LOANS HELD FOR INVESTMENT - Additional Information (Detail) $ in Thousands		3 Months Ended		9 Months Ended
	Oct. 31, 2022 USD ($) numberofcontracts	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		$ 11,298,618		$ 11,298,618			$ 11,060,658
Financing Receivable, Troubled Debt Restructuring		387,700		387,700
Interest Receivable		61,108		61,108			61,507
Escrow Deposit Related To Loans Sold			$ 2,000		$ 2,000
Financing Receivable Allowance For Credit Losses		257,859	288,360	257,859	288,360	$ 252,152	269,030	$ 324,958	$ 385,887
Financing Receivable, Allowance for Credit Loss, Writeoff		14,062	34,366	39,369	68,466
Loans and finance leases		14,352	(8,734)	10,028	(49,479)
Interest Income Recognized on Nonaccrual Loans		300	400	1,000	1,700
United States [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		2,050,620		2,050,620			1,946,740
Performing loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Troubled Debt Restructuring		340,100		340,100			$ 363,400
Nonaccrual loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable Accrued Interest Writeoff		$ 500	400	$ 1,200	1,700
Collateral Pledged [Member] \| Weighted Average [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
LTV Coverage %		76.00%		76.00%			78.00%
Loans and Finance Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest Receivable		$ 47,400		$ 47,400			$ 48,100
Loans and Finance Receivables [Member] \| Puerto Rico [Member] \| Product Concentration Risk [Member] \| Loan Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk concentration				79.00%
Loans and Finance Receivables [Member] \| United States [Member] \| Product Concentration Risk [Member] \| Loan Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk concentration				18.00%
Loans and Finance Receivables [Member] \| USVI and BVI [Member] \| Product Concentration Risk [Member] \| Loan Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk concentration				3.00%
Commercial And Industrial Sector [Member] \| Puerto Rico [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Sale				$ 35,200
GNMA [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase (decrease) in loans				115,700	147,400
Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		2,830,974		2,830,974			2,978,895
Residential mortgage loans in process of foreclosure		76,100		$ 76,100
Loans Foreclosure Delinquency Threshold				120 days
Financing Receivable, Real Estate Acquired Through Foreclosure [Policy Text Block]				The Corporation commences the foreclosure process on residential real estate loans when a borrower becomes 120 days delinquent, in accordance with the requirements of the Consumer Financial Protection Bureau (“CFPB”). Foreclosure procedures and timelines vary depending on whether the property is located in a judicial or non-judicial state. Occasionally, foreclosures may be delayed due to, among other reasons, mandatory mediations, bankruptcy, court delays and title issues.
Financing Receivable Allowance For Credit Losses		65,079	83,226	$ 65,079	83,226	65,231	74,837	112,882	120,311
Financing Receivable, Allowance for Credit Loss, Writeoff		1,466	25,418	6,073	31,170
Loans and finance leases		755	(6,206)	(6,913)	$ (9,556)
Residential Portfolio Segment [Member] \| TDR [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in trial				1,600
Residential Portfolio Segment [Member] \| Government [Member] \| PRHFA [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		86,700		86,700			92,800
Residential Portfolio Segment [Member] \| United States [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		415,742		415,742			429,322
Residential Portfolio Segment [Member] \| Performing loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		2,787,938		2,787,938			2,923,768
Residential Portfolio Segment [Member] \| Performing loans [Member] \| United States [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		410,224		410,224			422,170
Residential Portfolio Segment [Member] \| Nonaccrual loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		43,036		43,036			55,127
Financing Receivable, Sale			54,500
Financing Receivable Significant Sales Book Value			52,500
Proceeds From Sale Of Loans Receivable			$ 31,500
Financing Receivable, Percent Of Book Value Before Reserves			58.00%		58.00%
Financing Receivable Allowance For Credit Losses			$ 20,900		$ 20,900
Financing Receivable, Allowance for Credit Loss, Writeoff			23,100
Loans and finance leases			2,100
Residential Portfolio Segment [Member] \| Nonaccrual loans [Member] \| United States [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		5,518		5,518			7,152
Residential Portfolio Segment [Member] \| PCD loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Residential mortgage loans in process of foreclosure		10,000		10,000
Residential Portfolio Segment [Member] \| Conventional residential mortgage loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		2,712,011		2,712,011			2,853,503
Residential Portfolio Segment [Member] \| Conventional residential mortgage loans [Member] \| TDR [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Troubled Debt Restructuring		242,400		242,400
Residential Portfolio Segment [Member] \| Conventional residential mortgage loans [Member] \| United States [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		414,996		414,996			428,582
Residential Portfolio Segment [Member] \| Conventional residential mortgage loans [Member] \| Performing loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		2,668,975		2,668,975			2,798,376
Residential Portfolio Segment [Member] \| Conventional residential mortgage loans [Member] \| Performing loans [Member] \| United States [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		409,478		409,478			421,430
Residential Portfolio Segment [Member] \| Conventional residential mortgage loans [Member] \| Nonaccrual loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		43,036		43,036			55,127
Residential Portfolio Segment [Member] \| Conventional residential mortgage loans [Member] \| Nonaccrual loans [Member] \| United States [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		5,518		5,518			7,152
Residential Portfolio Segment [Member] \| FHA/VA government-guaranteed loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		118,963		118,963			125,392
Residential mortgage loans in process of foreclosure		32,600		32,600
