Fidelity Real Estate Index Fund (FSRNX) N-CSR20 Sep 24Certified annual shareholder report (management investment company)Financial data

Company Profile

Form N-CSR Cover

Form N-CSR Cover	12 Months Ended
Form N-CSR Cover	Jul. 31, 2024
Shareholder Report [Line Items]
Document Type	N-CSR
Amendment Flag	false
Registrant Name	Fidelity Salem Street Trust
Entity Central Index Key	0000035315
Entity Investment Company Type	N-1A
Document Period End Date	Jul. 31, 2024

Shareholder Report

Shareholder Report	12 Months Ended
Shareholder Report	Jul. 31, 2024 USD ($) shares
Shareholder Report [Line Items]
Document Type	N-CSR
Amendment Flag	false
Registrant Name	Fidelity Salem Street Trust
Entity Central Index Key	0000035315
Entity Investment Company Type	N-1A
Document Period End Date	Jul. 31, 2024
Fidelity SAI U.S. Quality Index Fund
Shareholder Report [Line Items]
Fund Name	Fidelity® SAI U.S. Quality Index Fund
Class Name	Fidelity® SAI U.S. Quality Index Fund
Trading Symbol	FUQIX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains information about Fidelity® SAI U.S. Quality Index 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.
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 U.S. Quality Index Fund $ 0.11 %
Expenses Paid, Amount	$ 12
Expense Ratio, Percent	0.11%
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-B25"><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 October 8, 2015 through July 31, 2024. Initial investment of $10,000. Fidelity® SAI U.S. Quality Index Fund $10,000 $10,901 $12,503 $15,093 $16,556 $19,890 $26,383 $24,654 $28,344 $35,673 Fidelity SAI U.S. Quality Index Fund Linked Index℠ $10,000 $10,911 $12,543 $15,159 $16,640 $19,994 $26,537 $24,791 $28,554 $35,908 Fidelity U.S. Quality Focus Index℠ $10,000 $10,901 $12,503 $15,093 $16,573 $19,914 $26,430 $24,691 $28,439 $35,763 S&P 500® Index $10,000 $10,983 $12,745 $14,815 $15,998 $17,911 $24,439 $23,305 $26,339 $32,172 2015 2016 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® SAI U.S. Quality Index Fund 25.86% 16.59% 15.51% Fidelity SAI U.S. Quality Index Fund Linked Index℠ 25.76% 16.63% 15.60% Fidelity U.S. Quality Focus Index℠ 25.76% 16.63% -% S&P 500® Index 22.15% 15.00% 14.17% A From October 8, 2015 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	Oct. 08, 2015
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	$ 14,176,823,098
Holdings Count \| shares	87
Advisory Fees Paid, Amount	$ 13,330,347
Investment Company Portfolio Turnover	53%
Additional Fund Statistics [Text Block]	Key Fund Statistics (as of July 31, 2024) KEY FACTS Fund Size $ Number of Holdings 87 Total Advisory Fee $ Portfolio Turnover 53 %
Holdings [Text Block]	MARKET SECTORS (% of Fund's net assets) Information Technology 41.0 Health Care 15.1 Communication Services 11.9 Financials 10.8 Industrials 7.0 Consumer Staples 6.8 Consumer Discretionary 5.8 Real Estate 1.1 Energy 0.2 Materials 0.1 Common Stocks 99.8 Short-Term Investments and Net Other Assets (Liabilities) 0.2 ASSET ALLOCATION (% of Fund's net assets) United States 99.8 Israel 0.2 GEOGRAPHIC DIVERSIFICATION (% of Fund's net assets)
Largest Holdings [Text Block]	TOP HOLDINGS (% of Fund's net assets) Apple Inc 9.7 NVIDIA Corp 8.6 Alphabet Inc Class A 6.5 Meta Platforms Inc Class A 4.9 Microsoft Corp 4.1 Johnson & Johnson 4.0 Mastercard Inc Class A 3.8 Visa Inc Class A 3.7 Coca-Cola Co/The 3.6 Adobe Inc 3.4 52.3
Fidelity SAI Small-Mid Cap 500 Index Fund
Shareholder Report [Line Items]
Fund Name	Fidelity® SAI Small-Mid Cap 500 Index Fund
Class Name	Fidelity® SAI Small-Mid Cap 500 Index Fund
Trading Symbol	FZFLX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains information about Fidelity® SAI Small-Mid Cap 500 Index 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 Small-Mid Cap 500 Index Fund $ 0.05 %
Expenses Paid, Amount	$ 6
Expense Ratio, Percent	0.05%
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-B53"><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 August 12, 2015 through July 31, 2024. Initial investment of $10,000. Fidelity® SAI Small-Mid Cap 500 Index Fund $10,000 $10,326 $11,608 $13,455 $14,162 $14,159 $20,812 $18,952 $20,529 $23,029 Russell SMID 500™ Index $10,000 $10,335 $11,622 $13,496 $14,206 $14,207 $20,895 $19,035 $20,592 $23,107 Russell 3000® Index $10,000 $10,538 $12,239 $14,245 $15,249 $16,916 $23,466 $21,741 $24,491 $29,653 2015 2016 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® SAI Small-Mid Cap 500 Index Fund 12.18% 10.21% 9.74% Russell SMID 500™ Index 12.21% 10.22% 9.78% Russell 3000® Index 21.07% 14.23% 12.87% A From August 12, 2015 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	Aug. 12, 2015
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	$ 1,734,459,634
Holdings Count \| shares	506
Advisory Fees Paid, Amount	$ 1,752,006
Investment Company Portfolio Turnover	31%
Additional Fund Statistics [Text Block]	Key Fund Statistics (as of July 31, 2024) KEY FACTS Fund Size $ Number of Holdings 506 Total Advisory Fee $ Portfolio Turnover 31 %
Holdings [Text Block]	MARKET SECTORS (% of Fund's net assets) Industrials 20.4 Financials 15.9 Consumer Discretionary 14.3 Information Technology 11.0 Health Care 9.5 Real Estate 7.5 Materials 6.9 Energy 5.1 Consumer Staples 3.9 Communication Services 3.4 Utilities 2.1 Common Stocks 100.0 Short-Term Investments and Net Other Assets (Liabilities) 0.0 ASSET ALLOCATION (% of Fund's net assets) United States 98.5 United Kingdom 0.4 Bermuda 0.3 Puerto Rico 0.2 Brazil 0.2 Belgium 0.2 Luxembourg 0.1 Japan 0.1 Finland 0.0 GEOGRAPHIC DIVERSIFICATION (% of Fund's net assets)
Largest Holdings [Text Block]	TOP HOLDINGS (% of Fund's net assets) Eqt Corp 0.7 Watsco Inc 0.6 Lennox International Inc 0.5 Packaging Corp of America 0.5 Textron Inc 0.5 EMCOR Group Inc 0.5 Reliance Inc 0.5 Avery Dennison Corp 0.5 Everest Group Ltd 0.5 Pure Storage Inc Class A 0.4 5.2
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 fees associated with this class changed during the reporting year. The variations in class fees are primarily the result of the following changes: • Operating expenses • Expense reductions
Material Fund Change Expenses [Text Block]	The fees associated with this class changed during the reporting year. The variations in class fees are primarily the result of the following changes: • Operating expenses • Expense reductions
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-B68"><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-B69"><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-B70"><span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:bold;">fundresearch.fidelity.com/prospectus/sec</span>
Fidelity SAI U.S. Momentum Index Fund
Shareholder Report [Line Items]
Fund Name	Fidelity® SAI U.S. Momentum Index Fund
Class Name	Fidelity® SAI U.S. Momentum Index Fund
Trading Symbol	FUMIX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains information about Fidelity® SAI U.S. Momentum Index 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 U.S. Momentum Index Fund $ 0.13 %
Expenses Paid, Amount	$ 15
Expense Ratio, Percent	0.13%
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-B87"><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 February 9, 2017 through July 31, 2024. Initial investment of $10,000. Fidelity® SAI U.S. Momentum Index Fund $10,000 $10,980 $13,432 $14,363 $16,770 $22,301 $19,835 $21,024 MSCI USA Custom Momentum Composite Index $10,000 $11,002 $13,464 $14,416 $16,851 $22,435 $19,974 $21,212 MSCI USA Index $10,000 $10,768 $12,450 $13,375 $15,041 $20,620 $19,123 $21,529 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® SAI U.S. Momentum Index Fund 35.08% 14.61% 14.98% MSCI USA Custom Momentum Composite Index 35.04% 14.72% 15.11% MSCI USA Index 21.48% 14.35% 13.72% A From February 9, 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	Feb. 09, 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	$ 645,694,919
Holdings Count \| shares	234
Advisory Fees Paid, Amount	$ 446,924
Investment Company Portfolio Turnover	104%
Additional Fund Statistics [Text Block]	Key Fund Statistics (as of July 31, 2024) KEY FACTS Fund Size $ Number of Holdings 234 Total Advisory Fee $ Portfolio Turnover 104 %
Holdings [Text Block]	MARKET SECTORS (% of Fund's net assets) Information Technology 30.9 Financials 15.4 Industrials 15.2 Communication Services 10.4 Consumer Discretionary 10.0 Health Care 9.8 Consumer Staples 4.1 Utilities 1.5 Materials 1.4 Energy 0.9 Real Estate 0.3 Common Stocks 99.9 Short-Term Investments and Net Other Assets (Liabilities) 0.1 ASSET ALLOCATION (% of Fund's net assets) United States 99.7 China 0.2 Brazil 0.1 GEOGRAPHIC DIVERSIFICATION (% of Fund's net assets)
Largest Holdings [Text Block]	TOP HOLDINGS (% of Fund's net assets) Broadcom Inc 5.2 Amazon.com Inc 5.2 NVIDIA Corp 5.1 Meta Platforms Inc Class A 4.9 Eli Lilly & Co 4.7 JPMorgan Chase & Co 3.8 Microsoft Corp 3.2 Costco Wholesale Corp 3.2 General Electric Co 2.3 Netflix Inc 1.9 39.5
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 fees associated with this class changed during the reporting year. The variations in class fees are primarily the result of the following changes: • Operating expenses
Material Fund Change Expenses [Text Block]	The fees associated with this class changed during the reporting year. The variations in class fees are primarily the result of the following changes: • Operating expenses
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-B102"><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-B103"><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-B104"><span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:bold;">fundresearch.fidelity.com/prospectus/sec</span>
Fidelity Real Estate Index Fund
Shareholder Report [Line Items]
Fund Name	Fidelity® Real Estate Index Fund
Class Name	Fidelity® Real Estate Index Fund
Trading Symbol	FSRNX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains information about Fidelity® Real Estate Index 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.
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® Real Estate Index Fund $ 0.07 %
Expenses Paid, Amount	$ 7
Expense Ratio, Percent	0.07%
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-B120"><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® Real Estate Index Fund $10,000 $11,129 $13,433 $12,680 $13,174 $14,602 $12,216 $17,069 $16,350 $14,764 $16,333 Fidelity Real Estate Linked Index℠ $10,000 $11,129 $13,457 $12,695 $13,185 $14,621 $12,238 $17,133 $16,409 $14,825 $16,415 MSCI US IMI Real Estate 25/25 Index $10,000 $11,129 $13,433 $13,204 $13,810 $15,636 $14,843 $20,304 $19,446 $17,568 $19,453 S&P 500® Index $10,000 $11,121 $11,745 $13,629 $15,843 $17,108 $19,153 $26,134 $24,921 $28,165 $34,403 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® Real Estate Index Fund 10.63% 2.27% 5.03% Fidelity Real Estate Linked Index℠ 10.73% 2.34% 5.08% MSCI US IMI Real Estate 25/25 Index 10.73% 4.46% -% S&P 500® Index 22.15% 15.00% 13.15% 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	$ 2,726,235,514
