Select Energy Services (WTTR) 10-K 25 Feb 20 2019 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Feb. 21, 2020	Jun. 28, 2019
Document and Entity Information
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	001-38066
Entity Registrant Name	Select Energy Services, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	81-4561945
Entity Address, Address Line One	1233 W. Loop South, Suite 1400
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77027
City Area Code	713
Local Phone Number	235-9500
Title of 12(b) Security	Class A common stock, par value $0.01 per share
Trading Symbol	WTTR
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 684.9
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Central Index Key	0001693256
Amendment Flag	false
Class A Common Stock
Document and Entity Information
Entity Common Stock, Shares Outstanding		87,057,036
Class B Common Stock
Document and Entity Information
Entity Common Stock, Shares Outstanding		16,221,101

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 79,268	$ 17,237
Accounts receivable trade, net of allowance for doubtful accounts of $5,773 and $5,329, respectively	267,628	341,711
Accounts receivable, related parties	4,677	1,119
Inventories	37,542	44,992
Prepaid expenses and other current assets	26,486	27,093
Total current assets	415,601	432,152
Property and equipment	1,015,379	1,114,378
Accumulated depreciation	(562,986)	(611,530)
Property and equipment held-for-sale, net	885
Total property and equipment, net	453,278	502,848
Right-of-use assets, net	70,635
Goodwill	266,934	273,801
Other intangible assets, net	136,952	148,377
Other assets, net	4,220	3,427
Total assets	1,347,620	1,360,605
Current liabilities
Accounts payable	35,686	53,847
Accrued accounts payable	47,547	62,536
Accounts payable and accrued expenses, related parties	2,789	5,056
Accrued salaries and benefits	20,079	22,113
Accrued insurance	8,843	14,849
Sales tax payable	2,119	5,820
Accrued expenses and other current liabilities	15,375	14,560
Current operating lease liabilities	19,315
Current portion of finance lease obligations	128	938
Total current liabilities	151,881	179,719
Long-term operating lease liabilities	72,143
Long-term operating lease liabilities		16,752
Other long-term liabilities	10,784	8,361
Long-term debt		45,000
Total liabilities	234,808	249,832
Commitments and contingencies (Note 10)
Preferred stock, $0.01 par value; 50,000,000 shares authorized; no shares issued and outstanding as of December 31, 2019 and December 31, 2018
Additional paid-in capital	914,699	813,599
Retained earnings	21,437	18,653
Accumulated other comprehensive deficit		(368)
Total stockholders' equity	937,177	832,934
Noncontrolling interests	175,635	277,839
Total equity	1,112,812	1,110,773
Total liabilities and equity	1,347,620	1,360,605
Class A Common Stock
Current liabilities
Common stock	879	790
Total equity	879
Class A-2 Common Stock
Current liabilities
Common stock
Class B Common Stock
Current liabilities
Common stock	162	$ 260
Total equity	$ 162

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Allowance for doubtful accounts	$ 5,773	$ 5,329
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	50,000,000	50,000,000
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Class A Common Stock
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	350,000,000	350,000,000
Common Stock, Shares, Issued	87,893,525	78,956,555
Common Stock, Shares, Outstanding	87,893,525	78,956,555
Class A-2 Common Stock
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	40,000,000	40,000,000
Common Stock, Shares, Issued	0	0
Common Stock, Shares, Outstanding	0	0
Class B Common Stock
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	150,000,000	150,000,000
Common Stock, Shares, Issued	16,221,101	26,026,843
Common Stock, Shares, Outstanding	16,221,101	26,026,843

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue
Total revenue	$ 1,291,589	$ 1,528,930	$ 692,491
Costs of revenue
Depreciation and amortization	116,809	130,537	101,645
Total costs of revenue	1,142,849	1,330,448	634,711
Gross profit	148,740	198,482	57,780
Operating expenses
Selling, general and administrative	111,622	103,156	82,403
Depreciation and amortization	3,860	3,176	1,804
Impairment of goodwill	4,396	17,894
Impairment of property and equipment	3,715	6,657
Impairment of cost-method investment		2,000
Lease abandonment costs	2,073	3,925	3,572
Total operating expenses	125,666	136,808	87,779
Income (loss) from operations	23,074	61,674	(29,999)
Other income (expense)
(Losses) gains on sales of property, equipment and divestitures, net	(11,626)	3,804	2,726
Interest expense, net	(2,688)	(5,311)	(6,629)
Foreign currency gain (loss), net	273	(1,292)	281
Other expense, net	(2,948)	(2,872)	(2,357)
Income (loss) before income tax expense	6,085	56,003	(35,978)
Income tax (expense) benefit	(1,949)	(1,704)	851
Net income (loss)	4,136	54,299	(35,127)
Less: net (income) loss attributable to noncontrolling interests	(1,352)	(17,787)	18,311
Net income (loss) attributable to Select Energy Services, Inc.	2,784	36,512	(16,816)
Water services
Revenue
Total revenue	772,311	896,783	418,869
Costs of revenue
Costs of revenue	598,405	681,546	317,262
Water infrastructure
Revenue
Total revenue	221,593	230,115	163,328
Costs of revenue
Costs of revenue	166,962	160,072	120,510
Oilfield chemicals
Revenue
Total revenue	268,614	259,791	41,586
Costs of revenue
Costs of revenue	230,434	233,454	37,024
Other
Revenue
Total revenue	29,071	142,241	68,708
Costs of revenue
Costs of revenue	30,239	124,839	58,270
Class A Common Stock
Other income (expense)
Net income (loss) attributable to Select Energy Services, Inc.	$ 2,784	$ 35,720	$ (12,560)
Net income (loss) per share attributable to common stockholders (Note 16):
Basic	$ 0.03	$ 0.49	$ (0.51)
Diluted	$ 0.03	$ 0.49	$ (0.51)
Class A-1 Common Stock
Other income (expense)
Net income (loss) attributable to Select Energy Services, Inc.			$ (3,691)
Net income (loss) per share attributable to common stockholders (Note 16):
Basic			$ (0.51)
Diluted			$ (0.51)
Class A-2 Common Stock
Other income (expense)
Net income (loss) attributable to Select Energy Services, Inc.		$ 792	$ (565)
Net income (loss) per share attributable to common stockholders (Note 16):
Basic		$ 0.49	$ (0.51)
Diluted		$ 0.49	$ (0.51)

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)
Net income (loss)	$ 4,136	$ 54,299	$ (35,127)
Other comprehensive income (loss)
Foreign currency translation adjustment, net of tax of $0	368	(670)	302
Net change in unrealized gain (loss)	368	(670)	302
Comprehensive income (loss)	4,504	53,629	(34,825)
Less: comprehensive (income) loss attributable to noncontrolling interests	(1,472)	(17,568)	18,154
Comprehensive income (loss) attributable to Select Energy Services, Inc.	$ 3,032	$ 36,061	$ (16,671)

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)
Foreign currency translation adjustment, tax amount	$ 0	$ 0	$ 0

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Thousands	Class A Common StockConversion of Class A-2 to Class A	Class A Common StockConversion of Class B to Class A	Class A Common Stock	Class A-1 Common StockConversion of Class B to Class A	Class A-1 Common Stock	Class A-2 Common StockConversion of Class A-2 to Class A	Class A-2 Common Stock	Class B Common StockConversion of Class B to Class A	Class B Common Stock	Conversion of Class B to Class ATotal Stockholders' Equity	Conversion of Class B to Class AAdditional Paid-In Capital	Conversion of Class B to Class ARetained Earnings (Accumulated Deficit)	Conversion of Class B to Class AAccumulated Other Comprehensive Income (Loss)	Conversion of Class B to Class ANoncontrolling Interests	Conversion of Class B to Class A	Total Stockholders' Equity	Additional Paid-In Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests	Total
Beginning balance at Dec. 31, 2016			$ 38		$ 161				$ 385							$ 112,716	$ 113,175	$ (1,043)		$ 221,992	$ 334,708
Beginning balance (in shares) at Dec. 31, 2016			3,802,972		16,100,000				38,462,541
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of common stock		$ 161		$ (161)
Conversion of common stock (in shares)		16,100,000		(16,100,000)
Exchange of shares of Class B common stock and SES Holdings, LLC units for shares of Class A common stock			$ 25						$ (25)							16,298	16,298			(16,298)
Exchange of shares of Class B common stock and SES Holdings, LLC common units for shares of Class A common stock (in shares)			2,487,029						(2,487,029)
Equity-based compensation																4,346	4,346			3,345	7,691
Issuance of shares for acquisition			$ 6													5,001	4,995			4,879	9,880
Issuance of shares for acquisition (in shares)			560,277
Issuance of shares for merger			$ 262				$ 67		$ 44							447,615	447,242			170,276	617,891
Issuance of shares for merger (in shares)			26,246,115				6,731,845		4,356,477
Issuance of shares for initial public offering			$ 100													87,369	87,269			41,135	128,504
Repurchase of common stock																(184)	(184)			(113)	(297)
Repurchase of common stock ( in shares)			(19,217)
Noncontrolling interest in subsidiary																				(368)	(368)
Foreign currency translation adjustment																302			$ 302	185	487
Net income																(16,816)		(16,816)		(18,311)	(35,127)
Ending balance at Dec. 31, 2017			$ 592				$ 67		$ 404							656,647	673,141	(17,859)	302	406,722	1,063,369
Ending balance (in shares) at Dec. 31, 2017			59,182,176				6,731,845		40,331,989
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of common stock	$ 67					$ (67)
Conversion of common stock (in shares)	6,731,839					(6,731,839)
Exchange of shares of Class B common stock and SES Holdings, LLC units for shares of Class A common stock		$ 144						$ (144)		$ 146,865	$ 146,865			$ (146,865)
Exchange of shares of Class B common stock and SES Holdings, LLC common units for shares of Class A common stock (in shares)		14,305,146						(14,305,146)
ESPP shares issued																132	132			(15)	117
ESPP shares issued (in shares)			9,793
Equity-based compensation																7,312	7,312			3,059	10,371
Issuance of restricted shares			$ 4													2,325	2,321			(2,325)
Issuance of restricted shares (in shares)			438,182
Exercise of restricted stock units																104	104			(104)
Exercise of restricted stock units (in shares)			27,860
Stock options exercised			$ 1													1,019	1,018			(374)	645
Stock options exercised (in shares)			79,333
Repurchase of common stock			$ (17)													(17,138)	(17,121)			576	(16,562)
Repurchase of common stock ( in shares)			(1,766,428)				(6)
Restricted shares forfeited			$ (1)													(383)	(382)			383
Restricted shares forfeited (in shares)			(51,346)
Distributions to noncontrolling interests, net																				506	506
NCI income tax adjustment																209	209			(209)
Foreign currency translation adjustment																(670)			(670)	(290)	(960)
Net income																36,512		36,512		17,787	54,299
Ending balance at Dec. 31, 2018		$ 790						$ 260		832,934	813,599	$ 18,653	$ (368)	277,839	$ 1,110,773						1,110,773
Ending balance (in shares) at Dec. 31, 2018		78,956,555						26,026,843
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exchange of shares of Class B common stock and SES Holdings, LLC units for shares of Class A common stock		$ 98						$ (98)		$ 107,062	$ 107,062			$ (107,062)
Exchange of shares of Class B common stock and SES Holdings, LLC common units for shares of Class A common stock (in shares)		9,805,742						(9,805,742)
ESPP shares issued																154	154			(42)	112
ESPP shares issued (in shares)			13,178
Equity-based compensation																12,050	12,050			3,435	15,485
Issuance of restricted shares			$ 14													3,653	3,639			(3,653)
Issuance of restricted shares (in shares)			1,417,458
Exercise of restricted stock units																4	4			(4)
Exercise of restricted stock units (in shares)			1,250
Stock options exercised																84	84			(54)	30
Stock options exercised (in shares)			5,282
Repurchase of common stock			$ (23)													(21,962)	(21,939)			3,362	(18,600)
Repurchase of common stock ( in shares)			(2,288,880)
Restricted shares forfeited																(39)	(39)			39
Restricted shares forfeited (in shares)			(17,060)
Distributions to noncontrolling interests, net																				404	404
NCI income tax adjustment																66	66			(66)
Foreign currency translation adjustment																387	19		$ 368	85	472
Net income																2,784		2,784		1,352	4,136
Ending balance at Dec. 31, 2019			$ 879						$ 162							$ 937,177	$ 914,699	$ 21,437		$ 175,635	$ 1,112,812
Ending balance (in shares) at Dec. 31, 2019			87,893,525						16,221,101

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities
Net income (loss)	$ 4,136	$ 54,299	$ (35,127)
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Depreciation and amortization	120,669	133,713	103,449
Net loss (gain) on disposal of property and equipment	7,950	(3,803)	(2,726)
Gain realized on previously held interest in Rockwater			(1,210)
Bad debt expense	2,553	2,210	1,542
Amortization of debt issuance costs	688	688	4,031
Inventory write-downs	250	442
Equity-based compensation	15,485	10,371	7,691
Impairment of goodwill	4,396	17,894
Impairment of property and equipment	3,715	6,657
Impairment of cost-method investment		2,000
Loss on divestitures	3,676
Other operating items, net	240	1,287	(353)
Changes in operating assets and liabilities
Accounts receivable	57,908	36,537	(100,485)
Prepaid expenses and other assets	11,321	(9,115)	(2,177)
Accounts payable and accrued liabilities	(29,039)	(20,771)	22,466
Net cash provided by (used in) operating activities	203,948	232,409	(2,899)
Cash flows from investing activities
Working capital settlement	691
Proceeds received from divestitures	24,872
Purchase of property and equipment	(110,143)	(165,360)	(98,722)
Acquisitions, net of cash received	(10,000)	(16,999)	(65,488)
Proceeds received from sales of property and equipment	17,223	13,998	7,479
Net cash used in investing activities	(77,357)	(168,361)	(156,731)
Cash flows from financing activities
Borrowings from revolving line of credit	5,000	60,000	109,000
Payments on long-term debt	(50,000)	(90,000)	(111,000)
Payments of finance lease obligations	(883)	(1,881)
Payment of debt issuance costs			(3,442)
Proceeds from initial public offering			140,070
Proceeds from share issuance	142	762
Payments incurred for initial public offering			(11,566)
Distributions to noncontrolling interests, net	(349)	(506)	(368)
Repurchase of common stock	(18,600)	(16,562)	(297)
Contingent consideration		(1,106)
Net cash (used in) provided by financing activities	(64,690)	(49,293)	122,397
Effect of exchange rate changes on cash	130	(292)	(34)
Net increase (decrease) in cash and cash equivalents	62,031	14,463	(37,267)
Cash and cash equivalents, beginning of period	17,237	2,774
Cash and cash equivalents, end of period	79,268	17,237	2,774
Supplemental cash flow disclosure:
Cash paid for interest	2,716	5,243	1,999
Cash paid (refunds received) for income taxes, net	1,793	(550)	(54)
Supplemental disclosure of noncash operating activities:
Lease liabilities arising from obtaining right-of-use assets	119,358
Supplemental disclosure of noncash investing activities:
Capital expenditures included in accounts payable and accrued liabilities	$ 10,472	$ 17,910	$ 11,137

BUSINESS AND BASIS OF PRESENTAT

BUSINESS AND BASIS OF PRESENTATION	12 Months Ended
	Dec. 31, 2019
BUSINESS AND BASIS OF PRESENTATION
BUSINESS AND BASIS OF PRESENTATION	NOTE 1—BUSINESS AND BASIS OF PRESENTATION Description of the business : Select Energy Services, Inc. (“we,” “Select Inc.” or “the Company”) was incorporated as a Delaware corporation on November 21, 2016. The Company is a holding company whose sole material asset consists of common units (“SES Holdings LLC Units”) in SES Holdings, LLC (“SES Holdings” or the “ We are a leading provider of comprehensive water-management solutions to the oil and gas industry in the United States (“U.S.”). We also develop, manufacture and deliver a full suite of chemical solutions for use in oil and gas well completion and production operations. Through a combination of organic growth and acquisitions over the last decade, we have developed a leading position in the relatively new water solutions industry. We believe we are the only company in the oilfield services industry that combines comprehensive water-management services with related chemical products. Furthermore, we believe we are one of the few large oilfield services companies whose primary focus is on the management and treatment of water and water resources in the oil and gas development industry. Accordingly, the importance of responsibly managing water resources through our operations to help conserve fresh water and protect the environment is paramount to our continued success. Select 144A Offering and Initial Public Offering : On December 20, 2016, Select Inc. completed a private placement (the “Select 144A Offering”) of Registration rights : In December 2016, in connection with the closing of the Select 144A Offering, Select Inc. entered into a registration rights agreement with FBR Capital Markets & Co. for the benefit of the investors in the Select 144A Offering. Under this registration rights agreement, the Company agreed, at its expense, to file with the SEC, in no event later than April 30, 2017, a shelf registration statement registering for resale the Rockwater Merger: which we issued approximately 25.9 million shares of Class A Common Stock, 6.7 million shares of Select Inc. Class A-2 common stock, par value $0.01 (the “Class A-2 Common Stock”) and 4.4 million shares of Class B Common Stock to the former holders of Rockwater common stock and a unit-for-unit transaction in which SES Holdings issued approximately 37.3 million SES Holdings LLC Units to the former holders of units in Rockwater LLC. See Note 3—Acquisitions for further discussion. ​ Rockwater Registration Rights Agreement: On January 12, 2018, the Company, pursuant to the Rockwater Registration Rights Agreement, filed with the SEC, a shelf registration statement registering for resale of 6,653,777 shares of Class A Common Stock into which certain of the outstanding shares of Class A-2 Common Stock registered under such registration statement were convertible. Pursuant to the Company’s Third Amended and Restated Certificate of Incorporation, upon the effectiveness of this registration statement on March 29, 2018, each outstanding share of Class A-2 Common Stock converted automatically into a share of Class A Common Stock on a one-for-one basis. No shares of Class A-2 Common Stock are currently outstanding. ​ Credit Agreement: . ​ Exchange rights : Under the Eighth Amended and Restated Limited Liability Company Agreement of SES Holdings (the “SES Holdings LLC Agreement”), Legacy Owner Holdco and its permitted transferees have the right (an “Exchange Right”) to cause SES Holdings to acquire all or a portion of its SES Holdings LLC Units for, at SES Holdings’ election, (i) shares of Class A Common Stock at an exchange ratio of one share of Class A Common Stock for each SES Holdings LLC Unit exchanged, subject to conversion rate adjustments for stock splits, stock dividends, reclassification and other similar transactions or (ii) cash in an amount equal to the Cash Election Value (as defined within the SES Holdings LLC Agreement) of such Class A Common Stock. Alternatively, upon the exercise of any Exchange Right, Select Inc. has the right (the “Call Right”) to acquire the tendered SES Holdings LLC Units from the exchanging unitholder for, at its election, (i) the number of shares of Class A Common Stock the exchanging unitholder would have received under the Exchange Right or (ii) cash in an amount equal to the Cash Election Value of such Class A Common Stock. In connection with any exchange of SES Holdings LLC Units pursuant to an Exchange Right or Call Right, the corresponding number of shares of Class B Common Stock will be cancelled. ​ Tax Receivable Agreements : In connection with the Company’s restructuring at the Select 144A Offering, Select Inc. entered into ​ Basis of presentation : The accompanying consolidated financial statements of the Company have been prepared in accordance with generally accepted accounting principles in the U.S. (“GAAP”) and pursuant to the rules and regulations of the SEC. The consolidated financial statements include the accounts of the Company and all of its majority-owned or controlled subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. ​ For investments in subsidiaries that are not wholly owned, but where the Company exercises control, the equity held by the minority owners and their portion of net income or loss are reflected as noncontrolling interests. Investments in entities in which the Company exercises significant influence over operating and financial policies are accounted for using the equity method, and investments in entities for which the Company does not have significant control or influence are accounted for using the cost-method. As of December 31, 2019 and December 31, 2018, the Company had no equity method investees and one cost-method investee. The Company’s investments are reviewed for impairment whenever events or circumstances indicate that the carrying value may not be recoverable. When circumstances indicate that the fair value of its investment is less than its carrying value and the reduction in value is other than temporary, the reduction in value is recognized in earnings. During the first quarter of 2018, the Company determined that its cost-method investee was no longer fully recoverable and was written down to its estimated fair value of $0.5 million. The impairment expense of $2.0 million is included in impairment of cost-method investment within the consolidated statements of operations. Segment reporting : The Water Services segment consists of the Company’s services businesses including water transfer, flowback and well testing, fluids hauling, water containment, water treatment and water network automation, primarily serving exploration and production (“E&P”) companies. Additionally, this segment includes the operations of our accommodations and rentals business, which were previously a part of the former Wellsite Services segment. The Water Infrastructure segment consists of the Company’s infrastructure assets and ongoing infrastructure development projects, including operations associated with our water sourcing and pipelines, produced water gathering systems and salt water disposal wells, primarily serving E&P companies. The Oilfield Chemicals segment develops, manufactures and provides a full suite of chemicals used in hydraulic fracturing, stimulation, cementing, and well completion and production services, including polymer slurries, crosslinkers, friction reducers, biocides, dry and liquid scale inhibitors, corrosion inhibitors, buffers, breakers and other chemical technologies. This segment also provides chemicals needed by our customers to increase oil and gas production and lower production costs over the life of a well. Our Oilfield Chemicals customers are primarily pressure pumpers, along with major integrated and independent oil and gas producers. The results of our divested service lines that were previously a part of the former Wellsite Services segment, including the operations of our Affirm subsidiary, our sand hauling operations and our Canadian operations, are combined in the “Other” category. As of December 31, 2019, these operations have ceased, and we do not expect regular recurring revenue going forward from this former segment. Reclassifications : Substantially complete liquidation: ​

