REVENUES - Disaggregation of revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of revenue:
Total revenues	$ 89,300	$ 358,516	$ 333,077	$ 693,172
Oilfield services transferred at a point in time
Disaggregation of revenue:
Total revenues	0	0	0	0
Oilfield services transferred over time
Disaggregation of revenue:
Total revenues	$ 89,300	$ 358,516	$ 333,077	$ 693,172