INVESTMENT SECURITIES - Investment Securities Available for Sale (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Schedule Of Available For Sale Securities [Line Items]
Amortized cost	$ 6,534,503	$ 4,584,851
Gross unrealized gain	28,900	68,995
Gross unrealized loss	108,537	5,517
Allowance for Credit Losses	1,105	1,310
Fair value	$ 6,453,761	$ 4,647,019
Weighted-average yield	1.03%	1.28%
Private label [Member]
Schedule Of Available For Sale Securities [Line Items]
Allowance for Credit Losses		$ 1,002	$ 0
U.S. Treasury securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost Due within one year		7,498
Gross Unrealized gains Due within one year		9
Gross Unrealized losses Due within one year		0
Allowance for Credit Losses within one year		0
Fair value Due within one year		$ 7,507
Weighted-average yield Due within one year		1.65%
Amortized cost After 1 to 5 years	$ 149,660
Gross Unrealized gains After 1 to 5 years	59
Gross Unrealized losses After 1 to 5 years	1,233
Allowance for Credit Losses After 1 to 5 years	0
Fair value After 1 to 5 years	$ 148,486
Weighted-average yield After 1 to 5 years	0.68%
U.S. government-sponsored agencies obigations [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost Due within one year		$ 24,413
Gross Unrealized gains Due within one year		273
Gross Unrealized losses Due within one year		0
Allowance for Credit Losses within one year		0
Fair value Due within one year		$ 24,686
Weighted-average yield Due within one year		1.95%
Amortized cost After 1 to 5 years	$ 1,877,181	$ 691,668
Gross Unrealized gains After 1 to 5 years	240	911
Gross Unrealized losses After 1 to 5 years	29,555	290
Allowance for Credit Losses After 1 to 5 years	0	0
Fair value After 1 to 5 years	$ 1,847,866	$ 692,289
Weighted-average yield After 1 to 5 years	0.60%	0.57%
Amortized cost After 5 to 10 years	$ 403,785	$ 441,454
Gross Unrealized gains After 5 to 10 years	175	821
Gross Unrealized losses After 5 to 10 years	10,856	347
Allowance for Credit Losses After 5 to 10 years	0	0
Fair value After 5 to 10 years	$ 393,104	$ 441,928
Weighted-average yield After 5 to 10 years	0.90%	0.83%
Amortized cost After 10 years	$ 15,788	$ 21,413
Gross Unrealized gains After 10 years	224	0
Gross Unrealized losses After 10 years	0	149
Allowance for Credit Losses After 10 years	0	0
Fair value After 10 years	$ 16,012	$ 21,264
Weighted-average yield After 10 years	0.63%	0.65%
Puerto Rico government obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost After 10 years	$ 3,574	$ 3,987
Gross Unrealized gains After 10 years	0	0
Gross Unrealized losses After 10 years	416	780
Allowance for Credit Losses After 10 years	308	308
Fair value After 10 years	$ 2,850	$ 2,899
Weighted-average yield After 10 years	0.00%	6.97%
Allowance for Credit Losses	$ 308	$ 308	0
United States And Puerto Rico Government Obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost	2,449,988	1,190,433
Gross unrealized gain	698	2,014
Gross unrealized loss	42,060	1,566
Allowance for Credit Losses	308	308
Fair value	$ 2,408,318	$ 1,190,573
Weighted-average yield	0.67%	0.72%
MBS [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost	$ 4,083,515	$ 3,393,768
Gross unrealized gain	28,202	66,981
Gross unrealized loss	66,477	3,951
Allowance for Credit Losses	797	1,002
Fair value	$ 4,044,443	$ 3,455,796
