LOANS (Composition of Loan Portfolio) (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Jun. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	$ 7,750,576		$ 7,534,379
Allowance for credit losses	(161,500)		(161,106)	$ (157,529)
Total loans held for investment, net	7,589,076		7,373,273
Total loans held-for-sale	15,624		28,345
Total loans	7,604,700		7,401,618
Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	3,118,381		3,076,903
Allowance for credit losses	(37,024)			(42,899)
Total loans held-for-sale	4,716		28,345
Commercial loans | Puerto Rico
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	2,437,993		2,321,675
Commercial loans | UNITED STATES
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	680,388		755,228
Mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	1,483,612		1,562,609
Allowance for credit losses	(12,292)			(16,367)
Total loans held-for-sale	10,908		0
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	664,308		620,446
Allowance for credit losses	(31,314)			(26,460)
Auto loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	2,484,275		2,274,421
Allowance for credit losses	(80,870)			(71,803)
Non-PCD
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	6,765,832		6,463,127
Allowance for credit losses	(155,133)	$ (150,849)	(152,610)	(148,210)	$ (150,167)	$ (141,841)
Total loans held for investment, net	6,610,699		6,310,517
Total loans held-for-sale	15,624		28,345
Total loans	6,626,323		6,338,862
Non-PCD | Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	2,999,352		2,941,456
Allowance for credit losses	(36,077)	(33,809)	(44,041)	(41,627)	(48,604)	(39,158)
Total loans held-for-sale	4,716		28,345
Non-PCD | Commercial loans | Puerto Rico
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	2,318,964		2,186,228
Non-PCD | Commercial loans | UNITED STATES
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	680,388		755,228
Non-PCD | Mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	619,121		629,247
Allowance for credit losses	(6,890)	(6,886)	(7,998)	(8,364)	(8,670)	(9,571)
Total loans held-for-sale	10,908		0
Non-PCD | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	663,748		619,894
Allowance for credit losses	(31,303)	(29,432)	(27,086)	(26,453)	(25,666)	(23,264)
Non-PCD | Auto loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	2,483,611		2,272,530
Allowance for credit losses	(80,863)	(80,722)	(73,485)	(71,766)	(67,227)	(69,848)
PCD
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	984,744		1,071,252
Allowance for credit losses	(6,367)	(6,452)	(8,496)	(9,319)	(9,756)	(10,832)
Total loans held for investment, net	978,377		1,062,756
Total loans held-for-sale	0		0
Total loans	978,377		1,062,756
PCD | Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	119,029		135,447
Allowance for credit losses	(947)	(789)	(1,113)	(1,272)	(1,408)	(1,388)
Total loans held-for-sale	0		0
PCD | Commercial loans | Puerto Rico
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	119,029		135,447
PCD | Commercial loans | UNITED STATES
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	0		0
PCD | Mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	864,491		933,362
Allowance for credit losses	(5,402)	(5,642)	(7,351)	(8,003)	(8,297)	(9,359)
Total loans held-for-sale	0		0
PCD | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	560		552
Allowance for credit losses	(11)	(8)	(7)	(7)	(8)	(14)
PCD | Auto loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	664		1,891
Allowance for credit losses	(7)	$ (13)	(25)	$ (37)	$ (43)	$ (71)
Commercial secured by real estate | Commercial loans | Puerto Rico
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	1,288,069		1,216,195
Commercial secured by real estate | Non-PCD | Commercial loans | Puerto Rico
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	1,181,022		1,095,207
Commercial secured by real estate | PCD | Commercial loans | Puerto Rico
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	107,047		120,988
Other commercial and industrial | Commercial loans | Puerto Rico
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	1,149,924		1,105,480
Other commercial and industrial | Non-PCD | Commercial loans | Puerto Rico
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	1,137,942		1,091,021
Other commercial and industrial | PCD | Commercial loans | Puerto Rico
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	11,982		14,459
Commercial US | Non-PCD | Commercial loans | UNITED STATES
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	680,388		755,228
Personal loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	615,817		568,622
Personal loans | Non-PCD | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	615,566		568,358
Personal loans | PCD | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	251		264
Credit lines | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	10,786		11,214
Credit lines | Non-PCD | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	10,477		10,926
Credit lines | PCD | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	309		288
Credit cards | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	37,298		40,314
Credit cards | Non-PCD | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	37,298		40,314
Credit cards | PCD | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	0		0
Overdraft | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	407		296
Overdraft | Non-PCD | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	407		296
Overdraft | PCD | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	$ 0		$ 0