| Form N-CSR Cover | 12 Months Ended |
| Jul. 31, 2024 | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSR |
| Amendment Flag | false |
| Registrant Name | Fidelity Oxford Street Trust |
| Entity Central Index Key | 0000028540 |
| Entity Investment Company Type | N-1A |
| Document Period End Date | Jul. 31, 2024 |
| Shareholder Report | 12 Months Ended |
| Jul. 31, 2024 USD ($) shares | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSR |
| Amendment Flag | false |
| Registrant Name | Fidelity Oxford Street Trust |
| Entity Central Index Key | 0000028540 |
| Entity Investment Company Type | N-1A |
| Document Period End Date | Jul. 31, 2024 |
| Fidelity SAI Inflation-Focused Fund | |
| Shareholder Report [Line Items] | |
| Fund Name | Fidelity® SAI Inflation-Focused Fund |
| Class Name | Fidelity® SAI Inflation-Focused Fund |
| Trading Symbol | FIFGX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains information about Fidelity® SAI Inflation-Focused Fund for the period August 1, 2023 to July 31, 2024. |
| Shareholder Report Annual or Semi-Annual | 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 1-800-544-3455 or by sending an e-mail to fidfunddocuments@fidelity.com. |
| Material Fund Change Notice [Text Block] | This report describes changes to the Fund that occurred during the reporting period. |
| Additional Information Phone Number | 1-800-544-3455 |
| 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 year? (based on hypothetical $10,000 investment) FUND COST (PREVIOUS YEAR) Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Fidelity® SAI Inflation-Focused Fund $ 0.39 % |
| Expenses Paid, Amount | $ 38 |
| Expense Ratio, Percent | 0.39% |
| Factors Affecting Performance [Text Block] | What affected the Fund's performance this period? • • • • • |
| Performance Past Does Not Indicate Future [Text] | The Fund's past performance is not a good predictor of the Fund's future performance.</span>" id="sjs-B26"><span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;">The Fund's past performance is not a good predictor of the Fund's future performance.</span> |
| Line Graph [Table Text Block] | How did the Fund perform over the life of Fund? CUMULATIVE PERFORMANCE December 20, 2018 through July 31, 2024. Initial investment of $10,000. Fidelity® SAI Inflation-Focused Fund $10,000 $10,351 $9,518 $13,953 $17,787 $15,330 $14,713 Fidelity Commodity Linked Index℠ $10,000 $10,166 $8,938 $12,538 $15,952 $14,695 $13,960 Bloomberg Commodity 50/50 Petroleum and ex-Petroleum Index $10,000 $10,351 $9,518 $13,953 $17,787 $15,671 $15,549 Bloomberg Commodity Index $10,000 $10,166 $8,938 $12,538 $15,952 $14,695 $13,935 2018 2019 2020 2021 2022 2023 2024 |
| Average Annual Return [Table Text Block] | AVERAGE ANNUAL TOTAL RETURNS: 1 Year 5 Year Life of Fund A Fidelity® SAI Inflation-Focused Fund -4.03% 7.29% 7.12% Fidelity Commodity Linked Index℠ -5.00% 6.55% 6.12% Bloomberg Commodity 50/50 Petroleum and ex-Petroleum Index -0.78% -% -% Bloomberg Commodity Index -5.17% 6.51% 6.09% A From December 20, 2018 Visit www.fidelity.com for more recent performance information. The Fund's past performance is not a good predictor of the Fund's future performance. The graph and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| Performance Inception Date | Dec. 20, 2018 |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| Net Assets | $ 4,273,799,379 |
| Holdings Count | shares | 53 |
| Advisory Fees Paid, Amount | $ 13,403,812 |
| Investment Company Portfolio Turnover | 0% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics (as of July 31, 2024) KEY FACTS Fund Size $ Number of Holdings 53 Total Advisory Fee $ Portfolio Turnover 0 % |
| Holdings [Text Block] | Energy 53.7 Agriculture 18.5 Precious Metals 14.3 Industrial Metals 8.8 Livestock 4.7 COMMODITY SECTOR DIVERSIFICATION (% of Fund's net assets) DERIVATIVE EXPOSURE (% of Fund's net assets) Futures Contracts 100.0 Futures Contracts 50.0 Short-Term Investments and Net Other Assets (Liabilities) 50.0 ASSET ALLOCATION (% of Fund's total exposure) |
| Material Fund Change [Text Block] | How has the Fund changed? This is a summary of certain changes to the Fund since August 1, 2023. For more complete information, you may review the Fund's next prospectus, which we expect to be available by September 28, 2024 at fundresearch.fidelity.com/prospectus/sec or upon request at 1-800-544-3455 or by sending an e-mail to fidfunddocuments fidelity.com . The fund's principal investment strategies were modified to provide more investment flexibility, as described in the prospectus. |