Holdings Count \| shares	156
Advisory Fees Paid, Amount	$ 1,716,716
Investment Company Portfolio Turnover	5%
Additional Fund Statistics [Text Block]	Key Fund Statistics (as of July 31, 2024) KEY FACTS Fund Size $ Number of Holdings 156 Total Advisory Fee $ Portfolio Turnover 5 %
Holdings [Text Block]	TOP INDUSTRIES (% of Fund's net assets) Specialized REITs 36.0 Retail REITs 13.1 Residential REITs 12.8 Industrial REITs 11.8 Health Care REITs 10.6 Real Estate Management & Development 7.6 Office REITs 3.3 Hotel & Resort REITs 2.5 Diversified REITs 1.9 Common Stocks 99.6 Short-Term Investments and Net Other Assets (Liabilities) 0.4 ASSET ALLOCATION (% of Fund's net assets) United States 100.0 GEOGRAPHIC DIVERSIFICATION (% of Fund's net assets)
Largest Holdings [Text Block]	TOP HOLDINGS (% of Fund's net assets) Prologis Inc 8.1 American Tower Corp 7.2 Equinix Inc 5.3 Welltower Inc 4.5 Simon Property Group Inc 3.6 Realty Income Corp 3.4 Crown Castle Inc 3.4 Public Storage Operating Co 3.2 Digital Realty Trust Inc 3.2 CBRE Group Inc Class A 2.4 44.3
Fidelity SAI U.S. Value Index Fund
Shareholder Report [Line Items]
Fund Name	Fidelity® SAI U.S. Value Index Fund
Class Name	Fidelity® SAI U.S. Value Index Fund
Trading Symbol	FSWCX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains information about Fidelity® SAI U.S. Value Index 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 U.S. Value Index Fund $ 0.11 %
Expenses Paid, Amount	$ 12
Expense Ratio, Percent	0.11%
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-B147"><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 19, 2017 through July 31, 2024. Initial investment of $10,000. Fidelity® SAI U.S. Value Index Fund $10,000 $10,367 $10,431 $9,375 $13,348 $14,044 $14,991 $17,716 Fidelity U.S. Value Focus Index℠ $10,000 $10,382 $10,441 $9,377 $13,369 $14,083 $15,064 $17,800 S&P 500® Index $10,000 $10,621 $11,469 $12,841 $17,520 $16,708 $18,882 $23,064 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® SAI U.S. Value Index Fund 18.17% 11.17% 9.02% Fidelity U.S. Value Focus Index℠ 18.16% 11.26% 9.10% S&P 500® Index 22.15% 15.00% 13.46% A From December 19, 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	Dec. 19, 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	$ 4,113,484,200
Holdings Count \| shares	204
Advisory Fees Paid, Amount	$ 1,879,685
Investment Company Portfolio Turnover	63%
Additional Fund Statistics [Text Block]	Key Fund Statistics (as of July 31, 2024) KEY FACTS Fund Size $ Number of Holdings 204 Total Advisory Fee $ Portfolio Turnover 63 %
Holdings [Text Block]	MARKET SECTORS (% of Fund's net assets) Financials 23.1 Information Technology 20.7 Energy 13.3 Health Care 12.9 Communication Services 8.6 Consumer Discretionary 5.9 Industrials 5.4 Materials 5.3 Consumer Staples 3.7 Real Estate 0.4 Utilities 0.2 Common Stocks 99.5 Short-Term Investments and Net Other Assets (Liabilities) 0.5 ASSET ALLOCATION (% of Fund's net assets) United States 99.2 Ireland 0.2 Bermuda 0.2 China 0.2 Peru 0.2 GEOGRAPHIC DIVERSIFICATION (% of Fund's net assets)
Largest Holdings [Text Block]	TOP HOLDINGS (% of Fund's net assets) Exxon Mobil Corp 3.8 JPMorgan Chase & Co 3.8 Chevron Corp 3.5 Bank of America Corp 3.3 Microsoft Corp 3.2 Apple Inc 3.2 NVIDIA Corp 2.8 Wells Fargo & Co 2.7 Cisco Systems Inc 2.6 International Business Machines Corp 2.4 31.3
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 fees associated with this class changed during the reporting year. The variations in class fees are primarily the result of the following changes: • Operating expenses
Material Fund Change Expenses [Text Block]	The fees associated with this class changed during the reporting year. The variations in class fees are primarily the result of the following changes: • Operating expenses
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-B162"><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-B163"><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-B164"><span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:bold;">fundresearch.fidelity.com/prospectus/sec</span>
Fidelity SAI Real Estate Index Fund
Shareholder Report [Line Items]
Fund Name	Fidelity® SAI Real Estate Index Fund
Class Name	Fidelity® SAI Real Estate Index Fund
Trading Symbol	FESIX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains information about Fidelity® SAI Real Estate Index 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 Real Estate Index Fund $ 0.07 %
Expenses Paid, Amount	$ 7
Expense Ratio, Percent	0.07%
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-B181"><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 February 2, 2016 through July 31, 2024. Initial investment of $10,000. Fidelity® SAI Real Estate Index Fund $10,000 $12,152 $11,471 $11,915 $13,200 $11,083 $15,485 $14,829 $13,395 Fidelity Real Estate Linked Index℠ $10,000 $12,170 $11,482 $11,924 $13,223 $11,068 $15,495 $14,841 $13,408 MSCI US IMI Real Estate 25/25 Index $10,000 $12,152 $11,940 $12,488 $14,139 $13,422 $18,360 $17,496 $15,886 S&P 500® Index $10,000 $11,549 $13,402 $15,579 $16,823 $18,834 $25,699 $24,506 $27,696 2016 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® SAI Real Estate Index Fund 10.30% 2.28% 4.70% Fidelity Real Estate Linked Index℠ 10.73% 2.34% 4.76% MSCI US IMI Real Estate 25/25 Index 10.73% 4.46% -% S&P 500® Index 22.15% 15.00% 15.42% A From February 2, 2016 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	Feb. 02, 2016
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	$ 2,578,643
Holdings Count \| shares	155
Advisory Fees Paid, Amount	$ 56,242
Investment Company Portfolio Turnover	7%
Additional Fund Statistics [Text Block]	Key Fund Statistics (as of July 31, 2024) KEY FACTS Fund Size $ Number of Holdings 155 Total Advisory Fee $ Portfolio Turnover 7 %
Holdings [Text Block]	TOP INDUSTRIES (% of Fund's net assets) Specialized REITs 35.6 Retail REITs 13.0 Residential REITs 12.6 Industrial REITs 11.7 Health Care REITs 10.4 Real Estate Management & Development 7.5 Office REITs 3.3 Hotel & Resort REITs 2.4 Diversified REITs 2.0 Common Stocks 98.5 Short-Term Investments and Net Other Assets (Liabilities) 1.5 ASSET ALLOCATION (% of Fund's net assets) United States 100.0 GEOGRAPHIC DIVERSIFICATION (% of Fund's net assets)
Largest Holdings [Text Block]	TOP HOLDINGS (% of Fund's net assets) Prologis Inc 8.0 American Tower Corp 7.1 Equinix Inc 5.2 Welltower Inc 4.3 Simon Property Group Inc 3.5 Realty Income Corp 3.4 Crown Castle Inc 3.3 Public Storage Operating Co 3.2 Digital Realty Trust Inc 3.2 CBRE Group Inc Class A 2.4 43.6
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 fees associated with this class changed during the reporting year. The variations in class fees are primarily the result of the following changes: • Operating expenses • Expense reductions
Material Fund Change Expenses [Text Block]	The fees associated with this class changed during the reporting year. The variations in class fees are primarily the result of the following changes: • Operating expenses • Expense reductions
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-B196"><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-B197"><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-B198"><span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:bold;">fundresearch.fidelity.com/prospectus/sec</span>
Fidelity SAI U.S. Large Cap Index Fund
Shareholder Report [Line Items]
Fund Name	Fidelity® SAI U.S. Large Cap Index Fund
Class Name	Fidelity® SAI U.S. Large Cap Index Fund
Trading Symbol	FLCPX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains information about Fidelity® SAI U.S. Large Cap Index 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 U.S. Large Cap Index Fund $ 0.02 %
Expenses Paid, Amount	$ 2
Expense Ratio, Percent	0.02%
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-B215"><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 February 2, 2016 through July 31, 2024. Initial investment of $10,000. Fidelity® SAI U.S. Large Cap Index Fund $10,000 $11,550 $13,401 $15,574 $16,816 $18,807 $25,659 $24,459 $27,635 S&P 500® Index $10,000 $11,549 $13,402 $15,579 $16,823 $18,834 $25,699 $24,506 $27,696 2016 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® SAI U.S. Large Cap Index Fund 22.14% 14.95% 15.39% S&P 500® Index 22.15% 15.00% 15.42% A From February 2, 2016 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	Feb. 02, 2016
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	$ 14,911,051,242
Holdings Count \| shares	507
Advisory Fees Paid, Amount	$ 1,842,847
Investment Company Portfolio Turnover	40%
Additional Fund Statistics [Text Block]	Key Fund Statistics (as of July 31, 2024) KEY FACTS Fund Size $ Number of Holdings 507 Total Advisory Fee $ Portfolio Turnover 40 %
Holdings [Text Block]	MARKET SECTORS (% of Fund's net assets) Information Technology 31.3 Financials 13.0 Health Care 11.8 Consumer Discretionary 10.0 Communication Services 8.8 Industrials 8.4 Consumer Staples 5.8 Energy 3.7 Utilities 2.4 Real Estate 2.3 Materials 2.2 Common Stocks 99.7 Short-Term Investments and Net Other Assets (Liabilities) 0.3 ASSET ALLOCATION (% of Fund's net assets) United States 99.5 Ireland 0.4 China 0.1 GEOGRAPHIC DIVERSIFICATION (% of Fund's net assets)
Largest Holdings [Text Block]	TOP HOLDINGS (% of Fund's net assets) Apple Inc 6.9 Microsoft Corp 6.7 NVIDIA Corp 6.3 Amazon.com Inc 3.7 Meta Platforms Inc Class A 2.2 Alphabet Inc Class A 2.2 Alphabet Inc Class C 1.8 Berkshire Hathaway Inc Class B 1.8 Broadcom Inc 1.6 Tesla Inc 1.4 34.6
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 fees associated with this class changed during the reporting year. The variations in class fees are primarily the result of the following changes: • Operating expenses
Material Fund Change Expenses [Text Block]	The fees associated with this class changed during the reporting year. The variations in class fees are primarily the result of the following changes: • Operating expenses
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-B230"><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-B231"><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-B232"><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

