DEBT SECURITIES - Investment Securities Available for Sale (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Schedule Of Available For Sale Securities [Line Items]
Amortized cost	$ 6,398,197	$ 6,534,503
Gross Unrealized Gains	247	28,900
Gross Unrealized Losses	798,466	108,537
Allowance for Credit Losses	458	1,105
Fair value	$ 5,599,520	$ 6,453,761
Weighted-average yield	1.22%	1.03%
Accrued interest receivable excluded from estimate of credit losses	$ 11,100	$ 10,100
U.S. Treasury securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost Due within one year	7,493
Gross Unrealized Gains Due within one year	0
Gross Unrealized Losses Due within one year	309
Allowance for Credit Losses within one year	0
Fair value Due within one year	$ 7,184
Weighted-average yield Due within one year	0.22%
Amortized cost After 1 to 5 years	$ 141,366	149,660
Gross Unrealized Gains After 1 to 5 years	0	59
Gross Unrealized Losses After 1 to 5 years	9,675	1,233
Allowance for Credit Losses After 1 to 5 years	0	0
Fair value After 1 to 5 years	$ 131,691	$ 148,486
Weighted-average yield After 1 to 5 years	0.70%	0.68%
U.S. GSE's obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost Due within one year	$ 129,018
Gross Unrealized Gains Due within one year	0
Gross Unrealized Losses Due within one year	4,036
Allowance for Credit Losses within one year	0
Fair value Due within one year	$ 124,982
Weighted-average yield Due within one year	0.32%
Amortized cost After 1 to 5 years	$ 2,395,273	$ 1,877,181
Gross Unrealized Gains After 1 to 5 years	22	240
Gross Unrealized Losses After 1 to 5 years	227,724	29,555
Allowance for Credit Losses After 1 to 5 years	0	0
Fair value After 1 to 5 years	$ 2,167,571	$ 1,847,866
Weighted-average yield After 1 to 5 years	0.83%	0.60%
Amortized cost After 5 to 10 years	$ 56,251	$ 403,785
Gross Unrealized Gains After 5 to 10 years	13	175
Gross Unrealized Losses After 5 to 10 years	7,670	10,856
Allowance for Credit Losses After 5 to 10 years	0	0
Fair value After 5 to 10 years	$ 48,594	$ 393,104
Weighted-average yield After 5 to 10 years	1.54%	0.90%
Amortized cost After 10 years	$ 12,170	$ 15,788
Gross Unrealized Gains After 10 years	36	224
Gross Unrealized Losses After 10 years	0	0
Allowance for Credit Losses After 10 years	0	0
Fair value After 10 years	$ 12,206	$ 16,012
Weighted-average yield After 10 years	4.62%	0.63%
Puerto Rico government obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost After 10 years	$ 3,331	$ 3,574
Gross Unrealized Gains After 10 years	0	0
Gross Unrealized Losses After 10 years	755	416
Allowance for Credit Losses After 10 years	375	308
Fair value After 10 years	$ 2,201	$ 2,850
Weighted-average yield After 10 years	0.00%	0.00%
Allowance for Credit Losses	$ 400	$ 300
United States And Puerto Rico Government Obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost	2,744,902	2,449,988
Gross Unrealized Gains	71	698
Gross Unrealized Losses	250,169	42,060
Allowance for Credit Losses	375	308
Fair value	$ 2,494,429	$ 2,408,318
Weighted-average yield	0.83%	0.67%
MBS [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost	$ 3,652,795	$ 4,083,515
Gross Unrealized Gains	176	28,202
Gross Unrealized Losses	548,297	66,477
Allowance for Credit Losses	83	797
Fair value	$ 3,104,591	$ 4,044,443
Weighted-average yield	1.52%	1.26%
MBS [Member] | FHLMC [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost After 1 to 5 years	$ 4,235	$ 2,811
Gross Unrealized Gains After 1 to 5 years	0	119
Gross Unrealized Losses After 1 to 5 years	169	0
Allowance for Credit Losses After 1 to 5 years	0	0
Fair value After 1 to 5 years	$ 4,066	$ 2,930
Weighted-average yield After 1 to 5 years	2.33%	2.65%
Amortized cost After 5 to 10 years	$ 204,085	$ 193,234
Gross Unrealized Gains After 5 to 10 years	0	2,419
Gross Unrealized Losses After 5 to 10 years	19,061	1,122
Allowance for Credit Losses After 5 to 10 years	0	0
Fair value After 5 to 10 years	$ 185,024	$ 194,531
Weighted-average yield After 5 to 10 years	1.55%	1.29%
Amortized cost After 10 years	$ 1,092,289	$ 1,240,964
Gross Unrealized Gains After 10 years	0	3,748
Gross Unrealized Losses After 10 years	186,558	23,503
Allowance for Credit Losses After 10 years	0	0
Fair value After 10 years	$ 905,731	$ 1,221,209
Weighted-average yield After 10 years	1.38%	1.18%
Amortized cost	$ 1,300,609	$ 1,437,009
Gross Unrealized Gains	0	6,286
Gross Unrealized Losses	205,788	24,625
Allowance for Credit Losses	0	0
Fair value	$ 1,094,821	$ 1,418,670
Weighted-average yield	1.41%	1.20%
MBS [Member] | GNMA [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost Due within one year	$ 5	$ 2
