LOANS HELD FOR INVESTMENT - Corporation's nonaccrual status and loans 90 days or more still accruing (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	$ 33,735		$ 33,735		$ 46,736
Nonaccrual Loans with ACL	88,406		88,406		158,353
Total Nonaccrual Loans	122,141		122,141		205,089
Loans Past Due 90 days or more Still Accruing	148,082		148,082		145,095
Interest Income Recognized on Nonaccrual Loans	406	$ 412	1,700	$ 1,497
Puerto Rico and Virgin Islands regions [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	33,244		33,244		43,591
Nonaccrual Loans with ACL	78,972		78,972		145,691
Total Nonaccrual Loans	112,216		112,216		189,282
Loans Past Due 90 days or more Still Accruing	147,832		147,832		144,845
Interest Income Recognized on Nonaccrual Loans	343	374	1,468	1,307
Florida region [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	491		491		3,145
Nonaccrual Loans with ACL	9,434		9,434		12,662
Total Nonaccrual Loans	9,925		9,925		15,807
Loans Past Due 90 days or more Still Accruing	250		250		250
Interest Income Recognized on Nonaccrual Loans	63	38	232	190
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	4,284		4,284		15,002
Nonaccrual Loans with ACL	56,305		56,305		110,365
Total Nonaccrual Loans	60,589		60,589		125,367
Loans Past Due 90 days or more Still Accruing	31,368		31,368		38,834
Interest Income Recognized on Nonaccrual Loans	244	288	1,203	969
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | Puerto Rico and Virgin Islands regions [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	4,284		4,284		12,418
Nonaccrual Loans with ACL	47,516		47,516		98,527
Total Nonaccrual Loans	51,800		51,800		110,945
Loans Past Due 90 days or more Still Accruing	31,368		31,368		38,834
Interest Income Recognized on Nonaccrual Loans	197	269	1,032	835
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | Florida region [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	0		0		2,584
Nonaccrual Loans with ACL	8,789		8,789		11,838
Total Nonaccrual Loans	8,789		8,789		14,422
Loans Past Due 90 days or more Still Accruing	0		0		0
Interest Income Recognized on Nonaccrual Loans	47	19	171	134
Residential Portfolio Segment [Member] | FHA/VA government-guaranteed loans [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	0		0		0
Nonaccrual Loans with ACL	0		0		0
Total Nonaccrual Loans	0		0		0
Loans Past Due 90 days or more Still Accruing	76,626		76,626		99,243
Interest Income Recognized on Nonaccrual Loans	0	0	0	0
Residential Portfolio Segment [Member] | FHA/VA government-guaranteed loans [Member] | Puerto Rico and Virgin Islands regions [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	0		0		0
Nonaccrual Loans with ACL	0		0		0
Total Nonaccrual Loans	0		0		0
Loans Past Due 90 days or more Still Accruing	76,376		76,376		98,993
Interest Income Recognized on Nonaccrual Loans	0	0	0	0
Residential Portfolio Segment [Member] | FHA/VA government-guaranteed loans [Member] | Florida region [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	0		0		0
Nonaccrual Loans with ACL	0		0		0
Total Nonaccrual Loans	0		0		0
Loans Past Due 90 days or more Still Accruing	250		250		250
Interest Income Recognized on Nonaccrual Loans	0	0	0	0
Commercial Portfolio Segment [Member] | Commercial And Industrial Sector [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	12,311		12,311		15,385
Nonaccrual Loans with ACL	6,679		6,679		5,496
Total Nonaccrual Loans	18,990		18,990		20,881
Loans Past Due 90 days or more Still Accruing	17,785		17,785		2,246
Interest Income Recognized on Nonaccrual Loans	51	43	136	119
Commercial Portfolio Segment [Member] | Commercial And Industrial Sector [Member] | Puerto Rico and Virgin Islands regions [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	11,820		11,820		14,824
Nonaccrual Loans with ACL	6,394		6,394		5,496