Shareholder Report, Line Graph (Details) - USD ($)

12 Months Ended

60 Months Ended

96 Months Ended

108 Months Ended

120 Months Ended

132 Months Ended

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

C000161034_0_LG_BBIndexMember_10YRMember

Account Value [Line Items]

Line Graph and Table Measure Name

S&P 500® Index" id="sjs-F5">S&P 500® Index

C000161034_0_BBIndexMember_AsOf_2015Member

Account Value [Line Items]

Account Value

$ 10,000

C000161034_0_BBIndexMember_AsOf_2016Member

Account Value [Line Items]

Account Value

$ 10,983

C000161034_0_BBIndexMember_AsOf_2017Member

Account Value [Line Items]

Account Value

$ 12,745

C000161034_0_BBIndexMember_AsOf_2018Member

Account Value [Line Items]

Account Value

$ 14,815

C000161034_0_BBIndexMember_AsOf_2019Member

Account Value [Line Items]

Account Value

$ 15,998

C000161034_0_BBIndexMember_AsOf_2020Member

Account Value [Line Items]

Account Value

$ 17,911

C000161034_0_BBIndexMember_AsOf_2021Member

Account Value [Line Items]

Account Value

$ 24,439

C000161034_0_BBIndexMember_AsOf_2022Member

Account Value [Line Items]

Account Value

$ 23,305

C000161034_0_BBIndexMember_AsOf_2023Member

Account Value [Line Items]

Account Value

$ 26,339

C000161034_0_BBIndexMember_AsOf_2024Member

Account Value [Line Items]

Account Value

$ 32,172

C000161034_2_BBIndexMember_1YRMember

Account Value [Line Items]

Average Annual Return, Percent

22.15%

C000161034_2_BBIndexMember_5YRMember

Account Value [Line Items]

Average Annual Return, Percent

15%

C000161034_2_BBIndexMember_LOCMember

Account Value [Line Items]

Average Annual Return, Percent

14.17%

C000158877_1_BBIndexMember_1YRMember

Account Value [Line Items]

Average Annual Return, Percent

21.07%

C000158877_1_BBIndexMember_5YRMember

Account Value [Line Items]

Average Annual Return, Percent

14.23%

C000158877_1_BBIndexMember_LOCMember

Account Value [Line Items]

Average Annual Return, Percent

12.87%

C000177148_1_BBIndexMember_1YRMember

Account Value [Line Items]

Average Annual Return, Percent

21.48%

C000177148_1_BBIndexMember_5YRMember

Account Value [Line Items]

Average Annual Return, Percent

14.35%

C000177148_1_BBIndexMember_LOCMember

Account Value [Line Items]

Average Annual Return, Percent

13.72%

C000103377_0_LG_BBIndexMember_11YRMember

Account Value [Line Items]

Line Graph and Table Measure Name

S&P 500® Index" id="sjs-G65">S&P 500® Index

C000103377_0_BBIndexMember_AsOf_2014Member

Account Value [Line Items]

Account Value

$ 10,000

C000103377_0_BBIndexMember_AsOf_2015Member

Account Value [Line Items]

Account Value

11,121

C000103377_0_BBIndexMember_AsOf_2016Member

Account Value [Line Items]

Account Value

11,745

C000103377_0_BBIndexMember_AsOf_2017Member

Account Value [Line Items]

Account Value

13,629

C000103377_0_BBIndexMember_AsOf_2018Member

Account Value [Line Items]

Account Value

15,843

C000103377_0_BBIndexMember_AsOf_2019Member

Account Value [Line Items]

Account Value

17,108

C000103377_0_BBIndexMember_AsOf_2020Member

Account Value [Line Items]

Account Value

19,153

C000103377_0_BBIndexMember_AsOf_2021Member

Account Value [Line Items]

Account Value

26,134

C000103377_0_BBIndexMember_AsOf_2022Member

Account Value [Line Items]

Account Value

24,921

C000103377_0_BBIndexMember_AsOf_2023Member

Account Value [Line Items]

Account Value

28,165

C000103377_0_BBIndexMember_AsOf_2024Member

Account Value [Line Items]

Account Value

$ 34,403

34,403

$ 34,403

C000103377_2_BBIndexMember_1YRMember

Account Value [Line Items]

Average Annual Return, Percent

22.15%

C000103377_2_BBIndexMember_5YRMember

Account Value [Line Items]

Average Annual Return, Percent

15%

C000103377_2_BBIndexMember_10YRMember

Account Value [Line Items]

Average Annual Return, Percent

13.15%

C000195574_1_BBIndexMember_1YRMember

Account Value [Line Items]

Average Annual Return, Percent

22.15%

C000195574_1_BBIndexMember_5YRMember

Account Value [Line Items]

Average Annual Return, Percent

15%

C000195574_1_BBIndexMember_LOCMember

Account Value [Line Items]

Average Annual Return, Percent

13.46%

C000163539_0_LG_BBIndexMember_9YRMember

Account Value [Line Items]

Line Graph and Table Measure Name

S&P 500® Index" id="sjs-E119">S&P 500® Index

C000163539_0_BBIndexMember_AsOf_2016Member

Account Value [Line Items]

Account Value

10,000

C000163539_0_BBIndexMember_AsOf_2017Member

Account Value [Line Items]

Account Value

11,549

C000163539_0_BBIndexMember_AsOf_2018Member

Account Value [Line Items]

Account Value

13,402

C000163539_0_BBIndexMember_AsOf_2019Member

Account Value [Line Items]

Account Value

15,579

C000163539_0_BBIndexMember_AsOf_2020Member

Account Value [Line Items]

Account Value

16,823

C000163539_0_BBIndexMember_AsOf_2021Member

Account Value [Line Items]

Account Value

18,834

C000163539_0_BBIndexMember_AsOf_2022Member

Account Value [Line Items]

Account Value

25,699

C000163539_0_BBIndexMember_AsOf_2023Member

Account Value [Line Items]

Account Value

24,506

C000163539_0_BBIndexMember_AsOf_2024Member

Account Value [Line Items]

Account Value

$ 27,696

27,696

$ 27,696

27,696

C000163539_2_BBIndexMember_1YRMember

Account Value [Line Items]

Average Annual Return, Percent

22.15%

C000163539_2_BBIndexMember_5YRMember

Account Value [Line Items]

Average Annual Return, Percent

15%

C000163539_2_BBIndexMember_LOCMember

Account Value [Line Items]

Average Annual Return, Percent

15.42%

C000163540_0_BBIndexMember_1YRMember

Account Value [Line Items]

Average Annual Return, Percent

22.15%

C000163540_0_BBIndexMember_5YRMember

Account Value [Line Items]

Average Annual Return, Percent

15%

C000163540_0_BBIndexMember_LOCMember

Account Value [Line Items]

Average Annual Return, Percent

15.42%

C000161034_LG_ClassMember_10YRMember

Account Value [Line Items]

Line Graph and Table Measure Name

Fidelity® SAI U.S. Quality Index Fund" id="sjs-F167">Fidelity® SAI U.S. Quality Index Fund

C000161034_ClassMember_AsOf_2015Member

Account Value [Line Items]

Account Value

10,000

C000161034_ClassMember_AsOf_2016Member

Account Value [Line Items]

Account Value

10,901

C000161034_ClassMember_AsOf_2017Member

Account Value [Line Items]

Account Value

12,503

C000161034_ClassMember_AsOf_2018Member

Account Value [Line Items]

Account Value

15,093

C000161034_ClassMember_AsOf_2019Member

Account Value [Line Items]

Account Value

16,556

C000161034_ClassMember_AsOf_2020Member

Account Value [Line Items]

Account Value

19,890

C000161034_ClassMember_AsOf_2021Member

Account Value [Line Items]

Account Value

26,383

C000161034_ClassMember_AsOf_2022Member

Account Value [Line Items]

Account Value

24,654

C000161034_ClassMember_AsOf_2023Member

Account Value [Line Items]

Account Value

28,344

C000161034_ClassMember_AsOf_2024Member

Account Value [Line Items]

Account Value

$ 35,673

35,673

$ 35,673

35,673

C000161034_LG_1_AdditionalIndexMember_10YRMember

Account Value [Line Items]

Line Graph and Table Measure Name

Fidelity SAI U.S. Quality Index Fund Linked Index℠" id="sjs-F200">Fidelity SAI U.S. Quality Index Fund Linked Index℠

C000161034_1_AdditionalIndexMember_AsOf_2015Member

Account Value [Line Items]

Account Value

10,000

C000161034_1_AdditionalIndexMember_AsOf_2016Member

Account Value [Line Items]

Account Value

10,911

C000161034_1_AdditionalIndexMember_AsOf_2017Member

Account Value [Line Items]

Account Value

12,543

C000161034_1_AdditionalIndexMember_AsOf_2018Member

Account Value [Line Items]

Account Value

15,159

C000161034_1_AdditionalIndexMember_AsOf_2019Member

Account Value [Line Items]

Account Value

16,640

C000161034_1_AdditionalIndexMember_AsOf_2020Member

Account Value [Line Items]

Account Value

19,994

C000161034_1_AdditionalIndexMember_AsOf_2021Member

Account Value [Line Items]

Account Value

26,537

C000161034_1_AdditionalIndexMember_AsOf_2022Member

Account Value [Line Items]

Account Value

24,791

C000161034_1_AdditionalIndexMember_AsOf_2023Member

Account Value [Line Items]

Account Value

28,554

C000161034_1_AdditionalIndexMember_AsOf_2024Member

Account Value [Line Items]

Account Value

35,908

$ 35,908

35,908

C000161034_LG_2_AdditionalIndexMember_10YRMember

Account Value [Line Items]

Line Graph and Table Measure Name

Fidelity U.S. Quality Focus Index℠" id="sjs-F233">Fidelity U.S. Quality Focus Index℠

C000161034_2_AdditionalIndexMember_AsOf_2015Member

Account Value [Line Items]

Account Value

10,000

C000161034_2_AdditionalIndexMember_AsOf_2016Member

Account Value [Line Items]

Account Value

10,901

C000161034_2_AdditionalIndexMember_AsOf_2017Member

Account Value [Line Items]

Account Value

12,503

C000161034_2_AdditionalIndexMember_AsOf_2018Member

Account Value [Line Items]

