FINANCIAL INSTRUMENTS - Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation (Details) - Fair Value, Inputs, Level 3 - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Level 3 liability, beginning of period	$ 563,281	$ 0
Addition		507,427
Change in fair value	(200,322)	55,854
Level 3 liability, end of period	$ 362,959	$ 563,281