REVENUES - Disaggregation of revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of revenue:
Total revenues	$ 188,757	$ 89,300	$ 371,367	$ 333,077
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	$ 188,757	$ 89,300	$ 371,367	$ 333,077