| Material Fund Change Strategies [Text Block] | The fund's principal investment strategies were modified to provide more investment flexibility, as described in the prospectus. |
| Summary of Change Legend [Text Block] | This is a summary of certain changes to the Fund since August 1, 2023. For more complete information, you may review the Fund's next prospectus, which we expect to be available by September 28, 2024 at fundresearch.fidelity.com/prospectus/sec or upon request at 1-800-544-3455 or by sending an e-mail to fidfunddocuments fidelity.com . |
| Updated Prospectus Phone Number | 1-800-544-3455</span>" id="sjs-B40"><span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;">1-800-544-3455</span> |
| Updated Prospectus Email Address | fidfunddocuments@fidelity.com</span>" id="sjs-B41"><span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;">fidfunddocuments@fidelity.com</span> |
| Updated Prospectus Web Address | fundresearch.fidelity.com/prospectus/sec</span>" id="sjs-B42"><span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:bold;">fundresearch.fidelity.com/prospectus/sec</span> |
| Fidelity Commodity Strategy Fund | |
| Shareholder Report [Line Items] | |
| Fund Name | Fidelity® Commodity Strategy Fund |
| Class Name | Fidelity® Commodity Strategy Fund |
| Trading Symbol | FYHTX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains information about Fidelity® Commodity Strategy Fund for the period August 1, 2023 to July 31, 2024. |
| Shareholder Report Annual or Semi-Annual | 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. |
| Material Fund Change Notice [Text Block] | This report describes changes to the Fund that occurred during the reporting period. |
| 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 year? (based on hypothetical $10,000 investment) FUND COST (PREVIOUS YEAR) Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Fidelity® Commodity Strategy Fund $ 0.63 % |
| Expenses Paid, Amount | $ 62 |
| Expense Ratio, Percent | 0.63% |
| Factors Affecting Performance [Text Block] | What affected the Fund's performance this period? • • • • • |
| Performance Past Does Not Indicate Future [Text] | The Fund's past performance is not a good predictor of the Fund's future performance.</span>" id="sjs-B59"><span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;">The Fund's past performance is not a good predictor of the Fund's future performance.</span> |
| Line Graph [Table Text Block] | How did the Fund perform over the life of Fund? CUMULATIVE PERFORMANCE May 30, 2017 through July 31, 2024. Initial investment of $10,000. Fidelity® Commodity Strategy Fund $10,000 $10,150 $10,329 $9,675 $8,505 $11,820 $14,785 $13,505 Bloomberg Commodity Index $10,000 $10,161 $10,438 $9,879 $8,686 $12,185 $15,502 $14,280 2017 2018 2019 2020 2021 2022 2023 2024 |
| Average Annual Return [Table Text Block] | AVERAGE ANNUAL TOTAL RETURNS: 1 Year 5 Year Life of Fund A Fidelity® Commodity Strategy Fund -5.45% 5.71% 3.47% Bloomberg Commodity Index -5.17% 6.51% 4.32% A From May 30, 2017 Visit www.fidelity.com for more recent performance information. The Fund's past performance is not a good predictor of the Fund's future performance. The graph and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| Performance Inception Date | May 30, 2017 |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| Net Assets | $ 43,751,003 |
| Holdings Count | shares | 27 |
| Advisory Fees Paid, Amount | $ 202,579 |
| Investment Company Portfolio Turnover | 0% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics (as of July 31, 2024) KEY FACTS Fund Size $ Number of Holdings 27 Total Advisory Fee $ Portfolio Turnover 0 % |
| Holdings [Text Block] | Energy 29.0 Agriculture 27.0 Precious Metals 22.7 Industrial Metals 15.6 Livestock 5.7 COMMODITY SECTOR DIVERSIFICATION (% of Fund's net assets) DERIVATIVE EXPOSURE (% of Fund's net assets) Futures Contracts 100.2 Futures Contracts 50.1 Short-Term Investments and Net Other Assets (Liabilities) 49.9 ASSET ALLOCATION (% of Fund's total exposure) |
| Material Fund Change [Text Block] | How has the Fund changed? This is a summary of certain changes to the Fund since August 1, 2023. For more complete information, you may review the Fund's next prospectus, which we expect to be available by September 28, 2024 at fundresearch.fidelity.com/prospectus/sec or upon request at 1-800-544-8544 or by sending an e-mail to fidfunddocuments fidelity.com . The fund modified its principal investment strategies during the reporting period. |
| Material Fund Change Strategies [Text Block] | The fund modified its principal investment strategies during the reporting period. |
