EFFECTS OF NATURAL DISASTERS- Additional information (Detail) - USD ($) $ in Thousands	12 Months Ended			15 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Sep. 30, 2017
Liability For Catastrophe Claims [Line Items]
Proceeds from the settlement of insurance claims	$ 7,673	$ 0	$ 0
Gain from insurance proceeds	537	0	$ 0
Commercial [Member] | General Allowance [Member]
Liability For Catastrophe Claims [Line Items]
Financing Receivable Allowance For Credit Losses	5,700			$ 5,700
Hurricane [Member]
Liability For Catastrophe Claims [Line Items]
Financing Receivable Allowance For Credit Losses	19,200	55,600		19,200	$ 66,500
Net Loan Loss Reserve Release	16,900
Increase Decrease In Deposits Excluding Brokered Certificates Of Deposits	$ 567,000			$ 928,500
Percentage Of Non Interest Bearing Demand Deposits	31.00%			51.00%
Insurance Settlements Receivable	$ 3,400	4,800		$ 3,400
Proceeds from the settlement of insurance claims	6,800
Gain from insurance proceeds	500
Recoveries of disaster response costs	1,000
Increase Decrease In Non Interest Bearing Demand Deposits	561,800			809,300
Hurricane [Member] | Consumer loans [Member]
Liability For Catastrophe Claims [Line Items]
Financing Receivable Allowance For Credit Losses	3,200	$ 25,000		3,200
Charge-offs	(10,900)
Hurricane [Member] | Commercial [Member]
Liability For Catastrophe Claims [Line Items]
Financing Receivable Allowance For Credit Losses	(5,700)			$ (5,700)
Hurricane [Member] | Loans Receivable [Member]
Liability For Catastrophe Claims [Line Items]
Proceeds from the settlement of insurance claims	$ 800