REVENUES - Disaggregation of revenues (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of revenue:
Total revenues	$ 182,610	$ 243,777
Oilfield services transferred at a point in time
Disaggregation of revenue:
Total revenues	0	0
Oilfield services transferred over time
Disaggregation of revenue:
Total revenues	$ 182,610	$ 243,777