ALLOWANCE FOR CREDIT LOSSES (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Increase (decrease) in allowance for credit losses	$ 1,100
Provision related to growth in loan balances	4,000
Provision (recapture of) for credit losses	1,551	$ 6,324
PCD
Financing Receivable, Allowance for Credit Loss [Line Items]
Provision (recapture of) for credit losses	(6,848)	3,326
Recoveries	4,028	986
PCD \| Commercial loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Provision (recapture of) for credit losses	(3,875)	(2,492)
Recoveries	3,023	436
PCD \| Commercial loans \| Puerto Rico \| Government
Financing Receivable, Allowance for Credit Loss [Line Items]
Recoveries	2,800
PCD \| Mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Provision (recapture of) for credit losses	(2,848)	5,994
Recoveries	845	146
Non-PCD
Financing Receivable, Allowance for Credit Loss [Line Items]
Provision (recapture of) for credit losses	8,563	2,943
Recoveries	7,812	7,427
Non-PCD \| Commercial loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Provision (recapture of) for credit losses	5,187	1,542
Recoveries	192	430
Non-PCD \| Mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Provision (recapture of) for credit losses	(2,418)	(2,480)
Recoveries	2,074	615
COVID-19 Pandemic
Financing Receivable, Allowance for Credit Loss [Line Items]
Provision (recapture of) for credit losses		(3,700)
Improved Macroeconomic Conditions
Financing Receivable, Allowance for Credit Loss [Line Items]
Increase (decrease) in allowance for credit losses	(5,700)
Total Past Due \| Commercial loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Increase (decrease) in allowance for credit losses	4,200
Provision (recapture of) for credit losses		$ 3,500
Total Past Due \| Non-PCD \| Mortgage \| Loan sales
Financing Receivable, Allowance for Credit Loss [Line Items]
Recoveries	$ 1,100

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