DERIVATIVE AND HEDGING INSTRUMENTS - Gross Presentation, Effects of Offsetting, and a Net Presentation of Derivatives (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Offsetting Assets:
Gross Amounts of Recognized Assets / Liabilities	$ 25,895	$ 11,240
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Assets / Liabilities presented in the Balance Sheet	25,895	11,240
Financial Instruments	0	(716)
Cash Collateral Received	0	0
Net Amount	25,895	10,524
Offsetting Liabilities:
Gross Amounts of Recognized Assets / Liabilities	0	716
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Assets / Liabilities presented in the Balance Sheet	0	716
Financial Instruments	0	(716)
Cash Collateral Received	0	0
Net Amount	$ 0	$ 0