v3.26.1
Form N-CSR Cover
12 Months Ended
Jun. 30, 2026
Shareholder Report [Line Items]  
Document Type N-CSR
Amendment Flag false
Registrant Name SIT LARGE CAP GROWTH FUND INC
Entity Central Index Key 0000356786
Entity Investment Company Type N-1A
Document Period End Date Jun. 30, 2026
Shareholder Report Annual or Semi-Annual Annual Shareholder Report