DEBT SECURITIES (Tables)	6 Months Ended
DEBT SECURITIES (Tables)	Jun. 30, 2025
Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]
ACL on Available-for-Sale Debt Securities [Table Text Block]	Quarter Ended June 30, 2025 2024 Private label MBS Puerto Rico Government Obligation Total Private label MBS Puerto Rico Government Obligation Total (In thousands) Beginning balance $ 176 $ 340 $ 516 $ 116 $ 326 $ 442 Provision for credit losses – (benefit) expense - (3) (3) - 60 60 Net recoveries - - - 47 - 47 ACL on available-for-sale debt securities $ 176 $ 337 $ 513 $ 163 $ 386 $ 549 Six-Month Period Ended June 30, 2025 2024 Private label MBS Puerto Rico Government Obligations Total Private label MBS Puerto Rico Government Obligations Total (In thousands) Beginning balance $ 176 $ 345 $ 521 $ 116 $ 395 $ 511 Provision for credit losses - benefit - (8) (8) - (9) (9) Net recoveries - - - 47 - 47 ACL on available-for-sale debt securities $ 176 $ 337 $ 513 $ 163 $ 386 $ 549
ACL on Held-to-Maturity Debt Securities [Table Text Block]	Puerto Rico Municipal Bonds Quarter Ended June 30, 2025 2024 (In thousands) Beginning balance $ 843 $ 1,235 Provision for credit losses – (benefit) expense (78) 32 ACL on held-to-maturity debt securities $ 765 $ 1,267 Puerto Rico Municipal Bonds Six-Month Period Ended June 30, 2025 2024 (In thousands) Beginning Balance $ 802 $ 2,197 Provision for credit losses - benefit (37) (930) ACL on held-to-maturity debt securities $ 765 $ 1,267
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]	June 30, 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 $ 217,634 $ 12 $ 214 $ - $ 217,432 3.94 U.S. government-sponsored entities' (“GSEs”) obligations: Due within one year 1,027,771 - 13,922 - 1,013,849 0.73 After 1 to 5 years 546,010 26 28,679 - 517,357 1.01 After 10 years 7,015 - 12 - 7,003 4.68 Puerto Rico government obligation: After 10 years (3) 2,833 - 920 337 1,576 - United States and Puerto Rico government obligations 1,801,263 38 43,747 337 1,757,217 1.21 Mortgage-backed securities (“MBS”): Residential MBS: Freddie Mac (“FHLMC”) certificates: After 1 to 5 years 11,321 - 274 - 11,047 2.14 After 5 to 10 years 141,349 - 10,269 - 131,080 1.46 After 10 years 868,484 428 136,249 - 732,663 1.58 1,021,154 428 146,792 - 874,790 1.57 Ginnie Mae (“GNMA”) certificates: Due within one year 153 - - - 153 2.61 After 1 to 5 years 5,863 - 203 - 5,660 0.72 After 5 to 10 years 60,226 4 4,414 - 55,816 1.74 After 10 years 149,091 76 19,182 - 129,985 2.94 215,333 80 23,799 - 191,614 2.54 Fannie Mae (“FNMA”) certificates: After 1 to 5 years 17,145 - 409 - 16,736 2.14 After 5 to 10 years 244,722 39 14,920 - 229,841 1.77 After 10 years 904,406 508 123,825 - 781,089 1.53 1,166,273 547 139,154 - 1,027,666 1.59 Collateralized mortgage obligations (“CMOs”) issued or guaranteed by the FHLMC, FNMA, and GNMA: After 10 years 484,723 1,724 44,570 - 441,877 3.32 Private label: After 5 to 10 years 5,447 - 1,490 176 3,781 6.57 Total Residential MBS 2,892,930 2,779 355,805 176 2,539,728 1.95 Commercial MBS: After 1 to 5 years 33,487 10 1,605 - 31,892 2.55 After 5 to 10 years 10,479 - 1,279 - 9,200 1.68 After 10 years 192,976 77 34,787 - 158,266 2.39 Total Commercial MBS 236,942 87 37,671 - 199,358 2.38 Total MBS 3,129,872 2,866 393,476 176 2,739,086 1.99 Other: Due within one year 500 - - - 500 2.35 Total available-for-sale debt securities $ 4,931,635 $ 2,904 $ 437,223 $ 513 $ 4,496,803 1.70 (1) Excludes accrued interest receivable on available-for-sale debt securities that totaled $ 8.8 million as of June 30, 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 $ 265.8 million (amortized cost - $ 304.4 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 June 30, 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 $ 104,471 $ 47 $ 1,545,519 $ 42,780 $ 1,649,990 $ 42,827 Puerto Rico government obligation - - 1,576 920 (1) 1,576 920 MBS: Residential MBS: FHLMC - - 829,030 146,792 829,030 146,792 GNMA 15,257 221 155,770 23,578 171,027 23,799 FNMA - - 969,968 139,154 969,968 139,154 CMOs issued or guaranteed by the FHLMC, FNMA, and GNMA 8,683 14 176,975 44,556 185,658 44,570 Private label - - 3,781 1,490 (1) 3,781 1,490 Commercial MBS 30,982 595 131,045 37,076 162,027 37,671 $ 159,393 $ 877 $ 3,813,664 $ 436,346 $ 3,973,057 $ 437,223 (1) Unrealized losses do not include the credit loss component recorded as part of the ACL. As of June 30, 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]	June 30, 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 $ 2,380 $ - $ 7 $ 2,373 $ 5 4.86 After 1 to 5 years 62,962 2,450 218 65,194 410 7.18 After 5 to 10 years 11,741 705 168 12,278 111 5.06 After 10 years 15,755 106 - 15,861 239 7.78 Total Puerto Rico municipal bonds 92,838 3,261 393 95,706 765 6.96 MBS: Residential MBS: FHLMC certificates: After 1 to 5 years 10,156 - 190 9,966 - 3.03 After 10 years 16,349 - 850 15,499 - 4.33 26,505 - 1,040 25,465 - 3.83 GNMA certificates: After 10 years 12,271 - 523 11,748 - 3.30 FNMA certificates: After 10 years 58,175 - 2,610 55,565 - 4.19 CMOs issued or guaranteed by FHLMC, FNMA, and GNMA: After 10 years 24,123 - 895 23,228 - 3.43 Total Residential MBS 121,074 - 5,068 116,006 - 3.87 Commercial MBS: Due within one year 9,160 - 86 9,074 - 3.48 After 10 years 84,214 - 5,154 79,060 - 1.90 Total Commercial MBS 93,374 - 5,240 88,134 - 2.06 Total MBS 214,448 - 10,308 204,140 - 3.08 Total held-to-maturity debt securities $ 307,286 $ 3,261 $ 10,701 $ 299,846 $ 765 4.25 (1) Excludes accrued interest receivable on held-to-maturity debt securities that totaled $ 3.8 million as of June 30, 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 $ 188.8 million (fair value - $ 185.7 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 June 30, 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 $ - $ - $ 22,209 $ 393 $ 22,209 $ 393 MBS: Residential MBS: FHLMC certificates - - 25,465 1,040 25,465 1,040 GNMA certificates - - 11,748 523 11,748 523 FNMA certificates - - 55,565 2,610 55,565 2,610 CMOs issued or guaranteed by FHLMC, FNMA, and GNMA - - 23,228 895 23,228 895 Commercial MBS - - 88,134 5,240 88,134 5,240 Total held-to-maturity debt securities $ - $ - $ 226,349 $ 10,701 $ 226,349 $ 10,701 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