v3.25.2
Cover Page - USD ($)
 12 Months Ended
Mar. 31, 2025
Jun. 23, 2025
Sep. 30, 2024
Cover [Abstract]      
Document Type 10-K    
Document Annual Report true    
Document Transition Report false    
Entity File Number 001-13007    
Entity Registrant Name CARVER BANCORP, INC.    
Entity Incorporation, State or Country Code DE    
Entity Address, Address Line One 75 West 125th Street    
Entity Address, City or Town New York    
Entity Address, State or Province NY    
Entity Tax Identification Number 13-3904174    
Entity Address, Postal Zip Code 10027    
City Area Code (718)    
Local Phone Number 230-2900    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Non-accelerated Filer    
Entity Smaller Reporting Company true    
Entity Emerging Growth Company false    
Entity Shell Company false    
Entity Public Float     $ 9,810,678
Entity Common Stock, Shares Outstanding   5,074,283  
Document Financial Statement Error Correction [Flag] false