DEBT SECURITIES (Tables)	3 Months Ended
DEBT SECURITIES (Tables)	Mar. 31, 2025
Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]
ACL on Available-for-Sale Debt Securities [Table Text Block]	Quarter Ended March 31, 2025 2024 Private label MBS Puerto Rico Government Obligation Total Private label MBS Puerto Rico Government Obligation Total (In thousands) Beginning balance $ 176 $ 345 $ 521 $ 116 $ 395 $ 511 Provision for credit losses – (benefit) - (5) (5) - (69) (69) ACL on available-for-sale debt securities $ 176 $ 340 $ 516 $ 116 $ 326 $ 442
ACL on Held-to-Maturity Debt Securities [Table Text Block]	Puerto Rico Municipal Bonds Quarter Ended March 31, 2025 2024 (In thousands) Beginning balance $ 802 $ 2,197 Provision for credit losses – expense (benefit) 41 (962) ACL on held-to-maturity debt securities $ 843 $ 1,235
Available-for-Sale Securities [Member]
Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]
Investments Classified by Contractual Maturity Date [Table Text Block]	March 31, 2025 Amortized cost (1) Gross Unrealized ACL Fair Value (2) Weighted- Gains Losses average yield% (Dollars in thousands) U.S. Treasury securities: Due within one year $ 19,960 $ - $ 348 $ - $ 19,612 0.65 U.S. government-sponsored entities' (“GSEs”) obligations: Due within one year 1,015,466 - 17,837 - 997,629 0.72 After 1 to 5 years 692,123 32 38,962 - 653,193 0.98 After 10 years 7,584 - 35 - 7,549 4.69 Puerto Rico government obligation: After 10 years (3) 2,899 - 960 340 1,599 - United States and Puerto Rico government obligations 1,738,032 32 58,142 340 1,679,582 0.84 Mortgage-backed securities (“MBS”): Residential MBS: Freddie Mac (“FHLMC”) certificates: After 1 to 5 years 12,881 - 346 - 12,535 2.14 After 5 to 10 years 116,041 - 8,184 - 107,857 1.52 After 10 years 912,039 341 147,069 - 765,311 1.52 1,040,961 341 155,599 - 885,703 1.53 Ginnie Mae (“GNMA”) certificates: Due within one year 392 - 2 - 390 2.46 After 1 to 5 years 6,889 - 267 - 6,622 0.72 After 5 to 10 years 64,042 3 5,001 - 59,044 1.84 After 10 years 139,482 49 19,576 - 119,955 2.78 210,805 52 24,846 - 186,011 2.43 Fannie Mae (“FNMA”) certificates: After 1 to 5 years 19,453 - 521 - 18,932 2.13 After 5 to 10 years 232,359 8 15,249 - 217,118 1.75 After 10 years 950,195 432 135,749 - 814,878 1.50 1,202,007 440 151,519 - 1,050,928 1.56 Collateralized mortgage obligations (“CMOs”) issued or guaranteed by the FHLMC, FNMA, and GNMA: After 10 years 361,783 624 47,198 - 315,209 2.82 Private label: After 5 to 10 years 5,905 - 1,695 176 4,034 6.60 Total Residential MBS 2,821,461 1,457 380,857 176 2,441,885 1.79 Commercial MBS: After 1 to 5 years 33,658 13 1,893 - 31,778 2.56 After 5 to 10 years 10,549 - 1,413 - 9,136 1.67 After 10 years 184,224 88 34,809 - 149,503 2.21 Total Commercial MBS 228,431 101 38,115 - 190,417 2.23 Total MBS 3,049,892 1,558 418,972 176 2,632,302 1.82 Other: Due within one year 1,000 - - - 1,000 2.31 Total available-for-sale debt securities $ 4,788,924 $ 1,590 $ 477,114 $ 516 $ 4,312,884 1.46 (1) Excludes accrued interest receivable on available-for-sale debt securities that totaled $ 9.0 million as of March 31, 2025 reported as part of accrued interest receivable on loans and investment securities in the consolidated statements of financial condition, and excluded from the estimate of credit losses. (2) Includes $ 467.4 million (amortized cost - $ 528.2 million) that was pledged at the FHLB as collateral for borrowings and letters