| Summary of Change Legend [Text Block] | This is a summary of certain changes to the Fund since August 1, 2023. For more complete information, you may review the Fund's next prospectus, which we expect to be available by September 28, 2024 at fundresearch.fidelity.com/prospectus/sec or upon request at 1-800-544-8544 or by sending an e-mail to fidfunddocuments fidelity.com . |
| Updated Prospectus Phone Number | 1-800-544-8544</span>" id="sjs-B73"><span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;">1-800-544-8544</span> |
| Updated Prospectus Email Address | fidfunddocuments@fidelity.com</span>" id="sjs-B74"><span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;">fidfunddocuments@fidelity.com</span> |
| Updated Prospectus Web Address | fundresearch.fidelity.com/prospectus/sec</span>" id="sjs-B75"><span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:bold;">fundresearch.fidelity.com/prospectus/sec</span> |
| Fidelity Series Commodity Strategy Fund | |
| Shareholder Report [Line Items] | |
| Fund Name | Fidelity® Series Commodity Strategy Fund |
| Class Name | Fidelity® Series Commodity Strategy Fund |
| Trading Symbol | FCSSX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains information about Fidelity® Series Commodity Strategy Fund for the period August 1, 2023 to July 31, 2024. |
| Shareholder Report Annual or Semi-Annual | 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. |
| Material Fund Change Notice [Text Block] | This report describes changes to the Fund that occurred during the reporting period. |
| 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 year? (based on hypothetical $10,000 investment) FUND COST (PREVIOUS YEAR) Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Fidelity® Series Commodity Strategy Fund $ A 0.00 % B A Amount represents less than $.50 B Amount represents less than 0.005% |
| Expenses Paid, Amount | $ 0 |
| Expense Ratio, Percent | 0% |
| Factors Affecting Performance [Text Block] | What affected the Fund's performance this period? • • • • • |
| Performance Past Does Not Indicate Future [Text] | The Fund's past performance is not a good predictor of the Fund's future performance.</span>" id="sjs-B91"><span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;">The Fund's past performance is not a good predictor of the Fund's future performance.</span> |
| Line Graph [Table Text Block] | How did the Fund perform over the past 10 years? CUMULATIVE PERFORMANCE July 31, 2014 through July 31, 2024. Initial investment of $10,000. Fidelity® Series Commodity Strategy Fund $10,000 $7,129 $6,517 $6,542 $6,690 $6,300 $5,561 $7,776 $9,838 $9,023 $8,570 Bloomberg Commodity Index $10,000 $7,177 $6,604 $6,655 $6,837 $6,470 $5,689 $7,980 $10,153 $9,353 $8,869 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 |
| Average Annual Return [Table Text Block] | AVERAGE ANNUAL TOTAL RETURNS: 1 Year 5 Year 10 Year Fidelity® Series Commodity Strategy Fund -5.01% 6.35% -1.53% Bloomberg Commodity Index -5.17% 6.51% -1.19% Visit www.fidelity.com for more recent performance information. The Fund's past performance is not a good predictor of the Fund's future performance. The graph and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares. |
| Net Assets | $ 2,193,676,783 |
| Holdings Count | shares | 57 |
| Advisory Fees Paid, Amount | $ 0 |
| Investment Company Portfolio Turnover | 0% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics (as of July 31, 2024) KEY FACTS Fund Size $ Number of Holdings 57 Total Advisory Fee $ Portfolio Turnover 0 % |
| Holdings [Text Block] | Energy 28.9 Agriculture 26.9 Precious Metals 22.7 Industrial Metals 15.8 Livestock 5.7 COMMODITY SECTOR DIVERSIFICATION (% of Fund's net assets) DERIVATIVE EXPOSURE (% of Fund's net assets) Futures Contracts 15.7 Swaps 87.3 Futures Contracts 7.7 Swaps 43.1 Short-Term Investments and Net Other Assets (Liabilities) 49.2 ASSET ALLOCATION (% of Fund's total exposure) |
| Material Fund Change [Text Block] | How has the Fund changed? This is a summary of certain changes to the Fund since August 1, 2023. For more complete information, you may review the Fund's next prospectus, which we expect to be available by September 28, 2024 at fundresearch.fidelity.com/prospectus/sec or upon request at 1-800-544-8544 . The fund modified its principal investment strategies during the reporting period. |
| Material Fund Change Strategies [Text Block] | The fund modified its principal investment strategies during the reporting period. |
