v3.26.1
Cover - shares
6 Months Ended
Jun. 30, 2026
Aug. 13, 2026
Cover [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Quarterly Report true  
Document Transition Report false  
Document Period End Date Jun. 30, 2026  
Document Fiscal Period Focus Q2  
Document Fiscal Year Focus 2026  
Current Fiscal Year End Date --12-31  
Entity File Number 000-56846  
Entity Registrant Name JBAAM Acquisition Corp II  
Entity Central Index Key 0002133917  
Entity Tax Identification Number 42-1864896  
Entity Incorporation, State or Country Code DE  
Entity Address, Address Line One 39 West  
Entity Address, Address Line Two 37th Street  
Entity Address, City or Town New York  
Entity Address, State or Province NY  
Entity Address, Postal Zip Code 10018  
City Area Code (212)  
Local Phone Number 822-2954  
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  
Elected Not To Use the Extended Transition Period false  
Entity Shell Company true  
Entity Common Stock, Shares Outstanding   10,000,000