Weighted-average yield	1.26%	1.47%
MBS [Member] | FHLMC [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost After 1 to 5 years	$ 2,811	$ 75
Gross Unrealized gains After 1 to 5 years	119	8
Gross Unrealized losses After 1 to 5 years	0	0
Allowance for Credit Losses After 1 to 5 years	0	0
Fair value After 1 to 5 years	$ 2,930	$ 83
Weighted-average yield After 1 to 5 years	2.65%	4.86%
Amortized cost After 5 to 10 years	$ 193,234	$ 60,773
Gross Unrealized gains After 5 to 10 years	2,419	2,850
Gross Unrealized losses After 5 to 10 years	1,122	0
Allowance for Credit Losses After 5 to 10 years	0	0
Fair value After 5 to 10 years	$ 194,531	$ 63,623
Weighted-average yield After 5 to 10 years	1.29%	2.15%
Amortized cost After 10 years	$ 1,240,964	$ 1,070,984
Gross Unrealized gains After 10 years	3,748	15,340
Gross Unrealized losses After 10 years	23,503	159
Allowance for Credit Losses After 10 years	0	0
Fair value After 10 years	$ 1,221,209	$ 1,086,165
Weighted-average yield After 10 years	1.18%	1.38%
Amortized cost	$ 1,437,009	$ 1,131,832
Gross unrealized gain	6,286	18,198
Gross unrealized loss	24,625	159
Allowance for Credit Losses	0	0
Fair value	$ 1,418,670	$ 1,149,871
Weighted-average yield	1.20%	1.42%
MBS [Member] | GNMA [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost Due within one year	$ 2	$ 1
Gross Unrealized gains Due within one year	0	0
Gross Unrealized losses Due within one year	0	0
Allowance for Credit Losses within one year	0	0
Fair value Due within one year	$ 2	$ 1
Weighted-average yield Due within one year	1.32%	1.93%
Amortized cost After 1 to 5 years	$ 16,714	$ 26,918
Gross Unrealized gains After 1 to 5 years	572	1,080
Gross Unrealized losses After 1 to 5 years	0	0
Allowance for Credit Losses After 1 to 5 years	0	0
Fair value After 1 to 5 years	$ 17,286	$ 27,998
Weighted-average yield After 1 to 5 years	2.90%	2.91%
Amortized cost After 5 to 10 years	$ 27,271	$ 40,727
Gross Unrealized gains After 5 to 10 years	80	128
Gross Unrealized losses After 5 to 10 years	139	69
Allowance for Credit Losses After 5 to 10 years	0	0
Fair value After 5 to 10 years	$ 27,212	$ 40,786
Weighted-average yield After 5 to 10 years	0.51%	0.42%
Amortized cost After 10 years	$ 338,927	$ 614,584
Gross Unrealized gains After 10 years	7,091	16,271
Gross Unrealized losses After 10 years	2,174	148
Allowance for Credit Losses After 10 years	0	0
Fair value After 10 years	$ 343,844	$ 630,707
Weighted-average yield After 10 years	1.45%	1.27%
Amortized cost	$ 382,914	$ 682,230
Gross unrealized gain	7,743	17,479
Gross unrealized loss	2,313	217
Allowance for Credit Losses	0	0
Fair value	$ 388,344	$ 699,492
Weighted-average yield	1.45%	1.29%
MBS [Member] | FNMA [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost Due within one year	$ 4,975
Gross Unrealized gains Due within one year	21
Gross Unrealized losses Due within one year	0
Allowance for Credit Losses within one year	0
Fair value Due within one year	$ 4,996
Weighted-average yield Due within one year	2.03%
Amortized cost After 1 to 5 years	$ 21,337	$ 24,812
Gross Unrealized gains After 1 to 5 years	424	891
Gross Unrealized losses After 1 to 5 years	0	0
Allowance for Credit Losses After 1 to 5 years	0	0
Fair value After 1 to 5 years	$ 21,761	$ 25,703
Weighted-average yield After 1 to 5 years	2.87%	2.81%
