v3.26.1
Document and Entity Information - shares
6 Months Ended
Jun. 30, 2026
Aug. 05, 2026
Cover [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Jun. 30, 2026  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q2  
Current Fiscal Year End Date --12-31  
Document Quarterly Report true  
Document Transition Report false  
Entity File Number 001-41925  
Entity Registrant Name CG Oncology, Inc.  
Entity Central Index Key 0001991792  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 37-1611499  
Entity Address, Address Line One 3000 Pegasus Park Drive  
Entity Address, Address Line Two Suite 1640  
Entity Address, City or Town Dallas  
Entity Address, State or Province TX  
Entity Address, Postal Zip Code 75247  
City Area Code 949  
Local Phone Number 409-3700  
Title of 12(b) Security Common Stock, par value $0.0001 per share  
Trading Symbol CGON  
Security Exchange Name NASDAQ  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   88,640,375