v3.25.4
S000006330 [Member] Average Annual Total Returns
 4 Months Ended 12 Months Ended 60 Months Ended 70 Months Ended 120 Months Ended 322 Months Ended 390 Months Ended
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)              
Prospectus [Line Items]              
Average Annual Return, Percent [1],[2]   7.30% (0.36%)   2.01%   4.43%
Bloomberg U.S. Securitized Index (reflects no deduction for fees, expenses or taxes)              
Prospectus [Line Items]              
Average Annual Return, Percent [2],[3]   8.49% 0.22%   1.68%  
I Class              
Prospectus [Line Items]              
Average Annual Return, Percent [2]   8.98% (0.77%)   1.70%   5.20%
Performance Inception Date             Jun. 17, 1993
I Class | After Taxes on Distributions              
Prospectus [Line Items]              
Average Annual Return, Percent [2]   6.04% (2.71%)   (0.04%)   2.96%
Performance Inception Date             Jun. 17, 1993
I Class | After Taxes on Distributions and Sales              
Prospectus [Line Items]              
Average Annual Return, Percent [2]   5.26% (1.42%)   0.55%   3.10%
Performance Inception Date             Jun. 17, 1993
N Class              
Prospectus [Line Items]              
Average Annual Return, Percent [2]   8.71% (0.97%)   1.45% 4.51%  
Performance Inception Date           Mar. 01, 1999  
Plan Class              
Prospectus [Line Items]              
Average Annual Return, Percent [2]   9.03% (0.74%) 0.03%    
Performance Inception Date       Feb. 28, 2020      
Class I-3              
Prospectus [Line Items]              
Performance Inception Date Aug. 25, 2025            
[1]
The Fund has adopted this broad-based index as its primary index. The Bloomberg U.S. Aggregate Bond Index is a market capitalization-weighted index of investment grade, U.S. dollar-denominated, fixed-rate debt issues, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable-rate mortgage), asset-backed securities and commercial mortgage-backed securities (agency and non-agency).
[2] Class I-3 shares of the Fund have an inception date of August 25, 2025, and therefore do not have a full year of performance history as of the date of this Prospectus.
[3]
The Fund has adopted this index as its secondary benchmark index. The Bloomberg U.S. Securitized Index is a market-value-weighted index of investment grade, U.S. dollar-denominated, securitized fixed-rate debt issues.