LOANS HELD FOR INVESTMENT - Additional Information IV (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	$ 12,311,448		$ 12,311,448	$ 12,185,483
Loans modified to borrowers experiencing financial difficulty	2,559	$ 2,180	40,135
Puerto Rico [Member] | Product Concentration Risk [Member] | Loans and Finance Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk concentration				80.00%
United States [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	2,103,118		2,103,118	$ 2,022,261
United States [Member] | Product Concentration Risk [Member] | Loans and Finance Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk concentration				17.00%
USVI and BVI [Member] | Product Concentration Risk [Member] | Loans and Finance Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk concentration				3.00%
Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	2,801,587		2,801,587	$ 2,821,726
Residential Portfolio Segment [Member] | Loans Insured or Guaranteed by US Government Authorities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	99,655		99,655	100,236
Loans modified to borrowers experiencing financial difficulty	1,100	$ 900
Residential Portfolio Segment [Member] | Puerto Rico [Member] | Government [Member] | Puerto Rico Housing Finance Authority [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	76,500		76,500	77,700
Residential Portfolio Segment [Member] | United States [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	474,347		474,347	465,720
Residential Portfolio Segment [Member] | United States [Member] | Loans Insured or Guaranteed by US Government Authorities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	701		701	943
Commercial Portfolio Segment [Member] | Puerto Rico [Member] | Government [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	203,500		203,500	187,700
Commercial Portfolio Segment [Member] | Puerto Rico [Member] | Government [Member] | Central Government [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	39,600		39,600
Commercial Portfolio Segment [Member] | Puerto Rico [Member] | Government [Member] | Property Tax Revenue [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	129,400		129,400
Commercial Portfolio Segment [Member] | Puerto Rico [Member] | Government [Member] | Municipal Special Obligation Bond [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	25,600		25,600
Commercial Portfolio Segment [Member] | Puerto Rico [Member] | Government [Member] | Puerto Rico Electric Power Authority [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	8,900		8,900
Commercial Portfolio Segment [Member] | V I [Member] | Government [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	$ 97,400		$ 97,400	$ 90,500