FAIR VALUE (Assets and Liabiliites Measured on a Recurring Basis) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Liabilities:
Interest rate swap derivative liabilities	$ 0	$ 5,961
Recurring
Assets:
Cash equivalents	50,272	50,135
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash equivalents	50,272	50,135
Recurring | Significant Other Observable Inputs (Level 2)
Assets:
Cash equivalents	0	0
Recurring | Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents	0	0
Interest rate swap contracts | Recurring
Assets:
Interest rate swap derivative assets	9,011	4,470
Liabilities:
Interest rate swap derivative liabilities	0	5,961
Interest rate swap contracts | Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Interest rate swap derivative assets	0	0
Liabilities:
Interest rate swap derivative liabilities	0	0
Interest rate swap contracts | Recurring | Significant Other Observable Inputs (Level 2)
Assets:
Interest rate swap derivative assets	9,011	4,470
Liabilities:
Interest rate swap derivative liabilities	0	5,961
Interest rate swap contracts | Recurring | Significant Unobservable Inputs (Level 3)
Assets:
Interest rate swap derivative assets	0	0
Liabilities:
Interest rate swap derivative liabilities	$ 0	$ 0