v3.26.1
Shareholder Report, Average Annual Return (Details)
12 Months Ended 60 Months Ended 120 Months Ended
Jan. 31, 2026
Jan. 31, 2026
Jan. 31, 2026
C000048850_1_BBIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 4.70%    
C000048850_1_BBIndexMember_5YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent   0.86%  
C000048850_1_BBIndexMember_10YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent     2.32%
C000235223_1_BBIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 4.70%    
C000235223_1_BBIndexMember_LOCMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 2.98%    
C000235227_1_BBIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 4.70%    
C000235227_1_BBIndexMember_LOCMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 2.98%    
C000235224_1_BBIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 4.70%    
C000235224_1_BBIndexMember_LOCMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 2.98%    
C000235226_1_BBIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 4.70%    
C000235226_1_BBIndexMember_LOCMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 2.98%    
C000235225_1_BBIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 4.70%    
C000235225_1_BBIndexMember_LOCMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 2.98%    
C000235228_1_BBIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 4.70%    
C000235228_1_BBIndexMember_LOCMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 2.98%    
C000131781_1_BBIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 15.31%    
C000131781_1_BBIndexMember_5YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent   14.09%  
C000131781_1_BBIndexMember_10YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent     15.38%
C000200825_1_BBIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 4.70%    
C000200825_1_BBIndexMember_5YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent   0.86%  
C000200825_1_BBIndexMember_LOCMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 2.62%    
C000235216_1_BBIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 4.70%    
C000235216_1_BBIndexMember_LOCMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 2.98%    
C000235213_2_BBIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 4.70%    
C000235213_2_BBIndexMember_LOCMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 3.95%    
C000245667_2_BBIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 4.70%    
C000245667_2_BBIndexMember_LOCMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 5.81%    
C000048850_NoLoadClassMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 4.96%    
C000048850_NoLoadClassMember_5YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent   1.04%  
C000048850_NoLoadClassMember_10YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent     2.58%
C000048850_0_AdditionalIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 4.77%    
C000048850_0_AdditionalIndexMember_5YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent   0.72%  
C000048850_0_AdditionalIndexMember_10YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent     2.39%
C000235223_NoLoadClassMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 5.70%    
C000235223_NoLoadClassMember_2025-02-01_2026-01-31Member      
Average Annual Return [Line Items]      
Average Annual Return, Percent 3.88%    
C000235223_0_AdditionalIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 5.72%    
C000235223_0_AdditionalIndexMember_LOCMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 3.37%    
C000235227_NoLoadClassMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 5.76%    
C000235227_NoLoadClassMember_2025-02-01_2026-01-31Member      
Average Annual Return [Line Items]      
Average Annual Return, Percent 3.94%    
C000235227_0_AdditionalIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 5.72%    
C000235227_0_AdditionalIndexMember_LOCMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 3.37%    
C000235224_ClassMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 1.12%    
C000235224_ClassMember_2025-02-01_2026-01-31Member      
Average Annual Return [Line Items]      
Average Annual Return, Percent 2.49%    
C000235224_NoLoadClassMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 5.33%    
C000235224_NoLoadClassMember_2025-02-01_2026-01-31Member      
Average Annual Return [Line Items]      
Average Annual Return, Percent 3.59%    
C000235224_0_AdditionalIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 5.72%    
C000235224_0_AdditionalIndexMember_LOCMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 3.37%    
C000235226_NoLoadClassMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 5.70%    
C000235226_NoLoadClassMember_2025-02-01_2026-01-31Member      
Average Annual Return [Line Items]      
Average Annual Return, Percent 3.88%    
C000235226_0_AdditionalIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 5.72%    
C000235226_0_AdditionalIndexMember_LOCMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 3.37%    
C000235225_ClassMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 3.55%    
C000235225_ClassMember_2025-02-01_2026-01-31Member      
Average Annual Return [Line Items]      
Average Annual Return, Percent 2.82%    
C000235225_NoLoadClassMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 4.55%    
C000235225_NoLoadClassMember_2025-02-01_2026-01-31Member      
Average Annual Return [Line Items]      
Average Annual Return, Percent 2.82%    
C000235225_0_AdditionalIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 5.72%    
C000235225_0_AdditionalIndexMember_LOCMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 3.37%    
C000235228_ClassMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 1.12%    
C000235228_ClassMember_2025-02-01_2026-01-31Member      
Average Annual Return [Line Items]      
Average Annual Return, Percent 2.49%    
C000235228_NoLoadClassMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 5.33%    
C000235228_NoLoadClassMember_2025-02-01_2026-01-31Member      
Average Annual Return [Line Items]      
Average Annual Return, Percent 3.59%    
C000235228_0_AdditionalIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 5.72%    
C000235228_0_AdditionalIndexMember_LOCMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 3.37%    
C000131781_NoLoadClassMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 15.78%    
C000131781_NoLoadClassMember_5YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent   12.55%  
C000131781_NoLoadClassMember_10YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent     11.62%
C000131781_0_AdditionalIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 15.83%    
C000131781_0_AdditionalIndexMember_5YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent   12.53%  
C000131781_0_AdditionalIndexMember_10YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent     11.61%
C000200825_NoLoadClassMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 4.57%    
C000200825_NoLoadClassMember_5YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent   1.13%  
C000200825_NoLoadClassMember_2025-02-01_2026-01-31Member      
Average Annual Return [Line Items]      
Average Annual Return, Percent 2.79%    
C000200825_0_AdditionalIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 4.77%    
C000200825_0_AdditionalIndexMember_5YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent   0.72%  
C000200825_0_AdditionalIndexMember_LOCMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 2.68%    
C000235216_NoLoadClassMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 5.28%    
C000235216_NoLoadClassMember_2025-02-01_2026-01-31Member      
Average Annual Return [Line Items]      
Average Annual Return, Percent 3.91%    
C000235216_0_AdditionalIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 4.78%    
C000235216_0_AdditionalIndexMember_LOCMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 2.99%    
C000235213_NoLoadClassMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 3.30%    
C000235213_NoLoadClassMember_2025-02-01_2026-01-31Member      
Average Annual Return [Line Items]      
Average Annual Return, Percent 3.10%    
C000235213_0_AdditionalIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 3.14%    
C000235213_0_AdditionalIndexMember_LOCMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 2.95%    
C000235213_1_AdditionalIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 3.50%    
C000235213_1_AdditionalIndexMember_LOCMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 2.89%    
C000245667_NoLoadClassMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 3.24%    
C000245667_NoLoadClassMember_2025-02-01_2026-01-31Member      
Average Annual Return [Line Items]      
Average Annual Return, Percent 3.60%    
C000245667_0_AdditionalIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 3.14%    
C000245667_0_AdditionalIndexMember_LOCMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 3.44%    
C000245667_1_AdditionalIndexMember_1YRMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 3.50%    
C000245667_1_AdditionalIndexMember_LOCMember      
Average Annual Return [Line Items]      
Average Annual Return, Percent 3.75%