LOANS HELD FOR INVESTMENT - Corporation's Residential Mortgage Loans By Origination Year Based on Original Credit Score (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable Recorded Investment [Line Items]
Loans held for investment	$ 11,847,275	$ 9,002,205
Puerto Rico and Virgin Islands regions [Member]
Financing Receivable Recorded Investment [Line Items]
Loans held for investment	9,834,201	7,128,277
Florida region [Member]
Financing Receivable Recorded Investment [Line Items]
Loans held for investment	2,013,074	1,873,928
Residential Portfolio Segment [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	59,105
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	130,248
Financing Receivable, Originated Two Years before Latest Fiscal Year	188,166
Financing Receivable, Originated Three Years before Latest Fiscal Year	179,929
Financing Receivable, Originated Four Years before Latest Fiscal Year	217,522
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	2,861,743
Financing Receivable, Revolving	0
Loans held for investment	3,636,713	2,933,773
Residential Portfolio Segment [Member] | Puerto Rico and Virgin Islands regions [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	30,680
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	74,990
Financing Receivable, Originated Two Years before Latest Fiscal Year	121,271
Financing Receivable, Originated Three Years before Latest Fiscal Year	82,549
Financing Receivable, Originated Four Years before Latest Fiscal Year	129,927
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	2,660,942
Financing Receivable, Revolving	0
Loans held for investment	3,100,359	2,367,587
Residential Portfolio Segment [Member] | Florida region [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	28,425
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	55,258
Financing Receivable, Originated Two Years before Latest Fiscal Year	66,895
Financing Receivable, Originated Three Years before Latest Fiscal Year	97,380
Financing Receivable, Originated Four Years before Latest Fiscal Year	87,595
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	200,801
Financing Receivable, Revolving	0
Loans held for investment	536,354	566,186
Residential Portfolio Segment [Member] | FHA/VA government-guaranteed loans [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	235
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	2,124
Financing Receivable, Originated Two Years before Latest Fiscal Year	2,900
Financing Receivable, Originated Three Years before Latest Fiscal Year	5,274
Financing Receivable, Originated Four Years before Latest Fiscal Year	10,406
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	141,863
Financing Receivable, Revolving	0
Loans held for investment	162,802	123,909
Residential Portfolio Segment [Member] | FHA/VA government-guaranteed loans [Member] | Puerto Rico and Virgin Islands regions [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	235
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	2,124
Financing Receivable, Originated Two Years before Latest Fiscal Year	2,900
Financing Receivable, Originated Three Years before Latest Fiscal Year	4,987
Financing Receivable, Originated Four Years before Latest Fiscal Year	10,406
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	140,974
Financing Receivable, Revolving	0
Loans held for investment	161,626	122,429
Residential Portfolio Segment [Member] | FHA/VA government-guaranteed loans [Member] | Florida region [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	0
Financing Receivable, Originated Three Years before Latest Fiscal Year	287
Financing Receivable, Originated Four Years before Latest Fiscal Year	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	889
Financing Receivable, Revolving	0
Loans held for investment	1,176	1,480
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans held for investment	3,473,911	2,809,864
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | Puerto Rico and Virgin Islands regions [Member]
Financing Receivable Recorded Investment [Line Items]
Loans held for investment	2,938,733	2,245,158
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | Florida region [Member]
Financing Receivable Recorded Investment [Line Items]
Loans held for investment	535,178	564,706
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | FICO Score Less than 620 [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	154
Financing Receivable, Originated Two Years before Latest Fiscal Year	2,984
Financing Receivable, Originated Three Years before Latest Fiscal Year	55
Financing Receivable, Originated Four Years before Latest Fiscal Year	75
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	322,039
Financing Receivable, Revolving	0
Loans held for investment	325,307	290,239
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | FICO Score Less than 620 [Member] | Puerto Rico and Virgin Islands regions [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	154
Financing Receivable, Originated Two Years before Latest Fiscal Year	466
Financing Receivable, Originated Three Years before Latest Fiscal Year	55
Financing Receivable, Originated Four Years before Latest Fiscal Year	75
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	321,212
Financing Receivable, Revolving	0
Loans held for investment	321,962	286,754
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | FICO Score Less than 620 [Member] | Florida region [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	2,518
Financing Receivable, Originated Three Years before Latest Fiscal Year	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	827
Financing Receivable, Revolving	0
