SEGMENT INFORMATION - Information about Reportable Segments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Interest income	$ 794,708	$ 692,982	$ 675,897
Interest expense	(64,779)	(92,660)	(108,816)
Net interest income (loss)	729,929	600,322	567,081
Provision for loan and lease losses	61,720	(168,717)	(40,225)
Non-interest income	121,164	111,226	90,572
Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	794,708	692,982	675,897
Net (charge) credit for transfer of funds	0	0	0
Interest expense	(64,779)	(92,660)	(108,816)
Net interest income (loss)	729,929	600,322	567,081
Provision for loan and lease losses	(65,698)	170,985	39,813
Non-interest income	121,164	111,226	90,572
Direct non-interest expenses	296,780	258,864	252,603
Segment income	620,011	281,699	365,237
Average earnings assets	19,235,941	14,201,505	11,497,408
Mortgage Banking Segment [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)	104,638	76,025	68,803
Non-interest income	24,278	22,069	16,825
Mortgage Banking Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	144,203	128,043	120,981
Net (charge) credit for transfer of funds	(39,565)	(52,018)	(52,178)
Interest expense	0	0	0
Net interest income (loss)	104,638	76,025	68,803
Provision for loan and lease losses	(16,030)	22,518	13,499
Non-interest income	24,278	22,069	16,825
Direct non-interest expenses	29,125	33,054	34,825
Segment income	115,821	42,522	37,304
Average earnings assets	2,506,365	2,241,753	2,161,772
Consumer Retail Banking Segment [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)	281,703	220,678	244,535
Non-interest income	69,774	50,962	51,729
Consumer Retail Banking Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	271,127	240,725	216,066
Net (charge) credit for transfer of funds	38,859	18,771	66,675
Interest expense	(28,283)	(38,818)	(38,206)
Net interest income (loss)	281,703	220,678	244,535
Provision for loan and lease losses	20,322	54,094	41,043
Non-interest income	69,774	50,962	51,729
Direct non-interest expenses	165,357	131,133	116,854
Segment income	165,798	86,413	138,367
Average earnings assets	2,551,278	2,202,595	1,960,352
Commercial And Corporate Segment [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)	191,917	135,591	91,266
Non-interest income	16,032	12,606	11,714
Commercial And Corporate Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	201,684	155,254	148,224
Net (charge) credit for transfer of funds	(9,767)	(19,663)	(56,958)
Interest expense	0	0	0
Net interest income (loss)	191,917	135,591	91,266
Provision for loan and lease losses	(67,544)	74,607	(17,977)
Non-interest income	16,032	12,606	11,714
Direct non-interest expenses	36,219	28,631	35,130
Segment income	239,274	44,959	85,827
Average earnings assets	3,793,945	3,039,786	2,489,933
Treasury And Investments Segment [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)	59,331	87,879	73,626
Non-interest income	227	13,708	(225)
Treasury And Investments Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	67,841	55,003	63,175
Net (charge) credit for transfer of funds	14,687	59,074	47,477
Interest expense	(23,197)	(26,198)	(37,026)
Net interest income (loss)	59,331	87,879	73,626
Provision for loan and lease losses	(136)	2,774	0
Non-interest income	227	13,708	(225)
Direct non-interest expenses	4,093	3,449	2,729
Segment income	55,601	95,364	70,672
Average earnings assets	7,827,326	4,232,144	2,487,084
United States Operations Segment [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)	65,967	54,025	62,539
Non-interest income	3,963	4,630	2,807
United States Operations Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	82,194	84,169	97,406
Net (charge) credit for transfer of funds	(4,214)	(6,164)	(5,016)
Interest expense	(12,013)	(23,980)	(29,851)
Net interest income (loss)	65,967	54,025	62,539
Provision for loan and lease losses	(975)	12,592	7,296
Non-interest income	3,963	4,630	2,807
Direct non-interest expenses	33,902	33,782	34,070
Segment income	37,003	12,281	23,980
Average earnings assets	2,126,528	2,026,619	1,931,015
Virgin Islands Operations Segment [Member]
Segment Reporting Information [Line Items]
Net interest income (loss)	26,373	26,124	26,312
Non-interest income	6,890	7,251	7,722
Virgin Islands Operations Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Interest income	27,659	29,788	30,045
Net (charge) credit for transfer of funds	0	0	0
Interest expense	(1,286)	(3,664)	(3,733)
Net interest income (loss)	26,373	26,124	26,312
Provision for loan and lease losses	(1,335)	4,400	(4,048)
Non-interest income	6,890	7,251	7,722
Direct non-interest expenses	28,084	28,815	28,995
Segment income	6,514	160	9,087
Average earnings assets	$ 430,499	$ 458,608	$ 467,252