Amortized cost After 5 to 10 years	$ 298,771	$ 110,832
Gross Unrealized gains After 5 to 10 years	4,387	5,783
Gross Unrealized losses After 5 to 10 years	1,917	0
Allowance for Credit Losses After 5 to 10 years	0	0
Fair value After 5 to 10 years	$ 301,241	$ 116,615
Weighted-average yield After 5 to 10 years	1.41%	2.13%
Amortized cost After 10 years	$ 1,389,381	$ 1,154,707
Gross Unrealized gains After 10 years	8,953	23,459
Gross Unrealized losses After 10 years	21,747	203
Allowance for Credit Losses After 10 years	0	0
Fair value After 10 years	$ 1,376,587	$ 1,177,963
Weighted-average yield After 10 years	1.21%	1.53%
Amortized cost	$ 1,714,464	$ 1,290,351
Gross unrealized gain	13,785	30,133
Gross unrealized loss	23,664	203
Allowance for Credit Losses	0	0
Fair value	$ 1,704,585	$ 1,320,281
Weighted-average yield	1.27%	1.61%
MBS [Member] | Collateralized mortgage obligations guaranteed by FHLMC, FNMA and GNMA [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost After 1 to 5 years	$ 24,007	$ 538
Gross Unrealized gains After 1 to 5 years	1	0
Gross Unrealized losses After 1 to 5 years	778	1
Allowance for Credit Losses After 1 to 5 years	0	0
Fair value After 1 to 5 years	$ 23,230	$ 537
Weighted-average yield After 1 to 5 years	1.31%	0.81%
Amortized cost After 5 to 10 years	$ 14,316	$ 18,438
Gross Unrealized gains After 5 to 10 years	97	152
Gross Unrealized losses After 5 to 10 years	0	0
Allowance for Credit Losses After 5 to 10 years	0	0
Fair value After 5 to 10 years	$ 14,413	$ 18,590
Weighted-average yield After 5 to 10 years	0.76%	0.80%
Amortized cost After 10 years	$ 500,811	$ 258,069
Gross Unrealized gains After 10 years	290	1,019
Gross Unrealized losses After 10 years	13,134	491
Allowance for Credit Losses After 10 years	0	0
Fair value After 10 years	$ 487,967	$ 258,597
Weighted-average yield After 10 years	1.23%	1.56%
Amortized cost	$ 539,134	$ 277,045
Gross unrealized gain	388	1,171
Gross unrealized loss	13,912	492
Allowance for Credit Losses	0	0
Fair value	$ 525,610	$ 277,724
Weighted-average yield	1.22%	1.51%
MBS [Member] | Private label [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost After 10 years	$ 9,994	$ 12,310
Gross Unrealized gains After 10 years	0	0
Gross Unrealized losses After 10 years	1,963	2,880
Allowance for Credit Losses After 10 years	797	1,002
Fair value After 10 years	$ 7,234	$ 8,428
Weighted-average yield After 10 years	2.21%	2.25%
Gross unrealized loss	$ 2,800
Allowance for Credit Losses	797	$ 1,000	$ 0
Fair value	$ 7,200
Weighted-average yield	2.21%
Other Debt Obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost Due within one year	$ 500
Gross Unrealized gains Due within one year	0
Gross Unrealized losses Due within one year	0
Allowance for Credit Losses within one year	0
Fair value Due within one year	$ 500
Weighted-average yield Due within one year	0.72%
Amortized cost After 1 to 5 years	$ 500	650
Gross Unrealized gains After 1 to 5 years	0	0
Gross Unrealized losses After 1 to 5 years	0	0
Allowance for Credit Losses After 1 to 5 years	0	0
Fair value After 1 to 5 years	$ 500	$ 650
Weighted-average yield After 1 to 5 years	0.84%	2.94%
Amortized cost	$ 1,000
Gross unrealized gain	0
Gross unrealized loss	0
Allowance for Credit Losses	0
Fair value	$ 1,000
Weighted-average yield	0.78%