| Summary of Change Legend [Text Block] | This is a summary of certain changes to the Fund since August 1, 2023. For more complete information, you may review the Fund's next prospectus, which we expect to be available by September 28, 2024 at fundresearch.fidelity.com/prospectus/sec or upon request at 1-800-544-8544 . |
| Updated Prospectus Phone Number | 1-800-544-8544</span>" id="sjs-B104"><span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;">1-800-544-8544</span> |
| Updated Prospectus Web Address | fundresearch.fidelity.com/prospectus/sec</span>" id="sjs-B105"><span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:bold;">fundresearch.fidelity.com/prospectus/sec</span> |
| Shareholder Report, Line Graph (Details) - USD ($) | 12 Months Ended | 60 Months Ended | 84 Months Ended | 96 Months Ended | 120 Months Ended | 132 Months Ended | ||||||||||
| Jul. 31, 2024 | Jul. 31, 2024 | Jul. 31, 2024 | Jul. 31, 2024 | Jul. 31, 2024 | Jul. 31, 2024 | Jul. 31, 2023 | Jul. 31, 2022 | Jul. 31, 2021 | Jul. 31, 2020 | Jul. 31, 2019 | Jul. 31, 2018 | Jul. 31, 2017 | Jul. 31, 2016 | Jul. 31, 2015 | Jul. 31, 2014 | |
| C000206762_0_LG_BBIndexMember_7YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Line Graph and Table Measure Name | Bloomberg Commodity Index</span>" id="sjs-D5"><span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Bloomberg Commodity Index</span> | |||||||||||||||
| C000206762_0_BBIndexMember_AsOf_2018Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 10,000 | |||||||||||||||
| C000206762_0_BBIndexMember_AsOf_2019Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 10,166 | |||||||||||||||
| C000206762_0_BBIndexMember_AsOf_2020Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 8,938 | |||||||||||||||
| C000206762_0_BBIndexMember_AsOf_2021Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 12,538 | |||||||||||||||
| C000206762_0_BBIndexMember_AsOf_2022Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 15,952 | |||||||||||||||
| C000206762_0_BBIndexMember_AsOf_2023Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 14,695 | |||||||||||||||
| C000206762_0_BBIndexMember_AsOf_2024Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 13,935 | $ 13,935 | $ 13,935 | $ 13,935 | $ 13,935 | $ 13,935 | ||||||||||
| C000206762_2_BBIndexMember_1YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Average Annual Return, Percent | (5.17%) | |||||||||||||||
| C000206762_2_BBIndexMember_5YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Average Annual Return, Percent | 6.51% | |||||||||||||||
| C000206762_2_BBIndexMember_LOCMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Average Annual Return, Percent | 6.09% | |||||||||||||||
| C000175832_0_BBIndexMember_1YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Average Annual Return, Percent | (5.17%) | |||||||||||||||
| C000175832_0_BBIndexMember_5YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Average Annual Return, Percent | 6.51% | |||||||||||||||
| C000175832_0_BBIndexMember_LOCMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Average Annual Return, Percent | 4.32% | |||||||||||||||
| C000130874_0_BBIndexMember_1YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Average Annual Return, Percent | (5.17%) | |||||||||||||||
| C000130874_0_BBIndexMember_5YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Average Annual Return, Percent | 6.51% | |||||||||||||||
| C000130874_0_BBIndexMember_10YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Average Annual Return, Percent | (1.19%) | |||||||||||||||
| C000206762_LG_ClassMember_7YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Line Graph and Table Measure Name | Fidelity® SAI Inflation-Focused Fund</span>" id="sjs-D56"><span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Fidelity® SAI Inflation-Focused Fund</span> | |||||||||||||||
| C000206762_ClassMember_AsOf_2018Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 10,000 | |||||||||||||||
| C000206762_ClassMember_AsOf_2019Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 10,351 | |||||||||||||||
| C000206762_ClassMember_AsOf_2020Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 9,518 | |||||||||||||||
| C000206762_ClassMember_AsOf_2021Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 13,953 | |||||||||||||||
| C000206762_ClassMember_AsOf_2022Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 17,787 | |||||||||||||||
| C000206762_ClassMember_AsOf_2023Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 15,330 | |||||||||||||||
| C000206762_ClassMember_AsOf_2024Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 14,713 | $ 14,713 | $ 14,713 | 14,713 | $ 14,713 | 14,713 | ||||||||||
