v3.26.1
N-2
3 Months Ended
Mar. 31, 2026
Cover [Abstract]  
Entity Central Index Key 0002028686
Amendment Flag false
Securities Act File Number 814-01754
Document Type 10-Q/A
Entity Registrant Name SL Investment Fund II LLC
Entity Address, Address Line One 1585 Broadway
Entity Address, City or Town New York
Entity Address, State or Province NY
Entity Address, Postal Zip Code 10036
City Area Code 212
Local Phone Number 761-4000
Entity Emerging Growth Company true
Entity Ex Transition Period true