Financing Receivable, Troubled Debt Restructuring		54,800		54,800			57,600
Residential Portfolio Segment [Member] \| FHA/VA government-guaranteed loans [Member] \| United States [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		746		746			740
Residential Portfolio Segment [Member] \| FHA/VA government-guaranteed loans [Member] \| Performing loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		118,963		118,963			125,392
Residential Portfolio Segment [Member] \| FHA/VA government-guaranteed loans [Member] \| Performing loans [Member] \| United States [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		746		746			740
Residential Portfolio Segment [Member] \| FHA/VA government-guaranteed loans [Member] \| Nonaccrual loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		0		0			0
Residential Portfolio Segment [Member] \| FHA/VA government-guaranteed loans [Member] \| Nonaccrual loans [Member] \| United States [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		0		0			0
Residential Portfolio Segment [Member] \| FNMA and FHLMC Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Purchase				300	300
Residential Portfolio Segment [Member] \| FNMA and FHLMC Loans \| Performing loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Sale				90,800	259,600
Residential Portfolio Segment [Member] \| GNMA [Member] \| Repurchase Option Program [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		8,100		8,100			7,200
Financing Receivable, Purchase				8,200	400
Commercial Portfolio Segment [Member] \| Criticized [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Sale					28,000
Commercial Portfolio Segment [Member] \| Puerto Rico [Member] \| Government [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		158,400		158,400			178,400
Commercial Portfolio Segment [Member] \| Puerto Rico [Member] \| Government [Member] \| Municipalities Borrower [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		28,000		28,000
Commercial Portfolio Segment [Member] \| Puerto Rico [Member] \| Government [Member] \| PREPA [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		11,500		11,500
Commercial Portfolio Segment [Member] \| Puerto Rico [Member] \| Government [Member] \| Property Tax Revenue [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		89,900		89,900
Commercial Portfolio Segment [Member] \| Puerto Rico [Member] \| Government [Member] \| Municipal Special Obligation Bond [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		29,000		29,000
Commercial Portfolio Segment [Member] \| USVI [Member] \| Government [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		37,600		37,600			39,200
Commercial Portfolio Segment [Member] \| Natural Disaster Deferral Or Extension Program [Member] \| Subsequent Event [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	$ 63,600
Deferral or extension agreements \| numberofcontracts	3,366
Commercial Portfolio Segment [Member] \| Construction loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		123,994		123,994			138,999
Financing Receivable Allowance For Credit Losses		1,821	5,319	1,821	5,319	2,020	4,048	4,757	5,380
Financing Receivable, Allowance for Credit Loss, Writeoff		63	7	123	52
Loans and finance leases		(179)	527	(2,242)	(125)
Commercial Portfolio Segment [Member] \| Construction loans [Member] \| TDR [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Troubled Debt Restructuring		1,300		1,300
Commercial Portfolio Segment [Member] \| Construction loans [Member] \| United States [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		96,278		96,278			95,866
Commercial Portfolio Segment [Member] \| Mortgage Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		2,265,614		2,265,614			2,167,469
Financing Receivable Allowance For Credit Losses		30,290	67,406	30,290	67,406	32,619	52,771	72,452	109,342
Financing Receivable, Allowance for Credit Loss, Writeoff		3	429	42	1,304
Loans and finance leases		(2,383)	(4,660)	(23,758)	(40,779)
Commercial Portfolio Segment [Member] \| Mortgage Receivable [Member] \| TDR [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Troubled Debt Restructuring		64,200		64,200
Commercial Portfolio Segment [Member] \| Mortgage Receivable [Member] \| United States [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		511,167		511,167			465,238
Commercial Portfolio Segment [Member] \| Commercial And Industrial Sector [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		2,858,286		2,858,286			2,887,251
Financing Receivable Allowance For Credit Losses		35,461	33,348	35,461	33,348	36,203	34,284	37,470	37,944
Financing Receivable, Allowance for Credit Loss, Writeoff		8	167	366	1,036
Loans and finance leases		(1,228)	(4,449)	(575)	(10,187)
Commercial Portfolio Segment [Member] \| Commercial And Industrial Sector [Member] \| TDR [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Troubled Debt Restructuring		67,200		67,200
Commercial Portfolio Segment [Member] \| Commercial And Industrial Sector [Member] \| United States [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		1,016,120		1,016,120			940,654
Financing Receivable, Purchase				135,400	78,100
Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		3,219,750		3,219,750			2,888,044
Financing Receivable Allowance For Credit Losses		125,208	99,061	125,208	99,061	$ 116,079	103,090	$ 97,397	$ 112,910
Financing Receivable, Allowance for Credit Loss, Writeoff		12,522	8,345	32,765	34,904
Loans and finance leases		17,387	$ 6,054	43,516	$ 11,168
Consumer Portfolio Segment [Member] \| TDR [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Troubled Debt Restructuring		12,600		12,600
Outstanding unfunded commitments on TDR loans		16		16
Consumer Portfolio Segment [Member] \| United States [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		11,313		11,313			15,660
Consumer Portfolio Segment [Member] \| Performing loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		3,206,963		3,206,963			2,877,590
Consumer Portfolio Segment [Member] \| Performing loans [Member] \| United States [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		11,179		11,179			15,527
Consumer Portfolio Segment [Member] \| Nonaccrual loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		12,787		12,787			10,454
Consumer Portfolio Segment [Member] \| Nonaccrual loans [Member] \| United States [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		$ 134		$ 134			$ 133