v3.26.3
Cover - shares
 9 Months Ended
Sep. 30, 2026
Nov. 13, 2026
Document Information [Line Items]    
Document Type 10-Q  
Amendment Flag false  
Entity Central Index Key 0002032019  
Document Period End Date Sep. 30, 2026  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q3  
Document Quarterly Report true  
Document Transition Report false  
Entity Registrant Name EQT Infrastructure Company LLC  
Entity File Number 000-56691  
Entity Interactive Data Current Yes  
Current Fiscal Year End Date --12-31  
Entity Tax Identification Number 99-3884445  
Entity Incorporation, State or Country Code DE  
Entity Current Reporting Status Yes  
Entity Filer Category Non-accelerated Filer  
Entity Shell Company false  
Entity Small Business false  
Entity Emerging Growth Company true  
Entity Address, Address Line One 245 Park Avenue  
Entity Address, Address Line Two 34th Floor  
Entity Address, City or Town New York  
Entity Address, State or Province NY  
Entity Address, Postal Zip Code 10167  
City Area Code 917  
Local Phone Number 281-0850  
Entity Ex Transition Period false  
Common Class A-I [Member]    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   32,385,474
Common Class A-S [Member]    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   4,148,543
Common Class M-I [Member]    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   1,737,549
Common Class M-S [Member]    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   2,091,019
Common Class M-I-TE [Member]    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   161,965
Common Class M-S-TE [Member]    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   305,772
Common Class I Shares [Member]    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   400
Common Class E Shares [Member]    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   3,851,545
Common Class Q Shares [Member]    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   40
Common Class T Shares [Member]    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   7,786
Common Class H Shares [Member]    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   40
Common Class D Shares [Member]    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   0
Common Class S Shares [Member]    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   0
Common Class A-D Shares [Member]    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   0