v3.26.3
Shareholder Report, Line Graph (Details) - USD ($)
12 Months Ended 96 Months Ended 108 Months Ended 120 Months Ended 132 Months Ended
Aug. 31, 2026
Aug. 31, 2026
Aug. 31, 2026
Aug. 31, 2026
Aug. 31, 2026
C000088099_LG_ClassMember_11YRMember          
Account Value [Line Items]          
Line Graph and Table Measure Name         <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Class C</span>
C000088099_ClassMember_AsOf_2016Member          
Account Value [Line Items]          
Accumulated Value $ 10,000        
C000088099_ClassMember_AsOf_2017Member          
Account Value [Line Items]          
Accumulated Value 10,175        
C000088099_ClassMember_AsOf_2018Member          
Account Value [Line Items]          
Accumulated Value 10,000        
C000088099_ClassMember_AsOf_2019Member          
Account Value [Line Items]          
Accumulated Value 11,178        
C000088099_ClassMember_AsOf_2020Member          
Account Value [Line Items]          
Accumulated Value 11,965        
C000088099_ClassMember_AsOf_2021Member          
Account Value [Line Items]          
Accumulated Value 12,139        
C000088099_ClassMember_AsOf_2022Member          
Account Value [Line Items]          
Accumulated Value 10,141        
C000088099_ClassMember_AsOf_2023Member          
Account Value [Line Items]          
Accumulated Value 10,135        
C000088099_ClassMember_AsOf_2024Member          
Account Value [Line Items]          
Accumulated Value 11,017        
C000088099_ClassMember_AsOf_2025Member          
Account Value [Line Items]          
Accumulated Value 11,419        
C000088099_ClassMember_AsOf_2026Member          
Account Value [Line Items]          
Accumulated Value 11,580        
C000088099_LG_1_AdditionalIndexMember_11YRMember          
Account Value [Line Items]          
Line Graph and Table Measure Name         <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Bloomberg U.S. Credit Bond Index</span>
C000088099_1_AdditionalIndexMember_AsOf_2016Member          
Account Value [Line Items]          
Accumulated Value 10,000        
C000088099_1_AdditionalIndexMember_AsOf_2017Member          
Account Value [Line Items]          
Accumulated Value 10,190        
C000088099_1_AdditionalIndexMember_AsOf_2018Member          
Account Value [Line Items]          
Accumulated Value 10,090        
C000088099_1_AdditionalIndexMember_AsOf_2019Member          
Account Value [Line Items]          
Accumulated Value 11,400        
C000088099_1_AdditionalIndexMember_AsOf_2020Member          
Account Value [Line Items]          
Accumulated Value 12,209        
C000088099_1_AdditionalIndexMember_AsOf_2021Member          
Account Value [Line Items]          
Accumulated Value 12,486        
C000088099_1_AdditionalIndexMember_AsOf_2022Member          
Account Value [Line Items]          
Accumulated Value 10,684        
C000088099_1_AdditionalIndexMember_AsOf_2023Member          
Account Value [Line Items]          
Accumulated Value 10,774        
C000088099_1_AdditionalIndexMember_AsOf_2024Member          
Account Value [Line Items]          
Accumulated Value 11,742        
C000088099_1_AdditionalIndexMember_AsOf_2025Member          
Account Value [Line Items]          
Accumulated Value 12,203        
C000088099_1_AdditionalIndexMember_AsOf_2026Member          
Account Value [Line Items]          
Accumulated Value 12,444        
C000088099_LG_2_AdditionalIndexMember_11YRMember          
Account Value [Line Items]          
Line Graph and Table Measure Name         <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Bloomberg U.S. Aggregate Bond Index</span>
C000088099_2_AdditionalIndexMember_AsOf_2016Member          
Account Value [Line Items]          
Accumulated Value 10,000        
C000088099_2_AdditionalIndexMember_AsOf_2017Member          
Account Value [Line Items]          
Accumulated Value 10,049        
C000088099_2_AdditionalIndexMember_AsOf_2018Member          
Account Value [Line Items]          
Accumulated Value 9,944        
C000088099_2_AdditionalIndexMember_AsOf_2019Member          
Account Value [Line Items]          
Accumulated Value 10,955        
C000088099_2_AdditionalIndexMember_AsOf_2020Member          
Account Value [Line Items]          
Accumulated Value 11,665        
C000088099_2_AdditionalIndexMember_AsOf_2021Member          
Account Value [Line Items]          
