ACCOUNTS RECEIVABLE (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Third-party customers	$ 203,068	$ 194,606
Less: allowance for bad debts and credit notes	(9,697)	(10,436)
Total accounts receivable	193,371	184,170
Provision for Doubtful Accounts	$ 800	$ 1,900	$ 3,800