v3.25.2
Shareholder Report
 6 Months Ended
May 31, 2025
USD ($)
shares
Shareholder Report [Line Items]  
Document Type N-CSRS
Amendment Flag false
Registrant Name Fidelity Salem Street Trust
Entity Central Index Key 0000035315
Entity Investment Company Type N-1A
Document Period End Date May 31, 2025
Fidelity Advisor Strategic Dividend & Income Fund - Class M  
Shareholder Report [Line Items]  
Fund Name Fidelity® Strategic Dividend & Income® Fund
Class Name Fidelity Advisor® Strategic Dividend & Income® Fund Class M
Trading Symbol FTSDX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains information about Fidelity® Strategic Dividend & Income® Fund for the period December 1, 2024 to May 31, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at fundresearch.fidelity.com/prospectus/sec. You can also request this information by contacting us at 1-877-208-0098 or by sending an e-mail to fidfunddocuments@fidelity.com.
Additional Information Phone Number 1-877-208-0098
Additional Information Email fidfunddocuments@fidelity.com
Additional Information Website fundresearch.fidelity.com/prospectus/sec
Expenses [Text Block] What were your Fund costs for the last six months?
(based on hypothetical $10,000 investment)
 
 
 
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
 
Class M 
$ 58 
1.17%
  
Expenses Paid, Amount $ 58
Expense Ratio, Percent 1.17%
Net Assets $ 5,130,265,466
Holdings Count | shares 664
Investment Company Portfolio Turnover 38.00%
Additional Fund Statistics [Text Block] Key Fund Statistics
(as of May 31, 2025)
 
KEY FACTS 
  
  
Fund Size
$5,130,265,466
  
Number of Holdings
664
  
Portfolio Turnover
38%
  
Holdings [Text Block]       MARKET SECTORS (% of Fund's net assets)     Financials 18.0   Real Estate 15.8   Information Technology 12.3   Industrials 9.5   Consumer Staples 8.6   Utilities 8.1   Health Care 8.1   Consumer Discretionary 6.6   Energy 6.6   Communication Services 3.9   Materials 1.7     Dividend-Paying Equities 50.5 Convertibles 18.1 REITs 14.4 Preferred Stock 13.5 Global Infrastructure Equities 3.1 MLPs 0.5 Commodity Equities 0.0 ASSET ALLOCATION (% of Fund's net assets)     Dividend-Paying Equities - 50.5            Convertibles - 18.1                        REITs - 14.4                               Preferred Stock - 13.5                     Global Infrastructure Equities - 3.1       MLPs - 0.5                                 Commodity Equities - 0.0                 Short-Term Investments and Net Other Assets (Liabilities) - (0.1)%   United States 91.9 Canada 2.4 United Kingdom 1.3 Taiwan 1.0 France 0.7 Ireland 0.6 Netherlands 0.5 Korea (South) 0.4 Japan 0.3 Others 0.9 GEOGRAPHIC DIVERSIFICATION (% of Fund's net assets)     United States - 91.9                       Canada - 2.4                               United Kingdom - 1.3                       Taiwan - 1.0                               France - 0.7                               Ireland - 0.6                              Netherlands - 0.5                          Korea (South) - 0.4                        Japan - 0.3                                Others - 0.9                                  
Largest Holdings [Text Block] TOP HOLDINGS (% of Fund's net assets)     Procter & Gamble Co/The 2.6   Exxon Mobil Corp 2.6   Coca-Cola Co/The 2.2   JPMorgan Chase & Co 1.7   Cisco Systems Inc 1.6   Equinix Inc 1.5   AbbVie Inc 1.5   McDonald's Corp 1.5   Prologis Inc 1.5   Johnson & Johnson 1.2     17.9  
Fidelity Advisor Strategic Dividend & Income Fund - Class I  
Shareholder Report [Line Items]  
Fund Name Fidelity® Strategic Dividend & Income® Fund
Class Name Fidelity Advisor® Strategic Dividend & Income® Fund Class I
Trading Symbol FSIDX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains information about Fidelity® Strategic Dividend & Income® Fund for the period December 1, 2024 to May 31, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at fundresearch.fidelity.com/prospectus/sec. You can also request this information by contacting us at 1-877-208-0098 or by sending an e-mail to fidfunddocuments@fidelity.com.
Additional Information Phone Number 1-877-208-0098
Additional Information Email fidfunddocuments@fidelity.com
Additional Information Website fundresearch.fidelity.com/prospectus/sec
Expenses [Text Block] What were your Fund costs for the last six months?
(based on hypothetical $10,000 investment)
 
