EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Calculation of basic and diluted earnings per share:
Antidilutive shares	1,400,008
Net income (loss)	$ 16,132	$ (12,280)
Net income (loss) attributable to noncontrolling interests	(6,033)	8,108
Net income (loss) attributable to Select Energy Services, Inc.	10,099	(4,172)
Add: Reallocation of net income attributable to noncontrolling interests for the dilutive effect of restricted stock	10
Add: Reallocation of net income attributable to noncontrolling interests for the dilutive effect of stock options	25
Net income attributable to Select Energy Services, Inc. — diluted	10,134
Class A Common Stock
Calculation of basic and diluted earnings per share:
Net income (loss) attributable to Select Energy Services, Inc.	9,097	$ (809)
Add: Reallocation of net income attributable to noncontrolling interests for the dilutive effect of restricted stock	11
Add: Reallocation of net income attributable to noncontrolling interests for the dilutive effect of stock options	29
Net income attributable to Select Energy Services, Inc. — diluted	$ 9,137
Weighted-average shares of common stock outstanding — basic	59,064,958
Dilutive effect of restricted stock	165,402
Dilutive effect of stock options	443,106
Weighted-average shares of common stock outstanding — diluted	59,673,466
Earnings per share, Basic	$ 0.15	$ (0.21)
Earnings per share, Diluted	$ 0.15	$ (0.21)
Weighted-average shares of common stock outstanding — basic & diluted		3,870,194
Basic & Diluted		$ (0.21)
Class A-2 Common Stock
Calculation of basic and diluted earnings per share:
Net income (loss) attributable to Select Energy Services, Inc.	$ 1,002	$ (3,363)
Add: Reallocation of net income attributable to noncontrolling interests for the dilutive effect of restricted stock	(1)
Add: Reallocation of net income attributable to noncontrolling interests for the dilutive effect of stock options	(4)
Net income attributable to Select Energy Services, Inc. — diluted	$ 997
Weighted-average shares of common stock outstanding — basic	6,507,445
Weighted-average shares of common stock outstanding — diluted	6,507,445
Earnings per share, Basic	$ 0.15
Earnings per share, Diluted	$ 0.15
Weighted-average shares of common stock outstanding — basic & diluted		16,100,000
Basic & Diluted		$ (0.21)
Class B Common Stock
Calculation of basic and diluted earnings per share:
Weighted-average shares of common stock outstanding — basic	40,331,989
Weighted-average shares of common stock outstanding — diluted	40,331,989
Weighted-average shares of common stock outstanding — basic & diluted		38,462,541