LOANS HELD FOR INVESTMENT - Corporation's Residential Mortgage Loans By Origination Year Based on Original Loan-to-Value-Ratio (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	$ 11,777,289	$ 9,002,205
Puerto Rico and Virgin Islands regions [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	9,788,106	7,128,277
Florida region [Member}
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	1,989,183	1,873,928
Residential Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	82,522
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	124,261
Financing Receivable, Originated Two Years before Latest Fiscal Year	180,927
Financing Receivable, Originated Three Years before Latest Fiscal Year	169,816
Financing Receivable, Originated Four Years before Latest Fiscal Year	202,665
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	2,761,763
Financing Receivable, Revolving	0
Loans held for investment	3,521,954	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	39,911
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	71,663
Financing Receivable, Originated Two Years before Latest Fiscal Year	117,519
Financing Receivable, Originated Three Years before Latest Fiscal Year	78,018
Financing Receivable, Originated Four Years before Latest Fiscal Year	121,758
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	2,573,334
Financing Receivable, Revolving	0
Loans held for investment	3,002,203	2,367,587
Residential Portfolio Segment [Member] | Florida region [Member}
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Originated in Current Fiscal Year	42,611
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	52,598
Financing Receivable, Originated Two Years before Latest Fiscal Year	63,408
Financing Receivable, Originated Three Years before Latest Fiscal Year	91,798
Financing Receivable, Originated Four Years before Latest Fiscal Year	80,907
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	188,429
Financing Receivable, Revolving	0
Loans held for investment	519,751	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	278
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	2,416
Financing Receivable, Originated Two Years before Latest Fiscal Year	2,594
Financing Receivable, Originated Three Years before Latest Fiscal Year	4,639
Financing Receivable, Originated Four Years before Latest Fiscal Year	9,673
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	131,134
Financing Receivable, Revolving	0
Loans held for investment	150,734	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	278
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	2,416
Financing Receivable, Originated Two Years before Latest Fiscal Year	2,594
Financing Receivable, Originated Three Years before Latest Fiscal Year	4,354
Financing Receivable, Originated Four Years before Latest Fiscal Year	9,673
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	130,249
Financing Receivable, Revolving	0
Loans held for investment	149,564	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	285
Financing Receivable, Originated Four Years before Latest Fiscal Year	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	885
Financing Receivable, Revolving	0
Loans held for investment	1,170	1,480
Residential Portfolio Segment [Member] | Conventional residential mortgage loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	3,371,220	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	2,852,639	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	518,581	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	71,830
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	111,765
Financing Receivable, Originated Two Years before Latest Fiscal Year	161,738
Financing Receivable, Originated Three Years before Latest Fiscal Year	152,655
Financing Receivable, Originated Four Years before Latest Fiscal Year	166,880
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	1,861,719
Financing Receivable, Revolving	0
Loans held for investment	2,526,587	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	37,989
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	61,202
Financing Receivable, Originated Two Years before Latest Fiscal Year	101,157
Financing Receivable, Originated Three Years before Latest Fiscal Year	65,334
Financing Receivable, Originated Four Years before Latest Fiscal Year	88,292
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	1,675,203
Financing Receivable, Revolving	0
Loans held for investment	2,029,177	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	33,841
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	50,563
Financing Receivable, Originated Two Years before Latest Fiscal Year	60,581
Financing Receivable, Originated Three Years before Latest Fiscal Year	87,321
Financing Receivable, Originated Four Years before Latest Fiscal Year	78,588
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	186,516
Financing Receivable, Revolving	0
Loans held for investment	497,410	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	10,414
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	9,141
Financing Receivable, Originated Two Years before Latest Fiscal Year	11,146
Financing Receivable, Originated Three Years before Latest Fiscal Year	9,757
Financing Receivable, Originated Four Years before Latest Fiscal Year	18,750
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	687,012
Financing Receivable, Revolving	0
Loans held for investment	746,220	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	1,644
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	7,106
Financing Receivable, Originated Two Years before Latest Fiscal Year	8,319
Financing Receivable, Originated Three Years before Latest Fiscal Year	5,565
Financing Receivable, Originated Four Years before Latest Fiscal Year	16,431
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	685,984
Financing Receivable, Revolving	0
Loans held for investment	725,049	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	8,770
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	2,035
Financing Receivable, Originated Two Years before Latest Fiscal Year	2,827
Financing Receivable, Originated Three Years before Latest Fiscal Year	4,192
Financing Receivable, Originated Four Years before Latest Fiscal Year	2,319
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	1,028
Financing Receivable, Revolving	0
Loans held for investment	21,171	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	939
Financing Receivable, Originated Two Years before Latest Fiscal Year	5,449
Financing Receivable, Originated Three Years before Latest Fiscal Year	2,765
Financing Receivable, Originated Four Years before Latest Fiscal Year	7,362
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	81,898
Financing Receivable, Revolving	0
Loans held for investment	98,413	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	939
Financing Receivable, Originated Two Years before Latest Fiscal Year	5,449
Financing Receivable, Originated Three Years before Latest Fiscal Year	2,765
Financing Receivable, Originated Four Years before Latest Fiscal Year	7,362
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	81,898
Financing Receivable, Revolving	0
Loans held for investment	98,413	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