SEGMENT INFORMATION - Total Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Assets	$ 1,391,009	$ 1,356,368
Operating segment | Water Solutions
Segment Reporting Information [Line Items]
Assets	1,045,321	994,159
Operating segment | Oilfield Chemicals
Segment Reporting Information [Line Items]
Assets	172,900	186,333
Operating segment | Wellsite Services
Segment Reporting Information [Line Items]
Assets	145,016	151,272
Corporate
Segment Reporting Information [Line Items]
Assets	$ 27,772	$ 24,604