Account Value

15,093

C000161034_2_AdditionalIndexMember_AsOf_2019Member

Account Value [Line Items]

Account Value

16,573

C000161034_2_AdditionalIndexMember_AsOf_2020Member

Account Value [Line Items]

Account Value

19,914

C000161034_2_AdditionalIndexMember_AsOf_2021Member

Account Value [Line Items]

Account Value

26,430

C000161034_2_AdditionalIndexMember_AsOf_2022Member

Account Value [Line Items]

Account Value

24,691

C000161034_2_AdditionalIndexMember_AsOf_2023Member

Account Value [Line Items]

Account Value

28,439

C000161034_2_AdditionalIndexMember_AsOf_2024Member

Account Value [Line Items]

Account Value

$ 35,763

35,763

$ 35,763

35,763

C000161034_NoLoadClassMember_1YRMember

Account Value [Line Items]

Average Annual Return, Percent

25.86%

C000161034_NoLoadClassMember_5YRMember

Account Value [Line Items]

Average Annual Return, Percent

16.59%

C000161034_NoLoadClassMember_2023-08-01_2024-07-31Member

Account Value [Line Items]

Average Annual Return, Percent

15.51%

C000161034_0_AdditionalIndexMember_1YRMember

Account Value [Line Items]

Average Annual Return, Percent

25.76%

C000161034_0_AdditionalIndexMember_5YRMember

Account Value [Line Items]

Average Annual Return, Percent

16.63%

C000161034_0_AdditionalIndexMember_LOCMember

Account Value [Line Items]

Average Annual Return, Percent

15.60%

C000161034_1_AdditionalIndexMember_1YRMember

Account Value [Line Items]

Average Annual Return, Percent

25.76%

C000161034_1_AdditionalIndexMember_5YRMember

Account Value [Line Items]

Average Annual Return, Percent

16.63%

C000161034_1_AdditionalIndexMember_LOCMember

Account Value [Line Items]

Average Annual Return, Percent

C000158877_LG_ClassMember_10YRMember

Account Value [Line Items]

Line Graph and Table Measure Name

Fidelity® SAI Small-Mid Cap 500 Index Fund" id="sjs-F293">Fidelity® SAI Small-Mid Cap 500 Index Fund

C000158877_ClassMember_AsOf_2015Member

Account Value [Line Items]

Account Value

10,000

C000158877_ClassMember_AsOf_2016Member

Account Value [Line Items]

Account Value

10,326

C000158877_ClassMember_AsOf_2017Member

Account Value [Line Items]

Account Value

11,608

C000158877_ClassMember_AsOf_2018Member

Account Value [Line Items]

Account Value

13,455

C000158877_ClassMember_AsOf_2019Member

Account Value [Line Items]

Account Value

14,162

C000158877_ClassMember_AsOf_2020Member

Account Value [Line Items]

Account Value

14,159

C000158877_ClassMember_AsOf_2021Member

Account Value [Line Items]

Account Value

20,812

C000158877_ClassMember_AsOf_2022Member

Account Value [Line Items]

Account Value

18,952

C000158877_ClassMember_AsOf_2023Member

Account Value [Line Items]

Account Value

20,529

C000158877_ClassMember_AsOf_2024Member

Account Value [Line Items]

Account Value

$ 23,029

23,029

$ 23,029

23,029

C000158877_LG_1_AdditionalIndexMember_10YRMember

Account Value [Line Items]

Line Graph and Table Measure Name

Russell SMID 500™ Index" id="sjs-F326">Russell SMID 500™ Index

C000158877_1_AdditionalIndexMember_AsOf_2015Member

Account Value [Line Items]

Account Value

10,000

C000158877_1_AdditionalIndexMember_AsOf_2016Member

Account Value [Line Items]

Account Value

10,335

C000158877_1_AdditionalIndexMember_AsOf_2017Member

Account Value [Line Items]

Account Value

11,622

C000158877_1_AdditionalIndexMember_AsOf_2018Member

Account Value [Line Items]

Account Value

13,496

C000158877_1_AdditionalIndexMember_AsOf_2019Member

Account Value [Line Items]

Account Value

14,206

C000158877_1_AdditionalIndexMember_AsOf_2020Member

Account Value [Line Items]

Account Value

14,207

C000158877_1_AdditionalIndexMember_AsOf_2021Member

Account Value [Line Items]

Account Value

20,895

C000158877_1_AdditionalIndexMember_AsOf_2022Member

Account Value [Line Items]

Account Value

19,035

C000158877_1_AdditionalIndexMember_AsOf_2023Member

Account Value [Line Items]

Account Value

20,592

C000158877_1_AdditionalIndexMember_AsOf_2024Member

Account Value [Line Items]

Account Value

23,107

$ 23,107

23,107

C000158877_LG_2_AdditionalIndexMember_10YRMember

Account Value [Line Items]

Line Graph and Table Measure Name

Russell 3000® Index" id="sjs-F359">Russell 3000® Index

C000158877_2_AdditionalIndexMember_AsOf_2015Member

Account Value [Line Items]

Account Value

10,000

C000158877_2_AdditionalIndexMember_AsOf_2016Member

Account Value [Line Items]

Account Value

10,538

C000158877_2_AdditionalIndexMember_AsOf_2017Member

Account Value [Line Items]

Account Value

12,239

C000158877_2_AdditionalIndexMember_AsOf_2018Member

Account Value [Line Items]

Account Value

14,245

C000158877_2_AdditionalIndexMember_AsOf_2019Member

Account Value [Line Items]

Account Value

15,249

C000158877_2_AdditionalIndexMember_AsOf_2020Member

Account Value [Line Items]

Account Value

16,916

C000158877_2_AdditionalIndexMember_AsOf_2021Member

Account Value [Line Items]

Account Value

23,466

C000158877_2_AdditionalIndexMember_AsOf_2022Member

Account Value [Line Items]

Account Value

21,741

C000158877_2_AdditionalIndexMember_AsOf_2023Member

Account Value [Line Items]

Account Value

24,491

C000158877_2_AdditionalIndexMember_AsOf_2024Member

Account Value [Line Items]

Account Value

$ 29,653

29,653

$ 29,653

29,653

C000158877_NoLoadClassMember_1YRMember

Account Value [Line Items]

Average Annual Return, Percent

12.18%

C000158877_NoLoadClassMember_5YRMember

Account Value [Line Items]

Average Annual Return, Percent

10.21%

C000158877_NoLoadClassMember_2023-08-01_2024-07-31Member

Account Value [Line Items]

Average Annual Return, Percent

9.74%

C000158877_0_AdditionalIndexMember_1YRMember

Account Value [Line Items]

Average Annual Return, Percent

12.21%

C000158877_0_AdditionalIndexMember_5YRMember

Account Value [Line Items]

Average Annual Return, Percent

10.22%

C000158877_0_AdditionalIndexMember_LOCMember

Account Value [Line Items]

Average Annual Return, Percent

9.78%

C000177148_LG_ClassMember_8YRMember

Account Value [Line Items]

Line Graph and Table Measure Name

Fidelity® SAI U.S. Momentum Index Fund" id="sjs-D410">Fidelity® SAI U.S. Momentum Index Fund

C000177148_ClassMember_AsOf_2017Member

Account Value [Line Items]

Account Value

10,000

C000177148_ClassMember_AsOf_2018Member

Account Value [Line Items]

Account Value

10,980

C000177148_ClassMember_AsOf_2019Member

Account Value [Line Items]

Account Value

13,432

C000177148_ClassMember_AsOf_2020Member

Account Value [Line Items]

Account Value

14,363

C000177148_ClassMember_AsOf_2021Member

Account Value [Line Items]

Account Value

16,770

C000177148_ClassMember_AsOf_2022Member

Account Value [Line Items]

Account Value

22,301

C000177148_ClassMember_AsOf_2023Member

Account Value [Line Items]

Account Value

19,835

C000177148_ClassMember_AsOf_2024Member

Account Value [Line Items]

Account Value

$ 21,024

21,024

C000177148_LG_1_AdditionalIndexMember_8YRMember

Account Value [Line Items]

Line Graph and Table Measure Name

MSCI USA Custom Momentum Composite Index" id="sjs-D437">MSCI USA Custom Momentum Composite Index

C000177148_1_AdditionalIndexMember_AsOf_2017Member

Account Value [Line Items]

Account Value

10,000

C000177148_1_AdditionalIndexMember_AsOf_2018Member

Account Value [Line Items]

Account Value

11,002

C000177148_1_AdditionalIndexMember_AsOf_2019Member

Account Value [Line Items]

Account Value

13,464

C000177148_1_AdditionalIndexMember_AsOf_2020Member

Account Value [Line Items]

Account Value

14,416

C000177148_1_AdditionalIndexMember_AsOf_2021Member

Account Value [Line Items]

Account Value

16,851

C000177148_1_AdditionalIndexMember_AsOf_2022Member

Account Value [Line Items]

Account Value

22,435

C000177148_1_AdditionalIndexMember_AsOf_2023Member

Account Value [Line Items]

Account Value

19,974

C000177148_1_AdditionalIndexMember_AsOf_2024Member

Account Value [Line Items]

Account Value

21,212

$ 21,212

21,212

C000177148_LG_2_AdditionalIndexMember_8YRMember

Account Value [Line Items]

Line Graph and Table Measure Name

MSCI USA Index" id="sjs-D464">MSCI USA Index

C000177148_2_AdditionalIndexMember_AsOf_2017Member

Account Value [Line Items]

Account Value

10,000

C000177148_2_AdditionalIndexMember_AsOf_2018Member

Account Value [Line Items]

Account Value

10,768

C000177148_2_AdditionalIndexMember_AsOf_2019Member

Account Value [Line Items]

Account Value

12,450

C000177148_2_AdditionalIndexMember_AsOf_2020Member

Account Value [Line Items]

Account Value

13,375

C000177148_2_AdditionalIndexMember_AsOf_2021Member

Account Value [Line Items]

Account Value

15,041

C000177148_2_AdditionalIndexMember_AsOf_2022Member

Account Value [Line Items]

Account Value

20,620

C000177148_2_AdditionalIndexMember_AsOf_2023Member

Account Value [Line Items]

Account Value

19,123

C000177148_2_AdditionalIndexMember_AsOf_2024Member

Account Value [Line Items]

Account Value

$ 21,529

21,529

$ 21,529

C000177148_NoLoadClassMember_1YRMember

Account Value [Line Items]

Average Annual Return, Percent

35.08%

C000177148_NoLoadClassMember_5YRMember

Account Value [Line Items]

Average Annual Return, Percent

14.61%

C000177148_NoLoadClassMember_2023-08-01_2024-07-31Member

Account Value [Line Items]

Average Annual Return, Percent

14.98%

C000177148_0_AdditionalIndexMember_1YRMember

Account Value [Line Items]

Average Annual Return, Percent

35.04%

C000177148_0_AdditionalIndexMember_5YRMember

Account Value [Line Items]

