FAIR VALUE MEASUREMENTS - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets
Marketable securities (Other assets)	$ 4,964	$ 5,081
Derivative contracts	417	879
Assets, fair value, total	5,381	5,960
Liabilities
Derivative contracts, liabilities	17,711	12,054
Liabilities, fair value, total	17,711	12,054
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Marketable securities (Other assets)	4,964	5,081
Derivative contracts	0	0
Assets, fair value, total	4,964	5,081
Liabilities
Derivative contracts, liabilities	0	0
Liabilities, fair value, total	0	0
Significant Other Observable Inputs (Level 2)
Assets
Marketable securities (Other assets)	0	0
Derivative contracts	0	0
Assets, fair value, total	0	0
Liabilities
Derivative contracts, liabilities	15,330	10,110
Liabilities, fair value, total	15,330	10,110
Significant Unobservable Inputs (Level 3)
Assets
Marketable securities (Other assets)	0	0
Derivative contracts	417	879
Assets, fair value, total	417	879
Liabilities
Derivative contracts, liabilities	2,381	1,944
Liabilities, fair value, total	$ 2,381	$ 1,944