REVENUE FROM CONTRACT WITH CUSTOMERS (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Net interest income	$ 140,181	$ 124,693
Non-interest income	22,543	22,784
Total Revenue	162,724	147,477
Service charges and fees on deposit accounts [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	5,716	5,088
Insurance commissions [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	4,250	3,355
Total Revenue	2,700	2,100
Merchant-related income [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	1,294	991
Credit and debit card fees [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	5,403	5,094
Other service charges and fees [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	1,528	2,254
Not inscope of Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	4,352	6,002
Mortgage Banking Segment [Member]
Disaggregation of Revenue [Line Items]
Net interest income	17,749	21,205
Non-interest income	3,606	4,084
Total Revenue	21,355	25,289
Mortgage Banking Segment [Member] | Service charges and fees on deposit accounts [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	0	0
Mortgage Banking Segment [Member] | Insurance commissions [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	0	0
Mortgage Banking Segment [Member] | Merchant-related income [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	0	0
Mortgage Banking Segment [Member] | Credit and debit card fees [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	0	0
Mortgage Banking Segment [Member] | Other service charges and fees [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	44	33
Mortgage Banking Segment [Member] | Not inscope of Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	3,562	4,051
Consumer Retail Banking Segment [Member]
Disaggregation of Revenue [Line Items]
Net interest income	61,534	51,049
Non-interest income	14,007	11,930
Total Revenue	75,541	62,979
Consumer Retail Banking Segment [Member] | Service charges and fees on deposit accounts [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	3,524	3,165
Consumer Retail Banking Segment [Member] | Insurance commissions [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	4,066	3,144
Consumer Retail Banking Segment [Member] | Merchant-related income [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	834	645
Consumer Retail Banking Segment [Member] | Credit and debit card fees [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	4,398	4,169
Consumer Retail Banking Segment [Member] | Other service charges and fees [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	843	800
Consumer Retail Banking Segment [Member] | Not inscope of Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	342	7
Commercial And Corporate Segment [Member]
Disaggregation of Revenue [Line Items]
Net interest income	20,933	18,920
Non-interest income	2,518	1,259
Total Revenue	23,451	20,179
Commercial And Corporate Segment [Member] | Service charges and fees on deposit accounts [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	1,324	1,092
Commercial And Corporate Segment [Member] | Insurance commissions [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	0	0
Commercial And Corporate Segment [Member] | Merchant-related income [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	196	161
Commercial And Corporate Segment [Member] | Credit and debit card fees [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	320	255
Commercial And Corporate Segment [Member] | Other service charges and fees [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	426	300
Commercial And Corporate Segment [Member] | Not inscope of Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	252	(549)
Treasury And Investments Segment [Member]
Disaggregation of Revenue [Line Items]
Net interest income	16,795	12,518
Non-interest income	74	2,378
Total Revenue	16,869	14,896
Treasury And Investments Segment [Member] | Service charges and fees on deposit accounts [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	0	0
Treasury And Investments Segment [Member] | Insurance commissions [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	0	0
Treasury And Investments Segment [Member] | Merchant-related income [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	0	0
Treasury And Investments Segment [Member] | Credit and debit card fees [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	0	0
Treasury And Investments Segment [Member] | Other service charges and fees [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	0	0
Treasury And Investments Segment [Member] | Not inscope of Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	74	2,378
United States Operations Segment [Member]
Disaggregation of Revenue [Line Items]
Net interest income	16,209	13,392
Non-interest income	533	1,408
Total Revenue	16,742	14,800
United States Operations Segment [Member] | Service charges and fees on deposit accounts [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	136	134
United States Operations Segment [Member] | Insurance commissions [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	11	12
United States Operations Segment [Member] | Merchant-related income [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	0	0
United States Operations Segment [Member] | Credit and debit card fees [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	169	128
United States Operations Segment [Member] | Other service charges and fees [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	133	1,039
United States Operations Segment [Member] | Not inscope of Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	84	95
Virgin Islands Operations Segment [Member]
Disaggregation of Revenue [Line Items]
Net interest income	6,961	7,609
Non-interest income	1,805	1,725
Total Revenue	8,766	9,334
Virgin Islands Operations Segment [Member] | Service charges and fees on deposit accounts [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	732	697
Virgin Islands Operations Segment [Member] | Insurance commissions [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	173	199
Virgin Islands Operations Segment [Member] | Merchant-related income [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	264	185
Virgin Islands Operations Segment [Member] | Credit and debit card fees [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	516	542
Virgin Islands Operations Segment [Member] | Other service charges and fees [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	82	82
Virgin Islands Operations Segment [Member] | Not inscope of Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Non-interest income	$ 38	$ 20