v3.26.1
Cover - USD ($)
12 Months Ended
Dec. 31, 2025
Mar. 26, 2026
Document Information [Line Items]    
Entity Registrant Name Churchill Capital Corp XI  
Document Type 10-K  
Current Fiscal Year End Date --12-31  
Amendment Flag false  
Entity Central Index Key 0002074973  
Document Period End Date Dec. 31, 2025  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus FY  
Entity File Number 001-43020  
Document Annual Report true  
Document Transition Report false  
Entity Interactive Data Current Yes  
Entity Tax Identification Number 86-1959629  
Entity Incorporation, State or Country Code E9  
Entity Current Reporting Status Yes  
Entity Shell Company true  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
Entity Address, Address Line One 640 Fifth Avenue  
Entity Address, Address Line Two 14th Floor  
Entity Address, City or Town New York  
Entity Address, State or Province NY  
Entity Address, Postal Zip Code 10019  
City Area Code (212)  
Local Phone Number 380-7500  
Entity Well-known Seasoned Issuer No  
Entity Voluntary Filers No  
Document Financial Statement Error Correction [Flag] false  
ICFR Auditor Attestation Flag false  
Entity Public Float $ 422,694,000  
Class A Ordinary Shares    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   41,900,000
Class B Ordinary Shares    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   13,800,000
Units, each consisting of one Class A Ordinary Share and one-tenth of one redeemable Warrant    
Document Information [Line Items]    
Title of 12(b) Security Units, each consisting of one Class A Ordinary Share and one-tenth of one redeemable Warrant  
Trading Symbol CCXIU  
Security Exchange Name NASDAQ  
Class A Ordinary Shares, par value $0.0001 per share    
Document Information [Line Items]    
Title of 12(b) Security Class A Ordinary Shares, par value $0.0001 per share  
Trading Symbol CCXI  
Security Exchange Name NASDAQ  
Warrants, each whole Warrant exercisable for one Class A Ordinary Share at an exercise price of $11.50 per share    
Document Information [Line Items]    
Title of 12(b) Security Warrants, each whole Warrant exercisable for one Class A Ordinary Share at an exercise price of $11.50 per share  
Trading Symbol CCXIW  
Security Exchange Name NASDAQ