Average Annual Return, Percent

14.72%

C000177148_0_AdditionalIndexMember_LOCMember

Account Value [Line Items]

Average Annual Return, Percent

15.11%

C000103377_LG_ClassMember_11YRMember

Account Value [Line Items]

Line Graph and Table Measure Name

Fidelity® Real Estate Index Fund" id="sjs-G509">Fidelity® Real Estate Index Fund

C000103377_ClassMember_AsOf_2014Member

Account Value [Line Items]

Account Value

10,000

C000103377_ClassMember_AsOf_2015Member

Account Value [Line Items]

Account Value

11,129

C000103377_ClassMember_AsOf_2016Member

Account Value [Line Items]

Account Value

13,433

C000103377_ClassMember_AsOf_2017Member

Account Value [Line Items]

Account Value

12,680

C000103377_ClassMember_AsOf_2018Member

Account Value [Line Items]

Account Value

13,174

C000103377_ClassMember_AsOf_2019Member

Account Value [Line Items]

Account Value

14,602

C000103377_ClassMember_AsOf_2020Member

Account Value [Line Items]

Account Value

12,216

C000103377_ClassMember_AsOf_2021Member

Account Value [Line Items]

Account Value

17,069

C000103377_ClassMember_AsOf_2022Member

Account Value [Line Items]

Account Value

16,350

C000103377_ClassMember_AsOf_2023Member

Account Value [Line Items]

Account Value

14,764

C000103377_ClassMember_AsOf_2024Member

Account Value [Line Items]

Account Value

$ 16,333

16,333

$ 16,333

C000103377_LG_1_AdditionalIndexMember_11YRMember

Account Value [Line Items]

Line Graph and Table Measure Name

Fidelity Real Estate Linked Index℠" id="sjs-G545">Fidelity Real Estate Linked Index℠

C000103377_1_AdditionalIndexMember_AsOf_2014Member

Account Value [Line Items]

Account Value

10,000

C000103377_1_AdditionalIndexMember_AsOf_2015Member

Account Value [Line Items]

Account Value

11,129

C000103377_1_AdditionalIndexMember_AsOf_2016Member

Account Value [Line Items]

Account Value

13,457

C000103377_1_AdditionalIndexMember_AsOf_2017Member

Account Value [Line Items]

Account Value

12,695

C000103377_1_AdditionalIndexMember_AsOf_2018Member

Account Value [Line Items]

Account Value

13,185

C000103377_1_AdditionalIndexMember_AsOf_2019Member

Account Value [Line Items]

Account Value

14,621

C000103377_1_AdditionalIndexMember_AsOf_2020Member

Account Value [Line Items]

Account Value

12,238

C000103377_1_AdditionalIndexMember_AsOf_2021Member

Account Value [Line Items]

Account Value

17,133

C000103377_1_AdditionalIndexMember_AsOf_2022Member

Account Value [Line Items]

Account Value

16,409

C000103377_1_AdditionalIndexMember_AsOf_2023Member

Account Value [Line Items]

Account Value

14,825

C000103377_1_AdditionalIndexMember_AsOf_2024Member

Account Value [Line Items]

Account Value

16,415

$ 16,415

C000103377_LG_2_AdditionalIndexMember_11YRMember

Account Value [Line Items]

Line Graph and Table Measure Name

MSCI US IMI Real Estate 25/25 Index" id="sjs-G581">MSCI US IMI Real Estate 25/25 Index

C000103377_2_AdditionalIndexMember_AsOf_2014Member

Account Value [Line Items]

Account Value

$ 10,000

C000103377_2_AdditionalIndexMember_AsOf_2015Member

Account Value [Line Items]

Account Value

$ 11,129

C000103377_2_AdditionalIndexMember_AsOf_2016Member

Account Value [Line Items]

Account Value

13,433

C000103377_2_AdditionalIndexMember_AsOf_2017Member

Account Value [Line Items]

Account Value

13,204

C000103377_2_AdditionalIndexMember_AsOf_2018Member

Account Value [Line Items]

Account Value

13,810

C000103377_2_AdditionalIndexMember_AsOf_2019Member

Account Value [Line Items]

Account Value

15,636

C000103377_2_AdditionalIndexMember_AsOf_2020Member

Account Value [Line Items]

Account Value

14,843

C000103377_2_AdditionalIndexMember_AsOf_2021Member

Account Value [Line Items]

Account Value

20,304

C000103377_2_AdditionalIndexMember_AsOf_2022Member

Account Value [Line Items]

Account Value

19,446

C000103377_2_AdditionalIndexMember_AsOf_2023Member

Account Value [Line Items]

Account Value

17,568

C000103377_2_AdditionalIndexMember_AsOf_2024Member

Account Value [Line Items]

Account Value

$ 19,453

19,453

$ 19,453

C000103377_NoLoadClassMember_1YRMember

Account Value [Line Items]

Average Annual Return, Percent

10.63%

C000103377_NoLoadClassMember_5YRMember

Account Value [Line Items]

Average Annual Return, Percent

2.27%

C000103377_NoLoadClassMember_10YRMember

Account Value [Line Items]

Average Annual Return, Percent

5.03%

C000103377_0_AdditionalIndexMember_1YRMember

Account Value [Line Items]

Average Annual Return, Percent

10.73%

C000103377_0_AdditionalIndexMember_5YRMember

Account Value [Line Items]

Average Annual Return, Percent

2.34%

C000103377_0_AdditionalIndexMember_10YRMember

Account Value [Line Items]

Average Annual Return, Percent

5.08%

C000103377_1_AdditionalIndexMember_1YRMember

Account Value [Line Items]

Average Annual Return, Percent

10.73%

C000103377_1_AdditionalIndexMember_5YRMember

Account Value [Line Items]

Average Annual Return, Percent

4.46%

C000103377_1_AdditionalIndexMember_10YRMember

Account Value [Line Items]

Average Annual Return, Percent

C000195574_LG_ClassMember_8YRMember

Account Value [Line Items]

Line Graph and Table Measure Name

Fidelity® SAI U.S. Value Index Fund" id="sjs-D644">Fidelity® SAI U.S. Value Index Fund

C000195574_ClassMember_AsOf_2017Member

Account Value [Line Items]

Account Value

10,000

C000195574_ClassMember_AsOf_2018Member

Account Value [Line Items]

Account Value

10,367

C000195574_ClassMember_AsOf_2019Member

Account Value [Line Items]

Account Value

10,431

C000195574_ClassMember_AsOf_2020Member

Account Value [Line Items]

Account Value

9,375

C000195574_ClassMember_AsOf_2021Member

Account Value [Line Items]

Account Value

13,348

C000195574_ClassMember_AsOf_2022Member

Account Value [Line Items]

Account Value

14,044

C000195574_ClassMember_AsOf_2023Member

Account Value [Line Items]

Account Value

14,991

C000195574_ClassMember_AsOf_2024Member

Account Value [Line Items]

Account Value

$ 17,716

17,716

$ 17,716

17,716

C000195574_LG_1_AdditionalIndexMember_8YRMember

Account Value [Line Items]

Line Graph and Table Measure Name

Fidelity U.S. Value Focus Index℠" id="sjs-D671">Fidelity U.S. Value Focus Index℠

C000195574_1_AdditionalIndexMember_AsOf_2017Member

Account Value [Line Items]

Account Value

10,000

C000195574_1_AdditionalIndexMember_AsOf_2018Member

Account Value [Line Items]

Account Value

10,382

C000195574_1_AdditionalIndexMember_AsOf_2019Member

Account Value [Line Items]

Account Value

10,441

C000195574_1_AdditionalIndexMember_AsOf_2020Member

Account Value [Line Items]

Account Value

9,377

C000195574_1_AdditionalIndexMember_AsOf_2021Member

Account Value [Line Items]

Account Value

13,369

C000195574_1_AdditionalIndexMember_AsOf_2022Member

Account Value [Line Items]

Account Value

14,083

C000195574_1_AdditionalIndexMember_AsOf_2023Member

Account Value [Line Items]

Account Value

15,064

C000195574_1_AdditionalIndexMember_AsOf_2024Member

Account Value [Line Items]

Account Value

17,800

$ 17,800

17,800

C000195574_LG_2_AdditionalIndexMember_8YRMember

Account Value [Line Items]

Line Graph and Table Measure Name

S&P 500® Index" id="sjs-D698">S&P 500® Index

C000195574_2_AdditionalIndexMember_AsOf_2017Member

Account Value [Line Items]

Account Value

10,000

C000195574_2_AdditionalIndexMember_AsOf_2018Member

Account Value [Line Items]

Account Value

10,621

C000195574_2_AdditionalIndexMember_AsOf_2019Member

Account Value [Line Items]

Account Value

11,469

C000195574_2_AdditionalIndexMember_AsOf_2020Member

Account Value [Line Items]

Account Value

12,841

C000195574_2_AdditionalIndexMember_AsOf_2021Member

Account Value [Line Items]

Account Value

17,520

C000195574_2_AdditionalIndexMember_AsOf_2022Member

Account Value [Line Items]

Account Value

16,708

C000195574_2_AdditionalIndexMember_AsOf_2023Member

Account Value [Line Items]

Account Value

18,882

C000195574_2_AdditionalIndexMember_AsOf_2024Member

Account Value [Line Items]

Account Value

$ 23,064

23,064

C000195574_NoLoadClassMember_1YRMember

Account Value [Line Items]

Average Annual Return, Percent

18.17%

C000195574_NoLoadClassMember_5YRMember

Account Value [Line Items]

Average Annual Return, Percent

11.17%

C000195574_NoLoadClassMember_2023-08-01_2024-07-31Member

Account Value [Line Items]

Average Annual Return, Percent

9.02%

C000195574_0_AdditionalIndexMember_1YRMember

Account Value [Line Items]

Average Annual Return, Percent

18.16%

C000195574_0_AdditionalIndexMember_5YRMember

Account Value [Line Items]

Average Annual Return, Percent

11.26%

C000195574_0_AdditionalIndexMember_LOCMember

Account Value [Line Items]

Average Annual Return, Percent

9.10%

C000163539_LG_ClassMember_9YRMember

Account Value [Line Items]

Line Graph and Table Measure Name

Fidelity® SAI Real Estate Index Fund" id="sjs-E743">Fidelity® SAI Real Estate Index Fund

C000163539_ClassMember_AsOf_2016Member

Account Value [Line Items]

Account Value

10,000

C000163539_ClassMember_AsOf_2017Member

Account Value [Line Items]

Account Value

12,152

C000163539_ClassMember_AsOf_2018Member

Account Value [Line Items]

Account Value

11,471

C000163539_ClassMember_AsOf_2019Member

Account Value [Line Items]

Account Value

11,915

C000163539_ClassMember_AsOf_2020Member

Account Value [Line Items]

Account Value

13,200

C000163539_ClassMember_AsOf_2021Member

Account Value [Line Items]