 
 
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
 
Class I 
$ 33 
0.67%
  
Expenses Paid, Amount $ 33
Expense Ratio, Percent 0.67%
Net Assets $ 5,130,265,466
Holdings Count | shares 664
Investment Company Portfolio Turnover 38.00%
Additional Fund Statistics [Text Block] Key Fund Statistics
(as of May 31, 2025)
 
KEY FACTS 
  
  
Fund Size
$5,130,265,466
  
Number of Holdings
664
  
Portfolio Turnover
38%
  
Holdings [Text Block]       MARKET SECTORS (% of Fund's net assets)     Financials 18.0   Real Estate 15.8   Information Technology 12.3   Industrials 9.5   Consumer Staples 8.6   Utilities 8.1   Health Care 8.1   Consumer Discretionary 6.6   Energy 6.6   Communication Services 3.9   Materials 1.7     Dividend-Paying Equities 50.5 Convertibles 18.1 REITs 14.4 Preferred Stock 13.5 Global Infrastructure Equities 3.1 MLPs 0.5 Commodity Equities 0.0 ASSET ALLOCATION (% of Fund's net assets)     Dividend-Paying Equities - 50.5            Convertibles - 18.1                        REITs - 14.4                               Preferred Stock - 13.5                     Global Infrastructure Equities - 3.1       MLPs - 0.5                                 Commodity Equities - 0.0                 Short-Term Investments and Net Other Assets (Liabilities) - (0.1)%   United States 91.9 Canada 2.4 United Kingdom 1.3 Taiwan 1.0 France 0.7 Ireland 0.6 Netherlands 0.5 Korea (South) 0.4 Japan 0.3 Others 0.9 GEOGRAPHIC DIVERSIFICATION (% of Fund's net assets)     United States - 91.9                       Canada - 2.4                               United Kingdom - 1.3                       Taiwan - 1.0                               France - 0.7                               Ireland - 0.6                              Netherlands - 0.5                          Korea (South) - 0.4                        Japan - 0.3                                Others - 0.9                                  
Largest Holdings [Text Block] TOP HOLDINGS (% of Fund's net assets)     Procter & Gamble Co/The 2.6   Exxon Mobil Corp 2.6   Coca-Cola Co/The 2.2   JPMorgan Chase & Co 1.7   Cisco Systems Inc 1.6   Equinix Inc 1.5   AbbVie Inc 1.5   McDonald's Corp 1.5   Prologis Inc 1.5   Johnson & Johnson 1.2     17.9  
Fidelity Advisor Strategic Dividend & Income Fund - Class C  
Shareholder Report [Line Items]  
Fund Name Fidelity® Strategic Dividend & Income® Fund
Class Name Fidelity Advisor® Strategic Dividend & Income® Fund Class C
Trading Symbol FCSDX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains information about Fidelity® Strategic Dividend & Income® Fund for the period December 1, 2024 to May 31, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at fundresearch.fidelity.com/prospectus/sec. You can also request this information by contacting us at 1-877-208-0098 or by sending an e-mail to fidfunddocuments@fidelity.com.
Additional Information Phone Number 1-877-208-0098
Additional Information Email fidfunddocuments@fidelity.com
Additional Information Website fundresearch.fidelity.com/prospectus/sec
Expenses [Text Block] What were your Fund costs for the last six months?
(based on hypothetical $10,000 investment)
 
 
 
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
 
Class C 
$ 82 
1.67%
  
Expenses Paid, Amount $ 82
Expense Ratio, Percent 1.67%
Net Assets $ 5,130,265,466
Holdings Count | shares 664
Investment Company Portfolio Turnover 38.00%
Additional Fund Statistics [Text Block] Key Fund Statistics
(as of May 31, 2025)
 
