v3.26.1
S000039473 [Member] N-1A Cover
Mar. 31, 2026
Prospectus [Line Items]  
Document Type 485BPOS
Amendment Flag false
Registrant Name SIT MUTUAL FUNDS II INC
Entity Central Index Key 0000746601
Entity Investment Company Type N-1A
Document Period End Date Mar. 31, 2026
Prospectus Date Aug. 01, 2026