Shareholder Report |
6 Months Ended | ||||||||||||
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Jun. 30, 2026
USD ($)
shares
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| Shareholder Report [Line Items] | |||||||||||||
| Document Type | N-CSRS | ||||||||||||
| Amendment Flag | false | ||||||||||||
| Registrant Name | Fidelity Hastings Street Trust | ||||||||||||
| Entity Central Index Key | 0000035348 | ||||||||||||
| Entity Investment Company Type | N-1A | ||||||||||||
| Document Period End Date | Jun. 30, 2026 | ||||||||||||
| Fidelity Series Emerging Markets Debt Local Currency Fund | |||||||||||||
| Shareholder Report [Line Items] | |||||||||||||
| Fund Name | Fidelity® Series Emerging Markets Debt Local Currency Fund | ||||||||||||
| Class Name | Fidelity® Series Emerging Markets Debt Local Currency Fund | ||||||||||||
| Trading Symbol | FSEDX | ||||||||||||
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains information about Fidelity® Series Emerging Markets Debt Local Currency Fund for the period January 1, 2026 to June 30, 2026. | ||||||||||||
| 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. | ||||||||||||
| Additional Information Phone Number | 1-800-544-8544 | ||||||||||||
| 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)
A Amount represents less than $.50
B Amount represents less than 0.005%
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| Expenses Paid, Amount | $ 0 | ||||||||||||
| Expense Ratio, Percent | 0.00% | ||||||||||||
| Net Assets | $ 457,401,935 | ||||||||||||
| Holdings Count | shares | 272 | ||||||||||||
| Investment Company Portfolio Turnover | 39.00% | ||||||||||||
| Additional Fund Statistics [Text Block] | Key Fund Statistics
(as of June 30, 2026)
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| Holdings [Text Block] | U.S. Government and U.S. Government Agency Obligations 0.5 AAA 2.8 AA 5.1 A 3.7 BBB 18.3 BB 11.1 Not Rated 49.7 Short-Term Investments and Net Other Assets (Liabilities) 8.8 QUALITY DIVERSIFICATION (% of Fund's net assets) U.S. Government and U.S. Government Agency Obligations - 0.5 AAA - 2.8 AA - 5.1 A - 3.7 BBB - 18.3 BB - 11.1 Not Rated - 49.7 Short-Term Investments and Net Other Assets (Liabilities) - 8.8 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 87.2 Corporate Bonds 3.5 U.S. Treasury Obligations 0.5 Short-Term Investments and Net Other Assets (Liabilities) 8.8 ASSET ALLOCATION (% of Fund's net assets) Foreign Government and Government Agency Obligations - 87.2 Corporate Bonds - 3.5 U.S. Treasury Obligations - 0.5 Short-Term Investments and Net Other Assets (Liabilities) - 8.8 Mexico 10.5 United States 9.3 Brazil 8.5 Indonesia 7.9 India 7.8 South Africa 7.5 Poland 7.3 Malaysia 4.9 Thailand 4.8 Others 31.5 GEOGRAPHIC DIVERSIFICATION (% of Fund's net assets) Mexico - 10.5 United States - 9.3 Brazil - 8.5 Indonesia - 7.9 India - 7.8 South Africa - 7.5 Poland - 7.3 Malaysia - 4.9 Thailand - 4.8 Others - 31.5 | ||||||||||||
| Largest Holdings [Text Block] | TOP HOLDINGS(% of Fund's net assets) United Mexican States 10.5 Indonesia Government 7.9 Republic of India 7.8 South African Republic 7.5 Republic of Poland 7.3 Brazilian Federative Republic 5.3 Malaysia Government 4.9 Kingdom of Thailand 4.8 Czech Republic 4.8 Colombian Republic 4.5 65.3 | ||||||||||||
| Fidelity Series Emerging Markets Debt Fund | |||||||||||||
| Shareholder Report [Line Items] | |||||||||||||
| Fund Name | Fidelity® Series Emerging Markets Debt Fund | ||||||||||||
| Class Name | Fidelity® Series Emerging Markets Debt Fund | ||||||||||||
| Trading Symbol | FEDCX | ||||||||||||
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains information about Fidelity® Series Emerging Markets Debt Fund for the period January 1, 2026 to June 30, 2026. | ||||||||||||
| 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. | ||||||||||||
| Additional Information Phone Number | 1-800-544-8544 | ||||||||||||
| 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)
A Amount represents less than $.50
B Amount represents less than 0.005%
|
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| Expenses Paid, Amount | $ 0 | ||||||||||||
| Expense Ratio, Percent | 0.00% | ||||||||||||
| Net Assets | $ 1,814,678,656 | ||||||||||||
| Holdings Count | shares | 570 | ||||||||||||
| Investment Company Portfolio Turnover | 23.00% | ||||||||||||
| Additional Fund Statistics [Text Block] | Key Fund Statistics
(as of June 30, 2026)
|
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| Holdings [Text Block] | U.S. Government and U.S. Government Agency Obligations 2.4 AA 6.9 A 2.8 BBB 22.5 BB 25.6 B 17.3 CCC,CC,C 9.3 D 0.2 Not Rated 4.8 Equities 0.9 Short-Term Investments and Net Other Assets (Liabilities) 7.3 QUALITY DIVERSIFICATION (% of Fund's net assets) U.S. Government and U.S. Government Agency Obligations - 2.4 AA - 6.9 A - 2.8 BBB - 22.5 BB - 25.6 B - 17.3 CCC,CC,C - 9.3 D - 0.2 Not Rated - 4.8 Equities - 0.9 Short-Term Investments and Net Other Assets (Liabilities) - 7.3 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 59.2 Corporate Bonds 28.8 U.S. Treasury Obligations 2.4 Preferred Securities 1.4 Fixed-Income Funds 0.3 International Equity Funds 0.2 Preferred Stocks 0.2 Common Stocks 0.2 Short-Term Investments and Net Other Assets (Liabilities) 7.3 ASSET ALLOCATION (% of Fund's net assets) Foreign Government and Government Agency Obligations - 59.2 Corporate Bonds - 28.8 U.S. Treasury Obligations - 2.4 Preferred Securities - 1.4 Fixed-Income Funds - 0.3 International Equity Funds - 0.2 Preferred Stocks - 0.2 Common Stocks - 0.2 Short-Term Investments and Net Other Assets (Liabilities) - 7.3 United States 10.3 Mexico 7.0 Brazil 5.1 Saudi Arabia 4.3 Colombia 4.3 Turkey 3.8 Argentina 3.5 United Arab Emirates 3.1 Chile 3.0 Others 55.6 GEOGRAPHIC DIVERSIFICATION (% of Fund's net assets) United States - 10.3 Mexico - 7.0 Brazil - 5.1 Saudi Arabia - 4.3 Colombia - 4.3 Turkey - 3.8 Argentina - 3.5 United Arab Emirates - 3.1 Chile - 3.0 Others - 55.6 | ||||||||||||
| Largest Holdings [Text Block] | TOP HOLDINGS(% of Fund's net assets) Argentine Republic 3.3 Turkish Republic 2.8 United Mexican States 2.6 Arab Republic of Egypt 2.6 Colombian Republic 2.5 Dominican Republic 2.5 Petroleos Mexicanos 2.3 Romanian Republic 2.2 Hungary Government 2.1 Republic of Nigeria 2.1 25.0 |