v3.25.3
Shareholder Report, Line Graph (Details) - USD ($)
12 Months Ended 24 Months Ended 96 Months Ended 132 Months Ended
Aug. 31, 2025
Aug. 31, 2025
Aug. 31, 2025
Aug. 31, 2025
C000132104_0_LG_BBIndexMember_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>
C000132104_0_BBIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value $ 10,000      
C000132104_0_BBIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,597      
C000132104_0_BBIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,649      
C000132104_0_BBIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,537      
C000132104_0_BBIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,609      
C000132104_0_BBIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 12,360      
C000132104_0_BBIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 12,350      
C000132104_0_BBIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,928      
C000132104_0_BBIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,797      
C000132104_0_BBIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,585      
C000132104_0_BBIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 11,949      
C000204996_0_LG_BBIndexMember_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>  
C000204996_0_BBIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000204996_0_BBIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,086      
C000204996_0_BBIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,804      
C000204996_0_BBIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,794      
C000204996_0_BBIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,436      
C000204996_0_BBIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,311      
C000204996_0_BBIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,064      
C000204996_0_BBIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 11,411      
C000014035_0_LG_BBIndexMember_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>
C000014035_0_BBIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014035_0_BBIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,597      
C000014035_0_BBIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,649      
C000014035_0_BBIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,537      
C000014035_0_BBIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,609      
C000014035_0_BBIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 12,360      
C000014035_0_BBIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 12,350      
C000014035_0_BBIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,928      
C000014035_0_BBIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,797      
C000014035_0_BBIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,585      
C000014035_0_BBIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 11,949      
C000014036_0_LG_BBIndexMember_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>
C000014036_0_BBIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014036_0_BBIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,597      
C000014036_0_BBIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,649      
C000014036_0_BBIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,537      
C000014036_0_BBIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,609      
C000014036_0_BBIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 12,360      
C000014036_0_BBIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 12,350      
C000014036_0_BBIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,928      
C000014036_0_BBIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,797      
C000014036_0_BBIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,585      
C000014036_0_BBIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 11,949      
C000014034_0_LG_BBIndexMember_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>
C000014034_0_BBIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014034_0_BBIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,597      
C000014034_0_BBIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,649      
C000014034_0_BBIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,537      
C000014034_0_BBIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,609      
C000014034_0_BBIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 12,360      
C000014034_0_BBIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 12,350      
C000014034_0_BBIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,928      
C000014034_0_BBIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,797      
C000014034_0_BBIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,585      
C000014034_0_BBIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 11,949      
C000014032_0_LG_BBIndexMember_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>
C000014032_0_BBIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014032_0_BBIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,597      
C000014032_0_BBIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,649      
C000014032_0_BBIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,537      
C000014032_0_BBIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,609      
C000014032_0_BBIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 12,360      
C000014032_0_BBIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 12,350      
C000014032_0_BBIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,928      
C000014032_0_BBIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,797      
C000014032_0_BBIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,585      
C000014032_0_BBIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 11,949      
C000250211_0_LG_BBIndexMember_2YRMember        
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>    
C000250211_0_BBIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000250211_0_BBIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 10,516      
C000203455_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 Investment Grade Securitized Fund</span>  
C000203455_ClassMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000203455_ClassMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 10,008      
C000203455_ClassMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 10,791      
C000203455_ClassMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,361      
C000203455_ClassMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 11,397      
C000203455_ClassMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,270      
C000203455_ClassMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 10,093      
C000203455_ClassMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 10,925      
C000203455_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. Securitized Index</span>  
C000203455_1_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000203455_1_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 10,016      
C000203455_1_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 10,745      
C000203455_1_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,241      
C000203455_1_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 11,237      
C000203455_1_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,145      
C000203455_1_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 9,947      
C000203455_1_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 10,698      
C000203455_LG_2_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>  
C000203455_2_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000203455_2_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 10,014      
C000203455_2_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,033      
C000203455_2_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,747      
C000203455_2_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 11,737      
C000203455_2_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,386      
C000203455_2_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 10,262      
C000203455_2_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 11,010      
C000014129_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® Mortgage Securities Fund</span>
C000014129_ClassMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014129_ClassMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,393      
C000014129_ClassMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,487      
C000014129_ClassMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,396      
