SEGMENT INFORMATION - Information about Reportable Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Segment Reporting Information [Line Items]
Interest income	$ 208,625	$ 201,459	$ 406,479	$ 396,101
Interest expense	(12,439)	(16,676)	(24,669)	(35,053)
Net interest income	196,186	184,783	381,810	361,048
Provision for loan and lease losses	(12,665)	26,302	4,324	40,745
Non-interest income	30,941	29,884	63,799	60,840
Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	208,625	201,459	406,479	396,101
Net (charge) credit for transfer of funds	0	0	0	0
Interest expense	(12,439)	(16,676)	(24,669)	(35,053)
Net interest income	196,186	184,783	381,810	361,048
Provision for loan and lease losses	(10,003)	26,155	3,799	41,407
Non-interest income	30,941	29,884	63,799	60,840
Direct non-interest expenses	(71,182)	(76,609)	(142,555)	(154,168)
Segment income	145,942	164,213	306,853	309,127
Average earnings assets	18,903,902	19,074,536	19,097,909	18,492,045
Mortgage Banking Segment [Member]
Segment Reporting Information [Line Items]
Net interest income	26,335	26,331	52,114	51,571
Non-interest income	4,167	6,137	9,419	13,253
Mortgage Banking Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	33,205	36,945	66,276	74,005
Net (charge) credit for transfer of funds	(6,870)	(10,614)	(14,162)	(22,434)
Interest expense	0	0	0	0
Net interest income	26,335	26,331	52,114	51,571
Provision for loan and lease losses	3,605	(1,030)	7,308	(244)
Non-interest income	4,167	6,137	9,419	13,253
Direct non-interest expenses	(5,681)	(7,525)	(12,587)	(15,522)
Segment income	28,426	23,913	56,254	49,058
Average earnings assets	2,243,188	2,563,768	2,268,279	2,611,065
Consumer Retail Banking Segment [Member]
Segment Reporting Information [Line Items]
Net interest income	102,397	64,751	191,943	123,234
Non-interest income	19,783	16,726	40,246	33,969
Consumer Retail Banking Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	73,487	66,237	143,924	131,970
Net (charge) credit for transfer of funds	34,039	5,901	58,321	6,956
Interest expense	(5,129)	(7,387)	(10,302)	(15,692)
Net interest income	102,397	64,751	191,943	123,234
Provision for loan and lease losses	(15,055)	(791)	(26,199)	(4,753)
Non-interest income	19,783	16,726	40,246	33,969
Direct non-interest expenses	(40,546)	(43,255)	(79,817)	(84,346)
Segment income	66,579	37,431	126,173	68,104
Average earnings assets	2,860,086	2,491,583	2,810,062	2,467,015
Commercial And Corporate Segment [Member]
Segment Reporting Information [Line Items]
Net interest income	31,379	51,498	71,794	100,479
Non-interest income	4,448	4,139	9,002	8,036
Commercial And Corporate Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	47,513	53,833	94,540	105,291
Net (charge) credit for transfer of funds	(16,134)	(2,335)	(22,746)	(4,812)
Interest expense	0	0	0	0
Net interest income	31,379	51,498	71,794	100,479
Provision for loan and lease losses	470	27,752	17,092	44,931
Non-interest income	4,448	4,139	9,002	8,036
Direct non-interest expenses	(9,048)	(8,298)	(17,907)	(19,836)
Segment income	27,249	75,091	79,981	133,610
Average earnings assets	3,624,176	3,888,725	3,662,720	3,957,859
Treasury And Investments Segment [Member]
Segment Reporting Information [Line Items]
Net interest income	11,466	19,039	18,875	40,622
Non-interest income	(51)	85	(163)	141
Treasury And Investments Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	27,143	16,708	49,327	29,470
Net (charge) credit for transfer of funds	(10,705)	8,191	(20,654)	23,125
Interest expense	(4,972)	(5,860)	(9,798)	(11,973)
Net interest income	11,466	19,039	18,875	40,622
Provision for loan and lease losses	35	0	423	127
Non-interest income	(51)	85	(163)	141
Direct non-interest expenses	(905)	(1,127)	(1,790)	(2,361)
Segment income	10,545	17,997	17,345	38,529
Average earnings assets	7,769,754	7,588,530	7,931,699	6,921,007
United States Operations Segment [Member]
Segment Reporting Information [Line Items]
Net interest income	18,688	16,406	35,170	31,429
Non-interest income	678	1,068	1,422	2,043
United States Operations Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	21,081	20,651	39,938	40,983
Net (charge) credit for transfer of funds	(330)	(1,143)	(759)	(2,835)
Interest expense	(2,063)	(3,102)	(4,009)	(6,719)
Net interest income	18,688	16,406	35,170	31,429
Provision for loan and lease losses	1,678	(860)	5,225	(623)
Non-interest income	678	1,068	1,422	2,043
Direct non-interest expenses	(8,237)	(9,103)	(16,716)	(17,397)
Segment income	12,807	7,511	25,101	15,452
Average earnings assets	2,036,108	2,103,002	2,050,791	2,090,898
Virgin Islands Operations Segment [Member]
Segment Reporting Information [Line Items]
Net interest income	5,921	6,758	11,914	13,713
Non-interest income	1,916	1,729	3,873	3,398
Virgin Islands Operations Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	6,196	7,085	12,474	14,382
Net (charge) credit for transfer of funds	0	0	0	0
Interest expense	(275)	(327)	(560)	(669)
Net interest income	5,921	6,758	11,914	13,713
Provision for loan and lease losses	(736)	1,084	(50)	1,969
Non-interest income	1,916	1,729	3,873	3,398
Direct non-interest expenses	(6,765)	(7,301)	(13,738)	(14,706)
Segment income	336	2,270	1,999	4,374
Average earnings assets	$ 370,590	$ 438,928	$ 374,358	$ 444,201