COMMITTMENTS AND CONTINGENCIES - Fair Value Supply Agreement (Details) - Supply Commitments - Fair Value, Inputs, Level 3 - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accrued expenses and other short-term liabilities | Supply Agreement Liability - Short-term
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning of Period		$ 166
Payments		(166)
Transfer from long-term to current portion		0
Balance, End of Period		0
Accrued expenses and other short-term liabilities | Supply Agreement Liability - Short-term | Selling, general and administrative
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Gain (Loss) from change in fair value		0
Accrued expenses and other short-term liabilities | Above Market Supply Agreement Liability - Short- Term
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning of Period	$ 2,641	0
Payments	(214)	0
Transfer from long-term to current portion		1,752
Transfer to accounts payable	(571)
Balance, End of Period	876	1,752
Accrued expenses and other short-term liabilities | Above Market Supply Agreement Liability - Short- Term | Selling, general and administrative
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Gain (Loss) from change in fair value	$ (980)	0
Other Long-term Liabilities | Above Market Supply Agreement Liability - Long-term
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning of Period		2,648
Payments		(155)
Transfer from long-term to current portion		(1,752)
Balance, End of Period		800
Other Long-term Liabilities | Above Market Supply Agreement Liability - Long-term | Selling, general and administrative
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Gain (Loss) from change in fair value		$ 59