KEY FACTS 
  
  
Fund Size
$5,130,265,466
  
Number of Holdings
664
  
Portfolio Turnover
38%
  
Holdings [Text Block]       MARKET SECTORS (% of Fund's net assets)     Financials 18.0   Real Estate 15.8   Information Technology 12.3   Industrials 9.5   Consumer Staples 8.6   Utilities 8.1   Health Care 8.1   Consumer Discretionary 6.6   Energy 6.6   Communication Services 3.9   Materials 1.7     Dividend-Paying Equities 50.5 Convertibles 18.1 REITs 14.4 Preferred Stock 13.5 Global Infrastructure Equities 3.1 MLPs 0.5 Commodity Equities 0.0 ASSET ALLOCATION (% of Fund's net assets)     Dividend-Paying Equities - 50.5            Convertibles - 18.1                        REITs - 14.4                               Preferred Stock - 13.5                     Global Infrastructure Equities - 3.1       MLPs - 0.5                                 Commodity Equities - 0.0                 Short-Term Investments and Net Other Assets (Liabilities) - (0.1)%   United States 91.9 Canada 2.4 United Kingdom 1.3 Taiwan 1.0 France 0.7 Ireland 0.6 Netherlands 0.5 Korea (South) 0.4 Japan 0.3 Others 0.9 GEOGRAPHIC DIVERSIFICATION (% of Fund's net assets)     United States - 91.9                       Canada - 2.4                               United Kingdom - 1.3                       Taiwan - 1.0                               France - 0.7                               Ireland - 0.6                              Netherlands - 0.5                          Korea (South) - 0.4                        Japan - 0.3                                Others - 0.9                                  
Largest Holdings [Text Block] TOP HOLDINGS (% of Fund's net assets)     Procter & Gamble Co/The 2.6   Exxon Mobil Corp 2.6   Coca-Cola Co/The 2.2   JPMorgan Chase & Co 1.7   Cisco Systems Inc 1.6   Equinix Inc 1.5   AbbVie Inc 1.5   McDonald's Corp 1.5   Prologis Inc 1.5   Johnson & Johnson 1.2     17.9  
Fidelity Advisor Strategic Dividend & Income Fund - Class A  
Shareholder Report [Line Items]  
Fund Name Fidelity® Strategic Dividend & Income® Fund
Class Name Fidelity Advisor® Strategic Dividend & Income® Fund Class A
Trading Symbol FASDX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains information about Fidelity® Strategic Dividend & Income® Fund for the period December 1, 2024 to May 31, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at fundresearch.fidelity.com/prospectus/sec. You can also request this information by contacting us at 1-877-208-0098 or by sending an e-mail to fidfunddocuments@fidelity.com.
Additional Information Phone Number 1-877-208-0098
Additional Information Email fidfunddocuments@fidelity.com
Additional Information Website fundresearch.fidelity.com/prospectus/sec
Expenses [Text Block] What were your Fund costs for the last six months?
(based on hypothetical $10,000 investment)
 
 
 
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
 
Class A 
$ 45 
0.92%
  
Expenses Paid, Amount $ 45
Expense Ratio, Percent 0.92%
Net Assets $ 5,130,265,466
Holdings Count | shares 664
Investment Company Portfolio Turnover 38.00%
Additional Fund Statistics [Text Block] Key Fund Statistics
(as of May 31, 2025)
 