Account Value

11,083

C000163539_ClassMember_AsOf_2022Member

Account Value [Line Items]

Account Value

15,485

C000163539_ClassMember_AsOf_2023Member

Account Value [Line Items]

Account Value

14,829

C000163539_ClassMember_AsOf_2024Member

Account Value [Line Items]

Account Value

$ 13,395

13,395

$ 13,395

13,395

C000163539_LG_1_AdditionalIndexMember_9YRMember

Account Value [Line Items]

Line Graph and Table Measure Name

Fidelity Real Estate Linked Index℠" id="sjs-E773">Fidelity Real Estate Linked Index℠

C000163539_1_AdditionalIndexMember_AsOf_2016Member

Account Value [Line Items]

Account Value

10,000

C000163539_1_AdditionalIndexMember_AsOf_2017Member

Account Value [Line Items]

Account Value

12,170

C000163539_1_AdditionalIndexMember_AsOf_2018Member

Account Value [Line Items]

Account Value

11,482

C000163539_1_AdditionalIndexMember_AsOf_2019Member

Account Value [Line Items]

Account Value

11,924

C000163539_1_AdditionalIndexMember_AsOf_2020Member

Account Value [Line Items]

Account Value

13,223

C000163539_1_AdditionalIndexMember_AsOf_2021Member

Account Value [Line Items]

Account Value

11,068

C000163539_1_AdditionalIndexMember_AsOf_2022Member

Account Value [Line Items]

Account Value

15,495

C000163539_1_AdditionalIndexMember_AsOf_2023Member

Account Value [Line Items]

Account Value

14,841

C000163539_1_AdditionalIndexMember_AsOf_2024Member

Account Value [Line Items]

Account Value

13,408

$ 13,408

13,408

C000163539_LG_2_AdditionalIndexMember_9YRMember

Account Value [Line Items]

Line Graph and Table Measure Name

MSCI US IMI Real Estate 25/25 Index" id="sjs-E803">MSCI US IMI Real Estate 25/25 Index

C000163539_2_AdditionalIndexMember_AsOf_2016Member

Account Value [Line Items]

Account Value

10,000

C000163539_2_AdditionalIndexMember_AsOf_2017Member

Account Value [Line Items]

Account Value

12,152

C000163539_2_AdditionalIndexMember_AsOf_2018Member

Account Value [Line Items]

Account Value

11,940

C000163539_2_AdditionalIndexMember_AsOf_2019Member

Account Value [Line Items]

Account Value

12,488

C000163539_2_AdditionalIndexMember_AsOf_2020Member

Account Value [Line Items]

Account Value

14,139

C000163539_2_AdditionalIndexMember_AsOf_2021Member

Account Value [Line Items]

Account Value

13,422

C000163539_2_AdditionalIndexMember_AsOf_2022Member

Account Value [Line Items]

Account Value

18,360

C000163539_2_AdditionalIndexMember_AsOf_2023Member

Account Value [Line Items]

Account Value

17,496

C000163539_2_AdditionalIndexMember_AsOf_2024Member

Account Value [Line Items]

Account Value

$ 15,886

15,886

$ 15,886

15,886

C000163539_NoLoadClassMember_1YRMember

Account Value [Line Items]

Average Annual Return, Percent

10.30%

C000163539_NoLoadClassMember_5YRMember

Account Value [Line Items]

Average Annual Return, Percent

2.28%

C000163539_NoLoadClassMember_2023-08-01_2024-07-31Member

Account Value [Line Items]

Average Annual Return, Percent

4.70%

C000163539_0_AdditionalIndexMember_1YRMember

Account Value [Line Items]

Average Annual Return, Percent

10.73%

C000163539_0_AdditionalIndexMember_5YRMember

Account Value [Line Items]

Average Annual Return, Percent

2.34%

C000163539_0_AdditionalIndexMember_LOCMember

Account Value [Line Items]

Average Annual Return, Percent

4.76%

C000163539_1_AdditionalIndexMember_1YRMember

Account Value [Line Items]

Average Annual Return, Percent

10.73%

C000163539_1_AdditionalIndexMember_5YRMember

Account Value [Line Items]

Average Annual Return, Percent

4.46%

C000163539_1_AdditionalIndexMember_LOCMember

Account Value [Line Items]

Average Annual Return, Percent

C000163540_LG_ClassMember_9YRMember

Account Value [Line Items]

Line Graph and Table Measure Name

Fidelity® SAI U.S. Large Cap Index Fund" id="sjs-E860">Fidelity® SAI U.S. Large Cap Index Fund

C000163540_ClassMember_AsOf_2016Member

Account Value [Line Items]

Account Value

10,000

C000163540_ClassMember_AsOf_2017Member

Account Value [Line Items]

Account Value

11,550

C000163540_ClassMember_AsOf_2018Member

Account Value [Line Items]

Account Value

13,401

C000163540_ClassMember_AsOf_2019Member

Account Value [Line Items]

Account Value

15,574

C000163540_ClassMember_AsOf_2020Member

Account Value [Line Items]

Account Value

16,816

C000163540_ClassMember_AsOf_2021Member

Account Value [Line Items]

Account Value

18,807

C000163540_ClassMember_AsOf_2022Member

Account Value [Line Items]

Account Value

25,659

C000163540_ClassMember_AsOf_2023Member

Account Value [Line Items]

Account Value

24,459

C000163540_ClassMember_AsOf_2024Member

Account Value [Line Items]

Account Value

$ 27,635

27,635

$ 27,635

27,635

C000163540_LG_1_AdditionalIndexMember_9YRMember

Account Value [Line Items]

Line Graph and Table Measure Name

S&P 500® Index" id="sjs-E890">S&P 500® Index

C000163540_1_AdditionalIndexMember_AsOf_2016Member

Account Value [Line Items]

Account Value

$ 10,000

C000163540_1_AdditionalIndexMember_AsOf_2017Member

Account Value [Line Items]

Account Value

$ 11,549

C000163540_1_AdditionalIndexMember_AsOf_2018Member

Account Value [Line Items]

Account Value

$ 13,402

C000163540_1_AdditionalIndexMember_AsOf_2019Member

Account Value [Line Items]

Account Value

$ 15,579

C000163540_1_AdditionalIndexMember_AsOf_2020Member

Account Value [Line Items]

Account Value

$ 16,823

C000163540_1_AdditionalIndexMember_AsOf_2021Member

Account Value [Line Items]

Account Value

$ 18,834

C000163540_1_AdditionalIndexMember_AsOf_2022Member

Account Value [Line Items]

Account Value

$ 25,699

C000163540_1_AdditionalIndexMember_AsOf_2023Member

Account Value [Line Items]

Account Value

$ 24,506

C000163540_1_AdditionalIndexMember_AsOf_2024Member

Account Value [Line Items]

Account Value

$ 27,696

C000163540_NoLoadClassMember_1YRMember

Account Value [Line Items]

Average Annual Return, Percent

22.14%

C000163540_NoLoadClassMember_5YRMember

Account Value [Line Items]

Average Annual Return, Percent

14.95%

C000163540_NoLoadClassMember_2023-08-01_2024-07-31Member

Account Value [Line Items]

