RECEIVABLES AND OTHER CURRENT ASSETS (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Tax Credit Carryforward [Line Items]
Government sales tax receivable	$ 2,457		$ 2,079
Marketable equity securities receivable	939
Other current assets	2,872		1,686
Receivables and other current assets	6,268		3,765
VAT collected	1,300	$ 6,100
Mexican Tax Authority
Tax Credit Carryforward [Line Items]
Government sales tax receivable	$ 1,200		$ 1,100