KEY FACTS 
  
  
Fund Size
$5,130,265,466
  
Number of Holdings
664
  
Portfolio Turnover
38%
  
Holdings [Text Block]       MARKET SECTORS (% of Fund's net assets)     Financials 18.0   Real Estate 15.8   Information Technology 12.3   Industrials 9.5   Consumer Staples 8.6   Utilities 8.1   Health Care 8.1   Consumer Discretionary 6.6   Energy 6.6   Communication Services 3.9   Materials 1.7     Dividend-Paying Equities 50.5 Convertibles 18.1 REITs 14.4 Preferred Stock 13.5 Global Infrastructure Equities 3.1 MLPs 0.5 Commodity Equities 0.0 ASSET ALLOCATION (% of Fund's net assets)     Dividend-Paying Equities - 50.5            Convertibles - 18.1                        REITs - 14.4                               Preferred Stock - 13.5                     Global Infrastructure Equities - 3.1       MLPs - 0.5                                 Commodity Equities - 0.0                 Short-Term Investments and Net Other Assets (Liabilities) - (0.1)%   United States 91.9 Canada 2.4 United Kingdom 1.3 Taiwan 1.0 France 0.7 Ireland 0.6 Netherlands 0.5 Korea (South) 0.4 Japan 0.3 Others 0.9 GEOGRAPHIC DIVERSIFICATION (% of Fund's net assets)     United States - 91.9                       Canada - 2.4                               United Kingdom - 1.3                       Taiwan - 1.0                               France - 0.7                               Ireland - 0.6                              Netherlands - 0.5                          Korea (South) - 0.4                        Japan - 0.3                                Others - 0.9                                  
Largest Holdings [Text Block] TOP HOLDINGS (% of Fund's net assets)     Procter & Gamble Co/The 2.6   Exxon Mobil Corp 2.6   Coca-Cola Co/The 2.2   JPMorgan Chase & Co 1.7   Cisco Systems Inc 1.6   Equinix Inc 1.5   AbbVie Inc 1.5   McDonald's Corp 1.5   Prologis Inc 1.5   Johnson & Johnson 1.2     17.9  
Fidelity Advisor Strategic Dividend & Income Fund - Class Z  
Shareholder Report [Line Items]  
Fund Name Fidelity® Strategic Dividend & Income® Fund
Class Name Fidelity Advisor® Strategic Dividend & Income® Fund Class Z
Trading Symbol FIQWX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains information about Fidelity® Strategic Dividend & Income® Fund for the period December 1, 2024 to May 31, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at fundresearch.fidelity.com/prospectus/sec. You can also request this information by contacting us at 1-877-208-0098 or by sending an e-mail to fidfunddocuments@fidelity.com.
Additional Information Phone Number 1-877-208-0098
Additional Information Email fidfunddocuments@fidelity.com
Additional Information Website fundresearch.fidelity.com/prospectus/sec
Expenses [Text Block] What were your Fund costs for the last six months?
(based on hypothetical $10,000 investment)
 
 
 
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
 
Class Z 
$ 27 
0.55%
  
Expenses Paid, Amount $ 27
Expense Ratio, Percent 0.55%
Net Assets $ 5,130,265,466
Holdings Count | shares 664
Investment Company Portfolio Turnover 38.00%
Additional Fund Statistics [Text Block] Key Fund Statistics
(as of May 31, 2025)
 