of credit as well as $ 2.8 billion (amortized cost - $ 3.1 billion) pledged as collateral for the uninsured portion of government deposits. The secured parties are not permitted to sell or repledge the collateral. (3) Consists of a residential pass-through MBS issued by the Puerto Rico Housing Finance Authority (the “PRHFA”) that is collateralized by certain second mortgages originated under a program launched by the Puerto Rico government in 2010 and is in nonaccrual status based on the delinquency status of the underlying second mortgage loans collateral. December 31, 2024 Amortized cost (1) Gross Unrealized ACL Fair value (2) Weighted- Gains Losses average yield% (Dollars in thousands) U.S. Treasury securities: Due within one year $ 59,992 $ - $ 803 $ - $ 59,189 0.75 U.S. GSEs’ obligations: Due within one year 1,090,678 - 22,826 - 1,067,852 0.79 After 1 to 5 years 817,835 39 53,195 - 764,679 0.96 After 10 years 7,835 - 35 - 7,800 4.73 Puerto Rico government obligation: After 10 years (3) 2,951 - 986 345 1,620 - United States and Puerto Rico government obligations 1,979,291 39 77,845 345 1,901,140 0.87 MBS: Residential MBS: FHLMC certificates: After 1 to 5 years 14,477 - 460 - 14,017 2.14 After 5 to 10 years 122,548 - 9,977 - 112,571 1.52 After 10 years 936,531 25 168,691 - 767,865 1.51 1,073,556 25 179,128 - 894,453 1.52 GNMA certificates: Due within one year 881 - 6 - 875 2.68 After 1 to 5 years 8,025 - 350 - 7,675 0.71 After 5 to 10 years 67,181 - 6,125 - 61,056 1.86 After 10 years 142,330 16 22,041 - 120,305 2.78 218,417 16 28,522 - 189,911 2.42 FNMA certificates: After 1 to 5 years 21,921 - 689 - 21,232 2.13 After 5 to 10 years 244,966 - 18,874 - 226,092 1.74 After 10 years 979,366 16 159,560 - 819,822 1.51 1,246,253 16 179,123 - 1,067,146 1.56 CMOs issued or guaranteed by the FHLMC, FNMA, and GNMA: After 10 years 377,812 74 52,338 - 325,548 2.88 Private label: After 5 to 10 years 4,886 - 1,430 57 3,399 6.69 After 10 years 1,200 - 285 119 796 6.32 6,086 - 1,715 176 4,195 6.62 Total Residential MBS 2,922,124 131 440,826 176 2,481,253 1.79 Commercial MBS: After 1 to 5 years 33,835 13 2,286 - 31,562 2.59 After 5 to 10 years 10,621 - 1,653 - 8,968 1.67 After 10 years 178,537 - 37,158 - 141,379 2.06 Total Commercial MBS 222,993 13 41,097 - 181,909 2.12 Total MBS 3,145,117 144 481,923 176 2,663,162 1.82 Other Due within one year 1,000 - - - 1,000 2.32 Total available-for-sale debt securities $ 5,125,408 $ 183 $ 559,768 $ 521 $ 4,565,302 1.45 (1) Excludes accrued interest receivable on available-for-sale debt securities that totaled $ 9.6 million as of December 31, 2024 reported as part of accrued interest receivable on loans and investment securities in the consolidated statements of financial condition, and excluded from the estimate of credit losses. (2) Includes $ 466.1 million (amortized cost - $ 533.7 million) that was pledged at the FHLB as collateral for borrowings and letters of credit as well as $ 3.0 billion (amortized cost - $ 3.3 billion) pledged as collateral for the uninsured portion of government deposits. The secured parties are not permitted to sell or repledge the collateral. (3) Consists of a residential pass-through MBS issued by the PRHFA that is collateralized by certain second mortgages originated under a program launched by the Puerto Rico government in 2010 and is in nonaccrual status based on the delinquency status of the underlying second mortgage loans collateral.
