REVENUE FROM CONTRACT WITH CUSTOMERS (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation Of Revenue [Line Items]
Net interest income	$ 525,383	$ 491,551	$ 484,118
Noninterest Income	82,310	$ 62,387	$ 87,954
Total Revenues	607,693
Service charges and fees on deposit accounts [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	21,668
Insurance commissions [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	8,431
Total Revenues	2,400
Merchant-related income [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	5,243
Credit and debit card fees [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	21,442
Other service charges and fees [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	7,870
Not inscope of Topic 606 [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	17,656
Mortgage Banking Segment [Member]
Disaggregation Of Revenue [Line Items]
Net interest income	79,389
Noninterest Income	17,073
Total Revenues	96,462
Mortgage Banking Segment [Member] | Service charges and fees on deposit accounts [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	0
Mortgage Banking Segment [Member] | Insurance commissions [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	0
Mortgage Banking Segment [Member] | Merchant-related income [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	0
Mortgage Banking Segment [Member] | Credit and debit card fees [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	0
Mortgage Banking Segment [Member] | Other service charges and fees [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	252
Mortgage Banking Segment [Member] | Not inscope of Topic 606 [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	16,821
Consumer Retail Banking Segment [Member]
Disaggregation Of Revenue [Line Items]
Net interest income	217,933
Noninterest Income	47,706
Total Revenues	265,639
Consumer Retail Banking Segment [Member] | Service charges and fees on deposit accounts [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	13,332
Consumer Retail Banking Segment [Member] | Insurance commissions [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	7,889
Consumer Retail Banking Segment [Member] | Merchant-related income [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	3,561
Consumer Retail Banking Segment [Member] | Credit and debit card fees [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	17,538
Consumer Retail Banking Segment [Member] | Other service charges and fees [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	4,391
Consumer Retail Banking Segment [Member] | Not inscope of Topic 606 [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	995
Commercial And Corporate Segment [Member]
Disaggregation Of Revenue [Line Items]
Net interest income	78,675
Noninterest Income	5,158
Total Revenues	83,833
Commercial And Corporate Segment [Member] | Service charges and fees on deposit accounts [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	4,965
Commercial And Corporate Segment [Member] | Insurance commissions [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	0
Commercial And Corporate Segment [Member] | Merchant-related income [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	748
Commercial And Corporate Segment [Member] | Credit and debit card fees [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	1,225
Commercial And Corporate Segment [Member] | Other service charges and fees [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	1,280
Commercial And Corporate Segment [Member] | Not inscope of Topic 606 [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	(3,060)
Treasury And Investments Segment [Member]
Disaggregation Of Revenue [Line Items]
Net interest income	61,628
Noninterest Income	2,505
Total Revenues	64,133
Treasury And Investments Segment [Member] | Service charges and fees on deposit accounts [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	0
Treasury And Investments Segment [Member] | Insurance commissions [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	0
Treasury And Investments Segment [Member] | Merchant-related income [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	0
Treasury And Investments Segment [Member] | Credit and debit card fees [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	0
Treasury And Investments Segment [Member] | Other service charges and fees [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	71
Treasury And Investments Segment [Member] | Not inscope of Topic 606 [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	2,434
United States Operations Segment [Member]
Disaggregation Of Revenue [Line Items]
Net interest income	59,056
Noninterest Income	3,020
Total Revenues	62,076
United States Operations Segment [Member] | Service charges and fees on deposit accounts [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	559
United States Operations Segment [Member] | Insurance commissions [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	87
United States Operations Segment [Member] | Merchant-related income [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	0
United States Operations Segment [Member] | Credit and debit card fees [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	618
United States Operations Segment [Member] | Other service charges and fees [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	1,351
United States Operations Segment [Member] | Not inscope of Topic 606 [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	405
Virgin Islands Operations Segment [Member]
Disaggregation Of Revenue [Line Items]
Net interest income	28,702
Noninterest Income	6,848
Total Revenues	35,550
Virgin Islands Operations Segment [Member] | Service charges and fees on deposit accounts [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	2,812
Virgin Islands Operations Segment [Member] | Insurance commissions [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	455
Virgin Islands Operations Segment [Member] | Merchant-related income [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	934
Virgin Islands Operations Segment [Member] | Credit and debit card fees [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	2,061
Virgin Islands Operations Segment [Member] | Other service charges and fees [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	525
Virgin Islands Operations Segment [Member] | Not inscope of Topic 606 [Member]
Disaggregation Of Revenue [Line Items]
Noninterest Income	$ 61