REVENUES - Schedule of Deferred Revenue (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Deferred Revenue Arrangement [Line Items]
Deferred revenue	$ 5,531	$ 6,104
Deferred revenue — related party	410	1,482
Related party
Deferred Revenue Arrangement [Line Items]
Deferred revenue — related party	0	1,072
Third-Party Customer
Deferred Revenue Arrangement [Line Items]
Other non-current liabilities	$ 7,372	$ 3,391