SIGNIFICANT ACCOUNTING POLICIES

SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2019
SIGNIFICANT ACCOUNTING POLICIES
SIGNIFICANT ACCOUNTING POLICIES	NOTE 2—SIGNIFICANT ACCOUNTING POLICIES Use of estimates : The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. On an ongoing basis, the Company evaluates its estimates, including those related to the recoverability of long-lived assets and intangibles, useful lives used in depreciation and amortization, uncollectible accounts receivable, income taxes, self-insurance liabilities, share-based compensation, inventory, incremental borrowing rate on leases and contingent liabilities. The Company bases its estimates on historical and other pertinent information that are believed to be reasonable under the circumstances. The accounting estimates used in the preparation of the consolidated financial statements may change as new events occur, as more experience is acquired, as additional information is obtained and as the Company’s operating environment changes. Cash and cash equivalents : The Company considers all highly liquid investments with an original maturity of three months or less to be cash equivalents. Accounts receivable and allowance for doubtful accounts : Accounts receivable are stated at the invoiced amount, or the earned but not yet invoiced amount, net of an allowance for doubtful accounts. The Company establishes an allowance for doubtful accounts based on the review of several factors, including historical collection experience, the current aging status of the customer accounts and financial condition of its customers. Accounts receivable are written off when a settlement is reached for an amount less than the outstanding historical balance or when the Company determines that it is probable the balance will not be collected. The change in allowance for doubtful accounts is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, ​ ​ 2019 ​ 2018 2017 ​ ​ (in thousands) Balance at beginning of year ​ $ 5,329 $ 2,979 $ 2,144 Provisions for bad debts, included in selling, general and administrative ​ 2,553 2,210 1,542 Uncollectible receivable (write-offs) recoveries ​ (2,109) 140 (707) Balance at end of year ​ $ 5,773 $ 5,329 $ 2,979 ​ Concentrations of credit and customer risk : Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash and cash equivalents and trade accounts receivable. The amounts held in financial institutions periodically exceed the federally insured limit. Management believes that the financial institutions are financially sound and the risk of loss is minimal. The Company minimizes its exposure to counterparty credit risk by performing credit evaluations and ongoing monitoring of the financial stability of its customers. There were Inventories : The Company values its inventories at lower of cost or net realizable value. Inventory costs are determined under the weighted-average method. Inventory costs primarily consist of chemicals and materials available for resale and parts and consumables used in operations. Debt issuance costs : Debt issuance costs consist of costs directly associated with obtaining credit with financial institutions. These costs are recorded as a long-term asset associated with the line of credit and amortized on a straight-line basis over the life of the credit agreement, which approximates the effective-interest method. During the year ended December 31, 2017, the Company expensed unamortized debt issuance costs of Property and equipment : Property and equipment are stated at cost less accumulated depreciation. Depreciation (and amortization of capital lease assets) is calculated on a straight line basis over the estimated useful life of each asset as noted below: ​ ​ ​ ​ Asset Classification Useful Life (years) Land Indefinite Buildings and leasehold improvements 30 or lease term Vehicles and equipment 4 - 7 or lease term Machinery and equipment 2 - 15 Computer equipment and software 3 - 4 or lease term Office furniture and equipment 7 Disposal wells 7 - 10 ​ ​ ​ ​ Depreciation expense related to the Company’s property and equipment, including amortization of property under finance leases, was $108.7 million, $120.4 million and $92.6 million for the years ended December 31, 2019, 2018 and 2017, respectively. Change in depreciable lives of property and equipment: The average estimated useful lives of the assets impacted in the vehicles and equipment category increased from 6.0 to 8.1 years, while the average estimated useful lives of assets impacted in machinery and equipment increased from 5.5 years to 6.9 years. The impact of the increase of useful lives was to defer and extend out depreciation expense, including lower expense in 2018. The impact of the increase in salvage values was to permanently lower current and future depreciation expense. The fixed assets obtained in 2017 through mergers and acquisitions, including the Rockwater Merger, had consistent useful life and salvage value estimates with the rest of the Company’s fixed assets. The change in the estimated useful lives of fixed assets and change in salvage value estimates was implemented on a prospective basis starting January 1, 2018. Excluding fixed assets attained through mergers and acquisitions during 2017, the impact of the change in useful estimate of fixed assets purchased on or before December 31, 2017 was to reduce and defer depreciation expense by $12.6 million during the year ended December 31, 2018. Also, the increase in estimated vehicle salvage value produced a permanent depreciation expense reduction of $3.9 million during the year ended December 31, 2018. For the year ended December 31, 2018, the changes in useful life estimate and increased salvage value produced an increase to net income of $10.9 million (including the impact of noncontrolling interests) and increased both basic and diluted earnings per share attributable to our stockholders by $0.15. Business Combinations: Goodwill and other intangible assets : Goodwill represents the excess of the purchase price of acquisitions over the fair value of the net assets acquired. Goodwill and other intangible assets not subject to amortization are tested for impairment annually or more frequently if events or changes in circumstances indicate that the asset might be impaired. Intangible assets with finite useful lives are amortized either on a straight-line basis over the asset’s estimated useful life or on a basis that reflects the pattern in which the economic benefits of the intangible assets are realized. Impairment of goodwill, long-lived assets and intangible assets : Long-lived assets, such as property and equipment and finite-lived intangible assets, are evaluated for impairment whenever events or changes in circumstances indicate that its carrying value may not be recoverable. Recoverability is measured by a comparison of its carrying amount to the estimated undiscounted cash flows to be generated by those assets. If the undiscounted cash flows are less than the carrying amount, the Company records impairment losses for the excess of its carrying value over the estimated fair value. The development of future cash flows and the estimate of fair value represent its best estimates based on industry trends and reference to market transactions and are subject to variability. The Company considers the factors within the fair value analysis to be Level 3 inputs within the fair value hierarchy. During the year ended December 31, 2018, the Company reviewed certain fluid disposal machinery and equipment used in our fluid hauling and disposal services that are included in our Water Infrastructure segment. Due to the condition of the equipment, the Company determined that long-lived assets with a carrying value of ​ The Company conducts its annual goodwill impairment tests in the fourth quarter of each year, and whenever impairment indicators arise, by examining relevant events and circumstances which could have a negative impact on its goodwill such as macroeconomic conditions, industry and market conditions, cost factors that have a negative effect on earnings and cash flows, overall financial performance, acquisitions and divestitures and other relevant entity-specific events. If a qualitative assessment indicates that it is more likely than not that the fair value of a reporting unit is less than its carrying amount, the Company is required to perform a quantitative impairment test for goodwill comparing the reporting unit’s carrying value to its fair value. The Company’s reporting units are based on its organizational and reporting structure. In determining fair values for the reporting units, the Company relies primarily on the income and market approaches for valuation. In the income approach, the Company discounts predicted future cash flows using a weighted-average cost of capital calculation based on publicly traded peer companies. In the market approach, valuation multiples are developed from both publicly traded peer companies as well as other company transactions. The cost approach, when used, considers replacement cost as the primary indicator of value. If the fair value of a reporting unit is less than its carrying value, goodwill impairment is calculated by subtracting the fair value of the reporting unit from the carrying value. Application of the goodwill impairment test requires judgment, including the identification of reporting units, allocation of assets (including goodwill) and liabilities to reporting units and determining the fair value. The determination of reporting unit fair value relies upon certain estimates and assumptions that are complex and are affected by numerous factors, including the general economic environment and levels of exploration and production (“E&P”) activity of oil and gas companies, the Company’s financial performance and trends and the Company’s strategies and business plans, among others. Unanticipated changes, including immaterial revisions, to these assumptions, could result in a provision for impairment in a future period. Given the nature of these evaluations and their application to specific assets and time frames, it is not possible to reasonably quantify the impact of changes in these assumptions. During the first quarter of 2019, goodwill related to our Affirm reporting unit was reduced to zero from the crane divestiture and impairment. The $4.4 million impairment was based on the estimated fair value of the proceeds from selling and winding down the remainder of the Affirm reporting unit business being less than the carrying value. Also, in connection with the Company’s segment realignment, the Company reallocated goodwill from reporting units in the 2018 Water Solutions segment to reporting units in the 2019 Water Services and Water Infrastructure segments based on the relative fair value of each as of March 31, 2019. See Note 8—Goodwill and Other Intangible Assets and Note 12—Fair Value Measurement for further discussion. Asset retirement obligations : The asset retirement obligation (“ARO”) liability reflects the present value of estimated costs of plugging, site reclamation and similar activities associated with the Company’s salt water disposal wells. The Company utilizes current retirement costs to estimate the expected cash outflows for retirement obligations. The Company also estimates the productive life of the disposal wells, a credit-adjusted risk-free discount rate and an inflation factor in order to determine the current present value of this obligation. The Company’s ARO liabilities are included in accrued expenses and other current liabilities and other long-term liabilities as of December 31, 2019 and 2018. The change in asset retirement obligations is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, ​ ​ ​ ​ ​ 2019 2018 ​ ​ ​ ​ (in thousands) ​ ​ Balance at beginning of year ​ $ 1,898 $ 1,846 ​ ​ Accretion expense, included in depreciation and amortization expense ​ ​ 115 ​ 183 ​ ​ Change in estimate ​ ​ — ​ 377 ​ ​ Disposals ​ ​ (486) ​ ​ — ​ ​ ​ Divestitures ​ ​ — ​ ​ (508) ​ ​ ​ Balance at end of year ​ $ 1,527 $ 1,898 ​ ​ ​ In addition to the obligations described above, the Company may be obligated to remove facilities or perform other remediation upon retirement of certain other assets. However, the fair value of the asset retirement obligation cannot currently be reasonably estimated because the settlement dates are indeterminable. If applicable, the Company will record an asset retirement obligation for these assets in the periods in which settlement dates are reasonably determinable Self-insurance : The Company self-insures, through deductibles and retentions, up to certain levels for losses related to general liability, workers’ compensation and employer’s liability and vehicle liability. The Company’s exposure (i.e. the retention or deductible) per occurrence is Employee benefit plans : The Company sponsors a defined contribution 401(k) Profit Sharing Plan (the “401(k) Plan”) for the benefit of substantially all employees of the Company. The 401(k) Plan allows eligible employees to make tax-deferred contributions, not to exceed annual limits established by the Internal Revenue Service. The Company did not make any matching contributions for the year ended December 31, 2016. Company reinstated matching contributions of 100% of employee contributions, up to 4% of compensation with immediate vesting for existing employees. Starting July 1, 2017, the vesting schedule for new hires is 25% for the first year, 50% for the second year, 75% for the third year and 100% for the fourth year. The Company’s contributions to the 401(k) Plan were $4.2 million and $3.6 million for the years ended December 31, 2019 and 2018, respectively. Revenue recognition : The Company follows ASU 2014-09, Revenue from Contracts with Customers (Topic 606). . Water Services and Water Infrastructure The Company’s agreements with its customers are often referred to as “price sheets” and sometimes provide pricing for multiple services. However, these agreements generally do not authorize the performance of specific services or provide for guaranteed throughput amounts. As customers are free to choose which services, if any, to use based on the Company’s price sheet, the Company prices its separate services on the basis of their standalone selling prices. Customer agreements generally do not provide for performance-, cancellation-, termination-, or refund-type provisions. Services based on price sheets with customers are generally performed under separately-issued “work orders” or “field tickets” as services are requested. Of the Company’s Water Solutions service lines, only sourcing and transfer of water are consistently provided as part of the same arrangement. In these instances, revenue for both sourcing and transfer are recognized concurrently when delivered. Accommodations and Rentals Oilfield Chemical Product Sales— Oilfield Chemicals products are generally sold under sales agreements based upon purchase orders or contracts with customers that do not include right of return provisions or other significant post-delivery obligations. The Company’s products are produced in a standard manufacturing operation, even if produced to the customer’s specifications. The prices of products are fixed and determinable and are established in price lists or customer purchases orders. The Company recognizes revenue from product sales when title passes to the customer, the customer assumes risks and rewards of ownership, collectability is reasonably assured and delivery occurs as directed by the customer. Equity-based compensation : The Company accounts for equity-based awards for restricted stock awards, restricted stock units, and stock settled appreciation awards by measuring the awards at the date of grant and recognizing the grant-date fair value as an expense using either straight-line or accelerated attribution, depending on the specific terms of the award agreements over the requisite service period, which is usually equivalent to the vesting period. The Company expenses awards with graded-vesting service conditions on a straight-line basis and accounts for forfeitures as they occur. The company accounts for performance share units by remeasuring the awards at the end of each reporting period based on the period end closing share price, factoring in the percentage expected to vest, Fair value measurements : The Company measures certain assets and liabilities pursuant to accounting guidance which establishes a three-tier fair value hierarchy and prioritizes the inputs used in measuring fair value. Level 1 inputs are unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 inputs are quoted prices or other market data for similar assets and liabilities in active markets, or inputs that are observable for the asset or liability, either directly or indirectly through market corroboration, for substantially the full term of the asset or liability. Level 3 inputs are unobservable inputs based upon its own judgment and assumptions used to measure assets and liabilities at fair value. See Note 12—Fair Value Measurement for further discussion. Income taxes The Company and its subsidiaries account for income taxes under the asset and liability method. Under this method, deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis. Deferred tax assets and liabilities are measured using enacted tax rates in effect for the year in which those temporary differences are expected to be recovered or settled pursuant to the provisions of Accounting Standards Codification (“ASC”) 740, Income Taxes. The effect on deferred tax assets and liabilities of a change in tax rate is recognized in earnings in the period that includes the enactment date. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts more likely than not to be realized. The determination of the provision for income taxes requires significant judgment, use of estimates and the interpretation and application of complex tax laws. Significant judgment is required in assessing the timing and amounts of deductible and taxable items and the probability of sustaining uncertain tax positions. The benefits of uncertain tax positions are recorded in the Company’s financial statements only after determining a more likely than not probability that the uncertain tax positions will withstand challenge, if any, from taxing authorities. When facts and circumstances change, the Company reassesses these probabilities and records any changes through the provision for income taxes. The Company recognizes interest and penalties relating to uncertain tax provisions as a component of tax expense. The Company identified no material uncertain tax positions as of December 31, 2019, 2018 and 2017. See Note 14—Income Taxes for further discussion. Recent accounting pronouncements Leases Leases (ASC 842): Targeted Improvements, which provides entities with an option to apply the guidance prospectively, instead of retrospectively, and allows for other classification provisions. ASU 2016-02 is effective for annual reporting periods beginning after December 15, 2018, including interim periods within those fiscal years, with early adoption permitted. The Company adopted ASU 2016-02 in the first quarter of 2019. The Company elected to recognize its lease assets and liabilities on a prospective basis, beginning on January 1, 2019, using the modified retrospective transition method. Additionally, the Company elected practical expedients to (i) exclude right-of-use assets and lease liabilities for short-term leases, (ii) elected to treat lease and non-lease components as a single lease component, (iii) grandfathered its current accounting for land easements that commenced before January 1, 2019, and (iv) used the package of practical expedients to retain prior lease classification, prior treatment of initial direct costs and prior determination of whether a contract constituted a lease. See Note 5—Leases for additional information. In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments ​ In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740)

