v3.26.1
S000006018 [Member] Expense Example, No Redemption - Versatile Bond Portfolio - Class C
Jan. 31, 2026
USD ($)
Prospectus [Line Items]  
Expense Example, No Redemption, 1 Year $ 169
Expense Example, No Redemption, 3 Years 643
Expense Example, No Redemption, 5 Years 1,144
Expense Example, No Redemption, 10 Years $ 2,521