DEBT SECURITIES (Tables)	9 Months Ended
DEBT SECURITIES (Tables)	Sep. 30, 2023
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 September 30, 2023 2022 Private label MBS Puerto Rico Government Obligations Total Private label MBS Puerto Rico Government Obligations Total (In thousands) Beginning balance $ 83 $ 350 $ 433 $ 290 $ 386 $ 676 Provision for credit losses - expense (benefit) - 32 32 - (12) (12) ACL on available-for-sale debt securities $ 83 $ 382 $ 465 $ 290 $ 374 $ 664 Nine-Month Period Ended September 30, 2023 2022 Private label MBS Puerto Rico Government Obligations Total Private label MBS Puerto Rico Government Obligations Total (In thousands) Beginning balance $ 83 $ 375 $ 458 $ 797 $ 308 $ 1,105 Provision for credit losses - expense (benefit) - 7 7 (501) 66 (435) Net charge-offs - - - (6) - (6) ACL on available-for-sale debt securities $ 83 $ 382 $ 465 $ 290 $ 374 $ 664
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Table Text Block]	Puerto Rico Municipal Bonds Quarter Ended September 30, 2023 2022 (In thousands) Beginning Balance $ 8,401 $ 8,885 Provision for credit losses - benefit (6,151) (628) ACL on held-to-maturity debt securities $ 2,250 $ 8,257 Puerto Rico Municipal Bonds Nine-Month Period Ended September 30, 2023 2022 (In thousands) Beginning Balance $ 8,286 $ 8,571 Provision for credit losses - benefit (6,036) (314) ACL on held-to-maturity debt securities $ 2,250 $ 8,257
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]	The amortized cost, gross unrecognized gains and losses, estimated fair value, ACL, weighted-average yield and contractual maturities of held-to-maturity debt securities as of September 30, 2023 and December 31, 2022 were as follows September 30, 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 $ 3,159 $ 15 $ 23 $ 3,151 $ 46 9.30 After 1 to 5 years 51,133 1,052 1,111 51,074 1,320 7.71 After 5 to 10 years 35,831 3,540 271 39,100 605 7.05 After 10 years 16,595 212 - 16,807 279 8.75 Total Puerto Rico municipal bonds 106,718 4,819 1,405 110,132 2,250 7.70 MBS: Residential MBS: FHLMC certificates: After 5 to 10 years 17,580 - 1,131 16,449 - 3.03 After 10 years 18,740 - 1,689 17,051 - 4.34 36,320 - 2,820 33,500 - 3.70 GNMA certificates: After 10 years 16,786 - 1,414 15,372 - 3.35 FNMA certificates: After 10 years 68,388 - 5,902 62,486 - 4.17 CMOs issued or guaranteed by FHLMC, FNMA, and GNMA After 10 years 29,156 - 1,898 27,258 - 3.49 Total Residential MBS 150,650 - 12,034 138,616 - 3.84 Commercial MBS: After 1 to 5 years 9,489 - 516 8,973 - 3.48 After 10 years 92,312 - 7,182 85,130 - 3.15 Total Commercial MBS 101,801 - 7,698 94,103 - 3.18 Total MBS 252,451 - 19,732 232,719 - 3.57 Total held-to-maturity debt securities $ 359,169 $ 4,819 $ 21,137 $ 342,851 $ 2,250 4.80 (1) Excludes accrued interest receivable on held-to-maturity debt securities that totaled $ 2.8 million as of September 30, 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 $ 179.9 million (fair value - $ 174.9 million) that serves as collateral for the uninsured portion of government deposits. The secured parties are not permitted to sell or repledge the collateral. December 31, 2022 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 $ 1,202 $ - $ 15 $ 1,187 $ 2 