ACQUISITIONS AND DIVESTITURES

ACQUISITIONS AND DIVESTITURES	12 Months Ended
	Dec. 31, 2019
ACQUISITIONS AND DIVESTITURES
ACQUISITIONS AND DIVESTITURES	NOTE 3—ACQUISITIONS AND DIVESTITURES Business combinations Well Chemical Services Acquisition On September 30, 2019, the Company acquired a well chemical services business (“WCS”), formerly a division of Baker Hughes Company, for $10.0 million, funded with cash on hand (the “WCS Acquisition”). WCS provides advanced water treatment solutions, specialized stimulation flow assurance and integrity additives and post-treatment monitoring service in the U.S. This acquisition expands the Company’s service offerings in oilfield water treatment across the full life-cycle of water, from pre-fracturing treatment through reuse and recycling. The WCS Acquisition was accounted for as a business combination under the acquisition method of accounting. When determining the fair values of assets acquired and liabilities assumed, management made significant estimates, judgments and assumptions. These estimates, judgments and assumptions and valuation of the inventory and property and equipment acquired, customer relationships, and current liabilities have been finalized as of December 31, 2019. The assets acquired and liabilities assumed are included in the Company’s Oilfield Chemicals segment. The following table summarizes the consideration transferred and the estimated fair value of identified assets acquired and liabilities assumed at the date of acquisition: ​ ​ ​ ​ ​ Purchase price allocation Amount Consideration transferred (in thousands) Cash paid ​ $ 10,000 Total consideration transferred ​ 10,000 Less: identifiable assets acquired and liabilities assumed ​ Inventory ​ 5,221 Property and equipment ​ 4,473 Customer relationships ​ 476 Current liabilities ​ ​ (170) Total identifiable net assets acquired ​ 10,000 Fair value allocated to net assets acquired ​ $ 10,000 ​ Pro Well Acquisition On November 20, 2018, the Company acquired Pro Well Testing and Wireline, Inc. (“Pro Well”) with an initial payment of $12.4 million, funded with cash on hand (the “Pro Well Acquisition”). During March 2019, upon final settlement, the purchase price was revised to $11.8 million. This acquisition expanded the Company’s flowback footprint into New Mexico and added new strategic customers. The Pro Well Acquisition was accounted for as a business combination under the acquisition method of accounting. When determining the fair values of assets acquired and liabilities assumed, management made significant estimates, judgments and assumptions. Management estimated that total consideration paid exceeded the fair value of the net assets acquired by $1.1 million, with the excess recorded as goodwill. The goodwill recognized was primarily attributable to expanding the Company’s flowback footprint into New Mexico and adding new strategic customers. The assets acquired, liabilities assumed and the results of operations of the acquired business are included in the Company’s Water Services segment. The goodwill acquired is deductible for tax purposes. The following table summarizes the consideration transferred and the estimated fair value of identified assets acquired and liabilities assumed at the date of acquisition: ​ ​ ​ ​ ​ ​ Purchase price allocation Amount Consideration transferred (in thousands) Cash paid ​ $ 11,754 Total consideration transferred ​ 11,754 Less: identifiable assets acquired and liabilities assumed ​ Working capital ​ 1,051 Property and equipment ​ 6,588 Customer relationship intangible assets ​ 3,000 Total identifiable net assets acquired ​ 10,639 Goodwill ​ ​ 1,115 Fair value allocated to net assets acquired ​ $ 11,754 ​ Rockwater Merger On November 1, 2017, the Company completed the Rockwater Merger in which the Company combined with Rockwater. The Rockwater Merger was accounted for as a business combination under the acquisition method of accounting. When determining the fair values of assets acquired and liabilities assumed, management made significant estimates, judgments and assumptions. The Company also engaged third-party valuation experts to assist in the purchase price allocation and the recorded valuation of property and equipment. Management estimated that total consideration paid exceeded the fair value of the net assets acquired and liabilities assumed by $264.5 million, with the excess recorded as goodwill. The goodwill recognized was primarily attributable to synergies driven by expanding into new geographies, service offerings and customer relationships, strengthening existing service lines and geographies, acquiring an established, trained workforce and expected cost reductions. Goodwill of $251.8 million and $12.7 million was allocated to reporting units within the Company’s 2018 Water Solutions and Oilfield Chemicals segments, respectively. The acquired goodwill is not deductible for tax purposes. The following table summarizes the consideration transferred and the estimated fair value of identified assets acquired and liabilities assumed at the date of acquisition: ​ ​ ​ ​ ​ Purchase price allocation ​ Amount Consideration transferred ​ (in thousands) Class A Common Stock (25,914,260 shares) ​ $ 423,957 Class A-2 Common Stock (6,731,845 shares) ​ ​ 110,133 Class B Common Stock (4,356,477 shares) and SES Holdings common units issued (4,356,477 units) ​ ​ 71,272 Fair value of previously held interest in Rockwater ​ 2,310 Fair value of Rockwater share-based awards attributed to pre-acquisition service ​ ​ 12,529 Total consideration transferred ​ 620,201 Less: identifiable assets acquired and liabilities assumed ​ ​ Working capital ​ 141,720 Property and equipment ​ 172,650 Intangible assets ​ ​ Customer relationships ​ ​ 89,661 Trademarks and patents ​ ​ 31,223 Non-compete agreements ​ ​ 3,811 Other long-term assets ​ ​ 88 Deferred tax liabilities ​ ​ (408) Long-term debt ​ ​ (80,555) Other long-term liabilities ​ ​ (2,517) Total identifiable net assets acquired ​ ​ 355,673 Goodwill ​ 264,528 Fair value allocated to net assets acquired $ 620,201 ​ ​ Resource Water Acquisition On September 15, 2017, the Company completed its acquisition (the “Resource Water Acquisition”) of Resource Water Transfer Services, L.P. and certain other affiliated assets (collectively, “Resource Water”). Resource Water provides water transfer services to E&P operators in West Texas and East Texas. Resource Water’s assets included 24 miles of layflat hose as well as numerous pumps and ancillary equipment required to support water transfer operations. Resource Water has longstanding customer relationships across its operating regions, which are viewed as strategic to the Company’s water services business. The acquired goodwill is deductible for tax purposes. The total consideration for the Resource Water Acquisition was $9.0 million, with $6.6 million paid in cash and $2.4 million paid in shares of Class A Common Stock valued at $15.17 per share. The Company funded the cash portion of the consideration for the Resource Water Acquisition with $6.6 million of cash on hand. The Resource Water Acquisition was accounted for as a business combination under the acquisition method of accounting. When determining the fair values of assets acquired and liabilities assumed, management made significant estimates, judgments and assumptions. Management estimated that total consideration paid exceeded the fair value of the net assets acquired by $1.9 million, with the excess recorded as goodwill. The goodwill recognized was attributable to Resource Water’s assembled workforce as well as synergies related to the Company’s comprehensive water solutions strategy. The assets acquired and liabilities assumed and the results of operations of the acquired business are included in the Company’s Water Services segment. The following table summarizes the consideration transferred and the estimated fair value of identified assets acquired and liabilities assumed at the date of acquisition: ​ ​ ​ ​ ​ Purchase price allocation Amount Consideration transferred (in thousands) Cash paid ​ $ 6,586 Class A Common Stock (156,909 shares) ​ 2,380 Total consideration transferred ​ 8,966 Less: identifiable assets acquired and liabilities assumed ​ Working capital ​ 1,189 Property and equipment ​ 3,485 Customer relationship intangible assets ​ 1,933 Other intangible assets ​ 465 Total identifiable net assets acquired ​ 7,072 Goodwill ​ 1,894 Fair value allocated to net assets acquired $ 8,966 ​ GRR Acquisition On March 10, 2017, the Company completed its acquisition (the “GRR Acquisition”) of Gregory Rockhouse Ranch, Inc. and certain other affiliated entities and assets (collectively, the “GRR Entities”). The GRR Entities provide water and water-related services to E&P companies in the Permian Basin and own and have rights to a vast array of fresh, brackish and effluent water sources with access to significant volumes of water annually and water transport infrastructure, including over 1,000 miles of temporary and permanent pipeline infrastructure and related storage facilities and pumps, all located in the Northern Delaware Basin portion of the Permian Basin. The total consideration for the GRR Acquisition was $59.6 million, with $53.0 million paid in cash, $1.1 million in assumed tax liabilities and $5.5 million paid to the sellers in shares of Class A Common Stock valued at $20.00 per share. The Company funded the cash portion of the consideration for the GRR Acquisition with $19.0 million of cash on hand and $34.0 million of borrowings under the Company’s Previous Credit Facility. For the year ended December 31, 2017, the Company expensed $1.0 million of transaction-related costs, which are included in selling, general and administrative expenses within the consolidated statements of operations. The GRR Acquisition was accounted for as a business combination under the acquisition method of accounting. When determining the fair values of assets acquired and liabilities assumed, management made significant estimates, judgments and assumptions. Management estimated that consideration paid exceeded the fair value of the net assets acquired by $12.0 million, with the excess recorded as goodwill. The goodwill recognized was primarily attributable to synergies related to the Company’s comprehensive water infrastructure strategy that is expected to arise from the GRR Acquisition and was attributable to the Company’s Water Infrastructure segment. The assets acquired and liabilities assumed and the results of operations of the acquired business are included in the Company’s Water Infrastructure segment. The acquired goodwill is deductible for tax purposes. The following table summarizes the consideration transferred and the estimated fair value of identified assets acquired and liabilities assumed at the date of acquisition: ​ ​ ​ ​ ​ Purchase price allocation Amount Consideration transferred (in thousands) Cash paid ​ $ 53,032 Class A Common Stock (274,998 shares) ​ 5,500 Assumed liabilities ​ 1,106 Total consideration transferred ​ 59,638 Less: identifiable assets acquired and liabilities assumed ​ Working capital ​ 7,728 Property and equipment ​ 13,225 Customer relationship intangible assets ​ 21,484 Other intangible assets ​ 5,152 Total identifiable net assets acquired ​ 47,589 Goodwill ​ ​ 12,049 Fair value allocated to net assets acquired ​ $ 59,638 ​ The following unaudited consolidated 2017 pro forma information is presented as if the Rockwater Merger, the Resource Water Acquisition and the GRR Acquisition had occurred on January 1, 2017. ​ ​ ​ ​ ​ ​ Pro Forma ​ ​ Year ended December 31, ​ ​ 2017 ​ ​ (unaudited) ​ ​ (in thousands) Revenue $ 1,270,736 Net loss ​ (13,079) Less: net loss attributable to noncontrolling interests (1) 5,299 Net loss attributable to Select Energy Services, Inc. (1) $ (7,780) (1) The allocation of net income (loss) attributable to noncontrolling interests and Select Inc. gives effect to the equity structure as of December 31, 2016 as though the Select 144A Offering, the IPO, the Rockwater Merger, the Resource Water Acquisition and the GRR Acquisition occurred as of January 1, 2017. However, the calculation of pro forma net income (loss) does not give effect to any other pro forma adjustments for the Select 144A Offering or the subsequent IPO. The unaudited pro forma amounts above have been calculated after applying the Company’s accounting policies and the Rockwater Merger, the Resource Water Acquisition, and the GRR Acquisition results to reflect the increase to depreciation and amortization that would have been charged assuming the fair value adjustments to property, plant and equipment and intangible assets had been applied from January 1, 2017 and other related pro forma adjustments. The pro forma amounts do not include any potential synergies, cost savings or other expected benefits of the, Rockwater Merger, the Resource Water Acquisition or the GRR Acquisition, and are presented for illustrative purposes only and are not necessarily indicative of results that would have been achieved if the Rockwater Merger, the Resource Water Acquisition and the GRR Acquisition had occurred as of January 1, 2017 or of future operating performance. Divestitures Affirm and Canadian Operations Divestitures During the year ended December 31, 2019, the Company closed on four sale transactions and wound down the remaining Affirm and Canadian operations. The Company sold property and equipment with a combined net book value of $18.6 million and assigned contracts to the buyers. Additionally, two of the four transactions included the assignment of working capital. The following table summarizes sales details for each of the four transactions: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Date of Divestiture ​ Entity ​ Initial Net Proceeds ​ Working Capital True Up ​ Adjusted Net Proceeds ​ Working Capital Status at ​ (Gain)/loss for the year ended December 31, 2019 ​ ​ ​ ​ (in thousands) February 26, 2019 ​ Affirm ​ $ 10,982 ​ $ (208) ​ $ 10,774 ​ Final ​ $ 208 June 28, 2019 ​ Affirm ​ ​ 6,968 ​ ​ — ​ ​ 6,968 ​ Final ​ ​ (1,646) March 19, 2019 ​ Canada ​ ​ 4,975 ​ ​ (302) ​ ​ 4,673 ​ Final ​ ​ 5,013 April 1, 2019 ​ Canada ​ ​ 2,242 ​ ​ — ​ ​ 2,242 ​ Final ​ ​ 101 ​ In connection with the Affirm crane operation divestiture in the first quarter of 2019, no gain or loss was initially recognized and goodwill was reduced by $2.6 million. Additionally, during the first quarter of 2019, the Company recorded an impairment of the remaining Affirm goodwill of $4.4 million (see Note 8).

REVENUE

REVENUE	12 Months Ended
	Dec. 31, 2019
REVENUE
REVENUE	NOTE 4—REVENUE Effective for the year ended December 31, 2018, the Company adopted ASU 2014-09, Revenue from Contracts with Customers (Topic 606). Leases ASU 2014-09 provides a five-step model for determining revenue recognition for arrangements that are within the scope of the standard: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that we will collect the consideration the Company is entitled to in exchange for the goods or services the Company transfers to the customer. The following factors are applicable to all three of the Company’s segments for the years 2019, 2018 and 2017, respectively: ● The vast majority of customer agreements are short-term, lasting less than one year. ● Contracts are seldom combined together as virtually all of our customer agreements constitute separate performance obligations. Each job is typically distinct, thereby not interdependent or interrelated with other customer agreements. ● Most contracts allow either party to terminate at any time without substantive penalties. If the customer terminates the contract, the Company is unconditionally entitled to the payments for the products delivered to date. ● Contract terminations before the end of the agreement are rare. ● Sales returns are rare and no sales return assets have been recognized on the balance sheet. ● There are minimal volume discounts. ● There are no service-type warranties. ● There is no long-term customer financing. ● Taxes collected by the Company to be remitted to a governmental authority are excluded from revenue. In the Water Services and Water Infrastructure segments, performance obligations arise in connection with services provided to customers in accordance with contractual terms, in an amount the Company expects to collect. Services are generally sold based upon customer orders or contracts with customers that include fixed or determinable prices. Revenues are generated by services rendered and measured based on output generated, which is usually simultaneously received and consumed by customers at their job sites. As a multi-job site organization, contract terms, including pricing for the Company’s services, are negotiated on a job site level on a per-job basis. Most jobs are completed in a short period of time, usually between one day and one month. Revenue is recognized as performance obligations are completed on a daily, hourly or per unit basis with unconditional rights to consideration for services rendered reflected as accounts receivable trade, net of allowance for doubtful accounts. In cases where a prepayment is received before the Company satisfies its performance obligations, a contract liability is recorded in accrued expenses and other current liabilities. Final billings generally occur once all of the proper approvals are obtained. No revenue is associated with mobilization or demobilization of personnel and equipment. Rather, mobilization and demobilization are factored into pricing for services. Billings and costs related to mobilization and demobilization is not material for customer agreements that start in one period and end in another. During the year ended December 31, 2019, the Company had one agreement considered long-term under Topic 606. In the Oilfield Chemicals segment, the typical performance obligation is to provide a specific quantity of chemicals to customers in accordance with the customer agreement in an amount the Company expects to collect. Products and services are generally sold based upon customer orders or contracts with customers that include fixed or determinable prices. Revenue is recognized as the customer takes title to chemical products in accordance with the agreement. Products may be provided to customers in packaging or delivered to the customers’ containers through a hose. In some cases, the customer takes title to the chemicals upon consumption from storage containers on their property, where the chemicals are considered inventory until customer usage. In cases where the Company delivers products and recognizes revenue before collecting payment, the Company has an unconditional right to payment reflected in accounts receivable trade, net of allowance for doubtful accounts. Customer returns are rare and immaterial and there were no in-process customer agreements as of December 31, 2019 lasting greater than one year. The Company accounts for accommodations and rentals agreements as an operating lease. The Company recognizes revenue from renting equipment on a straight-line basis. Accommodations and rental contract periods are generally daily, weekly or monthly. The average lease term is less than three months and as of December 31, 2019, no rental agreements lasted more than a year. The following table sets forth certain financial information with respect to the Company’s disaggregation of revenues by geographic location: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ 2019 ​ 2018 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Geographic Region ​ ​ ​ ​ ​ ​ ​ ​ ​ Permian Basin ​ $ 610,528 ​ $ 606,591 ​ $ 243,482 MidCon ​ ​ 176,216 ​ ​ 243,524 ​ ​ 96,844 Eagle Ford ​ ​ 156,621 ​ ​ 171,942 ​ ​ 104,934 Marcellus/Utica ​ ​ 96,454 ​ ​ 134,984 ​ ​ 32,805 Bakken ​ ​ 92,956 ​ ​ 153,212 ​ ​ 74,543 Rockies ​ ​ 85,339 ​ ​ 111,901 ​ ​ 80,180 Haynesville/E. Texas ​ ​ 73,658 ​ ​ 59,969 ​ ​ 49,600 All other/eliminations ​ ​ (183) ​ ​ 46,807 ​ ​ 10,103 Total ​ $ 1,291,589 ​ $ 1,528,930 ​ $ 692,491 ​ In the Water Services segment, the top three revenue producing regions are the Permian Basin, MidCon and Eagle Ford, which collectively comprised 74%, 72% and 71% of segment revenue for 2019, 2018 and 2017, respectively. In the Water Infrastructure segment, the top two revenue producing regions are the Permian Basin and Bakken, which collectively comprised 84%, 85% and 80% of segment revenue for 2019, 2018 and 2017, respectively. In the Oilfield Chemicals segment, the top two revenue producing regions are the Permian Basin and MidCon, which collectively comprised 77%, 77% and 72% of segment revenue for 2019, 2018 and 2017, respectively.

LEASES

LEASES	12 Months Ended
	Dec. 31, 2019
LEASES
LEASES	NOTE 5—LEASES As of December 31, 2019, the Company was the lessee for approximately 593 operating leases with durations greater than a year, approximately 15 subleases, approximately 25 finance leases, and is the lessor for three owned properties. Most of the operating leases either have renewal options of between one or convert to month-to-month agreements at the end of the specified lease term. In addition to normal lease activity, the Affirm and Canadian divestitures occurring during 2019 included the assignment of leases to the buyers. The assigned leases impacted expenses during 2019, but were not included in the December 31, 2019 consolidated balance sheet. The Company’s operating leases are primarily for (i) housing personnel for operations, (ii) operational yards for storing and staging equipment, (iii) equipment used in operations, (iv) facilities used for back-office functions and (v) equipment used for back office functions. The Company has determined that it is reasonably certain to exercise a future renewal option for one facility lease for the corporate office building in Gainesville, Texas. The majority of the Company’s long-term lease expenses are at fixed prices. The majority of the Company’s lease expenses are in connection with short-term agreements, including expenses incurred hourly, daily, monthly and for other periods of time of one year or less. Due to the volatility of the price of a barrel of oil and the short term nature of the vast majority of customer agreements, the Company must have flexibility to continuously scale operations at multiple locations. Consequently, the Company avoids committing to long-term agreements with numerous equipment rentals, vehicle fleet agreements and man-camp agreements, unless a business case supports a longer term agreement. Consequently, the Company’s future lease commitments at December 31, 2019 do not reflect all of the Company’s short-term lease commitments. Leases with an initial term of 12 months or less are not recorded on the consolidated balance sheets and the Company recognizes lease expense for these leases on a straight-line basis over the lease term. The Company has a significant number of short-term leases including month-to-month agreements that continue in perpetuity until the lessor or the Company terminates the lease agreement. Due to the factors listed above, the Company has determined that only a few short-term leases with renewal options are reasonably certain to last more than a year into the future. When available, the Company uses the rate implicit in the lease to discount lease payments to present value; however, most of the Company’s leases do not provide a readily determinable implicit rate. Therefore, the Company estimates the incremental borrowing rate based on what it would pay to borrow on a collateralized basis, over a similar term based on information available at lease commencement. The Company’s variable lease costs are comprised of variable royalties, variable common area maintenance, and variable reimbursement of lessor insurance and property taxes. Variable lease costs were $1.6 million during the year ended December 31, 2019, of which, $0.8 million of property tax expense is excluded from the lease expense discussed above. The lease disclosures in this Note 5—Leases exclude revenue governed by the new lease standard associated with the Company’s accommodations and rentals business, as all customer agreements are short-term. See Note 4—Revenue for a comprehensive discussion on revenue recognition. The Company previously had $18.8 million of short-term and long-term lease obligations associated with certain exit and disposal activities in connection with approximately 17 abandoned facility leases as of December 31, 2018. Upon adopting the new lease standard, the former exit-disposal cease use liability was reclassified and factored into the initial right-of-use (“ROU”) asset impairment calculation. The financial impact of leases is listed in the tables below: ​ ​ ​ ​ ​ ​ ​ Balance Sheet Classification As of December 31, 2019 ​ ​ ​ ​ (in thousands) Assets ​ ​ ​ ​ ​ ROU Assets (1) ​ Long-term right-of-use assets ​ $ 70,635 Finance lease assets (2) ​ Property and equipment ​ ​ 213 Liabilities ​ ​ ​ ​ ​ Operating lease liabilities ― ST ​ Current operating lease liabilities ​ $ 19,315 Operating lease liabilities ― LT (3) ​ Long-term operating lease liabilities ​ ​ 72,143 Finance lease liabilities ― ST ​ Current portion of finance lease obligations ​ ​ 128 Finance lease liabilities ― LT ​ Other long term liabilities ​ ​ 87 (1) (2) (3) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended Statements of Operations and Cash Flows Classification December 31, 2019 ​ ​ ​ ​ ​ ​ Operating lease cost: ​ ​ ​ ​ ​ Operating lease cost ― fixed ​ Cost of revenue and Selling, general and administrative ​ $ 27,856 Lease abandonment costs ​ Lease abandonment costs ​ ​ 2,073 ​ ​ ​ ​ ​ ​ Short-term agreements: ​ Cost of revenue ​ $ 93,949 ​ ​ ​ ​ ​ ​ Finance lease cost: ​ ​ ​ ​ ​ Amortization of leased assets ​ Depreciation and amortization ​ $ 916 Interest on lease liabilities ​ Interest expense, net ​ ​ 32 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Lessor income: ​ ​ ​ ​ ​ Sublease income ​ Cost of sales and lease abandonment costs ​ $ 1,544 Lessor income ​ Cost of sales ​ ​ 478 ​ ​ ​ ​ ​ ​ Statement of cash flows ​ ​ ​ ​ ​ Cash paid for operating leases ​ Operating cash flows ​ $ 30,670 Cash paid for finance leases lease interest ​ Operating cash flows ​ ​ 32 Cash paid for finance leases ​ Financing cash flows ​ ​ 883 ​ ​ ​ ​ ​ ​ Long Term and Discount Rate As of December 31, 2019 Weighted-average remaining lease term (years) ​ ​ ​ Operating leases ​ 7.9 ​ Finance leases ​ 1.6 ​ Weighted-average discount rate ​ ​ ​ Operating leases ​ 5.3 % Finance leases ​ 5.1 % ​ The Company has the following operating and finance lease commitments as of December 31, 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Period Operating Leases (1) Finance Leases Total ​ ​ (in thousands) 2020 ​ $ 24,742 ​ $ 135 ​ $ 24,877 2021 ​ 16,592 ​ 88 ​ 16,680 2022 ​ 13,231 ​ - ​ 13,231 2023 ​ 11,074 ​ - ​ 11,074 2024 ​ 10,589 ​ - ​ 10,589 Thereafter ​ 44,094 ​ - ​ 44,094 Total minimum lease payments ​ $ 120,322 ​ $ 223 ​ $ 120,545 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Less reconciling items to reconcile undiscounted cash flows to lease liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ Leases commencing in the future ​ ​ 5,793 ​ ​ — ​ ​ 5,793 Short-term leases excluded from balance sheet ​ ​ 693 ​ ​ — ​ ​ 693 Imputed interest ​ ​ 22,378 ​ ​ 8 ​ ​ 22,386 Total reconciling items ​ ​ 28,864 ​ ​ 8 ​ ​ 28,872 Total liabilities per balance sheet ​ ​ 91,458 ​ ​ 215 ​ ​ 91,673 ​ (1) The table above excludes sublease and lessor income of $1.6 million during 2020, $0.6 million during 2021 and $0.3 million during 2022. ​

INVENTORIES

INVENTORIES	12 Months Ended
	Dec. 31, 2019
INVENTORIES
INVENTORIES	NOTE 6—INVENTORIES Inventories, which are comprised of chemicals and materials available for resale and parts and consumables used in operations, are valued at the lower of cost and net realizable value, with cost determined under the weighted-average method. The significant components of inventory are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ ​ 2019 2018 ​ ​ ​ (in thousands) Raw materials ​ ​ $ 12,365 ​ $ 15,219 Finished goods ​ ​ 24,724 ​ 28,540 Materials and supplies ​ ​ 453 ​ 1,233 ​ ​ ​ $ 37,542 ​ $ 44,992 ​ During the year ended December 31, 2019, the Company added $5.2 million of finished goods inventory from the purchase of WCS (see Note 3). During the year ended December 31, 2019 and 2018, the Company recorded charges to the reserve for excess and obsolete inventory for $0.3 million and $0.4 million, respectively, which were recognized within costs of revenue on the accompanying consolidated statements of operations. The Company’s inventory reserve was $4.1 million and $4.8 million as of December 31, 2019 and December 31, 2018, respectively. The reserve for excess and obsolete inventories is determined based on the Company’s historical usage of inventory on hand, as well as future expectations, and the amount necessary to reduce the cost of the inventory to its estimated net realizable value.

