v3.26.1
DEBT SECURITIES - Additional Information (Details) - USD ($)
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Dec. 31, 2024
Schedule Of Investments [Line Items]        
Investments purchased, classified as available-for-sale debt securities $ 767,685,000 $ 12,264,000    
Proceeds from sales of available-for-sale debt securities 807,600,000      
Fair value 4,668,697,000   $ 4,554,032,000  
Gross Unrealized Losses 357,221,000   354,383,000  
Available-for-sale, allowance for credit losses 839,000 516,000 763,000 $ 521,000
Provision For Other Credit Losses Previous Expected Credit Losses (88,000) 5,000    
Allowance for credit losses, Held-to-Maturity securities 641,000   733,000  
Provision for credit loss expense (4,000) 36,000    
Debt Securities, Held-to-maturity 257,522,000   265,296,000  
Accrued interest receivable on loans and investments 67,722,000   71,351,000  
Available-for-Sale Securities [Member]        
Schedule Of Investments [Line Items]        
Accrued interest receivable on loans and investments 11,400,000   9,400,000  
Held-to-Maturity Securities [Member]        
Schedule Of Investments [Line Items]        
Accrued interest receivable on loans and investments 1,800,000   3,200,000  
Past Due [Member]        
Schedule Of Investments [Line Items]        
Debt Securities, Held-to-maturity 0   0  
Puerto Rico government obligations [Member]        
Schedule Of Investments [Line Items]        
Available-for-sale, allowance for credit losses 308,000 340,000 318,000 345,000
Provision For Other Credit Losses Previous Expected Credit Losses 10,000 5,000    
Residential MBS [Member]        
Schedule Of Investments [Line Items]        
Fair value 3,131,706,000   2,948,895,000  
Gross Unrealized Losses 302,533,000   297,249,000  
Available-for-sale, allowance for credit losses 531,000   445,000  
Allowance for credit losses, Held-to-Maturity securities 0   0  
Debt Securities, Held-to-maturity 107,821,000   111,451,000  
Residential MBS [Member] | Private label [Member]        
Schedule Of Investments [Line Items]        
Fair value 3,113,000   3,266,000  
Gross Unrealized Losses 1,203,000   1,361,000  
Available-for-sale, allowance for credit losses 531,000 176,000 445,000 $ 176,000
Provision For Other Credit Losses Previous Expected Credit Losses $ (98,000) $ 0    
Debt Instrument Description Of Variable Rate Basis 3-month CME Term SOFR      
Commercial MBS [Member]        
Schedule Of Investments [Line Items]        
Fair value $ 198,211,000   203,063,000  
Gross Unrealized Losses 35,537,000   35,542,000  
Available-for-sale, allowance for credit losses 0   0  
Allowance for credit losses, Held-to-Maturity securities 0   0  
Debt Securities, Held-to-maturity 69,913,000   $ 72,944,000  
U S Treasury Securities [Member]        
Schedule Of Investments [Line Items]        
Proceeds from sales of available-for-sale debt securities $ 370,600,000      
Purchased debt securities available for sale average yield 3.65%      
Government Agencies Debt Securities [Member]        
Schedule Of Investments [Line Items]        
Proceeds from sales of available-for-sale debt securities $ 437,000,000.0      
Purchased debt securities available for sale average yield 4.57%