DERIVATIVE FINANCIAL INSTRUMENTS - Interest rate swap positions (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Liabilities, at Fair Value	$ 30,097,000	$ 20,658,000
Swap [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	$ 625,000,000	$ 1,270,000,000
Average Fixed Pay Rate	1.65%	2.03%
Average Receive Rate	1.74%	1.92%
Net Estimated Fair Value	$ (30,097,000)	$ (20,146,000)
Swap [Member] | 1-3 Years
Derivatives, Fair Value [Line Items]
Notional Amount		$ 360,000,000
Average Fixed Pay Rate		2.05%
Average Receive Rate		1.90%
Net Estimated Fair Value		$ (3,680,000)
Swap [Member] | 3-5 Years
Derivatives, Fair Value [Line Items]
Notional Amount	$ 625,000,000	$ 910,000,000
Average Fixed Pay Rate	1.65%	2.03%
Average Receive Rate	1.74%	1.93%
Net Estimated Fair Value	$ (30,097,000)	$ (16,466,000)