SEGMENT INFORMATION - Information about reportable segments (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Interest Income	$ 165,264	$ 166,472
Interest expense	(26,615)	(26,291)
Net interest income	138,649	140,181
Provision for credit losses	(77,366)	(11,408)
Non-interest income	30,200	22,543
Commercial And Corporate Banking Segment [Member]
Segment Reporting Information [Line Items]
Net interest income	23,581	20,933
Non-interest income	2,011	2,518
Treasury And Investments Segment [Member]
Segment Reporting Information [Line Items]
Net interest income	19,875	16,795
Non-interest income	8,328	74
United States Operations Segment [Member]
Segment Reporting Information [Line Items]
Net interest income	13,785	16,209
Non-interest income	831	533
Virgin Islands Operations Segment [Member]
Segment Reporting Information [Line Items]
Net interest income	6,606	6,961
Non-interest income	1,662	1,805
Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest Income	165,264	166,472
Net (charge) credit for transfer of funds	0	0
Interest expense	(26,615)	(26,291)
Net interest income	138,649	140,181
Provision for credit losses	(77,366)	(11,408)
Non-interest income	30,200	22,543
Direct non-interest expenses	(62,211)	(64,111)
Segment income (loss)	29,272	87,205
Average earnings assets	11,841,095	11,280,192
Operating Segments [Member] | Mortgage Banking Segment [Member]
Segment Reporting Information [Line Items]
Interest Income	28,800	30,857
Net (charge) credit for transfer of funds	(11,742)	(13,108)
Interest expense	0	0
Net interest income	17,058	17,749
Provision for credit losses	(15,201)	(6,412)
Non-interest income	3,640	3,606
Direct non-interest expenses	(8,499)	(8,481)
Segment income (loss)	(3,002)	6,462
Average earnings assets	2,012,906	2,188,093
Operating Segments [Member] | Consumer (Retail) Banking Segment [Member]
Segment Reporting Information [Line Items]
Interest Income	58,096	49,975
Net (charge) credit for transfer of funds	10,030	19,662
Interest expense	(10,382)	(8,103)
Net interest income	57,744	61,534
Provision for credit losses	(32,153)	(9,412)
Non-interest income	13,728	14,007
Direct non-interest expenses	(29,476)	(29,404)
Segment income (loss)	9,843	36,725
Average earnings assets	2,131,502	1,824,240
Operating Segments [Member] | Commercial And Corporate Banking Segment [Member]
Segment Reporting Information [Line Items]
Interest Income	32,636	37,387
Net (charge) credit for transfer of funds	(9,055)	(16,454)
Interest expense	0	0
Net interest income	23,581	20,933
Provision for credit losses	(19,175)	8,462
Non-interest income	2,011	2,518
Direct non-interest expenses	(7,047)	(9,401)
Segment income (loss)	(630)	22,512
Average earnings assets	2,420,069	2,499,709
Operating Segments [Member] | Treasury And Investments Segment [Member]
Segment Reporting Information [Line Items]
Interest Income	16,066	16,249
Net (charge) credit for transfer of funds	11,491	11,250
Interest expense	(7,682)	(10,704)
Net interest income	19,875	16,795
Provision for credit losses	(1,502)	0
Non-interest income	8,328	74
Direct non-interest expenses	(763)	(723)
Segment income (loss)	25,938	16,146
Average earnings assets	2,877,104	2,392,467
Operating Segments [Member] | United States Operations Segment [Member]
Segment Reporting Information [Line Items]
Interest Income	22,155	24,157
Net (charge) credit for transfer of funds	(724)	(1,350)
Interest expense	(7,646)	(6,598)
Net interest income	13,785	16,209
Provision for credit losses	(6,564)	(4,364)
Non-interest income	831	533
Direct non-interest expenses	(8,991)	(8,362)
Segment income (loss)	(939)	4,016
Average earnings assets	1,944,385	1,902,771
Operating Segments [Member] | Virgin Islands Operations Segment [Member]
Segment Reporting Information [Line Items]
Interest Income	7,511	7,847
Net (charge) credit for transfer of funds	0	0
Interest expense	(905)	(886)
Net interest income	6,606	6,961
Provision for credit losses	(2,771)	318
Non-interest income	1,662	1,805
Direct non-interest expenses	(7,435)	(7,740)
Segment income (loss)	(1,938)	1,344
Average earnings assets	$ 455,129	$ 472,912