KEY FACTS 
  
  
Fund Size
$5,130,265,466
  
Number of Holdings
664
  
Portfolio Turnover
38%
  
Holdings [Text Block]       MARKET SECTORS (% of Fund's net assets)     Financials 18.0   Real Estate 15.8   Information Technology 12.3   Industrials 9.5   Consumer Staples 8.6   Utilities 8.1   Health Care 8.1   Consumer Discretionary 6.6   Energy 6.6   Communication Services 3.9   Materials 1.7     Dividend-Paying Equities 50.5 Convertibles 18.1 REITs 14.4 Preferred Stock 13.5 Global Infrastructure Equities 3.1 MLPs 0.5 Commodity Equities 0.0 ASSET ALLOCATION (% of Fund's net assets)     Dividend-Paying Equities - 50.5            Convertibles - 18.1                        REITs - 14.4                               Preferred Stock - 13.5                     Global Infrastructure Equities - 3.1       MLPs - 0.5                                 Commodity Equities - 0.0                 Short-Term Investments and Net Other Assets (Liabilities) - (0.1)%   United States 91.9 Canada 2.4 United Kingdom 1.3 Taiwan 1.0 France 0.7 Ireland 0.6 Netherlands 0.5 Korea (South) 0.4 Japan 0.3 Others 0.9 GEOGRAPHIC DIVERSIFICATION (% of Fund's net assets)     United States - 91.9                       Canada - 2.4                               United Kingdom - 1.3                       Taiwan - 1.0                               France - 0.7                               Ireland - 0.6                              Netherlands - 0.5                          Korea (South) - 0.4                        Japan - 0.3                                Others - 0.9                                  
Largest Holdings [Text Block] TOP HOLDINGS (% of Fund's net assets)     Procter & Gamble Co/The 2.6   Exxon Mobil Corp 2.6   Coca-Cola Co/The 2.2   JPMorgan Chase & Co 1.7   Cisco Systems Inc 1.6   Equinix Inc 1.5   AbbVie Inc 1.5   McDonald's Corp 1.5   Prologis Inc 1.5   Johnson & Johnson 1.2     17.9  
Fidelity Strategic Dividend & Income Fund  
Shareholder Report [Line Items]  
Fund Name Fidelity® Strategic Dividend & Income® Fund
Class Name Fidelity® Strategic Dividend & Income® Fund
Trading Symbol FSDIX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains information about Fidelity® Strategic Dividend & Income® Fund for the period December 1, 2024 to May 31, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at fundresearch.fidelity.com/prospectus/sec. You can also request this information by contacting us at 1-800-544-8544 or by sending an e-mail to fidfunddocuments@fidelity.com.
Additional Information Phone Number 1-800-544-8544
Additional Information Email fidfunddocuments@fidelity.com
Additional Information Website fundresearch.fidelity.com/prospectus/sec
Expenses [Text Block] What were your Fund costs for the last six months?
(based on hypothetical $10,000 investment)
 
 
 
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
 
Fidelity® Strategic Dividend & Income® Fund 
$ 31 
0.63%
  
Expenses Paid, Amount $ 31
Expense Ratio, Percent 0.63%
Net Assets $ 5,130,265,466
Holdings Count | shares 664
Investment Company Portfolio Turnover 38.00%
Additional Fund Statistics [Text Block] Key Fund Statistics
(as of May 31, 2025)
 
KEY FACTS 
  
  
Fund Size
$5,130,265,466
  
Number of Holdings
664
  
Portfolio Turnover
38%
  
Holdings [Text Block]       MARKET SECTORS (% of Fund's net assets)     Financials 18.0   Real Estate 15.8   Information Technology 12.3   Industrials 9.5   Consumer Staples 8.6   Utilities 8.1   Health Care 8.1   Consumer Discretionary 6.6   Energy 6.6   Communication Services 3.9   Materials 1.7     Dividend-Paying Equities 50.5 Convertibles 18.1 REITs 14.4 Preferred Stock 13.5 Global Infrastructure Equities 3.1 MLPs 0.5 Commodity Equities 0.0 ASSET ALLOCATION (% of Fund's net assets)     Dividend-Paying Equities - 50.5            Convertibles - 18.1                        REITs - 14.4                               Preferred Stock - 13.5                     Global Infrastructure Equities - 3.1       MLPs - 0.5                                 Commodity Equities - 0.0                 Short-Term Investments and Net Other Assets (Liabilities) - (0.1)%   United States 91.9 Canada 2.4 United Kingdom 1.3 Taiwan 1.0 France 0.7 Ireland 0.6 Netherlands 0.5 Korea (South) 0.4 Japan 0.3 Others 0.9 GEOGRAPHIC DIVERSIFICATION (% of Fund's net assets)     United States - 91.9                       Canada - 2.4                               United Kingdom - 1.3                       Taiwan - 1.0                               France - 0.7                               Ireland - 0.6                              Netherlands - 0.5                          Korea (South) - 0.4                        Japan - 0.3                                Others - 0.9                                  
Largest Holdings [Text Block] TOP HOLDINGS (% of Fund's net assets)     Procter & Gamble Co/The 2.6   Exxon Mobil Corp 2.6   Coca-Cola Co/The 2.2   JPMorgan Chase & Co 1.7   Cisco Systems Inc 1.6   Equinix Inc 1.5   AbbVie Inc 1.5   McDonald's Corp 1.5   Prologis Inc 1.5   Johnson & Johnson 1.2     17.9