REVENUES - Contract With Customer Asset And Liability (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
REVENUES
Contracts liability at the beginning of the period	$ 42,895	$ 25,015
Additions during the period	15,284	5,034
Revenue recognized during the period	(15,726)	(4,993)
Contracts liability at the end of the period	$ 42,453	$ 25,056