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S000006018 [Member] Average Annual Total Returns
 12 Months Ended 60 Months Ended 115 Months Ended 120 Months Ended 411 Months Ended
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Bloomberg Global Aggregate (Excluding Securitized) Bond Index (reflects no deduction for fees, expenses or taxes)          
Prospectus [Line Items]          
Average Annual Return, Percent [1] 7.94% (2.48%)   1.22% 4.24% [2],[3]
Performance Inception Date         Sep. 27, 1991
Class I          
Prospectus [Line Items]          
Average Annual Return, Percent 5.66% 2.96%   5.03% 3.67% [2],[3]
Performance Inception Date         Sep. 27, 1991
Class I | After Taxes on Distributions          
Prospectus [Line Items]          
Average Annual Return, Percent 4.12% 2.02%   3.94% 2.59% [2],[3]
Performance Inception Date         Sep. 27, 1991
Class I | After Taxes on Distributions and Sales          
Prospectus [Line Items]          
Average Annual Return, Percent 3.54% 1.96%   3.54% 2.47% [2],[3]
Performance Inception Date         Sep. 27, 1991
Class A          
Prospectus [Line Items]          
Average Annual Return, Percent 5.39% 2.70% 4.24% [2],[3]  
Performance Inception Date     May 31, 2016    
Class C          
Prospectus [Line Items]          
Average Annual Return, Percent 4.61% 1.94% 3.46% [2],[3]  
Performance Inception Date     May 31, 2016    
[1] The Portfolio changed its investment strategies on May 30, 2012. The Bloomberg Global Aggregate (Excluding Securitized) Bond Index has characteristics relevant to the Portfolio’s current investment strategies as described in this Prospectus.
[2] Inception date for Class I shares was September 27, 1991. Inception date for Class A and Class C shares was May 31, 2016. Date used to calculate performance since inception for the index is the inception date of the Class I shares.
[3] Performance for periods prior to May 30, 2012 reflects the Portfolio’s results under its prior investment strategies. Such performance should not be considered predictive or representative of results the Portfolio may experience under its current investment strategies.