SEGMENT INFORMATION - Total Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Assets	$ 911,314	$ 1,347,620
Operating segment | Water Services
Segment Reporting Information [Line Items]
Assets	559,889	831,123
Operating segment | Water Infrastructure
Segment Reporting Information [Line Items]
Assets	194,622	314,026
Operating segment | Oilfield Chemicals
Segment Reporting Information [Line Items]
Assets	149,727	192,224
Operating segment | Other
Segment Reporting Information [Line Items]
Assets	$ 7,076	$ 10,247