5.20 After 1 to 5 years 42,530 886 1,076 42,340 656 6.34 After 5 to 10 years 55,956 3,182 360 58,778 3,243 6.29 After 10 years 66,022 - 1,318 64,704 4,385 7.10 Total held-to-maturity debt securities 165,710 4,068 2,769 167,009 8,286 6.62 MBS: Residential MBS: FHLMC certificates: After 5 to 10 years 21,443 - 746 20,697 - 3.03 After 10 years 19,362 - 888 18,474 - 4.21 40,805 - 1,634 39,171 - 3.59 GNMA certificates: After 10 years 19,131 - 943 18,188 - 3.35 FNMA certificates: After 10 years 72,347 - 3,155 69,192 - 4.14 CMOs issued or guaranteed by FHLMC, FNMA, and GNMA After 10 years 34,456 - 1,424 33,032 - 3.49 Total Residential MBS 166,739 - 7,156 159,583 - 3.78 Commercial MBS: After 1 to 5 years 9,621 - 396 9,225 - 3.48 After 10 years 95,467 - 4,169 91,298 - 3.15 Total Commercial MBS 105,088 - 4,565 100,523 - 3.18 Total MBS 271,827 - 11,721 260,106 - 3.55 Total held-to-maturity debt securities $ 437,537 $ 4,068 $ 14,490 $ 427,115 $ 8,286 4.71 (1) Excludes accrued interest receivable on held-to-maturity debt securities that totaled $ 5.5 million as of December 31, 2022 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 $ 190.1 million (fair value - $ 189.4 million) that serves as collateral for the uninsured portion of government deposits. The secured parties are not permitted to sell or repledge the collateral.
Schedule of Unrealized Loss on Investments [Table Text Block]	The following tables present the Corporation’s held-to-maturity debt securities’ fair value and gross unrecognized losses, aggregated by category and length of time that individual securities had been in a continuous unrecognized loss position, as of September 30, 2023 and December 31, 2022, including debt securities for which an ACL was recorded: As of September 30, 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 $ - $ - $ 34,244 $ 1,405 $ 34,244 $ 1,405 MBS: Residential MBS: FHLMC certificates - - 33,500 2,820 33,500 2,820 GNMA certificates - - 15,372 1,414 15,372 1,414 FNMA certificates - - 62,486 5,902 62,486 5,902 CMOs issued or guaranteed by FHLMC, FNMA, and GNMA - - 27,258 1,898 27,258 1,898 Commercial MBS - - 94,103 7,698 94,103 7,698 Total held-to-maturity debt securities $ - $ - $ 266,963 $ 21,137 $ 266,963 $ 21,137 As of December 31, 2022 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 $ - $ - $ 98,797 $ 2,769 $ 98,797 $ 2,769 MBS: Residential MBS: FHLMC certificates 39,171 1,634 - - 39,171 1,634 GNMA certificates 18,188 943 - - 18,188 943 FNMA certificates 69,192 3,155 - - 69,192 3,155 CMOs issued or guaranteed by FHLMC, FNMA, and GNMA 33,032 1,424 - - 33,032 1,424 Commercial MBS 100,523 4,565 - - 100,523 4,565 Total held-to-maturity debt securities $ 260,106 $ 11,721 $ 98,797 $ 2,769 $ 358,903 $ 14,490
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]	The amortized cost, gross unrealized gains and losses, ACL, estimated fair value, and weighted-average yield of available-for-sale debt securities by contractual maturities as of September 30, 2023 were as follows: September 30, 2023 Amortized cost (1) Gross ACL Fair value (2) Unrealized Weighted- Gains Losses average yield% (Dollars in thousands) U.S. Treasury securities: Due within one year $ 47,585 $ - $ 1,313 $ - $ 46,272 0.54 After 1 to 5 