DERIVATIVES - Additional Information (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($) entity	Dec. 31, 2017 USD ($) entity
Derivative [Line Items]
Maximum derivative notional position as a percentage of assets	35.00%
Maximum credit exposure as a percentage of capital	3.00%
Maximum single counterparty credit risk exposure	$ 20,000
Inerest-bearing deposit liability	$ 2,358,312	$ 1,674,080
Number of counterparties | entity	14	13
Derivative Asset	$ 27,567	$ 12,682
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	27,565	12,687
Interest Rate Lock Commitments [Member]
Derivative [Line Items]
Inerest-bearing deposit liability	37,200	12,300
Other Credit Derivatives [Member]
Derivative [Line Items]
Inerest-bearing deposit liability	35,600	15,400
Credit Risk Derivative Liabilities, at Fair Value		100
Credit Risk Contract [Member]
Derivative [Line Items]
Inerest-bearing deposit liability	146,300	95,900
Credit Risk Derivative Liabilities, at Fair Value	100	54
Accrued interest and other liabilities | Derivative [Member]
Derivative [Line Items]
Inerest-bearing deposit liability	1,200,000	837,500
Derivative Asset	$ (21,800)
Derivative Financial Instruments, Liabilities, Fair Value Disclosure		$ 1,300