| C000206762_LG_1_AdditionalIndexMember_7YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Line Graph and Table Measure Name | Fidelity Commodity Linked Index℠</span>" id="sjs-D80"><span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Fidelity Commodity Linked Index℠</span> | |||||||||||||||
| C000206762_1_AdditionalIndexMember_AsOf_2018Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 10,000 | |||||||||||||||
| C000206762_1_AdditionalIndexMember_AsOf_2019Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 10,166 | |||||||||||||||
| C000206762_1_AdditionalIndexMember_AsOf_2020Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 8,938 | |||||||||||||||
| C000206762_1_AdditionalIndexMember_AsOf_2021Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 12,538 | |||||||||||||||
| C000206762_1_AdditionalIndexMember_AsOf_2022Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 15,952 | |||||||||||||||
| C000206762_1_AdditionalIndexMember_AsOf_2023Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 14,695 | |||||||||||||||
| C000206762_1_AdditionalIndexMember_AsOf_2024Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 13,960 | 13,960 | $ 13,960 | 13,960 | 13,960 | 13,960 | ||||||||||
| C000206762_LG_2_AdditionalIndexMember_7YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Line Graph and Table Measure Name | Bloomberg Commodity 50/50 Petroleum and ex-Petroleum Index </span>" id="sjs-D104"><span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Bloomberg Commodity 50/50 Petroleum and ex-Petroleum Index </span> | |||||||||||||||
| C000206762_2_AdditionalIndexMember_AsOf_2018Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 10,000 | |||||||||||||||
| C000206762_2_AdditionalIndexMember_AsOf_2019Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 10,351 | |||||||||||||||
| C000206762_2_AdditionalIndexMember_AsOf_2020Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 9,518 | |||||||||||||||
| C000206762_2_AdditionalIndexMember_AsOf_2021Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 13,953 | |||||||||||||||
| C000206762_2_AdditionalIndexMember_AsOf_2022Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 17,787 | |||||||||||||||
| C000206762_2_AdditionalIndexMember_AsOf_2023Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 15,671 | |||||||||||||||
| C000206762_2_AdditionalIndexMember_AsOf_2024Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 15,549 | $ 15,549 | $ 15,549 | $ 15,549 | 15,549 | 15,549 | ||||||||||
| C000206762_NoLoadClassMember_1YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Average Annual Return, Percent | (4.03%) | |||||||||||||||
| C000206762_NoLoadClassMember_5YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Average Annual Return, Percent | 7.29% | |||||||||||||||
| C000206762_NoLoadClassMember_2023-08-01_2024-07-31Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Average Annual Return, Percent | 7.12% | |||||||||||||||
| C000206762_0_AdditionalIndexMember_1YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Average Annual Return, Percent | (5.00%) | |||||||||||||||
| C000206762_0_AdditionalIndexMember_5YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Average Annual Return, Percent | 6.55% | |||||||||||||||
| C000206762_0_AdditionalIndexMember_LOCMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Average Annual Return, Percent | 6.12% | |||||||||||||||
| C000206762_1_AdditionalIndexMember_1YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Average Annual Return, Percent | (0.78%) | |||||||||||||||
| C000206762_1_AdditionalIndexMember_5YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Average Annual Return, Percent | ||||||||||||||||
| C000206762_1_AdditionalIndexMember_LOCMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Average Annual Return, Percent | ||||||||||||||||
| C000175832_LG_ClassMember_8YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Line Graph and Table Measure Name | Fidelity® Commodity Strategy Fund</span>" id="sjs-E155"><span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Fidelity® Commodity Strategy Fund</span> | |||||||||||||||
| C000175832_ClassMember_AsOf_2017Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 10,000 | |||||||||||||||
| C000175832_ClassMember_AsOf_2018Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 10,150 | |||||||||||||||
| C000175832_ClassMember_AsOf_2019Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 10,329 | |||||||||||||||
| C000175832_ClassMember_AsOf_2020Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 9,675 | |||||||||||||||
| C000175832_ClassMember_AsOf_2021Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 8,505 | |||||||||||||||
| C000175832_ClassMember_AsOf_2022Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 11,820 | |||||||||||||||
