DEBT SECURITIES (Tables)	6 Months Ended
DEBT SECURITIES (Tables)	Jun. 30, 2024
Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss [Table Text Block]	Quarter Ended June 30, 2024 2023 Private label MBS Puerto Rico Government Obligation Total Private label MBS Puerto Rico Government Obligation Total (In thousands) Beginning balance $ 116 $ 326 $ 442 $ 83 $ 366 $ 449 Provision for credit losses – expense (benefit) - 60 60 - (16) (16) Net recoveries 47 - 47 - - - ACL on available-for-sale debt securities $ 163 $ 386 $ 549 $ 83 $ 350 $ 433 Six-Month Period Ended June 30, 2024 2023 Private label MBS Puerto Rico Government Obligations Total Private label MBS Puerto Rico Government Obligations Total (In thousands) Beginning balance $ 116 $ 395 $ 511 $ 83 $ 375 $ 458 Provision for credit losses - benefit - (9) (9) - (25) (25) Net recoveries 47 - 47 - - - ACL on available-for-sale debt securities $ 163 $ 386 $ 549 $ 83 $ 350 $ 433
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Table Text Block]	Puerto Rico Municipal Bonds Quarter Ended June 30, 2024 2023 (In thousands) Beginning balance $ 1,235 $ 7,646 Provision for credit losses – expense 32 755 ACL on held-to-maturity debt securities $ 1,267 $ 8,401 Puerto Rico Municipal Bonds Six-Month Period Ended June 30, 2024 2023 (In thousands) Beginning Balance $ 2,197 $ 8,286 Provision for credit losses - (benefit) expense (930) 115 ACL on held-to-maturity debt securities $ 1,267 $ 8,401
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, 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 $ 100,370 $ - $ 2,156 $ - $ 98,214 0.70 After 1 to 5 years 19,901 - 1,042 - 18,859 0.65 U.S. government-sponsored entities' (“GSEs”) obligations: Due within one year 782,777 - 16,859 - 765,918 0.91 After 1 to 5 years 1,564,870 51 111,755 - 1,453,166 0.82 After 5 to 10 years 8,850 - 750 - 8,100 2.64 After 10 years 8,228 15 - - 8,243 5.69 Puerto Rico government obligation: After 10 years (3) 3,084 - 1,166 386 1,532 - United States and Puerto Rico government obligations 2,488,080 66 133,728 386 2,354,032 0.86 Mortgage-backed securities (“MBS”): Residential MBS: Freddie Mac (“FHLMC”) certificates: Due within one year 4 - - - 4 4.31 After 1 to 5 years 16,204 - 754 - 15,450 2.06 After 5 to 10 years 138,723 - 12,739 - 125,984 1.55 After 10 years 948,539 6 172,740 - 775,805 1.41 1,103,470 6 186,233 - 917,243 1.44 Ginnie Mae (“GNMA”) certificates: Due within one year 841 - 8 - 833 3.29 After 1 to 5 years 11,837 - 648 - 11,189 0.93 After 5 to 10 years 31,168 2 2,783 - 28,387 1.77 After 10 years 191,483 101 25,966 - 165,618 2.65 235,329 103 29,405 - 206,027 2.45 Fannie Mae (“FNMA”) certificates: After 1 to 5 years 26,921 - 1,236 - 25,685 2.11 After 5 to 10 years 272,851 - 23,789 - 249,062 1.74 After 10 years 988,450 2 165,091 - 823,361 1.36 1,288,222 2 190,116 - 1,098,108 1.45 Collateralized mortgage obligations (“CMOs”) issued or guaranteed by the FHLMC, FNMA, and GNMA: After 10 years 259,830 - 54,810 - 205,020 1.52 Private label: After 5 to 10 years 1,322 - 317 5 1,000 8.93 After 10 years 5,359 - 1,634 158 3,567 7.34 6,681 - 1,951 163 4,567 7.65 Total Residential MBS 2,893,532 111 462,515 163 2,430,965 1.55 Commercial MBS: After 1 to 5 years 44,240 9 7,121 - 37,128 2.18 After 5 to 10 years 22,121 - 2,795 - 19,326 2.16 After 10 years 146,191 - 31,331 - 114,860 1.98 Total Commercial MBS 212,552 9 41,247 - 171,314 2.04 Total MBS 3,106,084 120 503,762 163 2,602,279 1.58 Other: Due within one year 500 - - - 500 2.35 After 1 to 5 years 500 - - - 500 2.35 1,000 - - - 1,000 2.35 Total available-for-sale debt securities $ 5,595,164 $ 186 $ 637,490 $ 549 $ 4,957,311 1.26 (1) Excludes accrued interest receivable on available-for-sale debt securities that totaled $ 10.0 million as of June 30, 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 $ 465.5 million (amortized cost - $ 538.5 million) that was pledged at the FHLB as collateral for borrowings