v3.26.1
COVER - shares
6 Months Ended
Jun. 30, 2026
Aug. 04, 2026
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2026  
Document Transition Report false  
Entity File Number 001-41684  
Entity Registrant Name California BanCorp \ CA  
Entity Incorporation, State or Country Code CA  
Entity Tax Identification Number 84-3288397  
Entity Address, Address Line One 12265 El Camino Real  
Entity Address, Address Line Two Suite 210  
Entity Address, City or Town San Diego  
Entity Address, State or Province CA  
Entity Address, Postal Zip Code 92130  
City Area Code 844  
Local Phone Number 265-7622  
Title of 12(b) Security Common Stock, no par value per share  
Trading Symbol BCAL  
Security Exchange Name NASDAQ  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company true  
Entity Ex Transition Period true  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   32,150,541
Amendment Flag false  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q2  
Entity Central Index Key 0001795815  
Current Fiscal Year End Date --12-31