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	$ 5	$ 2
Weighted-average yield Due within one year	1.73%	1.32%
Amortized cost After 1 to 5 years	$ 15,508	$ 16,714
Gross Unrealized Gains After 1 to 5 years	0	572
Gross Unrealized Losses After 1 to 5 years	622	0
Allowance for Credit Losses After 1 to 5 years	0	0
Fair value After 1 to 5 years	$ 14,886	$ 17,286
Weighted-average yield After 1 to 5 years	2.00%	2.90%
Amortized cost After 5 to 10 years	$ 45,322	$ 27,271
Gross Unrealized Gains After 5 to 10 years	1	80
Gross Unrealized Losses After 5 to 10 years	3,809	139
Allowance for Credit Losses After 5 to 10 years	0	0
Fair value After 5 to 10 years	$ 41,514	$ 27,212
Weighted-average yield After 5 to 10 years	1.31%	0.51%
Amortized cost After 10 years	$ 232,632	$ 338,927
Gross Unrealized Gains After 10 years	51	7,091
Gross Unrealized Losses After 10 years	27,169	2,174
Allowance for Credit Losses After 10 years	0	0
Fair value After 10 years	$ 205,514	$ 343,844
Weighted-average yield After 10 years	2.47%	1.45%
Amortized cost	$ 293,467	$ 382,914
Gross Unrealized Gains	52	7,743
Gross Unrealized Losses	31,600	2,313
Allowance for Credit Losses	0	0
Fair value	$ 261,919	$ 388,344
Weighted-average yield	2.27%	1.45%
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	$ 9,685	$ 21,337
Gross Unrealized Gains After 1 to 5 years	0	424
Gross Unrealized Losses After 1 to 5 years	521	0
Allowance for Credit Losses After 1 to 5 years	0	0
Fair value After 1 to 5 years	$ 9,164	$ 21,761
Weighted-average yield After 1 to 5 years	1.76%	2.87%
Amortized cost After 5 to 10 years	$ 400,223	$ 298,771
Gross Unrealized Gains After 5 to 10 years	0	4,387
Gross Unrealized Losses After 5 to 10 years	36,871	1,917
Allowance for Credit Losses After 5 to 10 years	0	0
Fair value After 5 to 10 years	$ 363,352	$ 301,241
Weighted-average yield After 5 to 10 years	1.70%	1.41%
Amortized cost After 10 years	$ 1,186,635	$ 1,389,381
Gross Unrealized Gains After 10 years	124	8,953
Gross Unrealized Losses After 10 years	186,757	21,747
Allowance for Credit Losses After 10 years	0	0
Fair value After 10 years	$ 1,000,002	$ 1,376,587
Weighted-average yield After 10 years	1.38%	1.21%
Amortized cost	$ 1,596,543	$ 1,714,464
Gross Unrealized Gains	124	13,785
Gross Unrealized Losses	224,149	23,664
Allowance for Credit Losses	0	0
Fair value	$ 1,372,518	$ 1,704,585
Weighted-average yield	1.46%	1.27%
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	$ 30,578	$ 24,007
Gross Unrealized Gains After 1 to 5 years	0	1
Gross Unrealized Losses After 1 to 5 years	4,463	778
Allowance for Credit Losses After 1 to 5 years	0	0
Fair value After 1 to 5 years	$ 26,115	$ 23,230
Weighted-average yield After 1 to 5 years	2.43%	1.31%
Amortized cost After 5 to 10 years		$ 14,316
Gross Unrealized Gains After 5 to 10 years		97
Gross Unrealized Losses After 5 to 10 years		0
Allowance for Credit Losses After 5 to 10 years		0
Fair value After 5 to 10 years		$ 14,413
Weighted-average yield After 5 to 10 years		0.76%
Amortized cost After 10 years	$ 423,695	$ 500,811
Gross Unrealized Gains After 10 years	0	290
Gross Unrealized Losses After 10 years	80,271	13,134
Allowance for Credit Losses After 10 years	0	0
Fair value After 10 years	$ 343,424	$ 487,967
Weighted-average yield After 10 years	1.38%	1.23%
Amortized cost	$ 454,273	$ 539,134
Gross Unrealized Gains	0	388
Gross Unrealized Losses	84,734	13,912
Allowance for Credit Losses	0	0
Fair value	$ 369,539	$ 525,610
Weighted-average yield	1.45%	1.22%
MBS [Member] | Private label [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost After 10 years	$ 7,903	$ 9,994
Gross Unrealized Gains After 10 years	0	0
Gross Unrealized Losses After 10 years	2,026	1,963
Allowance for Credit Losses After 10 years	83	797
Fair value After 10 years	$ 5,794	$ 7,234
Weighted-average yield After 10 years	6.83%	2.21%
Gross Unrealized Losses	$ 2,100
Allowance for Credit Losses	100	$ 800
Fair value	$ 5,800
Weighted-average yield	6.83%
Other Debt Obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost Due within one year	$ 500	500
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	$ 500	$ 500
Weighted-average yield Due within one year	0.84%	0.72%
Amortized cost After 1 to 5 years		$ 500
Gross Unrealized Gains After 1 to 5 years		0
Gross Unrealized Losses After 1 to 5 years		0
Allowance for Credit Losses After 1 to 5 years		0
Fair value After 1 to 5 years		$ 500
Weighted-average yield After 1 to 5 years		0.84%
Amortized cost		$ 1,000
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Allowance for Credit Losses		0
Fair value		$ 1,000
Weighted-average yield		0.78%