and letters of credit as well as $ 2.7 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, 2023 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 $ 80,314 $ - $ 2,144 $ - $ 78,170 0.66 After 1 to 5 years 60,239 - 3,016 - 57,223 0.75 U.S. GSEs’ obligations: Due within one year 542,847 - 15,832 - 527,015 0.77 After 1 to 5 years 1,899,620 49 135,347 - 1,764,322 0.86 After 5 to 10 years 8,850 - 687 - 8,163 2.64 After 10 years 8,891 8 2 - 8,897 5.49 Puerto Rico government obligation: After 10 years (3) 3,156 - 1,346 395 1,415 - United States and Puerto Rico government obligations 2,603,917 57 158,374 395 2,445,205 0.85 MBS: Residential MBS: FHLMC certificates: After 1 to 5 years 19,561 - 868 - 18,693 2.06 After 5 to 10 years 153,308 - 12,721 - 140,587 1.55 After 10 years 991,060 15 161,197 - 829,878 1.41 1,163,929 15 174,786 - 989,158 1.44 GNMA certificates: Due within one year 254 - 3 - 251 3.27 After 1 to 5 years 16,882 - 872 - 16,010 1.19 After 5 to 10 years 27,916 8 2,247 - 25,677 1.62 After 10 years 206,254 87 22,786 - 183,555 2.57 251,306 95 25,908 - 225,493 2.38 FNMA certificates: After 1 to 5 years 32,489 - 1,423 - 31,066 2.11 After 5 to 10 years 293,492 - 23,146 - 270,346 1.70 After 10 years 1,047,298 83 156,344 - 891,037 1.37 1,373,279 83 180,913 - 1,192,449 1.46 CMOs issued or guaranteed by the FHLMC, FNMA, and GNMA: After 10 years 273,539 - 52,263 - 221,276 1.54 Private label: After 10 years 7,086 - 2,185 116 4,785 7.66 Total Residential MBS 3,069,139 193 436,055 116 2,633,161 1.55 Commercial MBS: After 1 to 5 years 45,022 - 6,898 - 38,124 2.17 After 5 to 10 years 22,386 - 2,685 - 19,701 2.16 After 10 years 122,830 - 29,037 - 93,793 1.36 Total Commercial MBS 190,238 - 38,620 - 151,618 1.64 Total MBS 3,259,377 193 474,675 116 2,784,779 1.55 Total available-for-sale debt securities $ 5,863,294 $ 250 $ 633,049 $ 511 $ 5,229,984 1.24 (1) Excludes accrued interest receivable on available-for-sale debt securities that totaled $ 10.6 million as of December 31, 2023 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 $ 477.9 million (amortized cost - $ 527.2 million) that was pledged at the FHLB as collateral for borrowings and letters of credit as well as $ 2.8 billion (amortized cost - $ 3.2 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.
Schedule of Unrealized Loss on Investments [Table Text Block]	As of June 30, 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 $ 875 $ - $ 2,338,381 $ 132,562 $ 2,339,256 $ 132,562 Puerto Rico government obligation - - 1,532 1,166 (1) 1,532 1,166 MBS: Residential MBS: FHLMC 1,191 15 915,156 186,218 916,347 186,233 GNMA 11,188 123 188,231 29,282 199,419 29,405 FNMA 8,135 99 1,088,394 190,017 1,096,529 190,116 CMOs issued or guaranteed by the FHLMC, FNMA, and GNMA - - 202,963 54,810 202,963 54,810 Private label - - 4,567 1,951 (1) 4,567 1,951 Commercial MBS 28,715 428 136,652 40,819 165,367 41,247 $ 50,104 $ 665 $ 4,875,876 $ 636,825 $ 4,925,980 $ 637,490 (1) Unrealized losses do not include the credit loss component recorded as part of the ACL. As of June 30, 2024, the PRHFA bond and private label MBS had an ACL of $ 0.4 million and $ 0.2 million, respectively. As of December 31, 2023 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 $ 2,544 $ 2 $ 2,428,784 $ 157,026 $ 2,431,328 $ 157,028 Puerto Rico government obligation - - 1,415 1,346 (1) 1,415 1,346 MBS: Residential MBS: FHLMC 9 - 988,092 174,786 988,101 174,786 GNMA 12,257 100 202,390 25,808 214,647 25,908 FNMA - - 1,183,275 180,913 1,183,275 180,913 CMOs issued or guaranteed by the FHLMC, FNMA, and GNMA - - 221,276 52,263 221,276 52,263 Private label - - 4,785 2,185 (1) 4,785 2,185 Commercial MBS 11,370 18 140,248 38,602 151,618 38,620 $ 26,180 $ 120 $ 5,170,265 $ 632,929 $ 5,196,445 $ 633,049 (1) Unrealized losses do not include the credit loss component recorded as part of the ACL. As of December 31, 2023, the PRHFA bond and private label MBS had an