C000014129_ClassMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,143      
C000014129_ClassMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,682      
C000014129_ClassMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,694      
C000014129_ClassMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,514      
C000014129_ClassMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,240      
C000014129_ClassMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,028      
C000014129_ClassMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 11,376      
C000014129_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. MBS Index</span>
C000014129_1_AdditionalIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014129_1_AdditionalIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,393      
C000014129_1_AdditionalIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,477      
C000014129_1_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,421      
C000014129_1_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,157      
C000014129_1_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,664      
C000014129_1_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,643      
C000014129_1_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,510      
C000014129_1_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,290      
C000014129_1_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,058      
C000014129_1_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 11,429      
C000014129_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>
C000014129_2_AdditionalIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014129_2_AdditionalIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,597      
C000014129_2_AdditionalIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,649      
C000014129_2_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,537      
C000014129_2_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,609      
C000014129_2_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 12,360      
C000014129_2_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 12,350      
C000014129_2_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,928      
C000014129_2_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,797      
C000014129_2_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,585      
C000014129_2_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 11,949      
C000204997_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;">Class Z</span>  
C000204997_ClassMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000204997_ClassMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 10,782      
C000204997_ClassMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,305      
C000204997_ClassMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,333      
C000204997_ClassMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,196      
C000204997_ClassMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 9,948      
C000204997_ClassMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 10,713      
C000204997_ClassMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 11,061      
C000204997_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. MBS Index</span>  
C000204997_1_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000204997_1_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 10,771      
C000204997_1_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,260      
C000204997_1_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,240      
C000204997_1_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,146      
C000204997_1_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 9,934      
C000204997_1_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 10,675      
C000204997_1_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 11,034      
C000204997_LG_2_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>  
C000204997_2_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000204997_2_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,086      
C000204997_2_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,804      
C000204997_2_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,794      
C000204997_2_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,436      
C000204997_2_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,311      
C000204997_2_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,064      
C000204997_2_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 11,411      
C000014045_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>
C000014045_ClassMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 9,600      
C000014045_ClassMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 9,934      
C000014045_ClassMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 9,989      
C000014045_ClassMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 9,876      
C000014045_ClassMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 10,548      
C000014045_ClassMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,011      
C000014045_ClassMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 10,991      
C000014045_ClassMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 9,839      
C000014045_ClassMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 9,558      
C000014045_ClassMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 10,249      
C000014045_ClassMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 10,534      
C000014045_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. MBS Index</span>
C000014045_1_AdditionalIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014045_1_AdditionalIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,393      
C000014045_1_AdditionalIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,477      
C000014045_1_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,421      
C000014045_1_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,157      
C000014045_1_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,664      
C000014045_1_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,643      
C000014045_1_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,510      
C000014045_1_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,290      
C000014045_1_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,058      
C000014045_1_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 11,429      
C000014045_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>
C000014045_2_AdditionalIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014045_2_AdditionalIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,597      
C000014045_2_AdditionalIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,649      
C000014045_2_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,537      
C000014045_2_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,609      
C000014045_2_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 12,360      
C000014045_2_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 12,350      
C000014045_2_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,928      
C000014045_2_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,797      
C000014045_2_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,585      
C000014045_2_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 11,949      
C000014046_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 I</span>
C000014046_ClassMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014046_ClassMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,388      
C000014046_ClassMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,468      
C000014046_ClassMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,381      
C000014046_ClassMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,125      
C000014046_ClassMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,650      
C000014046_ClassMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,668      
C000014046_ClassMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,481      
C000014046_ClassMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,198      
C000014046_ClassMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 10,976      
C000014046_ClassMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 11,305      
C000014046_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. MBS Index</span>
C000014046_1_AdditionalIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014046_1_AdditionalIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,393      