PROPERTY AND EQUIPMENT

PROPERTY AND EQUIPMENT	12 Months Ended
	Dec. 31, 2019
PROPERTY AND EQUIPMENT
PROPERTY AND EQUIPMENT	NOTE 7—PROPERTY AND EQUIPMENT Property and equipment consists of the following as of December 31, 2019 and 2018: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ ​ 2019 2018 ​ ​ ​ (in thousands) Land ​ ​ $ 16,030 ​ $ 17,799 Buildings and leasehold improvements ​ ​ 97,426 ​ 106,626 Vehicles and equipment ​ ​ 53,819 ​ 83,435 Vehicles and equipment - finance lease ​ ​ 1,291 ​ 1,833 Machinery and equipment ​ ​ 729,162 ​ 758,528 Machinery and equipment - finance lease ​ ​ 162 ​ 532 Computer equipment and software ​ ​ ​ 8,051 ​ ​ 15,775 Computer equipment and software - finance lease ​ ​ 356 ​ 356 Office furniture and equipment ​ ​ 1,157 ​ 4,612 Disposal wells ​ ​ 64,149 ​ 64,038 Other ​ ​ ​ 497 ​ ​ 497 Construction in progress ​ ​ 43,279 ​ 60,347 ​ ​ ​ 1,015,379 ​ 1,114,378 Less accumulated depreciation (1) ​ ​ (562,986) ​ (611,530) Property and equipment held-for-sale, net ​ ​ ​ 885 ​ ​ — Total property and equipment, net ​ ​ $ 453,278 ​ $ 502,848 (1) Includes $1.6 million and $1.3 million of accumulated depreciation related to finance leases as of December 31, 2019 and December 31, 2018, respectively. Total depreciation and amortization expense related to property and equipment and finance leases presented in the table above, as well as amortization of intangible assets presented in Note 8—Goodwill and Other Intangible Assets as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ 2019 ​ 2018 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Category ​ ​ ​ ​ ​ ​ ​ ​ ​ Depreciation expense from property and equipment ​ $ 107,738 ​ $ 119,114 ​ $ 92,402 Amortization expense from finance leases ​ ​ 916 ​ ​ 1,314 ​ ​ 168 Amortization expense from intangible assets ​ ​ 11,900 ​ ​ 13,102 ​ ​ 10,701 Accretion expense from asset retirement obligations ​ ​ 115 ​ ​ 183 ​ ​ 178 Total depreciation and amortization ​ $ 120,669 ​ $ 133,713 ​ $ 103,449 ​ Property and Equipment Held-for-Sale and Impairments Long-lived assets are evaluated for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. During the first quarter of 2019, the Company made the decision to sell and wind down certain operations within its former Wellsite Services segment, including the operations of its Affirm subsidiary, its sand hauling operations and its Canadian operations. All operations have been wound down, with $0.9 million remaining in held-for-sale as of December 31, 2019. The table below shows the former Wellsite Services segment property and equipment sold and divested as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net Book Value of Property and Type of sale event Business Equipment Sold or Divested ​ ​ ​ ​ (in thousands) Business divestitures ​ Affirm subsidiary ​ $ 11,275 Property and equipment sales ​ Affirm subsidiary ​ ​ 1,339 Business divestitures ​ Canadian operations ​ ​ 7,372 Property and equipment sales ​ Canadian operations ​ ​ 393 Property and equipment sales ​ Sand hauling operations ​ ​ 3,030 Total property and equipment sold and divested ​ ​ ​ $ 23,409 ​ During the year ended December 31, 2019, the Company recorded an impairment of $0.9 million of Canadian property and equipment to write down the carrying value based on the expected future sale proceeds. In addition, during the year ended December 31, 2019, the net loss on divestitures and sales of property and equipment held-for-sale was $3.9 million. During the year ended December 31, 2018, the Company reviewed certain fluid disposal machinery and equipment used in our fluid hauling and disposal services that are included in our Water Infrastructure segment. Due to the condition of the equipment, the Company determined that long-lived assets with a carrying value of $2.3 million were no longer recoverable and were written down to their estimated fair value of zero. Additionally, the Company determined that $4.4 million of Canadian fixed assets were impaired due to an expectation of a loss on asset disposals.

GOODWILL AND OTHER INTANGIBLE A

GOODWILL AND OTHER INTANGIBLE ASSETS	12 Months Ended
	Dec. 31, 2019
GOODWILL AND OTHER INTANGIBLE ASSETS.
GOODWILL AND OTHER INTANGIBLE ASSETS	NOTE 8—GOODWILL AND OTHER INTANGIBLE ASSETS Goodwill is evaluated for impairment on at least an annual basis, or more frequently if indicators of impairment exist. The annual impairment tests are based on Level 3 inputs (see Note 12—Fair Value Measurement). During 2019, the Affirm goodwill was reduced to zero from the crane divestiture and impairment. The $4.4 million of goodwill impairment was based on the expected proceeds from selling and winding down the rest of the Affirm business. Also, in connection with the Company’s segment realignment, the Company reallocated goodwill from ​ The Company performed a goodwill impairment test during the first quarter of 2019 as the result of the change in segments and also performed its annual goodwill impairment test in the fourth quarter of 2019 by assessing the fair value of each reporting unit and comparing it to the reporting units carrying amount which resulted in no impairment. During the fourth quarter of 2018, the Company incurred $12.7 million of goodwill impairment on a reporting unit within the Oilfield Chemicals segment using income and market valuation techniques. This also resulted in $5.2 million of goodwill impairment in connection with the Affirm subsidiary as the estimated fair value was not adequate to fully cover its carrying value using a cost valuation technique. The changes in the carrying amounts of goodwill by reportable segment for the years ended December 31, 2019 and 2018 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Oilfield ​ Water ​ Wellsite ​ Water ​ Water ​ ​ ​ ​ ​ ​ ​ Chemicals Solutions Services Services Infrastructure Other Total ​ ​ (in thousands) Balance as of December 31, 2017 ​ $ 15,637 ​ $ 245,542 ​ $ 12,242 ​ $ — ​ $ — ​ $ — ​ $ 273,421 Additions ​ ​ — ​ ​ 982 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 982 Impairment ​ ​ (12,652) ​ ​ — ​ ​ (5,242) ​ ​ — ​ ​ — ​ ​ — ​ ​ (17,894) Measurement period adjustments ​ (2,985) ​ 20,277 ​ — ​ — ​ — ​ — ​ 17,292 Balance as of December 31, 2018 ​ ​ — ​ ​ 266,801 ​ ​ 7,000 ​ ​ — ​ ​ — ​ ​ — ​ ​ 273,801 Resegmentation ​ — ​ (266,801) ​ (7,000) ​ 186,335 ​ 80,466 ​ 7,000 ​ — Measurement period adjustment (1) ​ ​ — ​ ​ — ​ ​ — ​ ​ 133 ​ ​ — ​ ​ — ​ ​ 133 Affirm crane business divestiture ​ — ​ — ​ — ​ — ​ ​ — ​ ​ (2,604) ​ (2,604) Affirm impairment ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (4,396) ​ ​ (4,396) Balance as of December 31, 2019 ​ $ — ​ $ — ​ $ — ​ $ 186,468 ​ $ 80,466 ​ $ — ​ $ 266,934 (1) See Note 3―Acquisitions for additional information. The components of other intangible assets as of December 31, 2019 and 2018 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2019 ​ As of December 31, 2018 ​ Gross Accumulated Net Gross Accumulated Net ​ ​ Value ​ Amortization ​ Value ​ Value ​ Amortization ​ Value ​ ​ (in thousands) ​ (in thousands) Definite-lived ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Customer relationships ​ $ 116,554 ​ $ 20,233 ​ $ 96,321 ​ $ 171,245 ​ $ 66,402 ​ $ 104,843 Patents ​ ​ 10,110 ​ ​ 2,420 ​ ​ 7,690 ​ ​ 10,110 ​ ​ 1,417 ​ ​ 8,693 Other ​ ​ 7,234 ​ ​ 4,766 ​ ​ 2,468 ​ 7,234 ​ 2,866 ​ 4,368 Total definite-lived ​ ​ 133,898 ​ ​ 27,419 ​ ​ 106,479 ​ ​ 188,589 ​ ​ 70,685 ​ ​ 117,904 Indefinite-lived ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Water rights ​ ​ 7,031 ​ ​ — ​ ​ 7,031 ​ ​ 7,031 ​ ​ — ​ ​ 7,031 Trademarks ​ ​ 23,442 ​ ​ — ​ ​ 23,442 ​ ​ 23,442 ​ ​ — ​ ​ 23,442 Total indefinite-lived ​ ​ 30,473 ​ ​ — ​ ​ 30,473 ​ ​ 30,473 ​ ​ — ​ ​ 30,473 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total other intangible assets, net ​ $ 164,371 ​ $ 27,419 ​ $ 136,952 ​ $ 219,062 ​ $ 70,685 ​ $ 148,377 ​ During the year ended December 31, 2019, the Company added $0.5 million of customer relationships. During the year ended December 31, 2018, the Company added $3.0 million in customer relationships and $1.8 million of water rights. The weighted average amortization period for customer relationships, patents and other definite-lived intangible assets as of December 31, 2019 was 10.7 years, 7.7 years and 2.2 years, respectively. The indefinite lived water trademarks five ​ ​ ​ ​ ​ Year Ending December 31, Amount ​ ​ (in thousands) 2020 ​ $ 11,656 2021 ​ 10,473 2022 ​ 10,259 2023 ​ 10,187 2024 ​ 10,118 Thereafter ​ ​ 53,786 ​ ​ $ 106,479 ​

DEBT

DEBT	12 Months Ended
	Dec. 31, 2019
DEBT
DEBT	NOTE 9—DEBT Credit facility and revolving line of credit The Company’s subsidiary, Select Energy Services, LLC’s (“Select LLC”) previous credit facility (the “Previous Credit Facility”), had a maturity date of February 28, 2020 and a revolving line of credit of $100.0 million. On November 1, 2017, in connection with the closing of the Rockwater Merger (the “Closing”), SES Holdings entered into the Credit Agreement, the obligations of SES Holdings and Select LLC under the Previous Credit Facility were repaid in full and the Previous Credit Facility was terminated. On November 1, 2017, SES Holdings and Select LLC entered into a $300.0 million senior secured revolving credit facility (the “Credit Agreement”), by and among SES Holdings, as parent, Select LLC, as Borrower and certain of SES Holdings’ subsidiaries, as guarantors, each of the lenders party thereto and Wells Fargo Bank, N.A., as administrative agent, issuing lender and swingline lender (the “Administrative Agent”). The Credit Agreement also has a sublimit of $40.0 million for letters of credit and a sublimit of $30.0 million for swingline loans. Subject to obtaining commitments from existing or new lenders, the Company has the option to increase the maximum amount under the Credit Agreement by $150.0 million during the first three years following the closing. The maturity date of the Credit Agreement is the earlier of (a) November 1, 2022, and (b) the earlier termination in whole of the Commitments pursuant to Section 2.1(b) of Article VII of the Credit Agreement. The Credit Agreement permits extensions of credit up to the lesser of $300.0 million and a borrowing base that is determined by calculating the amount equal to the sum of (i) 85% of the Eligible Billed Receivables (as defined in the Credit Agreement), plus (ii) 75% of Eligible Unbilled Receivables (as defined in the Credit Agreement), provided that this amount will not equal more than 35% of the borrowing base, plus (iii) the lesser of (A) the product of 70% multiplied by the value of Eligible Inventory (as defined in the Credit Agreement) at such time and (B) the product of 85% multiplied by the Net Recovery Percentage (as defined in the Credit Agreement) identified in the most recent Acceptable Appraisal of Inventory (as defined in the Credit Agreement), multiplied by the value of Eligible Inventory at such time, provided that this amount will not equal more than 30% of the borrowing base, minus (iv) the aggregate amount of Reserves (as defined in the Credit Agreement), if any, established by the Administrative Agent from time to time, including, if any, the amount of the Dilution Reserve (as defined in the Credit Agreement). The borrowing base is calculated on a monthly basis pursuant to a borrowing base certificate delivered by Select LLC to the Administrative Agent. Borrowings under the Credit Agreement bear interest, at Select LLC’s election, at either the (a) one-, two-, three- or six-month LIBOR (“Eurocurrency Rate”) or (b) the greatest of (i) the federal funds rate plus 0.5%, (ii) the one-month Eurocurrency Rate plus 1% and (iii) the Administrative Agent’s prime rate (the ”Base Rate”), in each case plus an applicable margin. Interest is payable monthly in arrears. The applicable margin for Eurocurrency Rate loans ranges from 1.50% to 2.00% and the applicable margin for Base Rate loans ranges from 0.50% to 1.00%, in each case, depending on Select LLC’s average excess availability under the Credit Agreement. During the continuance of a bankruptcy event of default, automatically and during the continuance of any other default, upon the Administrative Agent’s or the required lenders’ election, all outstanding amounts under the Credit Agreement will bear interest at 2.00% plus the otherwise applicable interest rate. ​ ​ ​ ​ ​ ​ ​ ​ Level ​ Average Excess Availability ​ Base Rate Margin ​ Eurocurrency Rate Margin ​ ​ ​ ​ ​ ​ ​ I ​ < 33% of the commitments ​ 1.00% ​ 2.00% II ​ < 66.67% of the commitments and ≥ 33.33% of the commitments ​ 0.75% ​ 1.75% III ​ ≥ 66.67% of the commitments ​ 0.50% ​ 1.50% ​ ​ ​ ​ ​ ​ Level ​ Average Revolver Usage ​ Unused Line Fee Percentage ​ ​ ​ ​ ​ I ​ ≥ 50% of the commitments ​ 0.250% II ​ < 50% of the commitments ​ 0.375% ​ The obligations under the Credit Agreement are guaranteed by SES Holdings and certain subsidiaries of SES Holdings and Select LLC and secured by a security interest in substantially all of the personal property assets of SES Holdings, Select LLC and their domestic subsidiaries. The Credit Agreement contains certain customary representations and warranties, affirmative and negative covenants and events of default. If an event of default occurs and is continuing, the lenders may declare all amounts outstanding under the Credit Agreement to be immediately due and payable. In addition, the Credit Agreement restricts SES Holdings’ and Select LLC’s ability to make distributions on, or redeem or repurchase, its equity interests, except for certain distributions, including distributions of cash so long as, both at the time of the distribution and after giving effect to the distribution, no default exists under the Credit Agreement and either (a) excess availability at all times during the preceding 30 consecutive days, on a pro forma basis and after giving effect to such distribution, is not less than the greater of (1) 25% of the lesser of (A) the maximum revolver amount and (B) the then-effective borrowing base and (2) $37.5 million or (b) if SES Holdings’ fixed charge coverage ratio is at least 1.0 to 1.0 on a pro forma basis, and excess availability at all times during the preceding 30 consecutive days, on a pro forma basis and after giving effect to such distribution, is not less than the greater of (1) 20% of the lesser of (A) the maximum revolver amount and (B) the then-effective borrowing base and (2) $30.0 million. Additionally, the Credit Agreement generally permits Select LLC to make distributions to allow Select Inc. to make payments required under the existing Tax Receivable Agreements. See Note 13-Related Party Transactions for further discussion of the Tax Receivable Agreements. The Credit Agreement also requires SES Holdings to maintain a fixed charge coverage ratio of at least 1.0 to 1.0 at any time availability under the Credit Agreement is less than the greater of (i) 10% of the lesser of (A) the maximum revolver amount and (B) the then-effective borrowing base and (ii) $15.0 million and continuing through and including the first day after such time that availability under the Credit Agreement has equaled or exceeded the greater of (i) 10% of the lesser of (A) the maximum revolver amount and (B) the then-effective borrowing base and (ii) $15.0 million for 60 consecutive calendar days. Certain lenders party to the Credit Agreement and their respective affiliates have from time to time performed, and may in the future perform, various financial advisory, commercial banking and investment banking services for the Company and its affiliates in the ordinary course of business for which they have received and would receive customary compensation. In addition, in the ordinary course of their various business activities, such parties and their respective affiliates may make or hold a broad array of investments and actively trade debt and equity securities (or related derivative securities) and financial instruments (including bank loans) for their own account and for the accounts of their customers, and such investments and securities activities may involve the Company’s securities and/or instruments. The Company had no borrowings and $45.0 million outstanding under the Credit Agreement as of December 31, 2019 and 2018, respectively. The weighted average interest rate of outstanding borrowings under the Credit Agreement was 4.256% as of December 31, 2018. As of December 31, 2019 and 2018, the borrowing base under the Credit Agreement was Debt issuance costs are amortized to interest expense over the life of the debt to which they pertain. Total unamortized debt issuance costs as of December 31, 2019 and 2018 were $2.0 million and $2.6 million, respectively. As the debt issuance costs relate to a revolving line of credit, they are presented as a deferred charge within other assets on the consolidated balance sheet. Amortization expense related to debt issuance costs were $0.7 million, $0.7 million and $4.0 million for the years ended December 31, 2019, 2018 and 2017, respectively. The Company was in compliance with all debt covenants as of and throughout the year ended December 31, 2019.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2019
COMMITMENTS AND CONTINGENCIES
COMMITMENTS AND CONTINGENCIES	NOTE 10—COMMITMENTS AND CONTINGENCIES Litigation The Company is subject to a number of lawsuits and claims arising out of the normal conduct of its business. The ability to predict the ultimate outcome of such matters involves judgments, estimates and inherent uncertainties. Based on a consideration of all relevant facts and circumstances, including applicable insurance coverage, it is not expected that the ultimate outcome of any currently pending lawsuits or claims against the Company will have a material adverse effect on its consolidated financial position, results of operations or cash flows; however, there can be no assurance as to the ultimate outcome of these matters. As previously disclosed, certain subsidiaries acquired in the Rockwater Merger are under investigation by the U.S. Attorney's Office for the Middle District of Pennsylvania and the U.S. Environmental Protection Agency. It is alleged that certain employees at some of the facilities altered emissions controls systems on 4% of the vehicles in the fleet in violation of the Clean Air Act. The Company is continuing to cooperate with the relevant authorities to resolve the matter including locating any pertinent information to determine if such violations occurred and what, if any, the applicable fine would be related to any such potential violations. At this time no administrative, civil or criminal charges have been brought against the Company. Additionally, while the Company cannot currently reasonably estimate an amount of possible fines or penalties, we do not believe that such amounts will be material to the Company’s financial statements. Self-Insured Reserves We are self-insured up to certain retention limits with respect to workers’ compensation, general liability and vehicle liability matters. We maintain accruals for self-insurance retentions that we estimate using third-party data and claims history.

