SEGMENT INFORMATION - Information by Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Interest income	$ 1,095,153	$ 1,023,486	$ 862,614
Interest expense	(287,674)	(226,376)	(67,321)
Net interest income (loss)	807,479	797,110	795,293
Provision for credit losses - (benefit) expense	59,921	60,940	27,696
Non-interest income	130,722	132,694	123,092
Employees' compensation and benefits	235,695	222,855	206,038
Occupancy and equipment	88,427	85,911	88,277
Business promotion	17,645	19,626	18,231
Professional fees	49,455	45,841	47,848
Taxes, other than income taxes	22,196	21,236	20,267
Federal Deposit Insurance Corporation (FDIC) deposit insurance	9,818	14,873	6,149
Net (gain) loss on OREO operations	(7,474)	(7,138)	(5,826)
Credit and debit card processing expenses	27,600	25,997	22,736
Other non-interest expenses	34,932	33,666	30,662
Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	1,095,153	1,023,486	862,614
Net (charge) credit for transfer of funds	0	0	0
Interest expense	(287,674)	(226,376)	(67,321)
Net interest income (loss)	807,479	797,110	795,293
Provision for credit losses - (benefit) expense	59,921	60,940	27,696
Non-interest income	130,722	132,694	123,092
Employees' compensation and benefits	235,695	222,855	206,038
Occupancy and equipment	88,427	85,911	88,277
Business promotion	17,645	19,626	18,231
Professional fees	49,455	45,841	47,848
Taxes, other than income taxes	22,196	21,236	20,267
Federal Deposit Insurance Corporation (FDIC) deposit insurance	9,818	14,873	6,149
Net (gain) loss on OREO operations	(7,474)	(7,138)	(5,826)
Credit and debit card processing expenses	27,600	25,997	22,736
Other non-interest expenses	43,711	42,227	39,385
Direct non-interest expenses	487,073	471,428	443,105
Segment income (loss)	391,207	397,436	447,584
Average earnings assets	18,126,256	17,866,846	18,517,104
Mortgage Banking Segment [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)	72,455	75,774	78,098
Non-interest income	13,507	11,213	15,698
Mortgage Banking Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	127,189	127,154	130,844
Net (charge) credit for transfer of funds	(54,734)	(51,380)	(52,746)
Interest expense	0	0	0
Net interest income (loss)	72,455	75,774	78,098
Provision for credit losses - (benefit) expense	(15,526)	(7,908)	(7,936)
Non-interest income	13,507	11,213	15,698
Employees' compensation and benefits	27,144	25,463	24,460
Occupancy and equipment	5,858	6,015	6,647
Business promotion	1,264	1,446	1,371
Professional fees	7,638	7,054	7,716
Taxes, other than income taxes	1,808	1,382	964
Federal Deposit Insurance Corporation (FDIC) deposit insurance	1,832	2,879	1,346
Net (gain) loss on OREO operations	(5,553)	(7,305)	(6,391)
Credit and debit card processing expenses	0	0	0
Other non-interest expenses	2,994	2,968	2,802
Direct non-interest expenses	42,985	39,902	38,915
Segment income (loss)	58,503	54,993	62,817
Average earnings assets	2,134,551	2,149,445	2,240,946
Consumer (Retail) Banking Segment [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)	550,820	484,306	463,203
Non-interest income	96,239	92,608	88,857
Consumer (Retail) Banking Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	423,738	390,619	331,558
Net (charge) credit for transfer of funds	284,065	214,392	161,946
Interest expense	(156,983)	(120,705)	(30,301)
Net interest income (loss)	550,820	484,306	463,203
Provision for credit losses - (benefit) expense	95,315	66,072	54,934
Non-interest income	96,239	92,608	88,857
Employees' compensation and benefits	139,176	133,422	120,356
Occupancy and equipment	59,478	58,000	58,036
Business promotion	12,331	13,787	12,754
Professional fees	27,618	25,251	25,120
Taxes, other than income taxes	16,702	16,891	17,105
Federal Deposit Insurance Corporation (FDIC) deposit insurance	3,415	5,043	1,983
Net (gain) loss on OREO operations	(51)	(58)	27
Credit and debit card processing expenses	23,620	22,258	19,452
Other non-interest expenses	26,159	25,878	23,644
Direct non-interest expenses	308,448	300,472	278,477
Segment income (loss)	243,296	210,370	218,649
Average earnings assets	4,042,201	3,770,393	3,372,309
Commercial and Corporate Segment [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)	157,672	142,313	143,776
Non-interest income	6,996	11,053	7,274
