v3.25.2
Cover - USD ($)
$ in Millions
 12 Months Ended
Jun. 30, 2025
Aug. 19, 2025
Dec. 31, 2024
Cover [Abstract]      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Jun. 30, 2025    
Current Fiscal Year End Date --06-30    
Document Transition Report false    
Entity File Number 001-37399    
Entity Registrant Name KEARNY FINANCIAL CORP.    
Entity Incorporation, State or Country Code MD    
Entity Tax Identification Number 30-0870244    
Entity Address, Address Line One 120 Passaic Avenue    
Entity Address, City or Town Fairfield    
Entity Address, State or Province NJ    
Entity Address, Postal Zip Code 07004    
City Area Code 973    
Local Phone Number 244-4500    
Title of 12(b) Security Common Stock, $0.01 par value    
Trading Symbol KRNY    
Security Exchange Name NASDAQ    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Accelerated Filer    
Entity Small Business false    
Entity Emerging Growth Company false    
ICFR Auditor Attestation Flag true    
Document Financial Statement Error Correction [Flag] false    
Entity Shell Company false    
Entity Public Float     $ 418.2
Entity Common Stock, Shares Outstanding   64,744,523  
Documents Incorporated by Reference Portions of the definitive Proxy Statement for the Registrant’s 2025 Annual Meeting of Stockholders. (Part III)    
Entity Central Index Key 0001617242    
Document Fiscal Year Focus 2025    
Document Fiscal Period Focus FY    
Amendment Flag false    
Auditor Name Crowe LLP