EQUITY-BASED COMPENSATION

EQUITY-BASED COMPENSATION	12 Months Ended
	Dec. 31, 2019
EQUITY-BASED COMPENSATION
EQUITY-BASED COMPENSATION	NOTE 11—EQUITY-BASED COMPENSATION The SES Holdings 2011 Equity Incentive Plan, (“2011 Plan”) was approved by the board of managers of SES Holdings in April 2011. In conjunction with the Select 144A Offering, the Company adopted the Select Energy Services, Inc. 2016 Equity Incentive Plan (as amended, the “2016 Plan”) for employees, consultants and directors of the Company and its affiliates. Options that were outstanding under the 2011 Plan immediately prior to the Select 144A Offering were cancelled in exchange for new options granted under the 2016 Plan. On July 18, 2017, the Select Inc. board of directors approved the First Amendment to the 2016 Plan (the “Equity Plan Amendment”), which clarified the treatment of substitute awards under the 2016 Plan (including substitute awards that may be granted in connection with the Rockwater Merger which occurred on November 1, 2017) and allowed for the assumption by the Company of shares eligible under any pre-existing stockholder-approved plan of an entity acquired by the Company or its affiliate (including the Rockwater Energy Solutions Inc. Amended and Restated 2017 Long Term Incentive Plan (the “Rockwater Equity Plan”)), in each case subject to the listing rules of the stock exchange on which the Company’s Class A Common Stock is listed. The effectiveness of the Equity Plan Amendment was subject to approval by the Company's stockholders and the consummation of the transactions contemplated by the Merger Agreement for the Rockwater Merger. The Company’s consenting stockholders, who held a majority of the outstanding common stock of the Company, approved the Equity Plan Amendment on July 18, 2017. The Equity Plan Amendment became effective on November 1, 2017 upon the consummation of the Rockwater Merger. Currently, the maximum number of shares reserved for issuance under the 2016 Plan, taking into account the impact of the Rockwater Merger, is approximately 9.3 million shares. For all share-based compensation award types, the Company accounts for forfeitures as they occur. Stock option awards Stock options were granted with an exercise price equal to or greater than the fair market value of a share of Class A Common Stock as of the date of grant. Prior to the IPO, the Company historically valued Class A Common Stock on a quarterly basis using a market approach that includes a comparison to publicly traded peer companies using earnings multiples based on their market values and a discount for lack of marketability. This fair value measurement relied on Level 3 inputs. The estimated fair value of its stock options is expensed over their vesting period, which is generally three years from the applicable date of grant. However, certain awards granted during the years ended December 31, 2017 and 2016 in exchange for cancelled awards were immediately vested and fully exercisable on the date of grant because they were either granted in exchange for the cancellation of outstanding options granted under the 2011 Plan or the Rockwater Equity Plan, as applicable, that were fully vested and exercisable prior to such cancellation. The Company utilized the Monte Carlo option pricing model to determine fair value of the options granted during 2018, which incorporates assumptions to value equity-based awards. The risk-free interest rate is based on the U.S. Treasury yield curve in effect for the expected term of the option at the time of grant. The expected life of the options was based on the vesting period and term of the options awarded, which is ten years. The table below presents the assumptions used in determining the fair value of stock options granted during the years ended December 31, 2018 and 2017, respectively. No options were granted during the year ended December 31, 2019. The weighted-average grant date fair value of stock options granted was $8.98 and $7.85 for the years ended December 31, 2018 and 2017, respectively. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, ​ ​ 2018 ​ ​ 2017 ​ Underlying equity $ 20.50 ​ ​ $ 20.00 ​ Strike price $ 20.50 - 30.75 ​ ​ $ 20.00 ​ Dividend yield (%) 0.0 % ​ 0.0 % Risk-free rate (%) 2.3 % ​ 2.0 - 2.7 % Volatility (%) 50.0 % ​ 46.6 - 46.8 % Expected term (years) 10.0 ​ ​ 4.0 6.0 ​ ​ A summary of the Company’s stock option activity and related information as of and for the year ended December 31, 2019 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average ​ ​ ​ ​ ​ ​ Weighted-average ​ Weighted-average ​ Grant Date Value Aggregate Intrinsic ​ Stock Options Grant Date Value ​ Exercise Price Term (Years) Value (in thousands) (a) Beginning balance, outstanding 3,865,678 ​ $ 7.95 ​ $ 16.00 ​ 4.9 ​ $ 19 Exercised ​ (5,282) ​ ​ 3.12 ​ ​ 5.68 ​ ​ ​ ​ ​ Forfeited (30,438) ​ ​ 8.33 ​ ​ 17.70 ​ ​ ​ ​ ​ Expired ​ (32,639) ​ ​ 7.45 ​ ​ 21.85 ​ ​ ​ ​ ​ Ending balance, outstanding 3,797,319 ​ $ 8.19 ​ $ 15.95 ​ 4.2 ​ $ 509 Ending balance, exercisable ​ 3,463,549 ​ $ 8.12 ​ $ 15.06 ​ 3.9 ​ $ 510 Nonvested at end of period ​ 333,770 ​ ​ N/A ​ $ 25.22 ​ ​ ​ ​ ​ (a) as of December 31, 2019 and 2018, respectively. The Company recognized $4.3 million, $5.2 million and $1.9 million of compensation expense related to stock options during the years ended December 31, 2019, 2018 and 2017, respectively. As of December 31, 2019, there was $0.2 million of unrecognized equity-based compensation expense related to non-vested stock options. This cost is expected to be recognized over a weighted-average period of 1.0 year. Restricted Stock Awards and Restricted Stock Units The value of the restricted stock awards and restricted stock units issued was established by the market price of the Class A Common Stock on the date of grant and is recorded as compensation expense ratably over the vesting term, which is generally one A summary of the Company’s restricted stock awards activity and related information for the year ended December 31, 2019 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2019 ​ ​ ​ ​ Weighted-average ​ Restricted Stock Awards Grant Date Fair Value Nonvested at December 31, 2018 ​ 496,945 ​ $ 19.02 Granted ​ 1,417,458 ​ ​ 8.80 Vested ​ (379,150) ​ ​ 16.69 Forfeited ​ (17,060) ​ ​ 15.97 Nonvested at December 31, 2019 ​ 1,518,193 ​ $ 10.08 ​ A summary of the Company’s restricted stock unit activity and related information for the year ended December 31, 2019 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2019 ​ ​ ​ ​ Weighted-average ​ Restricted Stock Units Grant Date Fair Value Nonvested at December 31, 2018 2,500 ​ $ 19.00 Vested (1,250) ​ ​ 19.00 Nonvested at December 31, 2019 1,250 ​ $ 19.00 ​ Performance Share Units During 2018 and 2019, the Company approved grants of performance share units (“PSUs”) that are subject to both performance-based and service-based vesting provisions. The number of shares of Class A Common Stock issued to a recipient upon vesting of the PSU will be calculated based on performance against certain metrics that relate to the Company’s return on asset performance over the January 1, 2018 through December 31, 2020 and January 1, 2019 through December 31, 2021 performance periods, respectively. ​ The target number of shares of Class A Common Stock subject to each PSU is ​ ​ ​ ​ Return on Assets at Performance Period End Date ​ Percentage of Target PSUs Earned Less than 9.6% ​ 0% 9.6% ​ 50% 12% ​ 100% 14.4% ​ 175% ​ The fair value on the date the PSUs were issued during 2019 and 2018 was $7.0 million and $5.9 million, respectively. Compensation expense related to the PSUs is determined by multiplying the number of shares of Class A Common Stock underlying such awards that, based on the Company’s estimate, are probable to vest, by the measurement-date (i.e., the last day of each reporting period date) fair value and recognized using the accelerated attribution method. The Company recognized compensation expense of $2.1 million and $0.5 million related to the PSUs for the years ended December 31, 2019 and 2018, respectively. As of December 31, 2019, the unrecognized compensation cost related to our unvested PSUs is estimated to be $4.2 million and is expected to be recognized over a weighted-average period of 1.4 years as of December 31, 2019. However, this compensation cost will be adjusted as appropriate throughout the applicable performance periods. The following table summarizes the information about the performance share units outstanding at December 31, 2019: ​ ​ ​ ​ ​ Performance Share Units Nonvested as of December 31, 2018 ​ 255,364 Target shares granted ​ 778,118 Target shares vested ​ — Target shares forfeited ​ (18,492) Target shares outstanding as of December 31, 2019 ​ 1,014,990 ​ Stock-Settled Incentive Awards Effective May 17, 2018, the Company approved grants of stock-settled incentive awards to certain key employees under the 2016 Equity Incentive Plan that are subject to both market-based and service-based vesting provisions. These awards will vest after a two-year service period and, if earned, settled in shares of the Company stock. The ultimate amount earned is based on the achievement of the market metrics, which is based on the stock price of the Company at the vesting date, for which payout could range from 0% to 200%. Any award not earned on the vesting date is forfeited. The target amount that becomes earned during the performance period will be determined in accordance with the following table: ​ ​ ​ ​ Stock Price at Vesting Date (1) ​ Percentage of Target Amount Earned Less than $20.00 ​ 0% At least $20.00, but less than $25.00 ​ 100% $25.00 or greater ​ 200% (1) The stock price at vesting date equals the greater of (i) the fair market value of a share of the Class A Common Stock on the vesting date, or (ii) the volume weighted average closing price of a share of the Class A Common Stock, as reported on the NYSE, for the 30 trading days preceding the vesting date. The target amount of stock-settled incentive awards granted was $3.9 million. However, the ultimate settlement of the awards will be in shares of Class A Common stock with fair market value equal to the earned amount, which could range from 0% to 200% of the target amount depending on the stock price at vesting date. The Company recognized $0.5 million and $0.4 million of compensation expense related to the stock-settled incentive awards during the years ended December 31, 2019 and 2018, respectively. As of December 31, 2019, the unrecognized compensation cost related to our unvested stock-settled incentive awards was $0.2 million and is expected to be recognized over approximately five months. The following table summarizes the information about the stock-settled incentive awards outstanding at December 31, 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Award Value ​ Value at Target Being Recognized Nonvested as of December 31, 2018 ​ $ 3,147 ​ $ 1,202 Forfeited during 2019 ​ ​ (210) ​ ​ (80) Nonvested as of December 31, 2019 ​ $ 2,937 ​ $ 1,122 ​ Employee Stock Purchase Plan (ESPP) The Company has an Employee Stock Purchase Plan (“ESPP”) under which employees that have been continuously employed for at least one year may purchase shares of our common stock at a discount. The plan provides for four The following table summarizes ESPP activity (in thousands, except shares): ​ ​ ​ ​ ​ ​ For the year ended ​ December 31, 2019 Cash received for shares issued ​ $ 112 Shares issued ​ ​ 13,178 ​ Phantom unit awards The Company’s phantom unit awards were cash-settled awards that were contingent upon meeting certain equity returns and a liquidation event. The settlement amount was based on the fair market value of a share of the Company’s Class A common stock on the date of completion of the IPO, which constituted a liquidation event with respect to such phantom unit awards. As a result of the cash-settlement feature of these awards, the Company considered these awards to be liability awards, which were measured at fair value at each reporting date and the pro rata vested portion of the award was recognized as a liability to the extent that the performance condition was deemed probable. On May 5, 2017, the Company settled its outstanding phantom unit awards for an aggregate amount equal to $7.8 million as a result of the completion of its IPO, which constituted a liquidity event with respect to such phantom unit awards. Based on the fair market value of a share of the Company’s Class A common stock on the date of the IPO of $14.00, the cash payment with respect to each phantom unit was approximately $5.53, before employer taxes. The Company recognized compensation expense of $7.8 million for the year ended 2017 related to the settlement of its phantom unit awards. No compensation expense was recognized in 2016 due to the non-occurrence of the performance condition, which was not considered probable. Share-repurchases During the years ended December 31, 2019 and 2018, the Company repurchased 2,180,806 and 1,703,651 shares, respectively, of Class A Common Stock in the open market and repurchased 108,074 and 62,777 shares, respectively, of Class A Common Stock in connection with employee minimum tax withholding requirements for units vested under the 2016 Plan. All repurchased shares were retired. During the year ended December 31, 2019, the repurchases were accounted for as a decrease to paid in-capital of $21.9 million and a decrease to Class A common stock of approximately $23,000.

FAIR VALUE MEASUREMENT

FAIR VALUE MEASUREMENT	12 Months Ended
	Dec. 31, 2019
FAIR VALUE MEASUREMENT
FAIR VALUE MEASUREMENT	NOTE 12—FAIR VALUE MEASUREMENT The Company utilizes fair value measurements to measure assets and liabilities in a business combination or assess impairment of property and equipment, intangible assets and goodwill. Fair value is defined as the amount at which an asset (or liability) could be bought (or incurred) or sold (or settled) in an orderly transaction between market participants at the measurement date. Further, ASC 820, Fair Value Measurements, establishes a framework for measuring fair value, establishes a fair value hierarchy based on the quality of inputs used to measure fair value, and includes certain disclosure requirements. Fair value estimates are based on either (i) actual market data or (ii) assumptions that other market participants would use in pricing an asset or liability, including estimates of risk. ASC 820 establishes a three-level valuation hierarchy for disclosure of fair value measurements. The valuation hierarchy categorizes assets and liabilities measured at fair value into one of three different levels depending on the observability of the inputs employed in the measurement. The three levels are defined as follows: Level 1 Level 2 Level 3 A financial instrument’s categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the asset or liability. There were no transfers into, or out Assets and liabilities measured at fair value on a non-recurring basis Nonfinancial assets and liabilities measured at fair value on a non-recurring basis include certain nonfinancial assets and liabilities as may be acquired in a business combination and measurements of goodwill and intangible impairment. As there is no corroborating market activity to support the assumptions used, the Company has designated these measurements as Level 3. Long-lived assets, such as property and equipment and finite-lived intangible assets, are evaluated for impairment whenever events or changes in circumstances indicate that its carrying value may not be recoverable. The development of future cash flows and the estimate of fair value represent the Company’s best estimates based on industry trends and reference to market transactions and are subject to variability. The Company’s estimates of fair value have been determined at discrete points in time based on relevant information. These estimates involve uncertainty and cannot be determined with precision. There were no significant changes in valuation techniques or related inputs for the years ended December 31, 2019, 2018 and 2017. The following table presents information about the Company’s assets measured at fair value on a non-recurring basis for the years ended December 31, 2019, 2018 and 2017. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value ​ ​ ​ ​ ​ ​ ​ ​ Measurements Using ​ Carrying ​ ​ ​ ​ Level 1 Level 2 Level 3 Value (1) Impairment ​ ​ (in thousands) Year Ended December 31, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Goodwill ​ $ — ​ $ — ​ $ — ​ $ 4,396 ​ $ 4,396 Property and equipment ​ ​ — ​ ​ — ​ ​ 7,325 ​ ​ 11,040 ​ ​ 3,715 Year Ended December 31, 2018 ​ ​ ​ ​ ​ Goodwill ​ $ — ​ $ — ​ $ 7,000 ​ $ 24,894 ​ $ 17,894 Cost-Method Investment ​ — ​ — ​ 500 ​ 2,500 ​ 2,000 Fixed Assets ​ ​ — ​ ​ — ​ ​ 10,262 ​ ​ 16,919 ​ ​ 6,657 Year Ended December 31, 2017 ​ $ — ​ $ — ​ $ — ​ $ — ​ $ — (1) Amount represents carrying value at the date of assessment. Other fair value considerations See Note 2—Significant Accounting Policies for a discussion of impairment reflected above incurred during the year ended December 31, 2019 and December 31, 2018, respectively. Also, see Note 3—Acquisitions and Divestitures for a discussion of the fair value incorporated into the purchase price allocation for the WCS and Pro Well acquisitions occurring during the years ended December 31, 2019 and December 31, 2018, respectively. The carrying values of the Company’s current financial instruments, which include cash and cash equivalents, accounts receivable trade and accounts payable, approximate their fair value at December 31, 2019 and 2018 due to the short- term maturity of these instruments. The Company did not have any bank debt as of December 31, 2019, however, the carrying value of debt as of December 31, 2018 approximated the fair value. The fair value of debt at December 31, 2018, which was a Level 3 measurement, was estimated based on the Company’s incremental borrowing rates for similar types of borrowing arrangements when quoted market prices are not available. The estimated fair values of the Company’s financial instruments are not necessarily indicative of the amounts that would be realized in a current market exchange. ​

RELATED PARTY TRANSACTIONS

RELATED PARTY TRANSACTIONS	12 Months Ended
	Dec. 31, 2019
RELATED PARTY TRANSACTIONS
RELATED PARTY TRANSACTIONS	NOTE 13—RELATED PARTY TRANSACTIONS The Company considers its related parties to be those stockholders who are beneficial owners of more than 5.0% of its common stock, executive officers, members of its board of directors or immediate family members of any of the foregoing persons and an unconsolidated joint venture. The Company has entered into a number of transactions with related parties. In accordance with the Company’s related persons transactions policy, the audit committee of the Company’s board of directors regularly reviews these transactions. However, the Company’s results of operations may have been different if these transactions were conducted with non-related parties. During the year ended December 31, 2019, sales to related parties were $16.8 million and purchases from related party vendors were $18.8 million. These purchases consisted of $3.0 million relating to purchases of property and equipment, $0.2 million relating to inventory and consumables, $14.3 million relating to the rental of certain equipment or other services used in operations and $1.3 million relating to management, consulting and other services. During the year ended December 31, 2018, sales to related parties were $8.3 million and purchases from related party vendors were $16.7 million. These purchases consisted of $4.7 million relating to purchases of property and equipment, $0.3 million relating to inventory and consumables, $10.3 million relating to the rental of certain equipment or other services used in operations and $1.4 million relating to management, consulting and other services. During the year ended December 31, 2017, sales to related parties were $9.0 million and purchases from related party vendors were $10.4 million. These purchases consisted of $3.8 million relating to purchases of property and equipment, $0.3 million relating to inventory and consumables, $2.7 million relating to the rental of certain equipment or other services used in operations and $3.6 million relating to management, consulting and other services. Tax Receivable Agreements In connection with the Select 144A Offering, the Company entered into the Tax Receivable Agreements with the TRA Holders. The first of the Tax Receivable Agreements, which the Company entered into with Legacy Owner Holdco and Crestview Partners II GP, L.P. (“Crestview GP”), generally provides for the payment by the Company to such TRA Holders of 85% of the net cash savings, if any, in U.S. federal, state and local income and franchise tax that the Company actually realizes (computed using simplifying assumptions to address the impact of state and local taxes) or is deemed to realize in certain circumstances in periods after the Select 144A Offering as a result of, as applicable to each such TRA Holder, (i) certain increases in tax basis that occur as a result of the Company’s acquisition (or deemed acquisition for U.S. federal income tax purposes) of all or a portion of such TRA Holder’s SES Holdings LLC Units in connection with the Select 144A Offering or pursuant to the exercise of the Exchange Right or the Company’s Call Right and (ii) imputed interest deemed to be paid by the Company as a result of, and additional tax basis arising from, any payments the Company makes under such Tax Receivable Agreement. The second of the Tax Receivable Agreements, which the Company entered into with an affiliate of the Contributing Legacy Owners and Crestview GP, generally provides for the payment by the Company to such TRA Holders of 85% of the net cash savings, if any, in U.S. federal, state and local income and franchise tax that the Company actually realizes (computed using simplifying assumptions to address the impact of state and local taxes) or is deemed to realize in certain circumstances in periods after the Select 144A Offering as a result of, as applicable to each such TRA Holder, (i) any net operating losses available to the Company as a result of certain reorganization transactions entered into in connection with the Select 144A Offering and (ii) imputed interest deemed to be paid by the Company as a result of any payments the Company makes under such Tax Receivable Agreement. On July 18, 2017, the Company’s board of directors approved amendments to each of the Tax Receivable Agreements revising the definition of a “change of control” for purposes of the Tax Receivable Agreements and acknowledging that the Rockwater Merger would not result in such a change of control. The Company has not recognized a liability associated with the Tax Receivable Agreements as of December 31, 2019 or 2018.

