LOANS HELD FOR INVESTMENT - Corporation's Residential Mortgage Loans by Origination Year Based on Original Loan-to-Value-Ratio (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable Recorded Investment [Line Items]
Loans held for investment	$ 9,366,216	$ 9,002,205
Puerto Rico and Virgin Islands regions [Member]
Financing Receivable Recorded Investment [Line Items]
Loans held for investment	7,356,082	7,128,277
Florida region [Member]
Financing Receivable Recorded Investment [Line Items]
Loans held for investment	2,010,134	1,873,928
Residential Portfolio Segment [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	35,988
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	122,815
Financing Receivable, Originated Two Years before Latest Fiscal Year	184,458
Financing Receivable, Originated Three Years before Latest Fiscal Year	173,091
Financing Receivable, Originated Four Years before Latest Fiscal Year	204,066
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	2,169,883
Financing Receivable, Revolving	0
Loans held for investment	2,890,301	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	18,356
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	66,321
Financing Receivable, Originated Two Years before Latest Fiscal Year	111,354
Financing Receivable, Originated Three Years before Latest Fiscal Year	73,975
Financing Receivable, Originated Four Years before Latest Fiscal Year	113,851
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	1,956,432
Financing Receivable, Revolving	0
Loans held for investment	2,340,289	2,367,587
Residential Portfolio Segment [Member] | Florida region [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	17,632
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	56,494
Financing Receivable, Originated Two Years before Latest Fiscal Year	73,104
Financing Receivable, Originated Three Years before Latest Fiscal Year	99,116
Financing Receivable, Originated Four Years before Latest Fiscal Year	90,215
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	213,451
Financing Receivable, Revolving	0
Loans held for investment	550,012	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	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	1,416
Financing Receivable, Originated Two Years before Latest Fiscal Year	3,831
Financing Receivable, Originated Three Years before Latest Fiscal Year	5,351
Financing Receivable, Originated Four Years before Latest Fiscal Year	10,934
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	131,400
Financing Receivable, Revolving	0
Loans held for investment	152,932	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	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	1,416
Financing Receivable, Originated Two Years before Latest Fiscal Year	3,831
Financing Receivable, Originated Three Years before Latest Fiscal Year	5,063
Financing Receivable, Originated Four Years before Latest Fiscal Year	10,934
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	130,507
Financing Receivable, Revolving	0
Loans held for investment	151,751	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	288
Financing Receivable, Originated Four Years before Latest Fiscal Year	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	893
Financing Receivable, Revolving	0
Loans held for investment	1,181	1,480
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans held for investment	2,737,369	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	2,188,538	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	548,831	564,706
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | Less than or equal to 90 percent [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	24,171
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	116,836
Financing Receivable, Originated Two Years before Latest Fiscal Year	165,183
Financing Receivable, Originated Three Years before Latest Fiscal Year	157,123
Financing Receivable, Originated Four Years before Latest Fiscal Year	171,810
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	1,534,644
Financing Receivable, Revolving	0
Loans held for investment	2,169,767	2,234,190
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | Less than or equal to 90 percent [Member] | Puerto Rico and Virgin Islands regions [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	10,830
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	62,391
Financing Receivable, Originated Two Years before Latest Fiscal Year	96,926
Financing Receivable, Originated Three Years before Latest Fiscal Year	63,239
Financing Receivable, Originated Four Years before Latest Fiscal Year	84,141
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	1,326,130
Financing Receivable, Revolving	0
Loans held for investment	1,643,657	1,684,340
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | Less than or equal to 90 percent [Member] | Florida region [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	13,341
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	54,445
Financing Receivable, Originated Two Years before Latest Fiscal Year	68,257
Financing Receivable, Originated Three Years before Latest Fiscal Year	93,884
Financing Receivable, Originated Four Years before Latest Fiscal Year	87,669
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	208,514
Financing Receivable, Revolving	0
Loans held for investment	526,110	549,850
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | Greater than 90 percent but less than or equal to 100 percent [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	11,817
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	3,628
Financing Receivable, Originated Two Years before Latest Fiscal Year	9,945
Financing Receivable, Originated Three Years before Latest Fiscal Year	7,487
Financing Receivable, Originated Four Years before Latest Fiscal Year	14,002
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	428,499
Financing Receivable, Revolving	0
Loans held for investment	475,378	475,675
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | Greater than 90 percent but less than or equal to 100 percent [Member] | Puerto Rico and Virgin Islands regions [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	7,526
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	1,579
Financing Receivable, Originated Two Years before Latest Fiscal Year	5,098
Financing Receivable, Originated Three Years before Latest Fiscal Year	2,543
Financing Receivable, Originated Four Years before Latest Fiscal Year	11,456
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	424,455
Financing Receivable, Revolving	0
Loans held for investment	452,657	460,879
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | Greater than 90 percent but less than or equal to 100 percent [Member] | Florida region [Member]
Financing Receivable Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	4,291
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	2,049
Financing Receivable, Originated Two Years before Latest Fiscal Year	4,847
Financing Receivable, Originated Three Years before Latest Fiscal Year	4,944
Financing Receivable, Originated Four Years before Latest Fiscal Year	2,546
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	4,044
Financing Receivable, Revolving	0
Loans held for investment	22,721	14,796
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | Greater than 100 percent [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	935
Financing Receivable, Originated Two Years before Latest Fiscal Year	5,499
Financing Receivable, Originated Three Years before Latest Fiscal Year	3,130
Financing Receivable, Originated Four Years before Latest Fiscal Year	7,320
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	75,340
Financing Receivable, Revolving	0
Loans held for investment	92,224	99,999
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | Greater than 100 percent [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	935
Financing Receivable, Originated Two Years before Latest Fiscal Year	5,499
Financing Receivable, Originated Three Years before Latest Fiscal Year	3,130
Financing Receivable, Originated Four Years before Latest Fiscal Year	7,320
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	75,340
Financing Receivable, Revolving	0
Loans held for investment	92,224	99,939
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member] | Greater than 100 percent [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	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	0
Financing Receivable, Revolving	0
Loans held for investment	$ 0	$ 60