Investments Fair Value and Gross Unrealized Losses [Table Text Block]	As of March 31, 2025 Less than 12 months 12 months or more Total Unrealized Unrealized Unrealized Fair Value Losses Fair Value Losses Fair Value Losses (In thousands) U.S. Treasury and U.S. GSEs’ obligations $ 8,099 $ 35 $ 1,664,851 $ 57,147 $ 1,672,950 $ 57,182 Puerto Rico government obligation - - 1,599 960 (1) 1,599 960 MBS: Residential MBS: FHLMC 1,188 1 851,798 155,598 852,986 155,599 GNMA 15,671 196 162,660 24,650 178,331 24,846 FNMA - - 999,306 151,519 999,306 151,519 CMOs issued or guaranteed by the FHLMC, FNMA, and GNMA 3,094 1 184,045 47,197 187,139 47,198 Private label - - 4,034 1,695 (1) 4,034 1,695 Commercial MBS 20,856 444 132,121 37,671 152,977 38,115 $ 48,908 $ 677 $ 4,000,414 $ 476,437 $ 4,049,322 $ 477,114 (1) Unrealized losses do not include the credit loss component recorded as part of the ACL. As of March 31, 2025, the PRHFA bond and private label MBS had an ACL of $ 0.3 million and $ 0.2 million, respectively. As of December 31, 2024 Less than 12 months 12 months or more Total Unrealized Unrealized Unrealized Fair Value Losses Fair Value Losses Fair Value Losses (In thousands) U.S. Treasury and U.S. GSEs’ obligations $ 8,005 $ 35 $ 1,886,046 $ 76,824 $ 1,894,051 $ 76,859 Puerto Rico government obligation - - 1,620 986 (1) 1,620 986 MBS: Residential MBS: FHLMC 36,224 85 857,492 179,043 893,716 179,128 GNMA 22,281 508 166,470 28,014 188,751 28,522 FNMA 53,325 132 1,012,331 178,991 1,065,656 179,123 CMOs issued or guaranteed by the FHLMC, FNMA, and GNMA 52,778 248 187,772 52,090 240,550 52,338 Private label - - 4,195 1,715 (1) 4,195 1,715 Commercial MBS 44,831 823 131,152 40,274 175,983 41,097 $ 217,444 $ 1,831 $ 4,247,078 $ 557,937 $ 4,464,522 $ 559,768 (1) Unrealized losses do not include the credit loss component recorded as part of the ACL. As of December 31, 2024, the PRHFA bond and private label MBS had an ACL of $ 0.3 million and $ 0.2 million, respectively.
Held-to-Maturity Securities [Member]
Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]
Investments Classified by Contractual Maturity Date [Table Text Block]	March 31, 2025 Amortized cost (1) (2) Gross Unrecognized Fair value Weighted- Gains Losses ACL average yield% (Dollars in thousands) Puerto Rico municipal bonds: Due within one year $ 2,297 $ 65 $ 5 $ 2,357 $ 6 4.87 After 1 to 5 years 62,792 2,797 253 65,336 464 7.19 After 5 to 10 years 11,678 771 164 12,285 121 5.07 After 10 years 15,755 275 - 16,030 252 7.78 Total Puerto Rico municipal bonds 92,522 3,908 422 96,008 843 6.97 MBS: Residential MBS: FHLMC certificates: After 1 to 5 years 11,120 - 239 10,881 - 3.03 After 10 years 16,654 - 880 15,774 - 4.33 27,774 - 1,119 26,655 - 3.81 GNMA certificates: After 10 years 12,987 - 605 12,382 - 3.30 FNMA certificates: After 10 years 59,962 - 2,759 57,203 - 4.19 CMOs issued or guaranteed by FHLMC, FNMA, and GNMA: After 10 years 24,833 - 1,060 23,773 - 3.49 Total Residential MBS 125,556 - 5,543 120,013 - 3.88 Commercial MBS: After 1 to 5 years 9,209 - 109 9,100 - 3.48 After 10 years 85,520 - 5,140 80,380 - 1.90 Total Commercial MBS 94,729 - 5,249 89,480 - 2.05 Total MBS 220,285 - 10,792 209,493 - 3.09 Total held-to-maturity debt securities $ 312,807 $ 3,908 $ 11,214 $ 305,501 $ 843 4.24 (1) Excludes accrued interest receivable on held-to-maturity debt securities that totaled $ 2.3 million