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2019
INCOME TAXES
INCOME TAXES	NOTE 14—INCOME TAXES Select Inc. is subject to U.S. federal and state income taxes as a corporation. SES Holdings and its subsidiaries, with the exception of certain corporate subsidiaries, are treated as flow-through entities for U.S. federal income tax purposes and as such, are generally not subject to U.S. federal income tax at the entity level. Rather, the tax liability with respect to their taxable income is passed through to their members or partners. Select Inc. recognizes a tax liability on its allocable share of SES Holdings’ taxable income. The Company’s effective tax rates for the years ended December 31, 2019, 2018 and 2017 were 32.0%, 3.0% and 2.4% respectively. The effective tax rates for the years ended December 31, 2019, 2018 and 2017 differ from the statutory rate of 21% for 2019 and 2018, and 35% for 2017, due to net income allocated to noncontrolling interests, state income taxes and valuation allowances. In addition, the effective tax rate for the year ended December 31, 2019 differs from the statutory tax rate due to the formation of a new subsidiary during the year. The components of the federal and state income tax expense (benefit) are summarized as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended ​ ​ December 31, ​ 2019 2018 2017 ​ ​ (in thousands) Current tax expense (benefit) ​ ​ ​ Federal income tax expense (benefit) ​ $ 696 ​ $ 1,073 ​ $ (338) State and local income tax expense (benefit) ​ 1,034 ​ 1,077 ​ (77) Total current expense (benefit) ​ 1,730 ​ 2,150 ​ (415) Deferred tax expense (benefit) ​ ​ ​ Federal income tax expense (benefit) ​ 49 ​ (20) ​ (422) State and local income tax expense (benefit) ​ 170 ​ (426) ​ (14) Total deferred expense (benefit) ​ 219 ​ (446) ​ (436) Total income tax expense (benefit) ​ $ 1,949 ​ $ 1,704 ​ $ (851) Tax expense (benefit) attributable to controlling interests ​ $ 1,488 ​ $ 1,425 ​ $ (405) Tax expense (benefit) attributable to noncontrolling interests ​ 461 ​ 279 ​ (446) Total income tax expense (benefit) ​ $ 1,949 ​ $ 1,704 ​ $ (851) ​ A reconciliation of the Company’s provision for income taxes as reported and the amount computed by multiplying income before taxes, less noncontrolling interest, by the U.S. federal statutory rate of 21% for 2019 and 2018, and 35% for 2017: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, ​ ​ ​ 2019 ​ 2018 ​ 2017 ​ ​ ​ (in thousands) ​ ​ ​ ​ Provision calculated at federal statutory income tax rate: ​ ​ ​ ​ ​ ​ ​ ​ Income (loss) before taxes ​ $ 6,085 ​ ​ $ 56,003 ​ ​ $ (35,978) ​ Statutory rate ​ 21 % ​ 21 % ​ 35 % Income tax expense (benefit) computed at statutory rate ​ 1,278 ​ ​ 11,761 ​ ​ (12,592) ​ Less: noncontrolling interests ​ (284) ​ ​ (3,735) ​ ​ 6,409 ​ Income tax expense (benefit) attributable to controlling interests ​ 994 ​ ​ 8,026 ​ ​ (6,183) ​ State and local income taxes, net of federal benefit ​ 884 ​ ​ 515 ​ ​ (91) ​ Change in enacted tax rate ​ — ​ ​ — ​ ​ 39,166 ​ Change in subsidiary tax status ​ ​ 587 ​ ​ ​ — ​ ​ ​ — ​ Other ​ ​ ​ ​ ​ ​ 580 ​ ​ ​ — ​ Deferred adjustment due to restructuring ​ ​ 856 ​ ​ ​ — ​ ​ ​ — ​ Change in valuation allowance ​ (1,833) ​ ​ (7,696) ​ ​ (33,297) ​ Income tax expense (benefit) attributable to controlling interests ​ 1,488 ​ ​ 1,425 ​ ​ (405) ​ Income tax expense (benefit) attributable to noncontrolling interests ​ 461 ​ ​ 279 ​ ​ (446) ​ Total income tax expense (benefit) ​ $ 1,949 ​ ​ $ 1,704 ​ ​ $ (851) ​ ​ Deferred taxes result from the temporary differences between financial reporting carrying amounts and the tax basis of existing assets and liabilities. As of December 31, 2019, and 2018, the Company had net deferred tax liabilities of $0.3 million and $0.1 million, respectively, which are recorded in other long-term liabilities on the consolidated balance sheets. The principal components of the deferred tax assets (liabilities) are summarized as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended ​ ​ December 31, ​ 2019 2018 ​ ​ (in thousands) Deferred tax assets ​ ​ Outside basis difference in SES Holdings ​ $ 27,935 ​ $ 38,739 Net operating losses ​ 46,782 ​ 45,927 Credits and other carryforwards ​ 1,451 ​ 1,679 Property and equipment ​ ​ — ​ ​ 150 Intangible assets ​ ​ — ​ ​ 1,284 Other ​ ​ 944 ​ ​ 468 Total deferred tax assets before valuation allowance ​ 77,112 ​ 88,247 Valuation allowance ​ ​ (76,883) ​ ​ (88,247) Total deferred tax assets ​ ​ 229 ​ ​ — Deferred tax liabilities ​ ​ Property and equipment ​ 540 ​ — Other ​ 32 ​ 123 Total deferred tax liabilities ​ 572 ​ 123 Net deferred tax liabilities ​ $ (343) ​ $ (123) ​ For the year ended December 31, 2019, the Company recorded a decrease in valuation allowance of $11.4 million against certain deferred tax assets. The Company has assessed the future potential to realize these deferred tax assets and has concluded it is more likely than not that these deferred tax assets will not be realized based on current economic conditions and expectations of the future. As a result, the Company has not recorded a liability for the effect of any associated Tax Receivable Agreement liabilities as the liability is based on the actual cash tax savings expected to be realized by the Company, which are not considered probable as of December 31, 2019. See Note 13—Related Party Transactions for further discussion of the Tax Receivable Agreements. The U.S. federal income tax legislation enacted in Public Law No. 115-97, commonly referred to as the Tax Cuts and Jobs Act, reduced the corporate income tax rate effective January 1, 2018 from 35% to 21%. As of December 31, 2018, the Company completed our accounting for the tax effects of the Tax Cuts and Jobs Act (TCJA). During the year ended December 31, 2017, the Company recognized the reasonably estimated (i) effects on our existing deferred tax balances and (ii) one-time transition tax. During the year ended December 31, 2018, the Company finalized the accounting for of the Tax Act and incurred $0.6 million in incremental income tax expense from transitioning to the TCJA. As of December 31, 2019, the Company and certain corporate subsidiaries of SES Holdings had approximately $190.4 million of U.S. federal net operating loss carryforwards (“NOLs”), of which $133.8 million will begin to expire in 2031 and $56.6 million have no expiration, approximately $102.0 million of state NOLs which will begin to expire in 2023, and approximately $5.5 million of foreign NOLs, which will begin to expire in 2037. Accounting for uncertainty in income taxes prescribes a recognition threshold and measurement methodology for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. As of December 31, 2019 and 2018 there was no material liability or expense for the periods then ended recorded for payments of interest and penalties associated with uncertain tax positions or material unrecognized tax positions and the Company’s unrecognized tax benefits were not material. Separate federal and state income tax returns are filed for Select Inc., SES Holdings and certain consolidated affiliates. The tax years 2015 through 2018 remain open to examination by the major taxing jurisdictions to which the Company is subject to income tax. The Louisiana Department of Revenue notified Select Inc. and Select Western, a corporate subsidiary of SES Holdings, that it intended to audit corporate income and franchise tax for the years ended 2016 through 2018. The audit is scheduled to begin in April, 2020. ​

NONCONTROLLING INTERESTS

NONCONTROLLING INTERESTS	12 Months Ended
	Dec. 31, 2019
NONCONTROLLING INTERESTS
NONCONTROLLING INTERESTS	NOTE 15—NONCONTROLLING INTERESTS The Company’s noncontrolling interests fall into two categories as follows: ● Noncontrolling interests attributable to joint ventures formed for water-related services. ● Noncontrolling interests attributable to holders of Class B shares. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31 ​ ​ 2019 2018 ​ ​ ​ (in thousands) Noncontrolling interests attributable to joint ventures formed for water-related services ​ ​ $ 2,674 $ 3,273 Noncontrolling interests attributable to holders of Class B Common Stock ​ ​ ​ 172,961 274,566 Total noncontrolling interests ​ ​ $ 175,635 $ 277,839 ​ During 2019, the Company dissolved one joint venture formed for water-related services with immaterial noncontrolling interests. For all periods presented, there were no other changes to Select’s ownership interest in joint ventures formed for water-related services. However, during the years ended December 31, 2019, 2018 and 2017, there were changes in Select’s ownership interest in SES Holdings LLC. The effects of the changes in Select’s ownership interest in SES Holdings LLC is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, ​ 2019 2018 2017 ​ ​ (in thousands) Net income (loss) attributable to Select Energy Services, Inc. ​ $ 2,784 $ 36,512 $ (16,816) Transfers (to) from noncontrolling interests: ​ ​ ​ ​ ​ Decrease in additional paid-in capital as a result of the contribution of proceeds from the IPO to SES Holdings, LLC in exchange for common units ​ ​ — ​ ​ — ​ ​ (41,135) Decrease in additional paid-in capital as a result of the contribution of net assets acquired to SES Holdings, LLC in exchange for common units ​ ​ — ​ ​ — ​ ​ (4,879) Decrease in additional paid-in capital as a result of the contribution of net assets from the Rockwater Merger to SES Holdings, LLC in exchange for common units ​ ​ — ​ ​ — ​ ​ (170,276) Increase in additional paid-in capital as a result of stock option exercises ​ 54 374 — Increase in additional paid-in capital as a result of restricted stock issuance, net of forfeitures ​ 3,614 1,942 — Increase in additional paid-in capital as a result of issuance of common stock due to vesting of restricted stock units ​ ​ 4 ​ ​ 104 ​ ​ — (Decrease) increase in additional paid-in capital as a result of the repurchase of SES Holdings LLC Units ​ (3,362) (576) 113 Increase in additional paid-in capital as a result of exchanges of SES Holdings LLC Units (an equivalent number of shares of Class B Common Stock) for shares of Class A Common Stock ​ ​ 107,062 ​ ​ 146,865 ​ ​ — Increase in additional paid-in capital as a result of the Employee Stock Purchase Plan shares issued ​ ​ 42 ​ ​ 15 ​ ​ — Change to equity from net income (loss) attributable to Select Energy Services, Inc. and transfers from noncontrolling interests ​ $ 110,198 $ 185,236 $ (232,993) ​

EARNINGS (LOSS) PER SHARE

EARNINGS (LOSS) PER SHARE	12 Months Ended
	Dec. 31, 2019
EARNINGS (LOSS) PER SHARE
EARNINGS (LOSS) PER SHARE	NOTE 16—EARNINGS (LOSS) PER SHARE Earnings per share are based on the amount of income allocated to the shareholders and the weighted-average number of shares outstanding during the period for each class of common stock. Outstanding options to purchase 2,961,439 and 2,706,159 shares are not included in the calculation of diluted weighted-average shares outstanding for the year ended December 31, 2019 and 2018 respectively, as the effect is antidilutive. The following tables present the Company’s calculation of basic and diluted earnings per share for the years ended December 31, 2019, 2018 and 2017 (dollars in thousands, except share and per share amounts): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, 2019 ​ ​ Select Energy ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Services, Inc. Class A Class A-2 Class B Numerator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income ​ $ 4,136 ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to noncontrolling interests ​ ​ (1,352) ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to Select Energy Services, Inc. — basic ​ ​ 2,784 ​ $ 2,784 ​ $ — ​ $ — Add: Reallocation of net income attributable to noncontrolling interests for the dilutive effect of restricted stock ​ ​ 7 ​ ​ 7 ​ ​ — ​ ​ — Add: Reallocation of net income attributable to noncontrolling interests for the dilutive effect of performance share units ​ ​ 2 ​ ​ 2 ​ ​ — ​ ​ — Add: Reallocation of net income attributable to noncontrolling interests for the dilutive effect of stock options ​ ​ 1 ​ ​ 1 ​ ​ — ​ ​ — Net income attributable to Select Energy Services, Inc. — diluted ​ $ 2,794 ​ $ 2,794 ​ $ — ​ $ — Denominator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average shares of common stock outstanding — basic ​ ​ ​ ​ ​ 80,176,323 ​ ​ — ​ ​ 23,806,646 Dilutive effect of restricted stock ​ ​ ​ ​ ​ 373,366 ​ ​ — ​ ​ — Dilutive effect of performance share units ​ ​ ​ ​ ​ 80,979 ​ ​ ​ ​ ​ — Dilutive effect of stock options ​ ​ ​ ​ ​ 40,215 ​ ​ — ​ ​ — Dilutive effect of ESPP ​ ​ ​ ​ ​ 446 ​ ​ — ​ ​ — Weighted-average shares of common stock outstanding — diluted ​ ​ ​ ​ ​ 80,671,330 ​ ​ — ​ ​ 23,806,646 Earnings per share: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic ​ ​ ​ ​ $ 0.03 ​ $ — ​ $ — Diluted ​ ​ ​ ​ $ 0.03 ​ $ — ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, 2018 ​ ​ Select Energy Services, Inc. ​ Class A ​ Class A-1 ​ Class A-2 ​ Class B Numerator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income ​ $ 54,299 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to noncontrolling interests ​ ​ (17,787) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to Select Energy Services, Inc. — basic ​ ​ 36,512 ​ $ 35,720 ​ $ ​ ​ $ 792 ​ $ — Add: Reallocation of net income attributable to noncontrolling interests for the dilutive effect of restricted stock ​ ​ 13 ​ ​ 13 ​ ​ — ​ ​ ​ ​ ​ — Add: Reallocation of net income attributable to noncontrolling interests for the dilutive effect of stock options ​ ​ 30 ​ ​ 30 ​ ​ — ​ ​ ​ ​ ​ — Net loss attributable to Select Energy Services, Inc. — diluted ​ $ 36,555 ​ $ 35,763 ​ $ — ​ $ 792 ​ $ — Denominator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average shares of common stock outstanding — basic ​ ​ ​ ​ ​ 72,403,318 ​ ​ ​ ​ ​ 1,604,575 ​ ​ 31,986,438 Dilutive effect of restricted stock ​ ​ ​ ​ ​ 71,718 ​ ​ — ​ ​ — ​ ​ — Dilutive effect of stock options ​ ​ ​ ​ ​ 166,999 ​ ​ — ​ ​ — ​ ​ — Dilutive effect of ESPP ​ ​ ​ ​ ​ 112 ​ ​ — ​ ​ — ​ ​ — Weighted-average shares of common stock outstanding — diluted ​ ​ ​ ​ ​ 72,642,147 ​ ​ — ​ ​ 1,604,575 ​ ​ 31,986,438 Earnings per share: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic ​ ​ ​ ​ $ 0.49 ​ $ — ​ $ 0.49 ​ $ — Diluted ​ ​ ​ ​ $ 0.49 ​ $ — ​ $ 0.49 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, 2017 ​ ​ Select Energy Services, Inc. ​ Class A ​ Class A-1 ​ Class A-2 ​ Class B Numerator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss ​ $ (35,127) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss attributable to noncontrolling interests ​ ​ 18,311 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss attributable to Select Energy Services, Inc. — basic ​ ​ (16,816) ​ $ (12,560) ​ $ (3,691) ​ $ (565) ​ $ — Net loss attributable to Select Energy Services, Inc. — diluted ​ $ (16,816) ​ $ (12,560) ​ $ (3,691) ​ $ (565) ​ $ — Denominator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average shares of common stock outstanding — basic ​ ​ ​ ​ ​ 24,612,853 ​ ​ 7,233,973 ​ ​ 1,106,605 ​ ​ 38,768,156 Dilutive effect of restricted stock ​ ​ ​ ​ ​ — ​ ​ — ​ ​ — ​ ​ — Dilutive effect of stock options ​ ​ ​ ​ ​ — ​ ​ — ​ ​ — ​ ​ — Dilutive effect of ESPP ​ ​ ​ ​ ​ — ​ ​ — ​ ​ — ​ ​ — Weighted-average shares of common stock outstanding — diluted ​ ​ ​ ​ ​ 24,612,853 ​ ​ 7,233,973 ​ ​ 1,106,605 ​ ​ 38,768,156 Loss per share: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic ​ ​ ​ ​ $ (0.51) ​ $ (0.51) ​ $ (0.51) ​ $ — Diluted ​ ​ ​ ​ $ (0.51) ​ $ (0.51) ​ $ (0.51) ​ $ — ​