C000014046_1_AdditionalIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,477      
C000014046_1_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,421      
C000014046_1_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,157      
C000014046_1_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,664      
C000014046_1_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,643      
C000014046_1_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,510      
C000014046_1_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,290      
C000014046_1_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,058      
C000014046_1_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 11,429      
C000014046_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>
C000014046_2_AdditionalIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014046_2_AdditionalIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,597      
C000014046_2_AdditionalIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,649      
C000014046_2_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,537      
C000014046_2_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,609      
C000014046_2_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 12,360      
C000014046_2_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 12,350      
C000014046_2_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,928      
C000014046_2_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,797      
C000014046_2_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,585      
C000014046_2_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 11,949      
C000014044_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>
C000014044_ClassMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014044_ClassMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,272      
C000014044_ClassMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,252      
C000014044_ClassMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,061      
C000014044_ClassMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 10,669      
C000014044_ClassMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,052      
C000014044_ClassMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 10,947      
C000014044_ClassMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 9,720      
C000014044_ClassMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 9,370      
C000014044_ClassMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 10,047      
C000014044_ClassMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 10,327      
C000014044_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. MBS Index</span>
C000014044_1_AdditionalIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014044_1_AdditionalIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,393      
C000014044_1_AdditionalIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,477      
C000014044_1_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,421      
C000014044_1_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,157      
C000014044_1_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,664      
C000014044_1_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,643      
C000014044_1_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,510      
C000014044_1_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,290      
C000014044_1_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,058      
C000014044_1_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 11,429      
C000014044_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>
C000014044_2_AdditionalIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014044_2_AdditionalIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,597      
C000014044_2_AdditionalIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,649      
C000014044_2_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,537      
C000014044_2_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,609      
C000014044_2_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 12,360      
C000014044_2_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 12,350      
C000014044_2_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,928      
C000014044_2_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,797      
C000014044_2_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,585      
C000014044_2_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 11,949      
C000014042_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>
C000014042_ClassMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 9,600      
C000014042_ClassMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 9,935      
C000014042_ClassMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 9,990      
C000014042_ClassMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 9,878      
C000014042_ClassMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 10,542      
C000014042_ClassMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,015      
C000014042_ClassMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 10,986      
C000014042_ClassMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 9,842      
C000014042_ClassMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 9,558      
C000014042_ClassMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 10,249      
C000014042_ClassMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 10,534      
C000014042_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. MBS Index</span>
C000014042_1_AdditionalIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014042_1_AdditionalIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,393      
C000014042_1_AdditionalIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,477      
C000014042_1_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,421      
C000014042_1_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,157      
C000014042_1_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,664      
C000014042_1_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,643      
C000014042_1_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,510      
C000014042_1_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,290      
C000014042_1_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,058      
C000014042_1_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 11,429      
C000014042_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>
C000014042_2_AdditionalIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014042_2_AdditionalIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,597      
C000014042_2_AdditionalIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,649      
C000014042_2_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,537      
C000014042_2_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,609      
C000014042_2_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 12,360      
C000014042_2_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 12,350      
C000014042_2_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,928      
C000014042_2_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,797      
C000014042_2_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,585      
C000014042_2_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 11,949      
C000132104_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® Limited Term Bond Fund</span>
C000132104_ClassMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000132104_ClassMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,306      
C000132104_ClassMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,451      
C000132104_ClassMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,440      
C000132104_ClassMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,071      
C000132104_ClassMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,610      
C000132104_ClassMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,692      
C000132104_ClassMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,938      
C000132104_ClassMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 11,197      
C000132104_ClassMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 12,070      
C000132104_ClassMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 12,741      
C000132104_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;">Fidelity Limited Term Composite Index℠</span>
