DEBT SECURITIES - Investment Securities Available for Sale (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Schedule Of Available For Sale Securities [Line Items]
Amortized cost	$ 6,300,696	$ 6,398,197
Gross Unrealized Gains	287	247
Gross Unrealized Losses	711,278	798,466
Allowance for Credit Losses	449	458
Fair value	$ 5,589,256	$ 5,599,520
Weighted-average yield	1.23%	1.22%
Accrued interest receivable excluded from estimate of credit losses	$ 10,700	$ 11,100
U.S. Treasury securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost Due within one year	27,744	7,493
Gross Unrealized Gains Due within one year	0	0
Gross Unrealized Losses Due within one year	890	309
Allowance for Credit Losses within one year	0	0
Fair value Due within one year	$ 26,854	$ 7,184
Weighted-average yield Due within one year	0.61%	0.22%
Amortized cost After 1 to 5 years	$ 120,916	$ 141,366
Gross Unrealized Gains After 1 to 5 years	0	0
Gross Unrealized Losses After 1 to 5 years	7,348	9,675
Allowance for Credit Losses After 1 to 5 years	0	0
Fair value After 1 to 5 years	$ 113,568	$ 131,691
Weighted-average yield After 1 to 5 years	0.69%	0.70%
U.S. GSE's obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost Due within one year	$ 189,174	$ 129,018
Gross Unrealized Gains Due within one year	0	0
Gross Unrealized Losses Due within one year	5,100	4,036
Allowance for Credit Losses within one year	0	0
Fair value Due within one year	$ 184,074	$ 124,982
Weighted-average yield Due within one year	0.42%	0.32%
Amortized cost After 1 to 5 years	$ 2,349,522	$ 2,395,273
Gross Unrealized Gains After 1 to 5 years	22	22
Gross Unrealized Losses After 1 to 5 years	190,986	227,724
Allowance for Credit Losses After 1 to 5 years	0	0
Fair value After 1 to 5 years	$ 2,158,558	$ 2,167,571
Weighted-average yield After 1 to 5 years	0.84%	0.83%
Amortized cost After 5 to 10 years	$ 41,916	$ 56,251
Gross Unrealized Gains After 5 to 10 years	8	13
Gross Unrealized Losses After 5 to 10 years	4,998	7,670
Allowance for Credit Losses After 5 to 10 years	0	0
Fair value After 5 to 10 years	$ 36,926	$ 48,594
Weighted-average yield After 5 to 10 years	1.64%	1.54%
Amortized cost After 10 years	$ 11,625	$ 12,170
Gross Unrealized Gains After 10 years	27	36
Gross Unrealized Losses After 10 years	0	0
Allowance for Credit Losses After 10 years	0	0
Fair value After 10 years	$ 11,652	$ 12,206
Weighted-average yield After 10 years	5.15%	4.62%
Puerto Rico government obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost After 10 years	$ 3,302	$ 3,331
Gross Unrealized Gains After 10 years	0	0
Gross Unrealized Losses After 10 years	733	755
Allowance for Credit Losses After 10 years	366	375
Fair value After 10 years	$ 2,203	$ 2,201
Weighted-average yield After 10 years	0.00%	0.00%
Allowance for Credit Losses	$ 400	$ 400
United States And Puerto Rico Government Obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost	2,744,199	2,744,902
Gross Unrealized Gains	57	71
Gross Unrealized Losses	210,055	250,169
Allowance for Credit Losses	366	375
Fair value	$ 2,533,835	$ 2,494,429
Weighted-average yield	0.83%	0.83%
Residential MBS [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost	$ 3,363,942	$ 3,455,864
Gross Unrealized Gains	223	176
Gross Unrealized Losses	467,427	514,499
Allowance for Credit Losses	83	83
Fair value	$ 2,896,655	$ 2,941,458
Weighted-average yield	1.55%	1.52%
Residential MBS [Member] \| FHLMC [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost After 1 to 5 years	$ 10,023	$ 4,235
Gross Unrealized Gains After 1 to 5 years	0	0
Gross Unrealized Losses After 1 to 5 years	454	169
Allowance for Credit Losses After 1 to 5 years	0	0
Fair value After 1 to 5 years	$ 9,569	$ 4,066
Weighted-average yield After 1 to 5 years	1.98%	2.33%
Amortized cost After 5 to 10 years	$ 187,007	$ 201,072
Gross Unrealized Gains After 5 to 10 years	0	0
Gross Unrealized Losses After 5 to 10 years	15,912	18,709
Allowance for Credit Losses After 5 to 10 years	0	0
Fair value After 5 to 10 years	$ 171,095	$ 182,363
Weighted-average yield After 5 to 10 years	1.56%	1.55%
Amortized cost After 10 years	$ 1,068,680	$ 1,092,289
Gross Unrealized Gains After 10 years	0	0
Gross Unrealized Losses After 10 years	170,021	186,558
Allowance for Credit Losses After 10 years	0	0
Fair value After 10 years	$ 898,659	$ 905,731
Weighted-average yield After 10 years	1.41%	1.38%
Amortized cost	$ 1,265,710	$ 1,297,596
Gross Unrealized Gains	0	0
Gross Unrealized Losses	186,387	205,436
Allowance for Credit Losses	0	0
Fair value	$ 1,079,323	$ 1,092,160
Weighted-average yield	1.44%	1.41%
Residential MBS [Member] \| GNMA [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost Due within one year	$ 3	$ 5
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	$ 3	$ 5
Weighted-average yield Due within one year	2.42%	1.73%
Amortized cost After 1 to 5 years	$ 23,293	$ 15,508
Gross Unrealized Gains After 1 to 5 years	0	0