ACL of $ 0.4 million and $ 0.1 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, 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 $ 3,178 $ - $ 18 $ 3,160 $ 37 9.30 After 1 to 5 years 51,424 972 620 51,776 468 7.72 After 5 to 10 years 36,253 3,393 201 39,445 451 7.03 After 10 years 16,595 350 - 16,945 311 8.78 Total Puerto Rico municipal bonds 107,450 4,715 839 111,326 1,267 7.70 MBS: Residential MBS: FHLMC certificates: After 5 to 10 years 14,243 - 578 13,665 - 3.03 After 10 years 17,879 - 1,146 16,733 - 4.35 32,122 - 1,724 30,398 - 3.76 GNMA certificates: After 10 years 15,047 - 951 14,096 - 3.30 FNMA certificates: After 10 years 64,591 - 3,927 60,664 - 4.19 CMOs issued or guaranteed by FHLMC, FNMA, and GNMA: After 10 years 26,855 - 1,640 25,215 - 3.49 Total Residential MBS 138,615 - 8,242 130,373 - 3.86 Commercial MBS: After 1 to 5 years 9,352 - 301 9,051 - 3.48 After 10 years 89,018 - 6,078 82,940 - 3.15 Total Commercial MBS 98,370 - 6,379 91,991 - 3.18 Total MBS 236,985 - 14,621 222,364 - 3.58 Total held-to-maturity debt securities $ 344,435 $ 4,715 $ 15,460 $ 333,690 $ 1,267 4.86 (1) Excludes accrued interest receivable on held-to-maturity debt securities that totaled $ 4.8 million as of June 30, 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 $ 189.7 million (fair value - $ 184.4 million) that serves as collateral for the uninsured portion of government deposits. The secured parties are not permitted to sell or repledge the collateral. December 31, 2023 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 $ 3,165 $ 8 $ 38 $ 3,135 $ 50 9.30 After 1 to 5 years 51,230 994 710 51,514 1,266 7.78 After 5 to 10 years 36,050 3,540 210 39,380 604 7.13 After 10 years 16,595 269 - 16,864 277 8.87 Total Puerto Rico municipal bonds 107,040 4,811 958 110,893 2,197 7.78 MBS: Residential MBS: FHLMC certificates: After 5 to 10 years 16,469 - 556 15,913 - 3.03 After 10 years 18,324 - 714 17,610 - 4.32 34,793 - 1,270 33,523 - 3.71 GNMA certificates: After 10 years 16,265 - 789 15,476 - 3.32 FNMA certificates: After 10 years 67,271 - 2,486 64,785 - 4.18 CMOs issued or guaranteed by FHLMC, FNMA, and GNMA: After 10 years 28,139 - 1,274 26,865 - 3.49 Total Residential MBS 146,468 - 5,819 140,649 - 3.84 Commercial MBS: After 1 to 5 years 9,444 - 297 9,147 - 3.48 After 10 years 91,226 - 5,783 85,443 - 3.15 Total Commercial MBS 100,670 - 6,080 94,590 - 3.18 Total MBS 247,138 - 11,899 235,239 - 3.57 Total held-to-maturity debt securities $ 354,178 $ 4,811 $ 12,857 $ 346,132 $ 2,197 4.84 (1) Excludes accrued interest receivable on held-to-maturity debt securities that totaled $ 4.8 million as of December 31, 2023 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 $ 126.6 million (fair value - $ 125.9 million) that serves as collateral for the uninsured portion of government deposits. The secured parties are not permitted to sell or repledge the collateral.
Schedule of Unrealized Loss on Investments [Table Text Block]	As of June 30, 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 $ - $ - $ 26,147 $ 839 $ 26,147 $ 839 MBS: Residential MBS: FHLMC certificates - - 30,398 1,724 30,398 1,724 GNMA certificates - - 14,096 951 14,096 951 FNMA certificates - - 60,664 3,927 60,664 3,927 CMOs issued or guaranteed by FHLMC, FNMA, and GNMA - - 25,215 1,640 25,215 1,640 Commercial MBS - - 91,991 6,379 91,991 6,379 Total held-to-maturity debt securities $ - $ - $ 248,511 $ 15,460 $ 248,511 $ 15,460 As of December 31, 2023 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 $ - $ - $ 34,682 $ 958 $ 34,682 $ 958 MBS: Residential MBS: FHLMC certificates - - 33,523 1,270 33,523 1,270 GNMA certificates - - 15,476 789 15,476 789 FNMA certificates - - 64,785 2,486 64,785 2,486 CMOs issued or guaranteed by FHLMC, FNMA, and GNMA - - 26,865 1,274 26,865 1,274 Commercial MBS - - 94,590 6,080 94,590 6,080 Total held-to-maturity debt securities $ - $ - $ 269,921 $ 12,857 $ 269,921 $ 12,857