v3.26.1
Shareholder Report, Average Annual Return (Details)
 12 Months Ended 29 Months Ended 40 Months Ended 60 Months Ended 83 Months Ended 120 Months Ended
May 31, 2026
May 31, 2026
May 31, 2026
May 31, 2026
May 31, 2026
May 31, 2026
C000106430 [Member]            
Average Annual Return [Line Items]            
Line Graph and Table Measure Name Income Fund (Class R6/JSNWX)          
Average Annual Return, Percent 5.78%     1.57%   2.86%
C000078713 [Member]            
Average Annual Return [Line Items]            
Line Graph and Table Measure Name Income Fund (Class R5/JSNVX)          
Average Annual Return, Percent 5.91%     1.52%   2.81%
C000078712 [Member]            
Average Annual Return [Line Items]            
Line Graph and Table Measure Name Income Fund (Class R4/JSNFX)          
Average Annual Return, Percent 5.69%     1.32%   2.60%
C000113489 [Member]            
Average Annual Return [Line Items]            
Line Graph and Table Measure Name Income Fund (Class R2/JSNSX)          
Average Annual Return, Percent 5.43%     1.06%   2.35%
C000001866 [Member]            
Average Annual Return [Line Items]            
Line Graph and Table Measure Name Income Fund (Class I/JSTIX)          
Average Annual Return, Percent 5.85%     1.49%   2.75%
C000001865 [Member]            
Average Annual Return [Line Items]            
Line Graph and Table Measure Name Income Fund (Class C/JSTCX)          
Average Annual Return, Percent 3.80%     0.45%   1.73%
C000001863 [Member]            
Average Annual Return [Line Items]            
Line Graph and Table Measure Name Income Fund (Class A/JHFIX)          
Average Annual Return, Percent 1.38%     0.34%   2.02%
C000212730 [Member]            
Average Annual Return [Line Items]            
Line Graph and Table Measure Name Managed Account Shares Investment-Grade Corporate Bond Portfolio (Investment-Grade Corporate Bond Portfolio/JMABX)          
Average Annual Return, Percent 7.04%     2.11% 3.09%  
C000212731 [Member]            
Average Annual Return [Line Items]            
Line Graph and Table Measure Name Managed Account Shares Non-Investment-Grade Corporate Bond Portfolio (Non-Investment-Grade Corporate Bond Portfolio/JMADX)          
Average Annual Return, Percent 7.52%     3.71% 4.18%  
C000212732 [Member]            
Average Annual Return [Line Items]            
Line Graph and Table Measure Name Managed Account Shares Securitized Debt Portfolio (Securitized Debt Portfolio/JMAEX)          
Average Annual Return, Percent 4.67%     2.61% 2.96%  
C000238026 [Member]            
Average Annual Return [Line Items]            
Line Graph and Table Measure Name Managed Account Shares Non-Investment-Grade Municipal Bond Portfolio (Non-Investment-Grade Municipal Bond Portfolio/JHFMX)          
Average Annual Return, Percent 7.29%   4.98%      
C000247081 [Member]            
Average Annual Return [Line Items]            
Line Graph and Table Measure Name Managed Account Shares Bond Completion Portfolio (Bond Completion Portfolio/JHBMX)          
Average Annual Return, Percent 5.97% 3.96%        
Without Sales Load [Member] | C000001865 [Member]            
Average Annual Return [Line Items]            
Line Graph and Table Measure Name Income Fund (Class C/JSTCX)—excluding sales charge          
Average Annual Return, Percent 4.80%     0.45%   1.73%
Without Sales Load [Member] | C000001863 [Member]            
Average Annual Return [Line Items]            
Line Graph and Table Measure Name Income Fund (Class A/JHFIX)—excluding sales charge          
Average Annual Return, Percent 5.53%     1.16%   2.44%
Bloomberg U S Aggregate Bond Index [Member]            
Average Annual Return [Line Items]            
Line Graph and Table Measure Name Bloomberg U.S. Aggregate Bond Index          
Average Annual Return, Percent 5.13% 3.96%   0.17% 1.21% 1.70%
Bloomberg Municipal Bond Index [Member]            
Average Annual Return [Line Items]            
Line Graph and Table Measure Name Bloomberg Municipal Bond Index          
Average Annual Return, Percent 6.67%   3.10%      
Bloomberg U S Corporate Bond Index [Member]            
Average Annual Return [Line Items]            
Line Graph and Table Measure Name Bloomberg U.S. Corporate Bond Index          
Average Annual Return, Percent 6.09%     0.63% 2.02%  
ICE BofA U S High Yield Index [Member]            
Average Annual Return [Line Items]            
Line Graph and Table Measure Name ICE BofA U.S. High Yield Index          
Average Annual Return, Percent 7.44%     4.36% 4.94%  
Bloomberg U S Securitized MBS ABS CMBS Index [Member]            
Average Annual Return [Line Items]            
Line Graph and Table Measure Name Bloomberg U.S. Securitized MBS ABS CMBS Index          
Average Annual Return, Percent 6.71%     0.52% 1.15%  
Bloomberg High Yield Municipal Bond Index [Member]            
Average Annual Return [Line Items]            
Line Graph and Table Measure Name Bloomberg High Yield Municipal Bond Index          
Average Annual Return, Percent 6.21%   4.84%