Average Annual Return, Percent

15.39%

Shareholder Report, Holdings (D

Shareholder Report, Holdings (Details)	Jul. 31, 2024
Fidelity SAI U.S. Quality Index Fund \| TH0Member
Holdings [Line Items]
Percent of Net Asset Value	9.70%
Fidelity SAI U.S. Quality Index Fund \| TH1Member
Holdings [Line Items]
Percent of Net Asset Value	8.60%
Fidelity SAI U.S. Quality Index Fund \| TH2Member
Holdings [Line Items]
Percent of Net Asset Value	6.50%
Fidelity SAI U.S. Quality Index Fund \| TH3Member
Holdings [Line Items]
Percent of Net Asset Value	4.90%
Fidelity SAI U.S. Quality Index Fund \| TH4Member
Holdings [Line Items]
Percent of Net Asset Value	4.10%
Fidelity SAI U.S. Quality Index Fund \| TH5Member
Holdings [Line Items]
Percent of Net Asset Value	4%
Fidelity SAI U.S. Quality Index Fund \| TH6Member
Holdings [Line Items]
Percent of Net Asset Value	3.80%
Fidelity SAI U.S. Quality Index Fund \| TH7Member
Holdings [Line Items]
Percent of Net Asset Value	3.70%
Fidelity SAI U.S. Quality Index Fund \| TH8Member
Holdings [Line Items]
Percent of Net Asset Value	3.60%
Fidelity SAI U.S. Quality Index Fund \| TH9Member
Holdings [Line Items]
Percent of Net Asset Value	3.40%
Fidelity SAI U.S. Quality Index Fund \| MSFinancialsSectorMember
Holdings [Line Items]
Percent of Net Asset Value	10.80%
Fidelity SAI U.S. Quality Index Fund \| Information Technology Member
Holdings [Line Items]
Percent of Net Asset Value	41%
Fidelity SAI U.S. Quality Index Fund \| Healthcare Sector
Holdings [Line Items]
Percent of Net Asset Value	15.10%
Fidelity SAI U.S. Quality Index Fund \| Real Estate Sector
Holdings [Line Items]
Percent of Net Asset Value	1.10%
Fidelity SAI U.S. Quality Index Fund \| Industrial Sector Member
Holdings [Line Items]
Percent of Net Asset Value	7%
Fidelity SAI U.S. Quality Index Fund \| Materials Sector Member
Holdings [Line Items]
Percent of Net Asset Value	0.10%
Fidelity SAI U.S. Quality Index Fund \| Consumer Discretionary Sector Member
Holdings [Line Items]
Percent of Net Asset Value	5.80%
Fidelity SAI U.S. Quality Index Fund \| Consumer Staples Sector Member
Holdings [Line Items]
Percent of Net Asset Value	6.80%
Fidelity SAI U.S. Quality Index Fund \| Communications Sector Member
Holdings [Line Items]
Percent of Net Asset Value	11.90%
Fidelity SAI U.S. Quality Index Fund \| Energy Sector
Holdings [Line Items]
Percent of Net Asset Value	0.20%
Fidelity SAI U.S. Quality Index Fund \| United States
Holdings [Line Items]
Percent of Net Asset Value	99.80%
Fidelity SAI U.S. Quality Index Fund \| Israel
Holdings [Line Items]
Percent of Net Asset Value	0.20%
Fidelity SAI U.S. Quality Index Fund \| AACommonStocksMember
Holdings [Line Items]
Percent of Net Asset Value	99.80%
Fidelity SAI U.S. Quality Index Fund \| AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember
Holdings [Line Items]
Percent of Net Asset Value	0.20%
Fidelity SAI Small-Mid Cap 500 Index Fund \| TH0Member
Holdings [Line Items]
Percent of Net Asset Value	0.70%
Fidelity SAI Small-Mid Cap 500 Index Fund \| TH1Member
Holdings [Line Items]
Percent of Net Asset Value	0.60%
Fidelity SAI Small-Mid Cap 500 Index Fund \| TH2Member
Holdings [Line Items]
Percent of Net Asset Value	0.50%
Fidelity SAI Small-Mid Cap 500 Index Fund \| TH3Member
Holdings [Line Items]
Percent of Net Asset Value	0.50%
Fidelity SAI Small-Mid Cap 500 Index Fund \| TH4Member
Holdings [Line Items]
Percent of Net Asset Value	0.50%
Fidelity SAI Small-Mid Cap 500 Index Fund \| TH5Member
Holdings [Line Items]
Percent of Net Asset Value	0.50%
Fidelity SAI Small-Mid Cap 500 Index Fund \| TH6Member
Holdings [Line Items]
Percent of Net Asset Value	0.50%
Fidelity SAI Small-Mid Cap 500 Index Fund \| TH7Member
Holdings [Line Items]
Percent of Net Asset Value	0.50%
Fidelity SAI Small-Mid Cap 500 Index Fund \| TH8Member
Holdings [Line Items]
Percent of Net Asset Value	0.50%
Fidelity SAI Small-Mid Cap 500 Index Fund \| TH9Member
Holdings [Line Items]
Percent of Net Asset Value	0.40%
Fidelity SAI Small-Mid Cap 500 Index Fund \| MSFinancialsSectorMember
Holdings [Line Items]
Percent of Net Asset Value	15.90%
Fidelity SAI Small-Mid Cap 500 Index Fund \| Information Technology Member
Holdings [Line Items]
Percent of Net Asset Value	11%
Fidelity SAI Small-Mid Cap 500 Index Fund \| Healthcare Sector
Holdings [Line Items]
Percent of Net Asset Value	9.50%
Fidelity SAI Small-Mid Cap 500 Index Fund \| Real Estate Sector
Holdings [Line Items]
Percent of Net Asset Value	7.50%
Fidelity SAI Small-Mid Cap 500 Index Fund \| Industrial Sector Member
Holdings [Line Items]
Percent of Net Asset Value	20.40%
Fidelity SAI Small-Mid Cap 500 Index Fund \| Materials Sector Member
Holdings [Line Items]
Percent of Net Asset Value	6.90%
Fidelity SAI Small-Mid Cap 500 Index Fund \| Consumer Discretionary Sector Member
Holdings [Line Items]
Percent of Net Asset Value	14.30%
Fidelity SAI Small-Mid Cap 500 Index Fund \| Consumer Staples Sector Member
Holdings [Line Items]
Percent of Net Asset Value	3.90%
Fidelity SAI Small-Mid Cap 500 Index Fund \| Communications Sector Member
Holdings [Line Items]
Percent of Net Asset Value	3.40%
Fidelity SAI Small-Mid Cap 500 Index Fund \| Energy Sector
Holdings [Line Items]
Percent of Net Asset Value	5.10%
Fidelity SAI Small-Mid Cap 500 Index Fund \| Utilities Sector Member
Holdings [Line Items]
Percent of Net Asset Value	2.10%
Fidelity SAI Small-Mid Cap 500 Index Fund \| United States
Holdings [Line Items]
Percent of Net Asset Value	98.50%
Fidelity SAI Small-Mid Cap 500 Index Fund \| United Kingdom
Holdings [Line Items]
Percent of Net Asset Value	0.40%
Fidelity SAI Small-Mid Cap 500 Index Fund \| Bermuda
Holdings [Line Items]
Percent of Net Asset Value	0.30%
Fidelity SAI Small-Mid Cap 500 Index Fund \| Puerto Rico
Holdings [Line Items]
Percent of Net Asset Value	0.20%
Fidelity SAI Small-Mid Cap 500 Index Fund \| Brazil
Holdings [Line Items]
Percent of Net Asset Value	0.20%
Fidelity SAI Small-Mid Cap 500 Index Fund \| Belgium
Holdings [Line Items]
Percent of Net Asset Value	0.20%
Fidelity SAI Small-Mid Cap 500 Index Fund \| Luxembourg
Holdings [Line Items]
Percent of Net Asset Value	0.10%
Fidelity SAI Small-Mid Cap 500 Index Fund \| Japan
Holdings [Line Items]
Percent of Net Asset Value	0.10%
Fidelity SAI Small-Mid Cap 500 Index Fund \| Finland
Holdings [Line Items]
Percent of Net Asset Value	0%
Fidelity SAI Small-Mid Cap 500 Index Fund \| AACommonStocksMember
Holdings [Line Items]
Percent of Net Asset Value	100%
Fidelity SAI Small-Mid Cap 500 Index Fund \| AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember
Holdings [Line Items]
Percent of Net Asset Value	0%
Fidelity SAI U.S. Momentum Index Fund \| TH0Member
Holdings [Line Items]
Percent of Net Asset Value	5.20%
Fidelity SAI U.S. Momentum Index Fund \| TH1Member
Holdings [Line Items]
Percent of Net Asset Value	5.20%
Fidelity SAI U.S. Momentum Index Fund \| TH2Member
Holdings [Line Items]
Percent of Net Asset Value	5.10%
Fidelity SAI U.S. Momentum Index Fund \| TH3Member
Holdings [Line Items]
Percent of Net Asset Value	4.90%
Fidelity SAI U.S. Momentum Index Fund \| TH4Member
Holdings [Line Items]
Percent of Net Asset Value	4.70%
Fidelity SAI U.S. Momentum Index Fund \| TH5Member
Holdings [Line Items]
Percent of Net Asset Value	3.80%
Fidelity SAI U.S. Momentum Index Fund \| TH6Member
Holdings [Line Items]
Percent of Net Asset Value	3.20%
Fidelity SAI U.S. Momentum Index Fund \| TH7Member
Holdings [Line Items]
Percent of Net Asset Value	3.20%
Fidelity SAI U.S. Momentum Index Fund \| TH8Member
Holdings [Line Items]
Percent of Net Asset Value	2.30%
Fidelity SAI U.S. Momentum Index Fund \| TH9Member
Holdings [Line Items]
Percent of Net Asset Value	1.90%
Fidelity SAI U.S. Momentum Index Fund \| MSFinancialsSectorMember
Holdings [Line Items]
Percent of Net Asset Value	15.40%
Fidelity SAI U.S. Momentum Index Fund \| Information Technology Member
Holdings [Line Items]
Percent of Net Asset Value	30.90%
Fidelity SAI U.S. Momentum Index Fund \| Healthcare Sector
Holdings [Line Items]
Percent of Net Asset Value	9.80%
Fidelity SAI U.S. Momentum Index Fund \| Real Estate Sector
Holdings [Line Items]
Percent of Net Asset Value	0.30%
Fidelity SAI U.S. Momentum Index Fund \| Industrial Sector Member
Holdings [Line Items]
Percent of Net Asset Value	15.20%
Fidelity SAI U.S. Momentum Index Fund \| Materials Sector Member
Holdings [Line Items]
Percent of Net Asset Value	1.40%
Fidelity SAI U.S. Momentum Index Fund \| Consumer Discretionary Sector Member
Holdings [Line Items]
Percent of Net Asset Value	10%
Fidelity SAI U.S. Momentum Index Fund \| Consumer Staples Sector Member
Holdings [Line Items]
Percent of Net Asset Value	4.10%
Fidelity SAI U.S. Momentum Index Fund \| Communications Sector Member
Holdings [Line Items]
Percent of Net Asset Value	10.40%
Fidelity SAI U.S. Momentum Index Fund \| Energy Sector
Holdings [Line Items]
Percent of Net Asset Value	0.90%
Fidelity SAI U.S. Momentum Index Fund \| Utilities Sector Member
Holdings [Line Items]
Percent of Net Asset Value	1.50%
Fidelity SAI U.S. Momentum Index Fund \| United States
Holdings [Line Items]
Percent of Net Asset Value	99.70%
Fidelity SAI U.S. Momentum Index Fund \| Brazil
Holdings [Line Items]
Percent of Net Asset Value	0.10%
Fidelity SAI U.S. Momentum Index Fund \| China
Holdings [Line Items]
Percent of Net Asset Value	0.20%
Fidelity SAI U.S. Momentum Index Fund \| AACommonStocksMember
Holdings [Line Items]
Percent of Net Asset Value	99.90%
Fidelity SAI U.S. Momentum Index Fund \| AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember
Holdings [Line Items]
Percent of Net Asset Value	0.10%
Fidelity Real Estate Index Fund \| TH0Member
Holdings [Line Items]
Percent of Net Asset Value	8.10%
Fidelity Real Estate Index Fund \| TH1Member
Holdings [Line Items]
Percent of Net Asset Value	7.20%
Fidelity Real Estate Index Fund \| TH2Member
Holdings [Line Items]
Percent of Net Asset Value	5.30%
Fidelity Real Estate Index Fund \| TH3Member
Holdings [Line Items]
Percent of Net Asset Value	4.50%
Fidelity Real Estate Index Fund \| TH4Member
Holdings [Line Items]
Percent of Net Asset Value	3.60%
Fidelity Real Estate Index Fund \| TH5Member
Holdings [Line Items]