Gross Unrealized Losses After 1 to 5 years	1,253	622
Allowance for Credit Losses After 1 to 5 years	0	0
Fair value After 1 to 5 years	$ 22,040	$ 14,886
Weighted-average yield After 1 to 5 years	1.31%	2.00%
Amortized cost After 5 to 10 years	$ 33,939	$ 45,322
Gross Unrealized Gains After 5 to 10 years	0	1
Gross Unrealized Losses After 5 to 10 years	2,720	3,809
Allowance for Credit Losses After 5 to 10 years	0	0
Fair value After 5 to 10 years	$ 31,219	$ 41,514
Weighted-average yield After 5 to 10 years	1.69%	1.31%
Amortized cost After 10 years	$ 225,680	$ 232,632
Gross Unrealized Gains After 10 years	119	51
Gross Unrealized Losses After 10 years	24,080	27,169
Allowance for Credit Losses After 10 years	0	0
Fair value After 10 years	$ 201,719	$ 205,514
Weighted-average yield After 10 years	2.58%	2.47%
Amortized cost	$ 282,915	$ 293,467
Gross Unrealized Gains	119	52
Gross Unrealized Losses	28,053	31,600
Allowance for Credit Losses	0	0
Fair value	$ 254,981	$ 261,919
Weighted-average yield	2.37%	2.27%
Residential MBS [Member] \| FNMA [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost After 1 to 5 years	$ 24,446	$ 9,685
Gross Unrealized Gains After 1 to 5 years	0	0
Gross Unrealized Losses After 1 to 5 years	1,249	521
Allowance for Credit Losses After 1 to 5 years	0	0
Fair value After 1 to 5 years	$ 23,197	$ 9,164
Weighted-average yield After 1 to 5 years	1.72%	1.76%
Amortized cost After 5 to 10 years	$ 353,397	$ 358,346
Gross Unrealized Gains After 5 to 10 years	0	0
Gross Unrealized Losses After 5 to 10 years	28,963	31,620
Allowance for Credit Losses After 5 to 10 years	0	0
Fair value After 5 to 10 years	$ 324,434	$ 326,726
Weighted-average yield After 5 to 10 years	1.74%	1.68%
Amortized cost After 10 years	$ 1,133,757	$ 1,186,635
Gross Unrealized Gains After 10 years	104	124
Gross Unrealized Losses After 10 years	168,025	186,757
Allowance for Credit Losses After 10 years	0	0
Fair value After 10 years	$ 965,836	$ 1,000,002
Weighted-average yield After 10 years	1.37%	1.38%
Amortized cost	$ 1,511,600	$ 1,554,666
Gross Unrealized Gains	104	124
Gross Unrealized Losses	198,237	218,898
Allowance for Credit Losses	0	0
Fair value	$ 1,313,467	$ 1,335,892
Weighted-average yield	1.47%	1.45%
Residential MBS [Member] \| Collateralized mortgage obligations guaranteed by FHLMC, FNMA and GNMA [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost After 10 years	$ 296,022	$ 302,232
Gross Unrealized Gains After 10 years	0	0
Gross Unrealized Losses After 10 years	52,540	56,539
Allowance for Credit Losses After 10 years	0	0
Fair value After 10 years	$ 243,482	$ 245,693
Weighted-average yield After 10 years	1.49%	1.44%
Residential MBS [Member] \| Private label [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost After 10 years	$ 7,695	$ 7,903
Gross Unrealized Gains After 10 years	0	0
Gross Unrealized Losses After 10 years	2,210	2,026
Allowance for Credit Losses After 10 years	83	83
Fair value After 10 years	$ 5,402	$ 5,794
Weighted-average yield After 10 years	7.25%	6.83%
Gross Unrealized Losses	$ 2,300
Allowance for Credit Losses	100	$ 100
Fair value	$ 5,400
Weighted-average yield	7.25%
Commercial Mortgage Backed Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost After 1 to 5 years	$ 27,584	30,578
Gross Unrealized Gains After 1 to 5 years	7	0
Gross Unrealized Losses After 1 to 5 years	4,551	4,463
Allowance for Credit Losses After 1 to 5 years	0	0
Fair value After 1 to 5 years	$ 23,040	$ 26,115
Weighted-average yield After 1 to 5 years	2.27%	2.43%
Amortized cost After 5 to 10 years	$ 44,584	$ 44,889
Gross Unrealized Gains After 5 to 10 years	0	0
Gross Unrealized Losses After 5 to 10 years	4,929	5,603
Allowance for Credit Losses After 5 to 10 years	0	0
Fair value After 5 to 10 years	$ 39,655	$ 39,286
Weighted-average yield After 5 to 10 years	1.90%	1.89%
Amortized cost After 10 years	$ 120,387	$ 121,464
Gross Unrealized Gains After 10 years	0	0
Gross Unrealized Losses After 10 years	24,316	23,732
Allowance for Credit Losses After 10 years	0	0
Fair value After 10 years	$ 96,071	$ 97,732
Weighted-average yield After 10 years	1.23%	1.23%
Amortized cost	$ 192,555	$ 196,931
Gross Unrealized Gains	7	0
Gross Unrealized Losses	33,796	33,798
Allowance for Credit Losses	0	0
Fair value	$ 158,766	$ 163,133
Weighted-average yield	1.53%	1.56%
Mortgage Backed Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized cost	$ 3,556,497	$ 3,652,795
Gross Unrealized Gains	230	176
Gross Unrealized Losses	501,223	548,297
Allowance for Credit Losses	83	83
Fair value	$ 3,055,421	$ 3,104,591
Weighted-average yield	1.54%	1.52%
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		0.84%

Accrued Interest Receivable Excluded From Estimate Of Credit Losses

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Weighted average yield of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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