Accumulated Value 11,655        
C000088099_2_AdditionalIndexMember_AsOf_2022Member          
Account Value [Line Items]          
Accumulated Value 10,313        
C000088099_2_AdditionalIndexMember_AsOf_2023Member          
Account Value [Line Items]          
Accumulated Value 10,189        
C000088099_2_AdditionalIndexMember_AsOf_2024Member          
Account Value [Line Items]          
Accumulated Value 10,933        
C000088099_2_AdditionalIndexMember_AsOf_2025Member          
Account Value [Line Items]          
Accumulated Value 11,276        
C000088099_2_AdditionalIndexMember_AsOf_2026Member          
Account Value [Line Items]          
Accumulated Value 11,489        
C000088100_LG_ClassMember_11YRMember          
Account Value [Line Items]          
Line Graph and Table Measure Name         <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Class M</span>
C000088100_ClassMember_AsOf_2016Member          
Account Value [Line Items]          
Accumulated Value 9,600        
C000088100_ClassMember_AsOf_2017Member          
Account Value [Line Items]          
Accumulated Value 9,825        
C000088100_ClassMember_AsOf_2018Member          
Account Value [Line Items]          
Accumulated Value 9,722        
C000088100_ClassMember_AsOf_2019Member          
Account Value [Line Items]          
Accumulated Value 10,950        
C000088100_ClassMember_AsOf_2020Member          
Account Value [Line Items]          
Accumulated Value 11,796        
C000088100_ClassMember_AsOf_2021Member          
Account Value [Line Items]          
Accumulated Value 12,057        
C000088100_ClassMember_AsOf_2022Member          
Account Value [Line Items]          
Accumulated Value 10,146        
C000088100_ClassMember_AsOf_2023Member          
Account Value [Line Items]          
Accumulated Value 10,212        
C000088100_ClassMember_AsOf_2024Member          
Account Value [Line Items]          
Accumulated Value 11,181        
C000088100_ClassMember_AsOf_2025Member          
Account Value [Line Items]          
Accumulated Value 11,584        
C000088100_ClassMember_AsOf_2026Member          
Account Value [Line Items]          
Accumulated Value 11,745        
C000088100_LG_1_AdditionalIndexMember_11YRMember          
Account Value [Line Items]          
Line Graph and Table Measure Name         <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Bloomberg U.S. Credit Bond Index</span>
C000088100_1_AdditionalIndexMember_AsOf_2016Member          
Account Value [Line Items]          
Accumulated Value 10,000        
C000088100_1_AdditionalIndexMember_AsOf_2017Member          
Account Value [Line Items]          
Accumulated Value 10,190        
C000088100_1_AdditionalIndexMember_AsOf_2018Member          
Account Value [Line Items]          
Accumulated Value 10,090        
C000088100_1_AdditionalIndexMember_AsOf_2019Member          
Account Value [Line Items]          
Accumulated Value 11,400        
C000088100_1_AdditionalIndexMember_AsOf_2020Member          
Account Value [Line Items]          
Accumulated Value 12,209        
C000088100_1_AdditionalIndexMember_AsOf_2021Member          
Account Value [Line Items]          
Accumulated Value 12,486        
C000088100_1_AdditionalIndexMember_AsOf_2022Member          
Account Value [Line Items]          
Accumulated Value 10,684        
C000088100_1_AdditionalIndexMember_AsOf_2023Member          
Account Value [Line Items]          
Accumulated Value 10,774        
C000088100_1_AdditionalIndexMember_AsOf_2024Member          
Account Value [Line Items]          
Accumulated Value 11,742        
C000088100_1_AdditionalIndexMember_AsOf_2025Member          
Account Value [Line Items]          
Accumulated Value 12,203        
C000088100_1_AdditionalIndexMember_AsOf_2026Member          
Account Value [Line Items]          
Accumulated Value 12,444        
C000088100_LG_2_AdditionalIndexMember_11YRMember          
Account Value [Line Items]          
Line Graph and Table Measure Name         <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Bloomberg U.S. Aggregate Bond Index</span>
C000088100_2_AdditionalIndexMember_AsOf_2016Member          
Account Value [Line Items]          
Accumulated Value 10,000        
C000088100_2_AdditionalIndexMember_AsOf_2017Member          
Account Value [Line Items]          
Accumulated Value 10,049        