| C000175832_ClassMember_AsOf_2023Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 14,785 | |||||||||||||||
| C000175832_ClassMember_AsOf_2024Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 13,505 | $ 13,505 | 13,505 | $ 13,505 | 13,505 | 13,505 | ||||||||||
| C000175832_LG_1_AdditionalIndexMember_8YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Line Graph and Table Measure Name | Bloomberg Commodity Index</span>" id="sjs-E182"><span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Bloomberg Commodity Index</span> | |||||||||||||||
| C000175832_1_AdditionalIndexMember_AsOf_2017Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 10,000 | |||||||||||||||
| C000175832_1_AdditionalIndexMember_AsOf_2018Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 10,161 | |||||||||||||||
| C000175832_1_AdditionalIndexMember_AsOf_2019Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 10,438 | |||||||||||||||
| C000175832_1_AdditionalIndexMember_AsOf_2020Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 9,879 | |||||||||||||||
| C000175832_1_AdditionalIndexMember_AsOf_2021Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 8,686 | |||||||||||||||
| C000175832_1_AdditionalIndexMember_AsOf_2022Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 12,185 | |||||||||||||||
| C000175832_1_AdditionalIndexMember_AsOf_2023Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 15,502 | |||||||||||||||
| C000175832_1_AdditionalIndexMember_AsOf_2024Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 14,280 | $ 14,280 | 14,280 | $ 14,280 | 14,280 | $ 14,280 | ||||||||||
| C000175832_NoLoadClassMember_1YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Average Annual Return, Percent | (5.45%) | |||||||||||||||
| C000175832_NoLoadClassMember_5YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Average Annual Return, Percent | 5.71% | |||||||||||||||
| C000175832_NoLoadClassMember_2023-08-01_2024-07-31Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Average Annual Return, Percent | 3.47% | |||||||||||||||
| C000130874_LG_ClassMember_11YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Line Graph and Table Measure Name | Fidelity® Series Commodity Strategy Fund</span>" id="sjs-G218"><span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Fidelity® Series Commodity Strategy Fund</span> | |||||||||||||||
| C000130874_ClassMember_AsOf_2014Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 10,000 | |||||||||||||||
| C000130874_ClassMember_AsOf_2015Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 7,129 | |||||||||||||||
| C000130874_ClassMember_AsOf_2016Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 6,517 | |||||||||||||||
| C000130874_ClassMember_AsOf_2017Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 6,542 | |||||||||||||||
| C000130874_ClassMember_AsOf_2018Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 6,690 | |||||||||||||||
| C000130874_ClassMember_AsOf_2019Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 6,300 | |||||||||||||||
| C000130874_ClassMember_AsOf_2020Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 5,561 | |||||||||||||||
| C000130874_ClassMember_AsOf_2021Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 7,776 | |||||||||||||||
| C000130874_ClassMember_AsOf_2022Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 9,838 | |||||||||||||||
| C000130874_ClassMember_AsOf_2023Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | 9,023 | |||||||||||||||
| C000130874_ClassMember_AsOf_2024Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 8,570 | $ 8,570 | 8,570 | 8,570 | 8,570 | $ 8,570 | ||||||||||
| C000130874_LG_1_AdditionalIndexMember_11YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Line Graph and Table Measure Name | Bloomberg Commodity Index</span>" id="sjs-G254"><span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Bloomberg Commodity Index</span> | |||||||||||||||
| C000130874_1_AdditionalIndexMember_AsOf_2014Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 10,000 | |||||||||||||||
| C000130874_1_AdditionalIndexMember_AsOf_2015Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 7,177 | |||||||||||||||
| C000130874_1_AdditionalIndexMember_AsOf_2016Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 6,604 | |||||||||||||||
| C000130874_1_AdditionalIndexMember_AsOf_2017Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 6,655 | |||||||||||||||
| C000130874_1_AdditionalIndexMember_AsOf_2018Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 6,837 | |||||||||||||||
