DERIVATIVE FINANCIAL INSTRUMENTS AND HEDGING ACTIVITIES - Offsetting Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Cash Collateral Pledged	$ 26,200	$ 10,700
MNA counterparty
Derivative [Line Items]
Cash Collateral Pledged	26,200	10,700
Customer loan derivative liability
Derivative [Line Items]
Derivative liabilities	(24,933)	(8,046)
Customer loan derivative liability | MNA counterparty
Derivative [Line Items]
Derivative liabilities	(15,463)	(4,669)
Customer loan derivative liability | RPA counterparty
Derivative [Line Items]
Derivative liabilities	(9,470)	(3,377)
Customer loan derivative asset
Derivative [Line Items]
Derivative Assets	24,933	8,046
Customer loan derivative asset | MNA counterparty
Derivative [Line Items]
Derivative Assets	15,463	4,669
Customer loan derivative asset | RPA counterparty
Derivative [Line Items]
Derivative Assets	$ 9,470	$ 3,377