years 100,671 - 6,220 - 94,451 0.74 U.S. government-sponsored entities (“GSEs”) obligations: Due within one year 271,134 - 7,334 - 263,800 0.73 After 1 to 5 years 2,225,242 55 201,084 - 2,024,213 0.84 After 5 to 10 years 10,097 - 1,158 - 8,939 2.95 After 10 years 10,621 18 1 - 10,638 5.65 Puerto Rico government obligations: After 10 years (3) 3,204 - 1,374 382 1,448 - United States and Puerto Rico government obligations 2,668,554 73 218,484 382 2,449,761 0.84 Mortgage-backed securities (“MBS”): Residential MBS: Freddie Mac (“FHLMC”) certificates: After 1 to 5 years 21,356 - 1,205 - 20,151 2.06 After 5 to 10 years 160,407 - 18,393 - 142,014 1.55 After 10 years 1,013,862 - 211,720 - 802,142 1.40 1,195,625 - 231,318 - 964,307 1.43 Ginnie Mae (“GNMA”) certificates: After 1 to 5 years 19,559 - 1,207 - 18,352 1.27 After 5 to 10 years 28,587 - 3,127 - 25,460 1.59 After 10 years 212,835 - 33,476 - 179,359 2.58 260,981 - 37,810 - 223,171 2.38 Fannie Mae (“FNMA”) certificates: After 1 to 5 years 35,343 - 1,992 - 33,351 2.11 After 5 to 10 years 307,379 - 35,138 - 272,241 1.70 After 10 years 1,072,667 - 207,428 - 865,239 1.36 1,415,389 - 244,558 - 1,170,831 1.45 Collateralized mortgage obligations (“CMOs”) issued or guaranteed by the FHLMC, FNMA, and GNMA: After 10 years 280,056 - 62,888 - 217,168 1.54 Private label: After 10 years 7,311 - 2,310 83 4,918 7.73 Total Residential MBS 3,159,362 - 578,884 83 2,580,395 1.54 Commercial MBS: After 1 to 5 years 44,111 - 8,631 - 35,480 2.18 After 5 to 10 years 25,522 - 4,067 - 21,455 2.13 After 10 years 123,523 - 34,811 - 88,712 1.36 Total Commercial MBS 193,156 - 47,509 - 145,647 1.65 Total MBS 3,352,518 - 626,393 83 2,726,042 1.55 Total available-for-sale debt securities $ 6,021,072 $ 73 $ 844,877 $ 465 $ 5,175,803 1.24 (1) Excludes accrued interest receivable on available-for-sale debt securities that totaled $ 10.8 million as of September 30, 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 $ 521.3 million (amortized cost - $ 587.0 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 Puerto Rico Housing Finance Authority (“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, 2022 Amortized cost (1) Gross ACL Fair value (2) Unrealized Weighted- Gains Losses average yield% (Dollars in thousands) U.S. Treasury securities: Due within one year $ 7,493 $ - $ 309 $ - $ 7,184 0.22 After 1 to 5 years 141,366 - 9,675 - 131,691 0.70 U.S. GSEs’ obligations: Due within one year 129,018 - 4,036 - 124,982 0.32 After 1 to 5 years 2,395,273 22 227,724 - 2,167,571 0.83 After 5 to 10 years 56,251 13 7,670 - 48,594 1.54 After 10 years 12,170 36 - - 12,206 4.62 Puerto Rico government obligations: After 10 years (3) 3,331 - 755 375 2,201 - United States and Puerto Rico government obligations 2,744,902 71 250,169 375 2,494,429 0.83 MBS: Residential MBS: FHLMC certificates: After 1 to 5 years 4,235 - 169 - 4,066 2.33 After 5 to 10 years 201,072 - 18,709 - 182,363 1.55 After 10 years 1,092,289 - 186,558 - 905,731 1.38 1,297,596 - 205,436 - 1,092,160 1.41 GNMA certificates: Due within one year 5 - - - 5 1.73 After 1 to 5 years 15,508 - 622 - 14,886 2.00 After 5 to 10 years 45,322 1 3,809 - 41,514 1.31 After 10 years 232,632 51 27,169 - 205,514 2.47 293,467 52 31,600 - 261,919 