v3.26.1
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) - USD ($)
$ / shares in Units, $ in Millions
12 Months Ended
Nov. 21, 2025
Jul. 15, 2021
Dec. 31, 2025
Nov. 24, 2025
Dec. 31, 2024
Lessee, Lease, Description [Line Items]          
Stock price per share   $ 10      
Gross offering proceeds   $ 277.7      
Charitable contribution in cash   $ 1.5      
Common shares purchased for ESOP   2,281,800      
Renewal or option to extend term (up to)     10 years    
Common stock, par value (in dollars per share)     $ 0.01   $ 0.01
Fulton Financial Corporation          
Lessee, Lease, Description [Line Items]          
Business combination, consideration transferred, equity interests issued and issuable, entity shares issued per acquiree share       $ 0.65  
Business combination, consideration transferred $ 243.0        
Fulton Financial Corporation          
Lessee, Lease, Description [Line Items]          
Common stock, par value (in dollars per share)       $ 2.50  
Minimum          
Lessee, Lease, Description [Line Items]          
Remaining lease terms     1 year    
Minimum | Performance Shares | Blue Foundry Bancorp 2022 Equity Incentive Plan (Equity Plan)          
Lessee, Lease, Description [Line Items]          
Percentage of target awarded     0.00%    
Maximum          
Lessee, Lease, Description [Line Items]          
Remaining lease terms     15 years    
Maximum | Performance Shares | Blue Foundry Bancorp 2022 Equity Incentive Plan (Equity Plan)          
Lessee, Lease, Description [Line Items]          
Percentage of target awarded     100.00%    
Public stock offering          
Lessee, Lease, Description [Line Items]          
Shares of common stock sold   27,772,500      
Donation of shares to Blue Foundry Charitable Foundation          
Lessee, Lease, Description [Line Items]          
Shares of common stock sold   750,000      
Blue Foundry Bancorp - NJ          
Lessee, Lease, Description [Line Items]          
Ownership interest percentage     100.00%