DERIVATIVES - Summary of Derivative Financial Instruments and Balances (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Derivative Asset	$ 308,819	$ 112,607
Derivative liabilities	308,888	112,616
Other Credit Derivatives [Member]
Derivatives, Fair Value [Line Items]
Credit Risk Derivative Liabilities, at Fair Value		900
Fair Value Hedges | Matched interest rate swaps | Accrued interest and other liabilities
Derivatives, Fair Value [Line Items]
Derivative Asset	6,306	2,636
Derivative liabilities	197,955	70,808
Fair Value Hedges | Matched interest rate swaps | Accrued interest and other assets
Derivatives, Fair Value [Line Items]
Derivative Asset	197,886	70,799
Derivative liabilities	$ 6,306	$ 2,636