2.27 FNMA certificates: After 1 to 5 years 9,685 - 521 - 9,164 1.76 After 5 to 10 years 358,346 - 31,620 - 326,726 1.68 After 10 years 1,186,635 124 186,757 - 1,000,002 1.38 1,554,666 124 218,898 - 1,335,892 1.45 CMOs issued or guaranteed by the FHLMC, FNMA, and GNMA: After 10 years 302,232 - 56,539 - 245,693 1.44 Private label: After 10 years 7,903 - 2,026 83 5,794 6.83 Total Residential MBS 3,455,864 176 514,499 83 2,941,458 1.52 Commercial MBS: After 1 to 5 years 30,578 - 4,463 - 26,115 2.43 After 5 to 10 years 44,889 - 5,603 - 39,286 1.89 After 10 years 121,464 - 23,732 - 97,732 1.23 Total Commercial MBS 196,931 - 33,798 - 163,133 1.56 Total MBS 3,652,795 176 548,297 83 3,104,591 1.52 Other Due within one year 500 - - - 500 0.84 Total available-for-sale debt securities $ 6,398,197 $ 247 $ 798,466 458 $ 5,599,520 1.22 (1) Excludes accrued interest receivable on available-for-sale debt securities that totaled $ 11.1 million as of December 31, 2022 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 $ 250.6 million (amortized cost - $ 286.5 million) that was pledged at the FHLB as collateral for borrowings and letters of credit as well as $ 2.4 billion (amortized cost - $ 2.8 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]	The following tables present the fair value and gross unrealized losses of the Corporation’s available-for-sale debt securities, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, as of September 30, 2023 and December 31, 2022. The tables also include debt securities for which an ACL was recorded. As of September 30, 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 $ 3,204 $ 5 $ 2,430,083 $ 217,105 $ 2,433,287 $ 217,110 Puerto Rico government obligations - - 1,448 1,374 (1) 1,448 1,374 MBS: Residential MBS: FHLMC 12 1 964,295 231,317 964,307 231,318 GNMA 22,811 1,220 200,360 36,590 223,171 37,810 FNMA 9,195 191 1,161,636 244,367 1,170,831 244,558 CMOs issued or guaranteed by the FHLMC, FNMA, and GNMA - - 217,168 62,888 217,168 62,888 Private label - - 4,918 2,310 (1) 4,918 2,310 Commercial MBS 11,509 202 134,138 47,307 145,647 47,509 $ 46,731 $ 1,619 $ 5,114,046 $ 843,258 $ 5,160,777 $ 844,877 (1) Unrealized losses do not include the credit loss component recorded as part of the ACL. As of September 30, 2023, the PRHFA bond and private label MBS had an ACL of $ 0.4 million and $ 0.1 million, respectively. As of December 31, 2022 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 $ 298,313 $ 18,057 $ 2,174,724 $ 231,357 $ 2,473,037 $ 249,414 Puerto Rico government obligations - - 2,201 755 (1) 2,201 755 MBS: Residential MBS: FHLMC 260,524 45,424 831,637 160,012 1,092,161 205,436 GNMA 74,829 3,433 179,854 28,167 254,683 31,600 FNMA 405,977 49,479 920,200 169,419 1,326,177 218,898 CMOs issued or guaranteed by the FHLMC, FNMA, and GNMA 45,370 6,735 200,323 49,804 245,693 56,539 Private label - - 5,794 2,026 (1) 5,794 2,026 Commercial MBS 30,179 2,215 132,953 31,583 163,132 33,798 $ 1,115,192 $ 125,343 $ 4,447,686 $ 673,123 $ 5,562,878 $ 798,466 (1) Unrealized losses do not include the credit loss component recorded as part of the ACL. As of December 31, 2022, the PRHFA bond and private label MBS had an ACL of $ 0.4 million and $ 0.1 million, respectively.