C000088100_2_AdditionalIndexMember_AsOf_2018Member          
Account Value [Line Items]          
Accumulated Value 9,944        
C000088100_2_AdditionalIndexMember_AsOf_2019Member          
Account Value [Line Items]          
Accumulated Value 10,955        
C000088100_2_AdditionalIndexMember_AsOf_2020Member          
Account Value [Line Items]          
Accumulated Value 11,665        
C000088100_2_AdditionalIndexMember_AsOf_2021Member          
Account Value [Line Items]          
Accumulated Value 11,655        
C000088100_2_AdditionalIndexMember_AsOf_2022Member          
Account Value [Line Items]          
Accumulated Value 10,313        
C000088100_2_AdditionalIndexMember_AsOf_2023Member          
Account Value [Line Items]          
Accumulated Value 10,189        
C000088100_2_AdditionalIndexMember_AsOf_2024Member          
Account Value [Line Items]          
Accumulated Value 10,933        
C000088100_2_AdditionalIndexMember_AsOf_2025Member          
Account Value [Line Items]          
Accumulated Value 11,276        
C000088100_2_AdditionalIndexMember_AsOf_2026Member          
Account Value [Line Items]          
Accumulated Value 11,489        
C000100043_LG_ClassMember_11YRMember          
Account Value [Line Items]          
Line Graph and Table Measure Name         <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Fidelity® U.S. Bond Index Fund</span>
C000100043_ClassMember_AsOf_2016Member          
Account Value [Line Items]          
Accumulated Value 10,000        
C000100043_ClassMember_AsOf_2017Member          
Account Value [Line Items]          
Accumulated Value 10,039        
C000100043_ClassMember_AsOf_2018Member          
Account Value [Line Items]          
Accumulated Value 9,917        
C000100043_ClassMember_AsOf_2019Member          
Account Value [Line Items]          
Accumulated Value 10,941        
C000100043_ClassMember_AsOf_2020Member          
Account Value [Line Items]          
Accumulated Value 11,649        
C000100043_ClassMember_AsOf_2021Member          
Account Value [Line Items]          
Accumulated Value 11,629        
C000100043_ClassMember_AsOf_2022Member          
Account Value [Line Items]          
Accumulated Value 10,289        
C000100043_ClassMember_AsOf_2023Member          
Account Value [Line Items]          
Accumulated Value 10,169        
C000100043_ClassMember_AsOf_2024Member          
Account Value [Line Items]          
Accumulated Value 10,903        
C000100043_ClassMember_AsOf_2025Member          
Account Value [Line Items]          
Accumulated Value 11,241        
C000100043_ClassMember_AsOf_2026Member          
Account Value [Line Items]          
Accumulated Value 11,459        
C000100043_LG_1_AdditionalIndexMember_11YRMember          
Account Value [Line Items]          
Line Graph and Table Measure Name         <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Bloomberg U.S. Aggregate Bond Index</span>
C000100043_1_AdditionalIndexMember_AsOf_2016Member          
Account Value [Line Items]          
Accumulated Value 10,000        
C000100043_1_AdditionalIndexMember_AsOf_2017Member          
Account Value [Line Items]          
Accumulated Value 10,049        
C000100043_1_AdditionalIndexMember_AsOf_2018Member          
Account Value [Line Items]          
Accumulated Value 9,944        
C000100043_1_AdditionalIndexMember_AsOf_2019Member          
Account Value [Line Items]          
Accumulated Value 10,955        
C000100043_1_AdditionalIndexMember_AsOf_2020Member          
Account Value [Line Items]          
Accumulated Value 11,665        
C000100043_1_AdditionalIndexMember_AsOf_2021Member          
Account Value [Line Items]          
Accumulated Value 11,655        
C000100043_1_AdditionalIndexMember_AsOf_2022Member          
Account Value [Line Items]          
Accumulated Value 10,313        
C000100043_1_AdditionalIndexMember_AsOf_2023Member          
Account Value [Line Items]          
Accumulated Value 10,189        
C000100043_1_AdditionalIndexMember_AsOf_2024Member          
Account Value [Line Items]          
Accumulated Value 10,933        
C000100043_1_AdditionalIndexMember_AsOf_2025Member          
Account Value [Line Items]          
Accumulated Value 11,276        
C000100043_1_AdditionalIndexMember_AsOf_2026Member          
Account Value [Line Items]          
Accumulated Value 11,489        
