v3.26.3
S000003461 [Member] N-1A Cover
Jun. 30, 2026
Prospectus [Line Items]  
Document Type 485BPOS
Amendment Flag false
Registrant Name SIT MUTUAL FUNDS INC
Entity Central Index Key 0000877880
Entity Investment Company Type N-1A
Document Period End Date Jun. 30, 2026
Prospectus Date Nov. 01, 2026