Percent of Net Asset Value	3.40%
Fidelity Real Estate Index Fund \| TH6Member
Holdings [Line Items]
Percent of Net Asset Value	3.40%
Fidelity Real Estate Index Fund \| TH7Member
Holdings [Line Items]
Percent of Net Asset Value	3.20%
Fidelity Real Estate Index Fund \| TH8Member
Holdings [Line Items]
Percent of Net Asset Value	3.20%
Fidelity Real Estate Index Fund \| TH9Member
Holdings [Line Items]
Percent of Net Asset Value	2.40%
Fidelity Real Estate Index Fund \| TI0Member
Holdings [Line Items]
Percent of Net Asset Value	36%
Fidelity Real Estate Index Fund \| TI1Member
Holdings [Line Items]
Percent of Net Asset Value	13.10%
Fidelity Real Estate Index Fund \| TI2Member
Holdings [Line Items]
Percent of Net Asset Value	12.80%
Fidelity Real Estate Index Fund \| TI3Member
Holdings [Line Items]
Percent of Net Asset Value	11.80%
Fidelity Real Estate Index Fund \| TI4Member
Holdings [Line Items]
Percent of Net Asset Value	10.60%
Fidelity Real Estate Index Fund \| TI5Member
Holdings [Line Items]
Percent of Net Asset Value	7.60%
Fidelity Real Estate Index Fund \| TI6Member
Holdings [Line Items]
Percent of Net Asset Value	3.30%
Fidelity Real Estate Index Fund \| TI7Member
Holdings [Line Items]
Percent of Net Asset Value	2.50%
Fidelity Real Estate Index Fund \| TI8Member
Holdings [Line Items]
Percent of Net Asset Value	1.90%
Fidelity Real Estate Index Fund \| United States
Holdings [Line Items]
Percent of Net Asset Value	100%
Fidelity Real Estate Index Fund \| AACommonStocksMember
Holdings [Line Items]
Percent of Net Asset Value	99.60%
Fidelity Real Estate Index Fund \| AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember
Holdings [Line Items]
Percent of Net Asset Value	0.40%
Fidelity SAI U.S. Value Index Fund \| TH0Member
Holdings [Line Items]
Percent of Net Asset Value	3.80%
Fidelity SAI U.S. Value Index Fund \| TH1Member
Holdings [Line Items]
Percent of Net Asset Value	3.80%
Fidelity SAI U.S. Value Index Fund \| TH2Member
Holdings [Line Items]
Percent of Net Asset Value	3.50%
Fidelity SAI U.S. Value Index Fund \| TH3Member
Holdings [Line Items]
Percent of Net Asset Value	3.30%
Fidelity SAI U.S. Value Index Fund \| TH4Member
Holdings [Line Items]
Percent of Net Asset Value	3.20%
Fidelity SAI U.S. Value Index Fund \| TH5Member
Holdings [Line Items]
Percent of Net Asset Value	3.20%
Fidelity SAI U.S. Value Index Fund \| TH6Member
Holdings [Line Items]
Percent of Net Asset Value	2.80%
Fidelity SAI U.S. Value Index Fund \| TH7Member
Holdings [Line Items]
Percent of Net Asset Value	2.70%
Fidelity SAI U.S. Value Index Fund \| TH8Member
Holdings [Line Items]
Percent of Net Asset Value	2.60%
Fidelity SAI U.S. Value Index Fund \| TH9Member
Holdings [Line Items]
Percent of Net Asset Value	2.40%
Fidelity SAI U.S. Value Index Fund \| MSFinancialsSectorMember
Holdings [Line Items]
Percent of Net Asset Value	23.10%
Fidelity SAI U.S. Value Index Fund \| Information Technology Member
Holdings [Line Items]
Percent of Net Asset Value	20.70%
Fidelity SAI U.S. Value Index Fund \| Healthcare Sector
Holdings [Line Items]
Percent of Net Asset Value	12.90%
Fidelity SAI U.S. Value Index Fund \| Real Estate Sector
Holdings [Line Items]
Percent of Net Asset Value	0.40%
Fidelity SAI U.S. Value Index Fund \| Industrial Sector Member
Holdings [Line Items]
Percent of Net Asset Value	5.40%
Fidelity SAI U.S. Value Index Fund \| Materials Sector Member
Holdings [Line Items]
Percent of Net Asset Value	5.30%
Fidelity SAI U.S. Value Index Fund \| Consumer Discretionary Sector Member
Holdings [Line Items]
Percent of Net Asset Value	5.90%
Fidelity SAI U.S. Value Index Fund \| Consumer Staples Sector Member
Holdings [Line Items]
Percent of Net Asset Value	3.70%
Fidelity SAI U.S. Value Index Fund \| Communications Sector Member
Holdings [Line Items]
Percent of Net Asset Value	8.60%
Fidelity SAI U.S. Value Index Fund \| Energy Sector
Holdings [Line Items]
Percent of Net Asset Value	13.30%
Fidelity SAI U.S. Value Index Fund \| Utilities Sector Member
Holdings [Line Items]
Percent of Net Asset Value	0.20%
Fidelity SAI U.S. Value Index Fund \| United States
Holdings [Line Items]
Percent of Net Asset Value	99.20%
Fidelity SAI U.S. Value Index Fund \| Bermuda
Holdings [Line Items]
Percent of Net Asset Value	0.20%
Fidelity SAI U.S. Value Index Fund \| China
Holdings [Line Items]
Percent of Net Asset Value	0.20%
Fidelity SAI U.S. Value Index Fund \| Ireland
Holdings [Line Items]
Percent of Net Asset Value	0.20%
Fidelity SAI U.S. Value Index Fund \| Peru
Holdings [Line Items]
Percent of Net Asset Value	0.20%
Fidelity SAI U.S. Value Index Fund \| AACommonStocksMember
Holdings [Line Items]
Percent of Net Asset Value	99.50%
Fidelity SAI U.S. Value Index Fund \| AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember
Holdings [Line Items]
Percent of Net Asset Value	0.50%
Fidelity SAI Real Estate Index Fund \| TH0Member
Holdings [Line Items]
Percent of Net Asset Value	8%
Fidelity SAI Real Estate Index Fund \| TH1Member
Holdings [Line Items]
Percent of Net Asset Value	7.10%
Fidelity SAI Real Estate Index Fund \| TH2Member
Holdings [Line Items]
Percent of Net Asset Value	5.20%
Fidelity SAI Real Estate Index Fund \| TH3Member
Holdings [Line Items]
Percent of Net Asset Value	4.30%
Fidelity SAI Real Estate Index Fund \| TH4Member
Holdings [Line Items]
Percent of Net Asset Value	3.50%
Fidelity SAI Real Estate Index Fund \| TH5Member
Holdings [Line Items]
Percent of Net Asset Value	3.40%
Fidelity SAI Real Estate Index Fund \| TH6Member
Holdings [Line Items]
Percent of Net Asset Value	3.30%
Fidelity SAI Real Estate Index Fund \| TH7Member
Holdings [Line Items]
Percent of Net Asset Value	3.20%
Fidelity SAI Real Estate Index Fund \| TH8Member
Holdings [Line Items]
Percent of Net Asset Value	3.20%
Fidelity SAI Real Estate Index Fund \| TH9Member
Holdings [Line Items]
Percent of Net Asset Value	2.40%
Fidelity SAI Real Estate Index Fund \| TI0Member
Holdings [Line Items]
Percent of Net Asset Value	35.60%
Fidelity SAI Real Estate Index Fund \| TI1Member
Holdings [Line Items]
Percent of Net Asset Value	13%
Fidelity SAI Real Estate Index Fund \| TI2Member
Holdings [Line Items]
Percent of Net Asset Value	12.60%
Fidelity SAI Real Estate Index Fund \| TI3Member
Holdings [Line Items]
Percent of Net Asset Value	11.70%
Fidelity SAI Real Estate Index Fund \| TI4Member
Holdings [Line Items]
Percent of Net Asset Value	10.40%
Fidelity SAI Real Estate Index Fund \| TI5Member
Holdings [Line Items]
Percent of Net Asset Value	7.50%
Fidelity SAI Real Estate Index Fund \| TI6Member
Holdings [Line Items]
Percent of Net Asset Value	3.30%
Fidelity SAI Real Estate Index Fund \| TI7Member
Holdings [Line Items]
Percent of Net Asset Value	2.40%
Fidelity SAI Real Estate Index Fund \| TI8Member
Holdings [Line Items]
Percent of Net Asset Value	2%
Fidelity SAI Real Estate Index Fund \| United States
Holdings [Line Items]
Percent of Net Asset Value	100%
Fidelity SAI Real Estate Index Fund \| AACommonStocksMember
Holdings [Line Items]
Percent of Net Asset Value	98.50%
Fidelity SAI Real Estate Index Fund \| AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember
Holdings [Line Items]
Percent of Net Asset Value	1.50%
Fidelity SAI U.S. Large Cap Index Fund \| TH0Member
Holdings [Line Items]
Percent of Net Asset Value	6.90%
Fidelity SAI U.S. Large Cap Index Fund \| TH1Member
Holdings [Line Items]
Percent of Net Asset Value	6.70%
Fidelity SAI U.S. Large Cap Index Fund \| TH2Member
Holdings [Line Items]
Percent of Net Asset Value	6.30%
Fidelity SAI U.S. Large Cap Index Fund \| TH3Member
Holdings [Line Items]
Percent of Net Asset Value	3.70%
Fidelity SAI U.S. Large Cap Index Fund \| TH4Member
Holdings [Line Items]
Percent of Net Asset Value	2.20%
Fidelity SAI U.S. Large Cap Index Fund \| TH5Member
Holdings [Line Items]
Percent of Net Asset Value	2.20%
Fidelity SAI U.S. Large Cap Index Fund \| TH6Member
Holdings [Line Items]
Percent of Net Asset Value	1.80%
Fidelity SAI U.S. Large Cap Index Fund \| TH7Member
Holdings [Line Items]
Percent of Net Asset Value	1.80%
Fidelity SAI U.S. Large Cap Index Fund \| TH8Member
Holdings [Line Items]
Percent of Net Asset Value	1.60%
Fidelity SAI U.S. Large Cap Index Fund \| TH9Member
Holdings [Line Items]
Percent of Net Asset Value	1.40%
Fidelity SAI U.S. Large Cap Index Fund \| MSFinancialsSectorMember
Holdings [Line Items]
Percent of Net Asset Value	13%
Fidelity SAI U.S. Large Cap Index Fund \| Information Technology Member
Holdings [Line Items]
Percent of Net Asset Value	31.30%
Fidelity SAI U.S. Large Cap Index Fund \| Healthcare Sector
Holdings [Line Items]
Percent of Net Asset Value	11.80%
Fidelity SAI U.S. Large Cap Index Fund \| Real Estate Sector
Holdings [Line Items]
Percent of Net Asset Value	2.30%
Fidelity SAI U.S. Large Cap Index Fund \| Industrial Sector Member
Holdings [Line Items]
Percent of Net Asset Value	8.40%
Fidelity SAI U.S. Large Cap Index Fund \| Materials Sector Member
Holdings [Line Items]
Percent of Net Asset Value	2.20%
Fidelity SAI U.S. Large Cap Index Fund \| Consumer Discretionary Sector Member
Holdings [Line Items]
Percent of Net Asset Value	10%
Fidelity SAI U.S. Large Cap Index Fund \| Consumer Staples Sector Member
Holdings [Line Items]
Percent of Net Asset Value	5.80%
Fidelity SAI U.S. Large Cap Index Fund \| Communications Sector Member
Holdings [Line Items]
Percent of Net Asset Value	8.80%
Fidelity SAI U.S. Large Cap Index Fund \| Energy Sector
Holdings [Line Items]
Percent of Net Asset Value	3.70%
Fidelity SAI U.S. Large Cap Index Fund \| Utilities Sector Member
Holdings [Line Items]
Percent of Net Asset Value	2.40%
Fidelity SAI U.S. Large Cap Index Fund \| United States
Holdings [Line Items]
Percent of Net Asset Value	99.50%
Fidelity SAI U.S. Large Cap Index Fund \| China
Holdings [Line Items]
Percent of Net Asset Value	0.10%
Fidelity SAI U.S. Large Cap Index Fund \| Ireland
Holdings [Line Items]
Percent of Net Asset Value	0.40%
Fidelity SAI U.S. Large Cap Index Fund \| AACommonStocksMember
Holdings [Line Items]
Percent of Net Asset Value	99.70%
Fidelity SAI U.S. Large Cap Index Fund \| AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember
Holdings [Line Items]
Percent of Net Asset Value	0.30%