C000205023_LG_ClassMember_9YRMember          
Account Value [Line Items]          
Line Graph and Table Measure Name     <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Class Z</span>    
C000205023_ClassMember_AsOf_2018Member          
Account Value [Line Items]          
Accumulated Value 10,000        
C000205023_ClassMember_AsOf_2019Member          
Account Value [Line Items]          
Accumulated Value 11,334        
C000205023_ClassMember_AsOf_2020Member          
Account Value [Line Items]          
Accumulated Value 12,275        
C000205023_ClassMember_AsOf_2021Member          
Account Value [Line Items]          
Accumulated Value 12,601        
C000205023_ClassMember_AsOf_2022Member          
Account Value [Line Items]          
Accumulated Value 10,652        
C000205023_ClassMember_AsOf_2023Member          
Account Value [Line Items]          
Accumulated Value 10,761        
C000205023_ClassMember_AsOf_2024Member          
Account Value [Line Items]          
Accumulated Value 11,847        
C000205023_ClassMember_AsOf_2025Member          
Account Value [Line Items]          
Accumulated Value 12,329        
C000205023_ClassMember_AsOf_2026Member          
Account Value [Line Items]          
Accumulated Value 12,555        
C000205023_LG_1_AdditionalIndexMember_9YRMember          
Account Value [Line Items]          
Line Graph and Table Measure Name     <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Bloomberg U.S. Credit Bond Index</span>    
C000205023_1_AdditionalIndexMember_AsOf_2018Member          
Account Value [Line Items]          
Accumulated Value 10,000        
C000205023_1_AdditionalIndexMember_AsOf_2019Member          
Account Value [Line Items]          
Accumulated Value 11,331        
C000205023_1_AdditionalIndexMember_AsOf_2020Member          
Account Value [Line Items]          
Accumulated Value 12,135        
C000205023_1_AdditionalIndexMember_AsOf_2021Member          
Account Value [Line Items]          
Accumulated Value 12,409        
C000205023_1_AdditionalIndexMember_AsOf_2022Member          
Account Value [Line Items]          
Accumulated Value 10,618        
C000205023_1_AdditionalIndexMember_AsOf_2023Member          
Account Value [Line Items]          
Accumulated Value 10,708        
C000205023_1_AdditionalIndexMember_AsOf_2024Member          
Account Value [Line Items]          
Accumulated Value 11,670        
C000205023_1_AdditionalIndexMember_AsOf_2025Member          
Account Value [Line Items]          
Accumulated Value 12,128        
C000205023_1_AdditionalIndexMember_AsOf_2026Member          
Account Value [Line Items]          
Accumulated Value 12,368        
C000205023_LG_2_AdditionalIndexMember_9YRMember          
Account Value [Line Items]          
Line Graph and Table Measure Name     <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Bloomberg U.S. Aggregate Bond Index</span>    
C000205023_2_AdditionalIndexMember_AsOf_2018Member          
Account Value [Line Items]          
Accumulated Value 10,000        
C000205023_2_AdditionalIndexMember_AsOf_2019Member          
Account Value [Line Items]          
Accumulated Value 11,086        
C000205023_2_AdditionalIndexMember_AsOf_2020Member          
Account Value [Line Items]          
Accumulated Value 11,804        
C000205023_2_AdditionalIndexMember_AsOf_2021Member          
Account Value [Line Items]          
Accumulated Value 11,794        
C000205023_2_AdditionalIndexMember_AsOf_2022Member          
Account Value [Line Items]          
Accumulated Value 10,436        
C000205023_2_AdditionalIndexMember_AsOf_2023Member          
Account Value [Line Items]          
Accumulated Value 10,311        
C000205023_2_AdditionalIndexMember_AsOf_2024Member          
Account Value [Line Items]          
Accumulated Value 11,064        
C000205023_2_AdditionalIndexMember_AsOf_2025Member          
Account Value [Line Items]          
Accumulated Value 11,411        
C000205023_2_AdditionalIndexMember_AsOf_2026Member          
Account Value [Line Items]          
Accumulated Value 11,626        
C000211071_LG_ClassMember_8YRMember          
Account Value [Line Items]          
Line Graph and Table Measure Name   <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Fidelity® Series Bond Index Fund</span>      
C000211071_ClassMember_AsOf_2019Member          
Account Value [Line Items]          
