SEGMENT INFORMATION - Information about Reportable Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
Interest income	$ 263,405	$ 222,683	$ 758,005	$ 629,162
Interest expense	(63,677)	(14,773)	(157,577)	(39,442)
Net interest income (loss)	199,728	207,910	600,428	589,720
Provision for credit losses - (benefit) expense	10,643	14,352	47,669	10,028
Non-interest income	30,296	29,693	99,085	93,492
Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	263,405	222,683	758,005	629,162
Net (charge) credit for transfer of funds	0	0	0	0
Interest expense	(63,677)	(14,773)	(157,577)	(39,442)
Net interest income (loss)	199,728	207,910	600,428	589,720
Provision for credit losses - (benefit) expense	4,396	15,783	42,128	11,984
Non-interest income	30,296	29,693	99,085	93,492
Direct non-interest expenses	74,430	74,382	219,428	216,937
Segment income (loss)	151,198	147,438	437,957	454,291
Average earnings assets	18,063,606	18,311,378	17,902,642	18,830,683
Mortgage Banking Segment [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)	18,279	24,338	61,427	76,452
Non-interest income	3,021	3,733	9,157	13,152
Mortgage Banking Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	31,208	32,349	94,720	98,625
Net (charge) credit for transfer of funds	(12,929)	(8,011)	(33,293)	(22,173)
Interest expense	0	0	0	0
Net interest income (loss)	18,279	24,338	61,427	76,452
Provision for credit losses - (benefit) expense	(3,288)	2,092	(7,623)	(5,216)
Non-interest income	3,021	3,733	9,157	13,152
Direct non-interest expenses	5,201	6,489	15,821	19,076
Segment income (loss)	19,387	19,490	62,386	75,744
Average earnings assets	2,127,641	2,211,675	2,147,521	2,249,203
Consumer Retail Banking Segment [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)	147,066	118,408	427,407	310,351
Non-interest income	20,170	19,121	62,425	59,367
Consumer Retail Banking Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	90,976	77,576	261,139	221,500
Net (charge) credit for transfer of funds	96,836	47,577	260,715	105,898
Interest expense	(40,746)	(6,745)	(94,447)	(17,047)
Net interest income (loss)	147,066	118,408	427,407	310,351
Provision for credit losses - (benefit) expense	13,707	16,705	42,600	42,904
Non-interest income	20,170	19,121	62,425	59,367
Direct non-interest expenses	43,431	42,080	126,872	121,897
Segment income (loss)	110,098	78,744	320,360	204,917
Average earnings assets	3,336,158	2,974,894	3,251,286	2,865,610
Commercial And Corporate Segment [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)	13,212	22,861	41,085	94,655
Non-interest income	4,468	4,276	16,788	13,278
Commercial And Corporate Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	68,138	53,506	195,837	148,046
Net (charge) credit for transfer of funds	(54,926)	(30,645)	(154,752)	(53,391)
Interest expense	0	0	0	0
Net interest income (loss)	13,212	22,861	41,085	94,655
Provision for credit losses - (benefit) expense	(7,235)	(3,519)	(2,096)	(20,611)
Non-interest income	4,468	4,276	16,788	13,278
Direct non-interest expenses	9,658	9,295	28,363	27,202
Segment income (loss)	15,257	21,361	31,606	101,342
Average earnings assets	3,769,370	3,622,907	3,751,359	3,654,906
Treasury And Investments Segment [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)	(4,055)	14,827	(7,502)	33,702
Non-interest income	(3)	33	1,837	(130)
Treasury And Investments Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	32,146	28,203	89,140	77,530
Net (charge) credit for transfer of funds	(27,817)	(8,447)	(70,095)	(29,101)
Interest expense	(8,384)	(4,929)	(26,547)	(14,727)
Net interest income (loss)	(4,055)	14,827	(7,502)	33,702
Provision for credit losses - (benefit) expense	32	(12)	7	(435)
Non-interest income	(3)	33	1,837	(130)
Direct non-interest expenses	958	942	2,828	2,732
Segment income (loss)	(5,048)	13,930	(8,500)	31,275
Average earnings assets	6,382,276	7,095,503	6,321,540	7,642,121
United States Operations Segment [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)	19,749	21,494	60,369	56,664
Non-interest income	847	773	2,849	2,195
United States Operations Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	33,560	24,804	96,772	64,742
Net (charge) credit for transfer of funds	(1,164)	(474)	(2,575)	(1,233)
Interest expense	(12,647)	(2,836)	(33,828)	(6,845)
Net interest income (loss)	19,749	21,494	60,369	56,664
Provision for credit losses - (benefit) expense	873	(624)	9,545	(5,849)
Non-interest income	847	773	2,849	2,195
Direct non-interest expenses	8,535	8,479	25,341	25,195
Segment income (loss)	11,188	14,412	28,332	39,513
Average earnings assets	2,041,662	2,040,656	2,049,281	2,047,375
Virgin Islands Operations Segment [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)	5,477	5,982	17,642	17,896
Non-interest income	1,793	1,757	6,029	5,630
Virgin Islands Operations Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	7,377	6,245	20,397	18,719
Net (charge) credit for transfer of funds	0	0	0	0
Interest expense	(1,900)	(263)	(2,755)	(823)
Net interest income (loss)	5,477	5,982	17,642	17,896
Provision for credit losses - (benefit) expense	307	1,141	(305)	1,191
Non-interest income	1,793	1,757	6,029	5,630
Direct non-interest expenses	6,647	7,097	20,203	20,835
Segment income (loss)	316	(499)	3,773	1,500
Average earnings assets	$ 406,499	$ 365,743	$ 381,655	$ 371,468