C000132104_1_AdditionalIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000132104_1_AdditionalIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,307      
C000132104_1_AdditionalIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,465      
C000132104_1_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,451      
C000132104_1_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,120      
C000132104_1_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,679      
C000132104_1_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,788      
C000132104_1_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 11,078      
C000132104_1_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 11,279      
C000132104_1_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 12,127      
C000132104_1_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 12,792      
C000132104_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. 1-5 Year Government/Credit Bond Index</span>
C000132104_2_AdditionalIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000132104_2_AdditionalIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,238      
C000132104_2_AdditionalIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,334      
C000132104_2_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,289      
C000132104_2_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 10,902      
C000132104_2_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,417      
C000132104_2_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,454      
C000132104_2_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,785      
C000132104_2_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,913      
C000132104_2_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,641      
C000132104_2_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 12,198      
C000204996_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;">Class Z</span>  
C000204996_ClassMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000204996_ClassMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 10,618      
C000204996_ClassMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,145      
C000204996_ClassMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,234      
C000204996_ClassMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,519      
C000204996_ClassMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,776      
C000204996_ClassMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,622      
C000204996_ClassMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 12,275      
C000204996_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;">Fidelity Limited Term Composite Index℠</span>  
C000204996_1_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000204996_1_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 10,650      
C000204996_1_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,185      
C000204996_1_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,290      
C000204996_1_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,610      
C000204996_1_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,802      
C000204996_1_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,615      
C000204996_1_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 12,252      
C000204996_LG_2_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. 1-5 Year Government/Credit Bond Index</span>  
C000204996_2_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000204996_2_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 10,616      
C000204996_2_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,117      
C000204996_2_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,153      
C000204996_2_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,502      
C000204996_2_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,626      
C000204996_2_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,335      
C000204996_2_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 11,878      
C000014035_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>
C000014035_ClassMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 9,725      
C000014035_ClassMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014035_ClassMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,109      
C000014035_ClassMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,058      
C000014035_ClassMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 10,642      
C000014035_ClassMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,118      
C000014035_ClassMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,162      
C000014035_ClassMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,408      
C000014035_ClassMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,633      
C000014035_ClassMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,418      
C000014035_ClassMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 12,018      
C000014035_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;">Fidelity Limited Term Composite Index℠</span>
C000014035_1_AdditionalIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014035_1_AdditionalIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,307      
C000014035_1_AdditionalIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,465      
C000014035_1_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,451      
C000014035_1_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,120      
C000014035_1_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,679      
C000014035_1_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,788      
C000014035_1_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 11,078      
C000014035_1_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 11,279      
C000014035_1_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 12,127      
C000014035_1_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 12,792      
C000014035_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. 1-5 Year Government/Credit Bond Index</span>
C000014035_2_AdditionalIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014035_2_AdditionalIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,238      
C000014035_2_AdditionalIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,334      
C000014035_2_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,289      
C000014035_2_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 10,902      
C000014035_2_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,417      
C000014035_2_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,454      
C000014035_2_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,785      
C000014035_2_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,913      
C000014035_2_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,641      
C000014035_2_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 12,198      
C000014036_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 I</span>
C000014036_ClassMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014036_ClassMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,310      
C000014036_ClassMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,450      
C000014036_ClassMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,425      
C000014036_ClassMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,050      
C000014036_ClassMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,583      
C000014036_ClassMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,659      
C000014036_ClassMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,902      
C000014036_ClassMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 11,157      
C000014036_ClassMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 12,027      
C000014036_ClassMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 12,696      
C000014036_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;">Fidelity Limited Term Composite Index℠</span>
C000014036_1_AdditionalIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014036_1_AdditionalIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,307      
C000014036_1_AdditionalIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,465      
C000014036_1_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,451      
C000014036_1_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,120      
C000014036_1_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,679      
C000014036_1_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,788      