Accumulated Value 10,000        
C000211071_ClassMember_AsOf_2020Member          
Account Value [Line Items]          
Accumulated Value 10,601        
C000211071_ClassMember_AsOf_2021Member          
Account Value [Line Items]          
Accumulated Value 11,282        
C000211071_ClassMember_AsOf_2022Member          
Account Value [Line Items]          
Accumulated Value 11,266        
C000211071_ClassMember_AsOf_2023Member          
Account Value [Line Items]          
Accumulated Value 9,962        
C000211071_ClassMember_AsOf_2024Member          
Account Value [Line Items]          
Accumulated Value 9,850        
C000211071_ClassMember_AsOf_2025Member          
Account Value [Line Items]          
Accumulated Value 10,563        
C000211071_ClassMember_AsOf_2026Member          
Account Value [Line Items]          
Accumulated Value 10,889        
C000211071_LG_1_AdditionalIndexMember_8YRMember          
Account Value [Line Items]          
Line Graph and Table Measure Name   <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Bloomberg U.S. Aggregate Bond Index</span>      
C000211071_1_AdditionalIndexMember_AsOf_2019Member          
Account Value [Line Items]          
Accumulated Value 10,000        
C000211071_1_AdditionalIndexMember_AsOf_2020Member          
Account Value [Line Items]          
Accumulated Value 10,596        
C000211071_1_AdditionalIndexMember_AsOf_2021Member          
Account Value [Line Items]          
Accumulated Value 11,282        
C000211071_1_AdditionalIndexMember_AsOf_2022Member          
Account Value [Line Items]          
Accumulated Value 11,272        
C000211071_1_AdditionalIndexMember_AsOf_2023Member          
Account Value [Line Items]          
Accumulated Value 9,974        
C000211071_1_AdditionalIndexMember_AsOf_2024Member          
Account Value [Line Items]          
Accumulated Value 9,855        
C000211071_1_AdditionalIndexMember_AsOf_2025Member          
Account Value [Line Items]          
Accumulated Value 10,574        
C000211071_1_AdditionalIndexMember_AsOf_2026Member          
Account Value [Line Items]          
Accumulated Value 10,906        
C000088097_LG_ClassMember_11YRMember          
Account Value [Line Items]          
Line Graph and Table Measure Name         <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Class A</span>
C000088097_ClassMember_AsOf_2016Member          
Account Value [Line Items]          
Accumulated Value 9,600        
C000088097_ClassMember_AsOf_2017Member          
Account Value [Line Items]          
Accumulated Value 9,833        
C000088097_ClassMember_AsOf_2018Member          
Account Value [Line Items]          
Accumulated Value 9,738        
C000088097_ClassMember_AsOf_2019Member          
Account Value [Line Items]          
Accumulated Value 10,977        
C000088097_ClassMember_AsOf_2020Member          
Account Value [Line Items]          
Accumulated Value 11,831        
C000088097_ClassMember_AsOf_2021Member          
Account Value [Line Items]          
Accumulated Value 12,096        
C000088097_ClassMember_AsOf_2022Member          
Account Value [Line Items]          
Accumulated Value 10,184        
C000088097_ClassMember_AsOf_2023Member          
Account Value [Line Items]          
Accumulated Value 10,255        
C000088097_ClassMember_AsOf_2024Member          
Account Value [Line Items]          
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C000088097_ClassMember_AsOf_2025Member          
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C000088097_LG_1_AdditionalIndexMember_11YRMember          
Account Value [Line Items]          
Line Graph and Table Measure Name         <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Bloomberg U.S. Credit Bond Index</span>
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Account Value [Line Items]          
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Account Value [Line Items]          
Accumulated Value 10,190        
C000088097_1_AdditionalIndexMember_AsOf_2018Member          
Account Value [Line Items]          
Accumulated Value 10,090        
C000088097_1_AdditionalIndexMember_AsOf_2019Member          
Account Value [Line Items]          
Accumulated Value 11,400        
C000088097_1_AdditionalIndexMember_AsOf_2020Member          
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C000088097_1_AdditionalIndexMember_AsOf_2024Member          