SEGMENT INFORMATION

SEGMENT INFORMATION	12 Months Ended
	Dec. 31, 2019
SEGMENT INFORMATION
SEGMENT INFORMATION	NOTE 17—SEGMENT INFORMATION Select Inc. is an oilfield services company that provides solutions to the onshore oil and natural gas industry in the U.S. The Company’s services are offered through three operating segments. Operating segments are defined as components of an enterprise for which separate financial information is evaluated regularly by the CODM in deciding how to allocate resources and assess performance. The Company’s CODM assesses performance and allocates resources on the basis of the three reportable segments. Corporate and other expenses that do not individually meet the criteria for segment reporting are reported separately as Corporate or Other. Each operating segment reflects a reportable segment led by separate managers that report directly to the Company’s CODM. In connection with the wind down of certain operations within the Company’s former Wellsite Services segment, the Company realigned its reporting segments in 2019. Accordingly, prior period segment information has been retrospectively revised to conform with current period presentation. The Company’s CODM assesses performance and allocates resources on the basis of the following three reportable segments: Water Services Water Infrastructure Oilfield Chemicals ​ Financial information by segment for the years ended December 31, 2019, 2018 and 2017 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2019 ​ ​ ​ Income (loss) Depreciation and Capital ​ ​ Revenue ​ before taxes ​ Amortization ​ Expenditures ​ ​ (in thousands) Water services ​ $ 773,946 ​ $ 51,185 ​ $ 80,664 ​ $ 37,692 Water infrastructure ​ ​ 221,661 ​ ​ 15,103 ​ ​ 25,665 ​ ​ 53,839 Oilfield chemicals ​ ​ 268,963 ​ ​ 17,942 ​ ​ 8,766 ​ ​ 11,110 Other ​ ​ 33,365 ​ ​ (8,066) ​ ​ 1,714 ​ ​ 64 Eliminations ​ (6,346) ​ — ​ — ​ — Income from operations ​ ​ ​ 76,164 ​ ​ ​ ​ Corporate ​ — ​ (53,090) ​ 3,860 ​ — Interest expense, net ​ — ​ (2,688) ​ — ​ — Other income, net ​ — ​ (14,301) ​ — ​ — ​ ​ $ 1,291,589 ​ $ 6,085 ​ $ 120,669 ​ $ 102,705 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2018 ​ ​ ​ Income (loss) Depreciation and Capital ​ ​ Revenue ​ before taxes ​ Amortization ​ Expenditures ​ ​ (in thousands) Water services ​ $ 897,160 ​ $ 89,826 ​ $ 82,875 ​ $ 120,883 Water infrastructure ​ ​ 230,130 ​ ​ 31,579 ​ ​ 23,042 ​ ​ 33,372 Oilfield chemicals ​ ​ 260,281 ​ ​ (7,107) ​ ​ 10,496 ​ ​ 10,832 Other ​ ​ 144,499 ​ ​ (14,021) ​ ​ 14,124 ​ ​ 7,045 Eliminations ​ (3,140) ​ — ​ — ​ — Income from operations ​ ​ ​ 100,277 ​ ​ ​ ​ Corporate ​ — ​ (38,603) ​ 3,176 ​ — Interest expense, net ​ — ​ (5,311) ​ — ​ — Other income, net ​ — ​ (360) ​ — ​ — ​ ​ $ 1,528,930 ​ $ 56,003 ​ $ 133,713 ​ $ 172,132 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2017 ​ ​ ​ Income (loss) Depreciation and Capital ​ ​ Revenue ​ before taxes ​ Amortization ​ Expenditures ​ ​ (in thousands) Water Services ​ $ 420,757 ​ $ 1,823 ​ $ 70,839 ​ $ 82,127 Water Infrastructure ​ ​ 163,386 ​ ​ 11,723 ​ ​ 22,481 ​ ​ 15,264 Oilfield Chemicals ​ ​ 41,586 ​ ​ 663 ​ ​ 2,040 ​ ​ 3,063 Other ​ ​ 69,382 ​ ​ (2,649) ​ ​ 6,286 ​ ​ 7,823 Eliminations ​ (2,620) ​ — ​ — ​ — Loss from operations ​ ​ ​ 11,560 ​ ​ ​ ​ Corporate ​ — ​ (41,559) ​ 1,803 ​ — Interest expense, net ​ — ​ (6,629) ​ — ​ — Other income, net ​ — ​ 650 ​ — ​ — ​ ​ $ 692,491 ​ $ (35,978) ​ $ 103,449 ​ $ 108,277 ​ Total assets by segment as of December 31, 2019 and 2018 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ ​ 2019 ​ 2018 ​ ​ (in thousands) Water services ​ $ 831,123 ​ $ 865,992 Water infrastructure ​ ​ 314,026 ​ 250,207 Oilfield chemicals ​ ​ 192,224 ​ 173,762 Other ​ ​ 10,247 ​ ​ 70,644 ​ ​ $ 1,347,620 ​ $ 1,360,605 ​ Revenue by groups of similar products and services are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, ​ 2019 2018 ​ 2017 ​ ​ (in thousands) Water transfer ​ $ 355,535 ​ $ 443,650 ​ $ 193,314 Oilfield chemicals ​ ​ 268,963 ​ 260,281 ​ ​ 41,586 Flowback and well testing ​ 208,572 ​ 223,828 ​ ​ 90,107 Accommodations and rentals ​ 150,793 ​ ​ 153,013 ​ ​ 63,107 Water sourcing ​ 120,517 ​ 129,958 ​ ​ 97,898 Pipeline logistics and disposal ​ ​ 101,145 ​ ​ 100,172 ​ ​ 65,488 Fluid hauling ​ ​ 63,156 ​ ​ 79,568 ​ ​ 75,273 Other ​ 22,908 ​ 138,460 ​ ​ 65,718 ​ ​ $ 1,291,589 ​ $ 1,528,930 ​ $ 692,491 ​ In connection with the Rockwater Merger in November 2017, the Company expanded into Canada and during 2019, the Company divested and wound down Canadian operations. The Company attributed revenue to the U.S. and Canada based on the location where services were performed or the destination of the products or equipment sold or rented. Long-lived assets consisted of property and equipment and are attributed to the U.S. and Canada based on the physical location of the asset at the end of the period. The Company’s revenue attributed to the U.S. was $1,283.4 million or 99.4%, $1,480.4 million or 96.8% and $680.9 million or 98.3% of total revenue during the years ended December 31, 2019, 2018 and 2017, respectively. The Company’s revenue attributed to Canada was $8.2 million or 0.6%, $48.6 million or 3.2% and $11.6 million or 1.7% of total revenue during the years ended December 31, 2019, 2018 and 2017, respectively. The Company’s net long-lived assets attributed to the U.S. was $452.4 million or 99.8%, $492.4 million or 97.9% and $451.7 million or 95.3% of total net long-lived assets as of December 31, 2019, December 31, 2018 and December 31, 2017, respectively. The Company’s net long-lived assets attributed to Canada was $0.9 million or 0.2%, $10.5 million or 2.1% and $22.4 million or 4.7% of total net long-lived assets as of December 31, 2019, December 31, 2018 and December 31, 2017, respectively.

QUARTERLY RESULTS OF OPERATIONS

QUARTERLY RESULTS OF OPERATIONS (UNAUDITED)	12 Months Ended
	Dec. 31, 2019
QUARTERLY RESULTS OF OPERATIONS (UNAUDITED)
QUARTERLY RESULTS OF OPERATIONS (UNAUDITED)	NOTE 18—QUARTERLY RESULTS OF OPERATIONS (UNAUDITED) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2019 ​ ​ First ​ Second ​ Third ​ Fourth ​ ​ Quarter ​ Quarter ​ Quarter Quarter ​ ​ (in thousands) Revenue ​ $ 362,646 ​ $ 323,887 ​ $ 328,968 ​ $ 276,088 Gross profit ​ 45,997 ​ 39,939 ​ 40,994 ​ 21,810 Income (loss) from operations ​ 6,633 ​ 11,179 ​ 12,475 ​ (7,213) Net income (loss) ​ 1,400 ​ 8,068 ​ 7,172 ​ (12,504) Net income (loss) attributable to Select Energy Services, Inc. ​ 1,135 ​ 6,200 ​ 5,379 ​ (9,930) Net income (loss) per share attributable to common stockholders: ​ ​ ​ ​ ​ ​ ​ ​ Class A-Basic & Diluted ​ $ 0.01 ​ $ 0.08 ​ $ 0.07 ​ $ (0.12) Class A-1-Basic & Diluted ​ $ — ​ $ — ​ $ — ​ $ — Class A-2-Basic & Diluted ​ $ — ​ $ — ​ $ — ​ $ — Class B-Basic & Diluted ​ $ — ​ $ — ​ $ — ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2018 ​ ​ First ​ Second ​ Third ​ Fourth ​ ​ Quarter ​ Quarter ​ Quarter Quarter ​ ​ (in thousands) Revenue ​ $ 376,395 ​ $ 393,247 ​ $ 396,970 ​ $ 362,318 Gross profit ​ 47,949 ​ 56,728 ​ 59,397 ​ 34,408 Income (loss) from operations ​ 18,603 ​ 24,795 ​ 32,258 ​ (13,982) Net income (loss) ​ 16,132 ​ 25,023 ​ 31,267 ​ (18,123) Net income (loss) attributable to Select Energy Services, Inc. ​ 10,099 ​ 16,963 ​ 22,951 ​ (13,501) Net income (loss) per share attributable to common stockholders: ​ ​ ​ ​ ​ ​ ​ ​ Class A-Basic & Diluted ​ $ 0.15 ​ $ 0.24 ​ $ 0.29 ​ $ (0.17) Class A-1-Basic & Diluted ​ $ — ​ $ — ​ $ — ​ $ — Class A-2-Basic & Diluted ​ $ 0.15 ​ $ — ​ $ — ​ $ — Class B-Basic & Diluted ​ $ — ​ $ — ​ $ — ​ $ — ​

SIGNIFICANT ACCOUNTING POLICI_2

SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2019
SIGNIFICANT ACCOUNTING POLICIES
Use of estimates	Use of estimates : The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. On an ongoing basis, the Company evaluates its estimates, including those related to the recoverability of long-lived assets and intangibles, useful lives used in depreciation and amortization, uncollectible accounts receivable, income taxes, self-insurance liabilities, share-based compensation, inventory, incremental borrowing rate on leases and contingent liabilities. The Company bases its estimates on historical and other pertinent information that are believed to be reasonable under the circumstances. The accounting estimates used in the preparation of the consolidated financial statements may change as new events occur, as more experience is acquired, as additional information is obtained and as the Company’s operating environment changes.
Cash and cash equivalents	Cash and cash equivalents : The Company considers all highly liquid investments with an original maturity of three months or less to be cash equivalents.
Accounts receivable and allowance for doubtful accounts	Accounts receivable and allowance for doubtful accounts : Accounts receivable are stated at the invoiced amount, or the earned but not yet invoiced amount, net of an allowance for doubtful accounts. The Company establishes an allowance for doubtful accounts based on the review of several factors, including historical collection experience, the current aging status of the customer accounts and financial condition of its customers. Accounts receivable are written off when a settlement is reached for an amount less than the outstanding historical balance or when the Company determines that it is probable the balance will not be collected. The change in allowance for doubtful accounts is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, ​ ​ 2019 ​ 2018 2017 ​ ​ (in thousands) Balance at beginning of year ​ $ 5,329 $ 2,979 $ 2,144 Provisions for bad debts, included in selling, general and administrative ​ 2,553 2,210 1,542 Uncollectible receivable (write-offs) recoveries ​ (2,109) 140 (707) Balance at end of year ​ $ 5,773 $ 5,329 $ 2,979
Concentrations of credit and customer risk	Concentrations of credit and customer risk : Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash and cash equivalents and trade accounts receivable. The amounts held in financial institutions periodically exceed the federally insured limit. Management believes that the financial institutions are financially sound and the risk of loss is minimal. The Company minimizes its exposure to counterparty credit risk by performing credit evaluations and ongoing monitoring of the financial stability of its customers. There were
Inventories	Inventories : The Company values its inventories at lower of cost or net realizable value. Inventory costs are determined under the weighted-average method. Inventory costs primarily consist of chemicals and materials available for resale and parts and consumables used in operations.
Debt issuance costs	Debt issuance costs : Debt issuance costs consist of costs directly associated with obtaining credit with financial institutions. These costs are recorded as a long-term asset associated with the line of credit and amortized on a straight-line basis over the life of the credit agreement, which approximates the effective-interest method. During the year ended December 31, 2017, the Company expensed unamortized debt issuance costs of
Property and equipment	Property and equipment : Property and equipment are stated at cost less accumulated depreciation. Depreciation (and amortization of capital lease assets) is calculated on a straight line basis over the estimated useful life of each asset as noted below: ​ ​ ​ ​ Asset Classification Useful Life (years) Land Indefinite Buildings and leasehold improvements 30 or lease term Vehicles and equipment 4 - 7 or lease term Machinery and equipment 2 - 15 Computer equipment and software 3 - 4 or lease term Office furniture and equipment 7 Disposal wells 7 - 10 ​ ​ ​ ​ Depreciation expense related to the Company’s property and equipment, including amortization of property under finance leases, was $108.7 million, $120.4 million and $92.6 million for the years ended December 31, 2019, 2018 and 2017, respectively. Change in depreciable lives of property and equipment: The average estimated useful lives of the assets impacted in the vehicles and equipment category increased from 6.0 to 8.1 years, while the average estimated useful lives of assets impacted in machinery and equipment increased from 5.5 years to 6.9 years. The impact of the increase of useful lives was to defer and extend out depreciation expense, including lower expense in 2018. The impact of the increase in salvage values was to permanently lower current and future depreciation expense. The fixed assets obtained in 2017 through mergers and acquisitions, including the Rockwater Merger, had consistent useful life and salvage value estimates with the rest of the Company’s fixed assets. The change in the estimated useful lives of fixed assets and change in salvage value estimates was implemented on a prospective basis starting January 1, 2018. Excluding fixed assets attained through mergers and acquisitions during 2017, the impact of the change in useful estimate of fixed assets purchased on or before December 31, 2017 was to reduce and defer depreciation expense by $12.6 million during the year ended December 31, 2018. Also, the increase in estimated vehicle salvage value produced a permanent depreciation expense reduction of $3.9 million during the year ended December 31, 2018. For the year ended December 31, 2018, the changes in useful life estimate and increased salvage value produced an increase to net income of $10.9 million (including the impact of noncontrolling interests) and increased both basic and diluted earnings per share attributable to our stockholders by $0.15.
Business combination	Business Combinations:
Goodwill and other intangible assets	Goodwill and other intangible assets : Goodwill represents the excess of the purchase price of acquisitions over the fair value of the net assets acquired. Goodwill and other intangible assets not subject to amortization are tested for impairment annually or more frequently if events or changes in circumstances indicate that the asset might be impaired. Intangible assets with finite useful lives are amortized either on a straight-line basis over the asset’s estimated useful life or on a basis that reflects the pattern in which the economic benefits of the intangible assets are realized.
Impairment of goodwill, long lived assets and intangible assets:	Impairment of goodwill, long-lived assets and intangible assets : Long-lived assets, such as property and equipment and finite-lived intangible assets, are evaluated for impairment whenever events or changes in circumstances indicate that its carrying value may not be recoverable. Recoverability is measured by a comparison of its carrying amount to the estimated undiscounted cash flows to be generated by those assets. If the undiscounted cash flows are less than the carrying amount, the Company records impairment losses for the excess of its carrying value over the estimated fair value. The development of future cash flows and the estimate of fair value represent its best estimates based on industry trends and reference to market transactions and are subject to variability. The Company considers the factors within the fair value analysis to be Level 3 inputs within the fair value hierarchy. During the year ended December 31, 2018, the Company reviewed certain fluid disposal machinery and equipment used in our fluid hauling and disposal services that are included in our Water Infrastructure segment. Due to the condition of the equipment, the Company determined that long-lived assets with a carrying value of ​ The Company conducts its annual goodwill impairment tests in the fourth quarter of each year, and whenever impairment indicators arise, by examining relevant events and circumstances which could have a negative impact on its goodwill such as macroeconomic conditions, industry and market conditions, cost factors that have a negative effect on earnings and cash flows, overall financial performance, acquisitions and divestitures and other relevant entity-specific events. If a qualitative assessment indicates that it is more likely than not that the fair value of a reporting unit is less than its carrying amount, the Company is required to perform a quantitative impairment test for goodwill comparing the reporting unit’s carrying value to its fair value. The Company’s reporting units are based on its organizational and reporting structure. In determining fair values for the reporting units, the Company relies primarily on the income and market approaches for valuation. In the income approach, the Company discounts predicted future cash flows using a weighted-average cost of capital calculation based on publicly traded peer companies. In the market approach, valuation multiples are developed from both publicly traded peer companies as well as other company transactions. The cost approach, when used, considers replacement cost as the primary indicator of value. If the fair value of a reporting unit is less than its carrying value, goodwill impairment is calculated by subtracting the fair value of the reporting unit from the carrying value. Application of the goodwill impairment test requires judgment, including the identification of reporting units, allocation of assets (including goodwill) and liabilities to reporting units and determining the fair value. The determination of reporting unit fair value relies upon certain estimates and assumptions that are complex and are affected by numerous factors, including the general economic environment and levels of exploration and production (“E&P”) activity of oil and gas companies, the Company’s financial performance and trends and the Company’s strategies and business plans, among others. Unanticipated changes, including immaterial revisions, to these assumptions, could result in a provision for impairment in a future period. Given the nature of these evaluations and their application to specific assets and time frames, it is not possible to reasonably quantify the impact of changes in these assumptions. During the first quarter of 2019, goodwill related to our Affirm reporting unit was reduced to zero from the crane divestiture and impairment. The $4.4 million impairment was based on the estimated fair value of the proceeds from selling and winding down the remainder of the Affirm reporting unit business being less than the carrying value. Also, in connection with the Company’s segment realignment, the Company reallocated goodwill from reporting units in the 2018 Water Solutions segment to reporting units in the 2019 Water Services and Water Infrastructure segments based on the relative fair value of each as of March 31, 2019. See Note 8—Goodwill and Other Intangible Assets and Note 12—Fair Value Measurement for further discussion. Asset retirement obligations : The asset retirement obligation (“ARO”) liability reflects the present value of estimated costs of plugging, site reclamation and similar activities associated with the Company’s salt water disposal wells. The Company utilizes current retirement costs to estimate the expected cash outflows for retirement obligations. The Company also estimates the productive life of the disposal wells, a credit-adjusted risk-free discount rate and an inflation factor in order to determine the current present value of this obligation. The Company’s ARO liabilities are included in accrued expenses and other current liabilities and other long-term liabilities as of December 31, 2019 and 2018. The change in asset retirement obligations is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, ​ ​ ​ ​ ​ 2019 2018 ​ ​ ​ ​ (in thousands) ​ ​ Balance at beginning of year ​ $ 1,898 $ 1,846 ​ ​ Accretion expense, included in depreciation and amortization expense ​ ​ 115 ​ 183 ​ ​ Change in estimate ​ ​ — ​ 377 ​ ​ Disposals ​ ​ (486) ​ ​ — ​ ​ ​ Divestitures ​ ​ — ​ ​ (508) ​ ​ ​ Balance at end of year ​ $ 1,527 $ 1,898 ​ ​ ​ In addition to the obligations described above, the Company may be obligated to remove facilities or perform other remediation upon retirement of certain other assets. However, the fair value of the asset retirement obligation cannot currently be reasonably estimated because the settlement dates are indeterminable. If applicable, the Company will record an asset retirement obligation for these assets in the periods in which settlement dates are reasonably determinable
Asset retirement obligations	During the first quarter of 2019, goodwill related to our Affirm reporting unit was reduced to zero from the crane divestiture and impairment. The $4.4 million impairment was based on the estimated fair value of the proceeds from selling and winding down the remainder of the Affirm reporting unit business being less than the carrying value. Also, in connection with the Company’s segment realignment, the Company reallocated goodwill from reporting units in the 2018 Water Solutions segment to reporting units in the 2019 Water Services and Water Infrastructure segments based on the relative fair value of each as of March 31, 2019. See Note 8—Goodwill and Other Intangible Assets and Note 12—Fair Value Measurement for further discussion.
Selfinsurance	Self-insurance : The Company self-insures, through deductibles and retentions, up to certain levels for losses related to general liability, workers’ compensation and employer’s liability and vehicle liability. The Company’s exposure (i.e. the retention or deductible) per occurrence is
Employee benefit plans	Employee benefit plans : The Company sponsors a defined contribution 401(k) Profit Sharing Plan (the “401(k) Plan”) for the benefit of substantially all employees of the Company. The 401(k) Plan allows eligible employees to make tax-deferred contributions, not to exceed annual limits established by the Internal Revenue Service. The Company did not make any matching contributions for the year ended December 31, 2016. Company reinstated matching contributions of 100% of employee contributions, up to 4% of compensation with immediate vesting for existing employees. Starting July 1, 2017, the vesting schedule for new hires is 25% for the first year, 50% for the second year, 75% for the third year and 100% for the fourth year. The Company’s contributions to the 401(k) Plan were $4.2 million and $3.6 million for the years ended December 31, 2019 and 2018, respectively.
Revenue recognition	Revenue recognition : The Company follows ASU 2014-09, Revenue from Contracts with Customers (Topic 606). . Water Services and Water Infrastructure The Company’s agreements with its customers are often referred to as “price sheets” and sometimes provide pricing for multiple services. However, these agreements generally do not authorize the performance of specific services or provide for guaranteed throughput amounts. As customers are free to choose which services, if any, to use based on the Company’s price sheet, the Company prices its separate services on the basis of their standalone selling prices. Customer agreements generally do not provide for performance-, cancellation-, termination-, or refund-type provisions. Services based on price sheets with customers are generally performed under separately-issued “work orders” or “field tickets” as services are requested. Of the Company’s Water Solutions service lines, only sourcing and transfer of water are consistently provided as part of the same arrangement. In these instances, revenue for both sourcing and transfer are recognized concurrently when delivered. Accommodations and Rentals Oilfield Chemical Product Sales— Oilfield Chemicals products are generally sold under sales agreements based upon purchase orders or contracts with customers that do not include right of return provisions or other significant post-delivery obligations. The Company’s products are produced in a standard manufacturing operation, even if produced to the customer’s specifications. The prices of products are fixed and determinable and are established in price lists or customer purchases orders. The Company recognizes revenue from product sales when title passes to the customer, the customer assumes risks and rewards of ownership, collectability is reasonably assured and delivery occurs as directed by the customer.
Equity-based compensation	Equity-based compensation : The Company accounts for equity-based awards for restricted stock awards, restricted stock units, and stock settled appreciation awards by measuring the awards at the date of grant and recognizing the grant-date fair value as an expense using either straight-line or accelerated attribution, depending on the specific terms of the award agreements over the requisite service period, which is usually equivalent to the vesting period. The Company expenses awards with graded-vesting service conditions on a straight-line basis and accounts for forfeitures as they occur. The company accounts for performance share units by remeasuring the awards at the end of each reporting period based on the period end closing share price, factoring in the percentage expected to vest,
Fair value measurements	Fair value measurements : The Company measures certain assets and liabilities pursuant to accounting guidance which establishes a three-tier fair value hierarchy and prioritizes the inputs used in measuring fair value. Level 1 inputs are unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 inputs are quoted prices or other market data for similar assets and liabilities in active markets, or inputs that are observable for the asset or liability, either directly or indirectly through market corroboration, for substantially the full term of the asset or liability. Level 3 inputs are unobservable inputs based upon its own judgment and assumptions used to measure assets and liabilities at fair value. See Note 12—Fair Value Measurement for further discussion.
Income taxes	Income taxes The Company and its subsidiaries account for income taxes under the asset and liability method. Under this method, deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis. Deferred tax assets and liabilities are measured using enacted tax rates in effect for the year in which those temporary differences are expected to be recovered or settled pursuant to the provisions of Accounting Standards Codification (“ASC”) 740, Income Taxes. The effect on deferred tax assets and liabilities of a change in tax rate is recognized in earnings in the period that includes the enactment date. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts more likely than not to be realized. The determination of the provision for income taxes requires significant judgment, use of estimates and the interpretation and application of complex tax laws. Significant judgment is required in assessing the timing and amounts of deductible and taxable items and the probability of sustaining uncertain tax positions. The benefits of uncertain tax positions are recorded in the Company’s financial statements only after determining a more likely than not probability that the uncertain tax positions will withstand challenge, if any, from taxing authorities. When facts and circumstances change, the Company reassesses these probabilities and records any changes through the provision for income taxes. The Company recognizes interest and penalties relating to uncertain tax provisions as a component of tax expense. The Company identified no material uncertain tax positions as of December 31, 2019, 2018 and 2017. See Note 14—Income Taxes for further discussion.
Recent accounting pronouncements:	Recent accounting pronouncements Leases Leases (ASC 842): Targeted Improvements, which provides entities with an option to apply the guidance prospectively, instead of retrospectively, and allows for other classification provisions. ASU 2016-02 is effective for annual reporting periods beginning after December 15, 2018, including interim periods within those fiscal years, with early adoption permitted. The Company adopted ASU 2016-02 in the first quarter of 2019. The Company elected to recognize its lease assets and liabilities on a prospective basis, beginning on January 1, 2019, using the modified retrospective transition method. Additionally, the Company elected practical expedients to (i) exclude right-of-use assets and lease liabilities for short-term leases, (ii) elected to treat lease and non-lease components as a single lease component, (iii) grandfathered its current accounting for land easements that commenced before January 1, 2019, and (iv) used the package of practical expedients to retain prior lease classification, prior treatment of initial direct costs and prior determination of whether a contract constituted a lease. See Note 5—Leases for additional information. In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments ​ In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740)

