Cover Page - shares	9 Months Ended
	Sep. 30, 2025	Nov. 13, 2025
Document And Entity Information
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2025
Document Transition Report	false
Entity File Number	001-41378
Entity Registrant Name	CARTESIAN GROWTH CORPORATION II
Entity Incorporation, State or Country Code	E9
Entity Tax Identification Number	00-0000000
Entity Address, Postal Zip Code	10017
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
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
Entity Central Index Key	0001889112
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	Q3
Amendment Flag	false
Units, each consisting of one Class A Ordinary Share and one-third of one Warrant
Document And Entity Information
Title of 12(b) Security	Units, each consisting of one Class A Ordinary Share and one-third of one Warrant
Trading Symbol	RENEU
Class A ordinary shares
Document And Entity Information
Title of 12(b) Security	Class A Ordinary Shares, par value $0.0001 per share
Trading Symbol	RENE
Entity Common Stock, Shares Outstanding		8,826,092
Warrants, each whole warrant exercisable for one Class A Ordinary Share, at an exercise price of $11.50
Document And Entity Information
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	RENEW
Class B ordinary shares
Document And Entity Information
Entity Common Stock, Shares Outstanding		2