v3.26.1
Document And Entity Information - shares
 4 Months Ended
Jun. 30, 2026
Aug. 07, 2026
Document Information Line Items    
Entity Central Index Key 0002126043  
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2026  
Document Fiscal Year Focus 2026  
Document Transition Report false  
Entity File Number 001-43368  
Entity Registrant Name CARTESIAN GROWTH CORPORATION IV  
Entity Incorporation, State or Country Code E9  
Entity Tax Identification Number 00-0000000  
Entity Address, Address Line One 505 Fifth Avenue  
Entity Address, Address Line Two 15th Floor  
Entity Address, City or Town New York  
Entity Address, State or Province NY  
Entity Address, Postal Zip Code 10017  
City Area Code 212  
Local Phone Number 461-6363  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
Entity Shell Company true  
Amendment Flag false  
Document Fiscal Period Focus Q2  
Current Fiscal Year End Date --12-31  
Units, each consisting of one Class A ordinary share and one-third of one redeemable warrant    
Document Information Line Items    
Title of 12(b) Security Units, each consisting of one Class A ordinary share and one-third of one redeemable warrant  
Trading Symbol CGCFU  
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 CGCF  
Security Exchange Name NASDAQ  
Warrants, each whole warrant exercisable for one Class A ordinary share at an exercise price of $11.50    
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  
Trading Symbol CGCFW  
Security Exchange Name NASDAQ  
Class A Ordinary Shares    
Document Information Line Items    
Entity Common Stock, Shares Outstanding   27,500,000
Class B Ordinary Shares    
Document Information Line Items    
Entity Common Stock, Shares Outstanding   7,187,500