| C000130874_1_AdditionalIndexMember_AsOf_2019Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 6,470 | |||||||||||||||
| C000130874_1_AdditionalIndexMember_AsOf_2020Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 5,689 | |||||||||||||||
| C000130874_1_AdditionalIndexMember_AsOf_2021Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 7,980 | |||||||||||||||
| C000130874_1_AdditionalIndexMember_AsOf_2022Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 10,153 | |||||||||||||||
| C000130874_1_AdditionalIndexMember_AsOf_2023Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 9,353 | |||||||||||||||
| C000130874_1_AdditionalIndexMember_AsOf_2024Member | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Account Value | $ 8,869 | $ 8,869 | $ 8,869 | $ 8,869 | $ 8,869 | $ 8,869 | ||||||||||
| C000130874_NoLoadClassMember_1YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Average Annual Return, Percent | (5.01%) | |||||||||||||||
| C000130874_NoLoadClassMember_5YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Average Annual Return, Percent | 6.35% | |||||||||||||||
| C000130874_NoLoadClassMember_10YRMember | ||||||||||||||||
| Account Value [Line Items] | ||||||||||||||||
| Average Annual Return, Percent | (1.53%) |
| Shareholder Report, Holdings (Details) | Jul. 31, 2024 |
| Fidelity SAI Inflation-Focused Fund | MSPreciousMetalsSectorMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 14.30% |
| Fidelity SAI Inflation-Focused Fund | MSIndustrialMetalsSectorMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.80% |
| Fidelity SAI Inflation-Focused Fund | MSLivestockSectorMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.70% |
| Fidelity SAI Inflation-Focused Fund | Agricultural Sector Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 18.50% |
| Fidelity SAI Inflation-Focused Fund | Energy Sector | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 53.70% |
| Fidelity SAI Inflation-Focused Fund | DEFuturesContractsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 100% |
| Fidelity SAI Inflation-Focused Fund | AAFuturesContractsMember | |
| Holdings [Line Items] | |
| Percent of Net Long Exposure | 50% |
| Fidelity SAI Inflation-Focused Fund | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember | |
| Holdings [Line Items] | |
| Percent of Net Long Exposure | 50% |
| Fidelity Commodity Strategy Fund | MSPreciousMetalsSectorMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 22.70% |
| Fidelity Commodity Strategy Fund | MSIndustrialMetalsSectorMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 15.60% |
| Fidelity Commodity Strategy Fund | MSLivestockSectorMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.70% |
| Fidelity Commodity Strategy Fund | Agricultural Sector Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 27% |
| Fidelity Commodity Strategy Fund | Energy Sector | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 29% |
| Fidelity Commodity Strategy Fund | DEFuturesContractsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 100.20% |
| Fidelity Commodity Strategy Fund | AAFuturesContractsMember | |
| Holdings [Line Items] | |
| Percent of Net Long Exposure | 50.10% |
| Fidelity Commodity Strategy Fund | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember | |
| Holdings [Line Items] | |
| Percent of Net Long Exposure | 49.90% |
| Fidelity Series Commodity Strategy Fund | MSPreciousMetalsSectorMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 22.70% |
| Fidelity Series Commodity Strategy Fund | MSIndustrialMetalsSectorMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 15.80% |
| Fidelity Series Commodity Strategy Fund | MSLivestockSectorMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.70% |
| Fidelity Series Commodity Strategy Fund | Agricultural Sector Member | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 26.90% |
| Fidelity Series Commodity Strategy Fund | Energy Sector | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 28.90% |
| Fidelity Series Commodity Strategy Fund | DEFuturesContractsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 15.70% |
| Fidelity Series Commodity Strategy Fund | AAFuturesContractsMember | |
| Holdings [Line Items] | |
| Percent of Net Long Exposure | 7.70% |
| Fidelity Series Commodity Strategy Fund | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember | |
| Holdings [Line Items] | |
| Percent of Net Long Exposure | 49.20% |
| Fidelity Series Commodity Strategy Fund | DESwapsMember | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 87.30% |
| Fidelity Series Commodity Strategy Fund | AASwapsMember | |
| Holdings [Line Items] | |
| Percent of Net Long Exposure | 43.10% |