Total Nonaccrual Loans	18,214		18,214		20,320
Loans Past Due 90 days or more Still Accruing	17,785		17,785		2,246
Interest Income Recognized on Nonaccrual Loans	36	24	83	67
Commercial Portfolio Segment [Member] | Commercial And Industrial Sector [Member] | Florida region [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	491		491		561
Nonaccrual Loans with ACL	285		285		0
Total Nonaccrual Loans	776		776		561
Loans Past Due 90 days or more Still Accruing	0		0		0
Interest Income Recognized on Nonaccrual Loans	15	19	53	52
Commercial Portfolio Segment [Member] | Mortgage Receivable [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	9,626		9,626		11,777
Nonaccrual Loans with ACL	17,186		17,186		17,834
Total Nonaccrual Loans	26,812		26,812		29,611
Loans Past Due 90 days or more Still Accruing	19,593		19,593		3,252
Interest Income Recognized on Nonaccrual Loans	49	35	151	142
Commercial Portfolio Segment [Member] | Mortgage Receivable [Member] | Puerto Rico and Virgin Islands regions [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	9,626		9,626		11,777
Nonaccrual Loans with ACL	17,186		17,186		17,834
Total Nonaccrual Loans	26,812		26,812		29,611
Loans Past Due 90 days or more Still Accruing	19,593		19,593		3,252
Interest Income Recognized on Nonaccrual Loans	49	35	151	142
Commercial Portfolio Segment [Member] | Mortgage Receivable [Member] | Florida region [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	0		0		0
Nonaccrual Loans with ACL	0		0		0
Total Nonaccrual Loans	0		0		0
Loans Past Due 90 days or more Still Accruing	0		0		0
Interest Income Recognized on Nonaccrual Loans	0	0	0	0
Commercial Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	4,109		4,109		4,546
Nonaccrual Loans with ACL	1,984		1,984		8,425
Total Nonaccrual Loans	6,093		6,093		12,971
Loans Past Due 90 days or more Still Accruing	2		2		0
Interest Income Recognized on Nonaccrual Loans	16	19	48	61
Commercial Portfolio Segment [Member] | Construction Loans [Member] | Puerto Rico and Virgin Islands regions [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	4,109		4,109		4,546
Nonaccrual Loans with ACL	1,984		1,984		8,425
Total Nonaccrual Loans	6,093		6,093		12,971
Loans Past Due 90 days or more Still Accruing	2		2		0
Interest Income Recognized on Nonaccrual Loans	16	19	48	61
Commercial Portfolio Segment [Member] | Construction Loans [Member] | Florida region [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	0		0		0
Nonaccrual Loans with ACL	0		0		0
Total Nonaccrual Loans	0		0		0
Loans Past Due 90 days or more Still Accruing	0		0		0
Interest Income Recognized on Nonaccrual Loans	0	0	0	0
Consumer Portfolio Segment [Member] | Auto loans [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	3,137		3,137		26
Nonaccrual Loans with ACL	3,020		3,020		8,861
Total Nonaccrual Loans	6,157		6,157		8,887
Loans Past Due 90 days or more Still Accruing	0		0		0
Interest Income Recognized on Nonaccrual Loans	26	17	79	138
Consumer Portfolio Segment [Member] | Auto loans [Member] | Puerto Rico and Virgin Islands regions [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	3,137		3,137		26
Nonaccrual Loans with ACL	2,971		2,971		8,638
Total Nonaccrual Loans	6,108		6,108		8,664
Loans Past Due 90 days or more Still Accruing	0		0		0
Interest Income Recognized on Nonaccrual Loans	26	17	79	138
Consumer Portfolio Segment [Member] | Auto loans [Member] | Florida region [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	0		0		0
Nonaccrual Loans with ACL	49		49		223
Total Nonaccrual Loans	49		49		223
Loans Past Due 90 days or more Still Accruing	0		0		0
Interest Income Recognized on Nonaccrual Loans	0	0	0	0
Consumer Portfolio Segment [Member] | Finance Leases [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	251		251		0
Nonaccrual Loans with ACL	447		447		1,466
