DERIVATIVES - Additional Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) entity	Dec. 31, 2018 USD ($) 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	$ 2,813,828	$ 2,719,980
Number of counterparties | entity	13	13
Derivative Asset	$ 38,801	$ 29,189
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	38,808	29,188
Interest Rate Lock Commitments [Member]
Derivative [Line Items]
Inerest-bearing deposit liability	32,800	20,800
Other Credit Derivatives [Member]
Derivative [Line Items]
Inerest-bearing deposit liability	32,800	12,300
Credit Risk Derivative Liabilities, at Fair Value	100
Credit Risk Contract [Member]
Derivative [Line Items]
Inerest-bearing deposit liability	119,800	138,400
Credit Risk Derivative Liabilities, at Fair Value	100	75
Accrued interest and other liabilities | Derivative [Member]
Derivative [Line Items]
Inerest-bearing deposit liability	1,400,000	1,400,000
Derivative Asset	$ 27,100
Derivative Financial Instruments, Liabilities, Fair Value Disclosure		$ 4,900