DERIVATIVES - Additional Information (Details) $ in Thousands	Jun. 30, 2019 USD ($) entity	Dec. 31, 2018 USD ($) entity
Derivative [Line Items]
Inerest-bearing deposit liability	$ 3,170,900	$ 2,719,980
Number of counterparties | entity	16	13
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	$ 68,932	$ 29,188
Interest Rate Lock Commitments [Member]
Derivative [Line Items]
Inerest-bearing deposit liability	52,800	20,800
Other Credit Derivatives [Member]
Derivative [Line Items]
Inerest-bearing deposit liability	52,800	12,300
Credit Risk Derivative Liabilities, at Fair Value	0	0
Credit Risk Contract [Member]
Derivative [Line Items]
Inerest-bearing deposit liability	155,600	138,400
Credit Risk Derivative Liabilities, at Fair Value	300	100
Accrued interest and other liabilities | Derivative [Member]
Derivative [Line Items]
Inerest-bearing deposit liability	1,600,000	1,400,000
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	$ 64,100	$ 4,900