Total Nonaccrual Loans	698		698		1,466
Loans Past Due 90 days or more Still Accruing	0		0		0
Interest Income Recognized on Nonaccrual Loans	0	2	1	23
Consumer Portfolio Segment [Member] | Finance Leases [Member] | Puerto Rico and Virgin Islands regions [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	251		251		0
Nonaccrual Loans with ACL	447		447		1,466
Total Nonaccrual Loans	698		698		1,466
Loans Past Due 90 days or more Still Accruing	0		0		0
Interest Income Recognized on Nonaccrual Loans	0	2	1	23
Consumer Portfolio Segment [Member] | Finance Leases [Member] | Florida region [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	0		0		0
Nonaccrual Loans with ACL	0		0		0
Total Nonaccrual Loans	0		0		0
Loans Past Due 90 days or more Still Accruing	0		0		0
Interest Income Recognized on Nonaccrual Loans	0	0	0	0
Consumer Portfolio Segment [Member] | Personal Loans [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	1		1		0
Nonaccrual Loans with ACL	991		991		1,623
Total Nonaccrual Loans	992		992		1,623
Loans Past Due 90 days or more Still Accruing	0		0		0
Interest Income Recognized on Nonaccrual Loans	17	8	71	36
Consumer Portfolio Segment [Member] | Personal Loans [Member] | Puerto Rico and Virgin Islands regions [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	1		1		0
Nonaccrual Loans with ACL	991		991		1,623
Total Nonaccrual Loans	992		992		1,623
Loans Past Due 90 days or more Still Accruing	0		0		0
Interest Income Recognized on Nonaccrual Loans	17	8	71	36
Consumer Portfolio Segment [Member] | Personal Loans [Member] | Florida region [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	0		0		0
Nonaccrual Loans with ACL	0		0		0
Total Nonaccrual Loans	0		0		0
Loans Past Due 90 days or more Still Accruing	0		0		0
Interest Income Recognized on Nonaccrual Loans	0	0	0	0
Consumer Portfolio Segment [Member] | Credit cards [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	0		0		0
Nonaccrual Loans with ACL	0		0		0
Total Nonaccrual Loans	0		0		0
Loans Past Due 90 days or more Still Accruing	2,708		2,708		1,520
Interest Income Recognized on Nonaccrual Loans	0	0	0	0
Consumer Portfolio Segment [Member] | Credit cards [Member] | Puerto Rico and Virgin Islands regions [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	0		0		0
Nonaccrual Loans with ACL	0		0		0
Total Nonaccrual Loans	0		0		0
Loans Past Due 90 days or more Still Accruing	2,708		2,708		1,520
Interest Income Recognized on Nonaccrual Loans	0	0	0	0
Consumer Portfolio Segment [Member] | Credit cards [Member] | Florida region [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	0		0		0
Nonaccrual Loans with ACL	0		0		0
Total Nonaccrual Loans	0		0		0
Loans Past Due 90 days or more Still Accruing	0		0		0
Interest Income Recognized on Nonaccrual Loans	0	0	0	0
Consumer Portfolio Segment [Member] | Other Loans [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	16		16		0
Nonaccrual Loans with ACL	1,794		1,794		4,283
Total Nonaccrual Loans	1,810		1,810		4,283
Loans Past Due 90 days or more Still Accruing	0		0		0
Interest Income Recognized on Nonaccrual Loans	3	0	11	9
Consumer Portfolio Segment [Member] | Other Loans [Member] | Puerto Rico and Virgin Islands regions [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	16		16		0
Nonaccrual Loans with ACL	1,483		1,483		3,682
Total Nonaccrual Loans	1,499		1,499		3,682
Loans Past Due 90 days or more Still Accruing	0		0		0
Interest Income Recognized on Nonaccrual Loans	2	0	3	5
Consumer Portfolio Segment [Member] | Other Loans [Member] | Florida region [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans with No ACL	0		0		0
Nonaccrual Loans with ACL	311		311		601
Total Nonaccrual Loans	311		311		601
Loans Past Due 90 days or more Still Accruing	0		0		$ 0
Interest Income Recognized on Nonaccrual Loans	$ 1	$ 0	$ 8	$ 4