REVENUES - Disaggregation of revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of revenue:
Total revenues	$ 116,588	$ 293,240	$ 449,665	$ 986,412
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	$ 116,588	$ 293,240	$ 449,665	$ 986,412