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C000088097_1_AdditionalIndexMember_AsOf_2025Member          
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C000088097_1_AdditionalIndexMember_AsOf_2026Member          
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C000088097_LG_2_AdditionalIndexMember_11YRMember          
Account Value [Line Items]          
Line Graph and Table Measure Name         <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Bloomberg U.S. Aggregate Bond Index</span>
C000088097_2_AdditionalIndexMember_AsOf_2016Member          
Account Value [Line Items]          
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Accumulated Value 10,049        
C000088097_2_AdditionalIndexMember_AsOf_2018Member          
Account Value [Line Items]          
Accumulated Value 9,944        
C000088097_2_AdditionalIndexMember_AsOf_2019Member          
Account Value [Line Items]          
Accumulated Value 10,955        
C000088097_2_AdditionalIndexMember_AsOf_2020Member          
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C000088097_2_AdditionalIndexMember_AsOf_2024Member          
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C000088097_2_AdditionalIndexMember_AsOf_2025Member          
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Account Value [Line Items]          
Line Graph and Table Measure Name         <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Fidelity® Series Investment Grade Bond Fund</span>
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Account Value [Line Items]          
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C000069436_ClassMember_AsOf_2018Member          
Account Value [Line Items]          
Accumulated Value 10,099        
C000069436_ClassMember_AsOf_2019Member          
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C000069436_ClassMember_AsOf_2020Member          
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C000069436_ClassMember_AsOf_2025Member          
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C000069436_LG_1_AdditionalIndexMember_11YRMember          
Account Value [Line Items]          
Line Graph and Table Measure Name         <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Bloomberg U.S. Aggregate Bond Index</span>
C000069436_1_AdditionalIndexMember_AsOf_2016Member          
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Account Value [Line Items]          
Accumulated Value 9,944        
C000069436_1_AdditionalIndexMember_AsOf_2019Member          
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Accumulated Value 10,955        
C000069436_1_AdditionalIndexMember_AsOf_2020Member          
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Account Value [Line Items]          
Line Graph and Table Measure Name         <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Fidelity® Corporate Bond Fund</span>
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Account Value [Line Items]          
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C000088096_ClassMember_AsOf_2019Member          
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C000088096_ClassMember_AsOf_2020Member          
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Line Graph and Table Measure Name         <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Bloomberg U.S. Credit Bond Index</span>
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Account Value [Line Items]          
Accumulated Value 10,090        
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C000088096_LG_2_AdditionalIndexMember_11YRMember          
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Line Graph and Table Measure Name         <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Bloomberg U.S. Aggregate Bond Index</span>
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C000088096_2_AdditionalIndexMember_AsOf_2020Member          
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Line Graph and Table Measure Name         <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Fidelity® Series Short-Term Credit Fund</span>
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Line Graph and Table Measure Name         <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Bloomberg U.S. Credit 1-3 Years Bond Index</span>