Commercial and Corporate Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	251,899	229,217	177,526
Net (charge) credit for transfer of funds	(78,291)	(71,813)	(30,130)
Interest expense	(15,936)	(15,091)	3,620
Net interest income (loss)	157,672	142,313	143,776
Provision for credit losses - (benefit) expense	(12,928)	(5,997)	(17,759)
Non-interest income	6,996	11,053	7,274
Employees' compensation and benefits	19,538	17,426	16,841
Occupancy and equipment	5,725	4,987	5,449
Business promotion	1,166	1,218	1,061
Professional fees	4,022	3,501	3,990
Taxes, other than income taxes	2,107	1,272	816
Federal Deposit Insurance Corporation (FDIC) deposit insurance	2,926	4,311	1,793
Net (gain) loss on OREO operations	(2,483)	96	610
Credit and debit card processing expenses	764	1,457	1,292
Other non-interest expenses	5,956	5,332	4,619
Direct non-interest expenses	39,721	39,600	36,471
Segment income (loss)	137,875	119,763	132,338
Average earnings assets	3,518,554	3,299,209	3,165,020
Treasury and Investments Segment [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)	(112,151)	(31,944)	(13,964)
Non-interest income	455	2,125	(161)
Treasury and Investments Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	116,734	116,382	102,991
Net (charge) credit for transfer of funds	(184,627)	(111,433)	(96,178)
Interest expense	(44,258)	(36,893)	(20,777)
Net interest income (loss)	(112,151)	(31,944)	(13,964)
Provision for credit losses - (benefit) expense	(50)	20	(434)
Non-interest income	455	2,125	(161)
Employees' compensation and benefits	3,648	3,354	3,168
Occupancy and equipment	739	717	814
Business promotion	727	881	901
Professional fees	1,313	654	1,292
Taxes, other than income taxes	407	425	370
Federal Deposit Insurance Corporation (FDIC) deposit insurance	0	0	0
Net (gain) loss on OREO operations	0	0	0
Credit and debit card processing expenses	0	0	0
Other non-interest expenses	2,363	2,562	2,451
Direct non-interest expenses	9,197	8,593	8,996
Segment income (loss)	(120,843)	(38,432)	(22,687)
Average earnings assets	5,850,884	6,186,018	7,300,208
United States Operations Segment [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)	77,988	70,798	74,168
Non-interest income	3,589	6,839	3,006
United States Operations Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	146,637	132,490	94,782
Net (charge) credit for transfer of funds	(7,215)	(12,830)	(9,065)
Interest expense	(61,434)	(48,862)	(11,549)
Net interest income (loss)	77,988	70,798	74,168
Provision for credit losses - (benefit) expense	(6,661)	8,687	(3,073)
Non-interest income	3,589	6,839	3,006
Employees' compensation and benefits	28,203	25,960	24,626
Occupancy and equipment	7,607	6,959	7,141
Business promotion	1,280	1,221	1,104
Professional fees	4,383	4,300	4,472
Taxes, other than income taxes	503	552	419
Federal Deposit Insurance Corporation (FDIC) deposit insurance	962	1,524	565
Net (gain) loss on OREO operations	(4)	(150)	(172)
Credit and debit card processing expenses	10	10	11
Other non-interest expenses	2,640	2,393	2,531
Direct non-interest expenses	45,584	42,769	40,697
Segment income (loss)	42,654	26,181	39,550
Average earnings assets	2,176,701	2,072,292	2,069,030
Virgin Islands Operations Segment [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)	60,695	55,863	50,012
Non-interest income	9,936	8,856	8,418
Virgin Islands Operations Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	28,956	27,624	24,913
Net (charge) credit for transfer of funds	40,802	33,064	26,173
Interest expense	(9,063)	(4,825)	(1,074)
Net interest income (loss)	60,695	55,863	50,012
Provision for credit losses - (benefit) expense	(229)	66	1,964
Non-interest income	9,936	8,856	8,418
Employees' compensation and benefits	17,986	17,230	16,587
Occupancy and equipment	9,020	9,233	10,190
Business promotion	877	1,073	1,040
Professional fees	4,481	5,081	5,258
Taxes, other than income taxes	669	714	593
Federal Deposit Insurance Corporation (FDIC) deposit insurance	683	1,116	462
Net (gain) loss on OREO operations	617	279	100
Credit and debit card processing expenses	3,206	2,272	1,981
Other non-interest expenses	3,599	3,094	3,338
Direct non-interest expenses	41,138	40,092	39,549
Segment income (loss)	29,722	24,561	16,917
Average earnings assets	$ 403,365	$ 389,489	$ 369,591