SEGMENT INFORMATION - Total Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Assets	$ 1,026,908	$ 1,347,620
Operating segment | Water services
Segment Reporting Information [Line Items]
Assets	600,200	831,123
Operating segment | Water infrastructure
Segment Reporting Information [Line Items]
Assets	230,899	314,026
Operating segment | Oilfield chemicals
Segment Reporting Information [Line Items]
Assets	188,472	192,224
Operating segment | Other
Segment Reporting Information [Line Items]
Assets	$ 7,337	$ 10,247