v3.26.1
S000001260 [Member] Investment Objectives and Goals - TAX-EXEMPT FUND
Mar. 31, 2026
Prospectus [Line Items]  
Risk/Return [Heading] TAX-EXEMPT FUND
Objective [Heading] INVESTMENT OBJECTIVE
Objective, Primary [Text Block]
The Fund seeks to provide a high level of current income exempt from regular federal income tax by investing in municipal instruments.