INVESTMENT SECURITIES - Available-For-Sale Investments' Fair Value And Gross Unrealized Losses (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Schedule of Available-for-sale Securities [Line Items]
Fair Value Less than 12 months	$ 43,784	$ 278,893
Unrealized Losses Less than 12 months	650	1,634
Fair Value 12 months or more	36,886	358,629
Unrealized Losses 12 months or more	5,912	8,422
Total Fair Value	80,670	637,522
Total Unrealized Losses	6,562	10,056
Puerto Rico Government obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value Less than 12 months	0	0
Unrealized Losses Less than 12 months	0	0
Fair Value 12 months or more	2,969	2,974
Unrealized Losses 12 months or more	1,144	1,192
Total Fair Value	2,969	2,974
Total Unrealized Losses	1,144	1,192
U.S. Treasury and U.S. government agencies obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value Less than 12 months	3,213	45,073
Unrealized Losses Less than 12 months	1	172
Fair Value 12 months or more	22,280	99,764
Unrealized Losses 12 months or more	75	252
Total Fair Value	25,493	144,837
Total Unrealized Losses	76	424
Mortgage Backed Securities [Member] | FNMA [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value Less than 12 months		58,668
Unrealized Losses Less than 12 months		499
Fair Value 12 months or more		173,708
Unrealized Losses 12 months or more		1,353
Total Fair Value		232,376
Total Unrealized Losses		1,852
Mortgage Backed Securities [Member] | FHLMC [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value Less than 12 months	0	74,134
Unrealized Losses Less than 12 months	0	270
Fair Value 12 months or more	728	63,864
Unrealized Losses 12 months or more	2	716
Total Fair Value	728	137,998
Total Unrealized Losses	2	986
Mortgage Backed Securities [Member] | GNMA [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value Less than 12 months	0	79,145
Unrealized Losses Less than 12 months	0	472
Fair Value 12 months or more	609	7,203
Unrealized Losses 12 months or more	2	28
Total Fair Value	609	86,348
Total Unrealized Losses	2	500
Mortgage Backed Securities [Member] | Collateralized mortgage obligations guaranteed by the FHLMC, FNMA and GNMA [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value Less than 12 months	40,571	21,873
Unrealized Losses Less than 12 months	649	221
Fair Value 12 months or more	0	0
Unrealized Losses 12 months or more	0	0
Total Fair Value	40,571	21,873
Total Unrealized Losses	649	221
Mortgage Backed Securities [Member] | Private label [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value Less than 12 months	0	0
Unrealized Losses Less than 12 months	0	0
Fair Value 12 months or more	10,300	11,116
Unrealized Losses 12 months or more	4,689	4,881
Total Fair Value	10,300	11,116
Total Unrealized Losses	$ 4,689	$ 4,881