as of March 31, 2025 reported as part of accrued interest receivable on loans and investment securities in the consolidated statements of financial condition, and excluded from the estimate of credit losses. (2) Includes $ 150.3 million (fair value - $ 148.8 million) that serves as collateral for the uninsured portion of government deposits. The secured parties are not permitted to sell or repledge the collateral. December 31, 2024 Amortized cost (1) (2) Gross Unrecognized Fair value Weighted- Gains Losses ACL average yield% (Dollars in thousands) Puerto Rico municipal bonds: Due within one year $ 2,214 $ 134 $ 6 $ 2,342 $ 6 5.07 After 1 to 5 years 61,289 2,724 438 63,575 433 7.33 After 5 to 10 years 13,184 811 205 13,790 127 5.79 After 10 years 15,755 146 - 15,901 236 8.07 Total Puerto Rico municipal bonds 92,442 3,815 649 95,608 802 7.18 MBS: Residential MBS: FHLMC certificates: After 5 to 10 years 12,112 - 353 11,759 - 3.03 After 10 years 16,936 - 1,142 15,794 - 4.30 29,048 - 1,495 27,553 - 3.77 GNMA certificates: After 10 years 13,472 - 842 12,630 - 3.29 FNMA certificates: After 10 years 61,233 - 3,786 57,447 - 4.19 CMOs issued or guaranteed by FHLMC, FNMA, and GNMA: After 10 years 25,566 - 1,321 24,245 - 3.49 Total Residential MBS 129,319 - 7,444 121,875 - 3.86 Commercial MBS: After 1 to 5 years 9,258 - 151 9,107 - 3.48 After 10 years 86,767 - 5,317 81,450 - 3.92 Total Commercial MBS 96,025 - 5,468 90,557 - 3.88 Total MBS 225,344 - 12,912 212,432 - 3.87 Total held-to-maturity debt securities $ 317,786 $ 3,815 $ 13,561 $ 308,040 $ 802 4.83 (1) Excludes accrued interest receivable on held-to-maturity debt securities that totaled $ 4.1 million as of December 31, 2024 reported as part of accrued interest receivable on loans and investment securities in the consolidated statements of financial condition, and excluded from the estimate of credit losses. (2) Includes $ 198.6 million (fair value - $ 192.4 million) that serves as collateral for the uninsured portion of government deposits. The secured parties are not permitted to sell or repledge the collateral.
Investments Fair Value and Gross Unrealized Losses [Table Text Block]	As of March 31, 2025 Less than 12 months 12 months or more Total Unrecognized Unrecognized Unrecognized Fair Value Losses Fair Value Losses Fair Value Losses (In thousands) Puerto Rico municipal bonds $ - $ - $ 20,287 $ 422 $ 20,287 $ 422 MBS: Residential MBS: FHLMC certificates - - 26,655 1,119 26,655 1,119 GNMA certificates - - 12,382 605 12,382 605 FNMA certificates - - 57,203 2,759 57,203 2,759 CMOs issued or guaranteed by FHLMC, FNMA, and GNMA - - 23,773 1,060 23,773 1,060 Commercial MBS - - 89,480 5,249 89,480 5,249 Total held-to-maturity debt securities $ - $ - $ 229,780 $ 11,214 $ 229,780 $ 11,214 As of December 31, 2024 Less than 12 months 12 months or more Total Unrecognized Unrecognized Unrecognized Fair Value Losses Fair Value Losses Fair Value Losses (In thousands) Puerto Rico municipal bonds $ - $ - $ 20,071 $ 649 $ 20,071 $ 649 MBS: Residential MBS: FHLMC certificates - - 27,553 1,495 27,553 1,495 GNMA certificates - - 12,630 842 12,630 842 FNMA certificates - - 57,447 3,786 57,447 3,786 CMOs issued or guaranteed by FHLMC, FNMA, and GNMA - - 24,245 1,321 24,245 1,321 Commercial MBS - - 90,557 5,468 90,557 5,468 Total held-to-maturity debt securities $ - $ - $ 232,503 $ 13,561 $ 232,503 $ 13,561