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C000153158_1_AdditionalIndexMember_AsOf_2020Member          
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Line Graph and Table Measure Name         <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Bloomberg U.S. Aggregate Bond Index</span>
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Line Graph and Table Measure Name       <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Fidelity Flex® U.S. Bond Index Fund</span>  
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Line Graph and Table Measure Name       <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Bloomberg U.S. Aggregate Bond Index</span>  
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Accumulated Value 10,202        
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Account Value [Line Items]          
Accumulated Value 12,434        
C000088101_ClassMember_AsOf_2026Member          
Account Value [Line Items]          
Accumulated Value 12,645        
C000088101_LG_1_AdditionalIndexMember_11YRMember          
Account Value [Line Items]          
Line Graph and Table Measure Name         <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Bloomberg U.S. Credit Bond Index</span>
C000088101_1_AdditionalIndexMember_AsOf_2016Member          
Account Value [Line Items]          
Accumulated Value 10,000        
C000088101_1_AdditionalIndexMember_AsOf_2017Member          
Account Value [Line Items]          
Accumulated Value 10,190        
C000088101_1_AdditionalIndexMember_AsOf_2018Member          
Account Value [Line Items]          
Accumulated Value 10,090        
C000088101_1_AdditionalIndexMember_AsOf_2019Member          
Account Value [Line Items]          
Accumulated Value 11,400        
C000088101_1_AdditionalIndexMember_AsOf_2020Member          
Account Value [Line Items]          
Accumulated Value 12,209        
C000088101_1_AdditionalIndexMember_AsOf_2021Member          
Account Value [Line Items]          
Accumulated Value 12,486        
C000088101_1_AdditionalIndexMember_AsOf_2022Member          
Account Value [Line Items]          
Accumulated Value 10,684        
C000088101_1_AdditionalIndexMember_AsOf_2023Member          
Account Value [Line Items]          
Accumulated Value 10,774        
C000088101_1_AdditionalIndexMember_AsOf_2024Member          
Account Value [Line Items]          
Accumulated Value 11,742        
C000088101_1_AdditionalIndexMember_AsOf_2025Member          
Account Value [Line Items]          
Accumulated Value 12,203        
C000088101_1_AdditionalIndexMember_AsOf_2026Member          
Account Value [Line Items]          
Accumulated Value 12,444        
C000088101_LG_2_AdditionalIndexMember_11YRMember          
Account Value [Line Items]          
Line Graph and Table Measure Name         <span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;">Bloomberg U.S. Aggregate Bond Index</span>
C000088101_2_AdditionalIndexMember_AsOf_2016Member          
Account Value [Line Items]          
Accumulated Value 10,000        
C000088101_2_AdditionalIndexMember_AsOf_2017Member          
Account Value [Line Items]          
Accumulated Value 10,049        
C000088101_2_AdditionalIndexMember_AsOf_2018Member          
Account Value [Line Items]          
Accumulated Value 9,944        
C000088101_2_AdditionalIndexMember_AsOf_2019Member          
Account Value [Line Items]          
Accumulated Value 10,955        
C000088101_2_AdditionalIndexMember_AsOf_2020Member          
Account Value [Line Items]          
Accumulated Value 11,665        
C000088101_2_AdditionalIndexMember_AsOf_2021Member          
Account Value [Line Items]          
Accumulated Value 11,655        
C000088101_2_AdditionalIndexMember_AsOf_2022Member          
Account Value [Line Items]          
Accumulated Value 10,313        
C000088101_2_AdditionalIndexMember_AsOf_2023Member          
Account Value [Line Items]          
Accumulated Value 10,189        
C000088101_2_AdditionalIndexMember_AsOf_2024Member          
Account Value [Line Items]          
Accumulated Value 10,933        
C000088101_2_AdditionalIndexMember_AsOf_2025Member          
Account Value [Line Items]          
Accumulated Value 11,276        
C000088101_2_AdditionalIndexMember_AsOf_2026Member          
Account Value [Line Items]          
Accumulated Value $ 11,489