C000014036_1_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 11,078      
C000014036_1_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 11,279      
C000014036_1_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 12,127      
C000014036_1_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 12,792      
C000014036_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. 1-5 Year Government/Credit Bond Index</span>
C000014036_2_AdditionalIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014036_2_AdditionalIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,238      
C000014036_2_AdditionalIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,334      
C000014036_2_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,289      
C000014036_2_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 10,902      
C000014036_2_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,417      
C000014036_2_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,454      
C000014036_2_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,785      
C000014036_2_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,913      
C000014036_2_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,641      
C000014036_2_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 12,198      
C000014034_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>
C000014034_ClassMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014034_ClassMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,205      
C000014034_ClassMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,237      
C000014034_ClassMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,107      
C000014034_ClassMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 10,612      
C000014034_ClassMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,001      
C000014034_ClassMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 10,959      
C000014034_ClassMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,138      
C000014034_ClassMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,267      
C000014034_ClassMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,035      
C000014034_ClassMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 11,615      
C000014034_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;">Fidelity Limited Term Composite Index℠</span>
C000014034_1_AdditionalIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014034_1_AdditionalIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,307      
C000014034_1_AdditionalIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,465      
C000014034_1_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,451      
C000014034_1_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,120      
C000014034_1_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,679      
C000014034_1_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,788      
C000014034_1_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 11,078      
C000014034_1_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 11,279      
C000014034_1_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 12,127      
C000014034_1_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 12,792      
C000014034_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. 1-5 Year Government/Credit Bond Index</span>
C000014034_2_AdditionalIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014034_2_AdditionalIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,238      
C000014034_2_AdditionalIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,334      
C000014034_2_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,289      
C000014034_2_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 10,902      
C000014034_2_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,417      
C000014034_2_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,454      
C000014034_2_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,785      
C000014034_2_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,913      
C000014034_2_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,641      
C000014034_2_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 12,198      
C000014032_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>
C000014032_ClassMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 9,725      
C000014032_ClassMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 9,992      
C000014032_ClassMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,111      
C000014032_ClassMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,060      
C000014032_ClassMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 10,636      
C000014032_ClassMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,122      
C000014032_ClassMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,166      
C000014032_ClassMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,413      
C000014032_ClassMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,627      
C000014032_ClassMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,423      
C000014032_ClassMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 12,022      
C000014032_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;">Fidelity Limited Term Composite Index℠</span>
C000014032_1_AdditionalIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014032_1_AdditionalIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,307      
C000014032_1_AdditionalIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,465      
C000014032_1_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,451      
C000014032_1_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 11,120      
C000014032_1_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,679      
C000014032_1_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,788      
C000014032_1_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 11,078      
C000014032_1_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 11,279      
C000014032_1_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 12,127      
C000014032_1_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 12,792      
C000014032_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. 1-5 Year Government/Credit Bond Index</span>
C000014032_2_AdditionalIndexMember_AsOf_2015Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000014032_2_AdditionalIndexMember_AsOf_2016Member        
Account Value [Line Items]        
Accumulated Value 10,238      
C000014032_2_AdditionalIndexMember_AsOf_2017Member        
Account Value [Line Items]        
Accumulated Value 10,334      
C000014032_2_AdditionalIndexMember_AsOf_2018Member        
Account Value [Line Items]        
Accumulated Value 10,289      
C000014032_2_AdditionalIndexMember_AsOf_2019Member        
Account Value [Line Items]        
Accumulated Value 10,902      
C000014032_2_AdditionalIndexMember_AsOf_2020Member        
Account Value [Line Items]        
Accumulated Value 11,417      
C000014032_2_AdditionalIndexMember_AsOf_2021Member        
Account Value [Line Items]        
Accumulated Value 11,454      
C000014032_2_AdditionalIndexMember_AsOf_2022Member        
Account Value [Line Items]        
Accumulated Value 10,785      
C000014032_2_AdditionalIndexMember_AsOf_2023Member        
Account Value [Line Items]        
Accumulated Value 10,913      
C000014032_2_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 11,641      
C000014032_2_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 12,198      
C000250211_LG_ClassMember_2YRMember        
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® Limited Term Securitized Completion Fund</span>    
C000250211_ClassMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000250211_ClassMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 10,317      
C000250211_LG_1_AdditionalIndexMember_2YRMember        
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 Limited Term Securitized Completion Fund Composite Blended Index</span>    
C000250211_1_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000250211_1_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value 10,316      
C000250211_LG_2_AdditionalIndexMember_2YRMember        
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 US Fixed Rate Asset-Backed Securities Index</span>    
C000250211_2_AdditionalIndexMember_AsOf_2024Member        
Account Value [Line Items]        
Accumulated Value 10,000      
C000250211_2_AdditionalIndexMember_AsOf_2025Member        
Account Value [Line Items]        
Accumulated Value $ 10,317