Loans held for investment	3,345	3,485
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | FICO Score Greater than or equal to 620 and less than 680 [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	4,662
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	8,180
Financing Receivable, Originated Two Years before Latest Fiscal Year	11,695
Financing Receivable, Originated Three Years before Latest Fiscal Year	17,222
Financing Receivable, Originated Four Years before Latest Fiscal Year	20,023
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	511,739
Financing Receivable, Revolving	0
Loans held for investment	573,521	467,930
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | FICO Score Greater than or equal to 620 and less than 680 [Member] | Puerto Rico and Virgin Islands regions [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	1,873
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	3,093
Financing Receivable, Originated Two Years before Latest Fiscal Year	8,052
Financing Receivable, Originated Three Years before Latest Fiscal Year	7,703
Financing Receivable, Originated Four Years before Latest Fiscal Year	8,526
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	494,428
Financing Receivable, Revolving	0
Loans held for investment	523,675	416,766
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | FICO Score Greater than or equal to 620 and less than 680 [Member] | Florida region [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	2,789
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	5,087
Financing Receivable, Originated Two Years before Latest Fiscal Year	3,643
Financing Receivable, Originated Three Years before Latest Fiscal Year	9,519
Financing Receivable, Originated Four Years before Latest Fiscal Year	11,497
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	17,311
Financing Receivable, Revolving	0
Loans held for investment	49,846	51,164
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | FICO Score Greater than or equal to 680 and less than 740 [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	18,473
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	42,364
Financing Receivable, Originated Two Years before Latest Fiscal Year	56,868
Financing Receivable, Originated Three Years before Latest Fiscal Year	54,974
Financing Receivable, Originated Four Years before Latest Fiscal Year	67,779
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	752,176
Financing Receivable, Revolving	0
Loans held for investment	992,634	777,835
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | FICO Score Greater than or equal to 680 and less than 740 [Member] | Puerto Rico and Virgin Islands regions [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	11,013
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	25,947
Financing Receivable, Originated Two Years before Latest Fiscal Year	42,268
Financing Receivable, Originated Three Years before Latest Fiscal Year	24,329
Financing Receivable, Originated Four Years before Latest Fiscal Year	39,764
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	708,342
Financing Receivable, Revolving	0
Loans held for investment	851,663	626,291
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | FICO Score Greater than or equal to 680 and less than 740 [Member] | Florida region [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	7,460
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	16,417
Financing Receivable, Originated Two Years before Latest Fiscal Year	14,600
Financing Receivable, Originated Three Years before Latest Fiscal Year	30,645
Financing Receivable, Originated Four Years before Latest Fiscal Year	28,015
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	43,834
Financing Receivable, Revolving	0
Loans held for investment	140,971	151,544
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | FICO Score Greater than or equal to 740 [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	35,735
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	77,426
Financing Receivable, Originated Two Years before Latest Fiscal Year	113,719
Financing Receivable, Originated Three Years before Latest Fiscal Year	102,404
Financing Receivable, Originated Four Years before Latest Fiscal Year	119,239
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	1,133,926
Financing Receivable, Revolving	0
Loans held for investment	1,582,449	1,273,860
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | FICO Score Greater than or equal to 740 [Member] | Puerto Rico and Virgin Islands regions [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	17,559
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	43,672
Financing Receivable, Originated Two Years before Latest Fiscal Year	67,585
Financing Receivable, Originated Three Years before Latest Fiscal Year	45,475
Financing Receivable, Originated Four Years before Latest Fiscal Year	71,156
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	995,986
Financing Receivable, Revolving	0
Loans held for investment	1,241,433	915,347
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | FICO Score Greater than or equal to 740 [Member] | Florida region [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	18,176
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	33,754
Financing Receivable, Originated Two Years before Latest Fiscal Year	46,134
Financing Receivable, Originated Three Years before Latest Fiscal Year	56,929
Financing Receivable, Originated Four Years before Latest Fiscal Year	48,083
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	137,940
Financing Receivable, Revolving	0
Loans held for investment	$ 341,016	$ 358,513