 6.40% |
| C000206228 [Member] | QDAAMember [Member] | ||
| Percent of Net Asset Value | oef_PctOfNav | 6.40% |
| C000206232 [Member] | QDAAMember [Member] | ||
| Percent of Net Asset Value | oef_PctOfNav | 6.40% |
| C000048888 [Member] | QDAAMember [Member] | ||
| Percent of Net Asset Value | oef_PctOfNav | 6.40% |