SIGNIFICANT ACCOUNTING POLICI_3

SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2019
SIGNIFICANT ACCOUNTING POLICIES
Schedule of change in allowance for doubtful accounts	The change in allowance for doubtful accounts is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, ​ ​ 2019 ​ 2018 2017 ​ ​ (in thousands) Balance at beginning of year ​ $ 5,329 $ 2,979 $ 2,144 Provisions for bad debts, included in selling, general and administrative ​ 2,553 2,210 1,542 Uncollectible receivable (write-offs) recoveries ​ (2,109) 140 (707) Balance at end of year ​ $ 5,773 $ 5,329 $ 2,979
Schedule of estimated useful life of property and equipment	​ ​ ​ ​ Asset Classification Useful Life (years) Land Indefinite Buildings and leasehold improvements 30 or lease term Vehicles and equipment 4 - 7 or lease term Machinery and equipment 2 - 15 Computer equipment and software 3 - 4 or lease term Office furniture and equipment 7 Disposal wells 7 - 10 ​ ​ ​
Summary of change in asset retirement obligations	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, ​ ​ ​ ​ ​ 2019 2018 ​ ​ ​ ​ (in thousands) ​ ​ Balance at beginning of year ​ $ 1,898 $ 1,846 ​ ​ Accretion expense, included in depreciation and amortization expense ​ ​ 115 ​ 183 ​ ​ Change in estimate ​ ​ — ​ 377 ​ ​ Disposals ​ ​ (486) ​ ​ — ​ ​ ​ Divestitures ​ ​ — ​ ​ (508) ​ ​ ​ Balance at end of year ​ $ 1,527 $ 1,898 ​ ​

ACQUISITIONS AND DIVESTITURES (

ACQUISITIONS AND DIVESTITURES (Tables)	12 Months Ended
	Dec. 31, 2019
Schedule of unaudited consolidated pro forma information	​ ​ ​ ​ ​ ​ Pro Forma ​ ​ Year ended December 31, ​ ​ 2017 ​ ​ (unaudited) ​ ​ (in thousands) Revenue $ 1,270,736 Net loss ​ (13,079) Less: net loss attributable to noncontrolling interests (1) 5,299 Net loss attributable to Select Energy Services, Inc. (1) $ (7,780) (1) The allocation of net income (loss) attributable to noncontrolling interests and Select Inc. gives effect to the equity structure as of December 31, 2016 as though the Select 144A Offering, the IPO, the Rockwater Merger, the Resource Water Acquisition and the GRR Acquisition occurred as of January 1, 2017. However, the calculation of pro forma net income (loss) does not give effect to any other pro forma adjustments for the Select 144A Offering or the subsequent IPO.
Schedule of sales details	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Date of Divestiture ​ Entity ​ Initial Net Proceeds ​ Working Capital True Up ​ Adjusted Net Proceeds ​ Working Capital Status at ​ (Gain)/loss for the year ended December 31, 2019 ​ ​ ​ ​ (in thousands) February 26, 2019 ​ Affirm ​ $ 10,982 ​ $ (208) ​ $ 10,774 ​ Final ​ $ 208 June 28, 2019 ​ Affirm ​ ​ 6,968 ​ ​ — ​ ​ 6,968 ​ Final ​ ​ (1,646) March 19, 2019 ​ Canada ​ ​ 4,975 ​ ​ (302) ​ ​ 4,673 ​ Final ​ ​ 5,013 April 1, 2019 ​ Canada ​ ​ 2,242 ​ ​ — ​ ​ 2,242 ​ Final ​ ​ 101
Well Chemical Services Acquisition
Schedule Of consideration transferred and the estimated fair value of identified assets acquired and liabilities	​ ​ ​ ​ ​ Purchase price allocation Amount Consideration transferred (in thousands) Cash paid ​ $ 10,000 Total consideration transferred ​ 10,000 Less: identifiable assets acquired and liabilities assumed ​ Inventory ​ 5,221 Property and equipment ​ 4,473 Customer relationships ​ 476 Current liabilities ​ ​ (170) Total identifiable net assets acquired ​ 10,000 Fair value allocated to net assets acquired ​ $ 10,000
Pro Well Acquisition
Schedule Of consideration transferred and the estimated fair value of identified assets acquired and liabilities	​ ​ ​ ​ ​ Purchase price allocation Amount Consideration transferred (in thousands) Cash paid ​ $ 11,754 Total consideration transferred ​ 11,754 Less: identifiable assets acquired and liabilities assumed ​ Working capital ​ 1,051 Property and equipment ​ 6,588 Customer relationship intangible assets ​ 3,000 Total identifiable net assets acquired ​ 10,639 Goodwill ​ ​ 1,115 Fair value allocated to net assets acquired ​ $ 11,754
Rockwater Merger
Schedule Of consideration transferred and the estimated fair value of identified assets acquired and liabilities	​ ​ ​ ​ ​ Purchase price allocation ​ Amount Consideration transferred ​ (in thousands) Class A Common Stock (25,914,260 shares) ​ $ 423,957 Class A-2 Common Stock (6,731,845 shares) ​ ​ 110,133 Class B Common Stock (4,356,477 shares) and SES Holdings common units issued (4,356,477 units) ​ ​ 71,272 Fair value of previously held interest in Rockwater ​ 2,310 Fair value of Rockwater share-based awards attributed to pre-acquisition service ​ ​ 12,529 Total consideration transferred ​ 620,201 Less: identifiable assets acquired and liabilities assumed ​ ​ Working capital ​ 141,720 Property and equipment ​ 172,650 Intangible assets ​ ​ Customer relationships ​ ​ 89,661 Trademarks and patents ​ ​ 31,223 Non-compete agreements ​ ​ 3,811 Other long-term assets ​ ​ 88 Deferred tax liabilities ​ ​ (408) Long-term debt ​ ​ (80,555) Other long-term liabilities ​ ​ (2,517) Total identifiable net assets acquired ​ ​ 355,673 Goodwill ​ 264,528 Fair value allocated to net assets acquired $ 620,201 ​
Resource Water Acquisition
Schedule Of consideration transferred and the estimated fair value of identified assets acquired and liabilities	​ ​ ​ ​ ​ Purchase price allocation Amount Consideration transferred (in thousands) Cash paid ​ $ 6,586 Class A Common Stock (156,909 shares) ​ 2,380 Total consideration transferred ​ 8,966 Less: identifiable assets acquired and liabilities assumed ​ Working capital ​ 1,189 Property and equipment ​ 3,485 Customer relationship intangible assets ​ 1,933 Other intangible assets ​ 465 Total identifiable net assets acquired ​ 7,072 Goodwill ​ 1,894 Fair value allocated to net assets acquired $ 8,966
GRR Acquisition
Schedule Of consideration transferred and the estimated fair value of identified assets acquired and liabilities	​ ​ ​ ​ ​ Purchase price allocation Amount Consideration transferred (in thousands) Cash paid ​ $ 53,032 Class A Common Stock (274,998 shares) ​ 5,500 Assumed liabilities ​ 1,106 Total consideration transferred ​ 59,638 Less: identifiable assets acquired and liabilities assumed ​ Working capital ​ 7,728 Property and equipment ​ 13,225 Customer relationship intangible assets ​ 21,484 Other intangible assets ​ 5,152 Total identifiable net assets acquired ​ 47,589 Goodwill ​ ​ 12,049 Fair value allocated to net assets acquired ​ $ 59,638

REVENUE (Tables)

REVENUE (Tables)	12 Months Ended
	Dec. 31, 2019
REVENUE
Schedule of disaggregation of revenue by geographic location	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ 2019 ​ 2018 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Geographic Region ​ ​ ​ ​ ​ ​ ​ ​ ​ Permian Basin ​ $ 610,528 ​ $ 606,591 ​ $ 243,482 MidCon ​ ​ 176,216 ​ ​ 243,524 ​ ​ 96,844 Eagle Ford ​ ​ 156,621 ​ ​ 171,942 ​ ​ 104,934 Marcellus/Utica ​ ​ 96,454 ​ ​ 134,984 ​ ​ 32,805 Bakken ​ ​ 92,956 ​ ​ 153,212 ​ ​ 74,543 Rockies ​ ​ 85,339 ​ ​ 111,901 ​ ​ 80,180 Haynesville/E. Texas ​ ​ 73,658 ​ ​ 59,969 ​ ​ 49,600 All other/eliminations ​ ​ (183) ​ ​ 46,807 ​ ​ 10,103 Total ​ $ 1,291,589 ​ $ 1,528,930 ​ $ 692,491

LEASES (Tables)

LEASES (Tables)	12 Months Ended
	Dec. 31, 2019
LEASES
Schedule of financial impact of leases	​ ​ ​ ​ ​ ​ ​ Balance Sheet Classification As of December 31, 2019 ​ ​ ​ ​ (in thousands) Assets ​ ​ ​ ​ ​ ROU Assets (1) ​ Long-term right-of-use assets ​ $ 70,635 Finance lease assets (2) ​ Property and equipment ​ ​ 213 Liabilities ​ ​ ​ ​ ​ Operating lease liabilities ― ST ​ Current operating lease liabilities ​ $ 19,315 Operating lease liabilities ― LT (3) ​ Long-term operating lease liabilities ​ ​ 72,143 Finance lease liabilities ― ST ​ Current portion of finance lease obligations ​ ​ 128 Finance lease liabilities ― LT ​ Other long term liabilities ​ ​ 87 (1) (2) (3) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended Statements of Operations and Cash Flows Classification December 31, 2019 ​ ​ ​ ​ ​ ​ Operating lease cost: ​ ​ ​ ​ ​ Operating lease cost ― fixed ​ Cost of revenue and Selling, general and administrative ​ $ 27,856 Lease abandonment costs ​ Lease abandonment costs ​ ​ 2,073 ​ ​ ​ ​ ​ ​ Short-term agreements: ​ Cost of revenue ​ $ 93,949 ​ ​ ​ ​ ​ ​ Finance lease cost: ​ ​ ​ ​ ​ Amortization of leased assets ​ Depreciation and amortization ​ $ 916 Interest on lease liabilities ​ Interest expense, net ​ ​ 32 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Lessor income: ​ ​ ​ ​ ​ Sublease income ​ Cost of sales and lease abandonment costs ​ $ 1,544 Lessor income ​ Cost of sales ​ ​ 478 ​ ​ ​ ​ ​ ​ Statement of cash flows ​ ​ ​ ​ ​ Cash paid for operating leases ​ Operating cash flows ​ $ 30,670 Cash paid for finance leases lease interest ​ Operating cash flows ​ ​ 32 Cash paid for finance leases ​ Financing cash flows ​ ​ 883 ​ ​ ​ ​ ​ ​ Long Term and Discount Rate As of December 31, 2019 Weighted-average remaining lease term (years) ​ ​ ​ Operating leases ​ 7.9 ​ Finance leases ​ 1.6 ​ Weighted-average discount rate ​ ​ ​ Operating leases ​ 5.3 % Finance leases ​ 5.1 %
Schedule of operating and finance lease commitments	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Period Operating Leases (1) Finance Leases Total ​ ​ (in thousands) 2020 ​ $ 24,742 ​ $ 135 ​ $ 24,877 2021 ​ 16,592 ​ 88 ​ 16,680 2022 ​ 13,231 ​ - ​ 13,231 2023 ​ 11,074 ​ - ​ 11,074 2024 ​ 10,589 ​ - ​ 10,589 Thereafter ​ 44,094 ​ - ​ 44,094 Total minimum lease payments ​ $ 120,322 ​ $ 223 ​ $ 120,545 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Less reconciling items to reconcile undiscounted cash flows to lease liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ Leases commencing in the future ​ ​ 5,793 ​ ​ — ​ ​ 5,793 Short-term leases excluded from balance sheet ​ ​ 693 ​ ​ — ​ ​ 693 Imputed interest ​ ​ 22,378 ​ ​ 8 ​ ​ 22,386 Total reconciling items ​ ​ 28,864 ​ ​ 8 ​ ​ 28,872 Total liabilities per balance sheet ​ ​ 91,458 ​ ​ 215 ​ ​ 91,673 ​ (1) The table above excludes sublease and lessor income of $1.6 million during 2020, $0.6 million during 2021 and $0.3 million during 2022.

INVENTORIES (Tables)

INVENTORIES (Tables)	12 Months Ended
	Dec. 31, 2019
INVENTORIES
Schedule of inventory	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ ​ 2019 2018 ​ ​ ​ (in thousands) Raw materials ​ ​ $ 12,365 ​ $ 15,219 Finished goods ​ ​ 24,724 ​ 28,540 Materials and supplies ​ ​ 453 ​ 1,233 ​ ​ ​ $ 37,542 ​ $ 44,992

PROPERTY AND EQUIPMENT (Tables)

PROPERTY AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2019
PROPERTY AND EQUIPMENT
Schedule of property and equipment	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ ​ 2019 2018 ​ ​ ​ (in thousands) Land ​ ​ $ 16,030 ​ $ 17,799 Buildings and leasehold improvements ​ ​ 97,426 ​ 106,626 Vehicles and equipment ​ ​ 53,819 ​ 83,435 Vehicles and equipment - finance lease ​ ​ 1,291 ​ 1,833 Machinery and equipment ​ ​ 729,162 ​ 758,528 Machinery and equipment - finance lease ​ ​ 162 ​ 532 Computer equipment and software ​ ​ ​ 8,051 ​ ​ 15,775 Computer equipment and software - finance lease ​ ​ 356 ​ 356 Office furniture and equipment ​ ​ 1,157 ​ 4,612 Disposal wells ​ ​ 64,149 ​ 64,038 Other ​ ​ ​ 497 ​ ​ 497 Construction in progress ​ ​ 43,279 ​ 60,347 ​ ​ ​ 1,015,379 ​ 1,114,378 Less accumulated depreciation (1) ​ ​ (562,986) ​ (611,530) Property and equipment held-for-sale, net ​ ​ ​ 885 ​ ​ — Total property and equipment, net ​ ​ $ 453,278 ​ $ 502,848 (1) Includes $1.6 million and $1.3 million of accumulated depreciation related to finance leases as of December 31, 2019 and December 31, 2018, respectively.
Schedule of amortization of intangible assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ 2019 ​ 2018 2017 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Category ​ ​ ​ ​ ​ ​ ​ ​ ​ Depreciation expense from property and equipment ​ $ 107,738 ​ $ 119,114 ​ $ 92,402 Amortization expense from finance leases ​ ​ 916 ​ ​ 1,314 ​ ​ 168 Amortization expense from intangible assets ​ ​ 11,900 ​ ​ 13,102 ​ ​ 10,701 Accretion expense from asset retirement obligations ​ ​ 115 ​ ​ 183 ​ ​ 178 Total depreciation and amortization ​ $ 120,669 ​ $ 133,713 ​ $ 103,449
Schedule of property and equipment sold and divested	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net Book Value of Property and Type of sale event Business Equipment Sold or Divested ​ ​ ​ ​ (in thousands) Business divestitures ​ Affirm subsidiary ​ $ 11,275 Property and equipment sales ​ Affirm subsidiary ​ ​ 1,339 Business divestitures ​ Canadian operations ​ ​ 7,372 Property and equipment sales ​ Canadian operations ​ ​ 393 Property and equipment sales ​ Sand hauling operations ​ ​ 3,030 Total property and equipment sold and divested ​ ​ ​ $ 23,409

GOODWILL AND OTHER INTANGIBLE_2

GOODWILL AND OTHER INTANGIBLE ASSETS (Tables)	12 Months Ended
	Dec. 31, 2019
GOODWILL AND OTHER INTANGIBLE ASSETS.
Schedule of changes in the carrying amounts of goodwill by reportable segment	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Oilfield ​ Water ​ Wellsite ​ Water ​ Water ​ ​ ​ ​ ​ ​ ​ Chemicals Solutions Services Services Infrastructure Other Total ​ ​ (in thousands) Balance as of December 31, 2017 ​ $ 15,637 ​ $ 245,542 ​ $ 12,242 ​ $ — ​ $ — ​ $ — ​ $ 273,421 Additions ​ ​ — ​ ​ 982 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 982 Impairment ​ ​ (12,652) ​ ​ — ​ ​ (5,242) ​ ​ — ​ ​ — ​ ​ — ​ ​ (17,894) Measurement period adjustments ​ (2,985) ​ 20,277 ​ — ​ — ​ — ​ — ​ 17,292 Balance as of December 31, 2018 ​ ​ — ​ ​ 266,801 ​ ​ 7,000 ​ ​ — ​ ​ — ​ ​ — ​ ​ 273,801 Resegmentation ​ — ​ (266,801) ​ (7,000) ​ 186,335 ​ 80,466 ​ 7,000 ​ — Measurement period adjustment (1) ​ ​ — ​ ​ — ​ ​ — ​ ​ 133 ​ ​ — ​ ​ — ​ ​ 133 Affirm crane business divestiture ​ — ​ — ​ — ​ — ​ ​ — ​ ​ (2,604) ​ (2,604) Affirm impairment ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (4,396) ​ ​ (4,396) Balance as of December 31, 2019 ​ $ — ​ $ — ​ $ — ​ $ 186,468 ​ $ 80,466 ​ $ — ​ $ 266,934 (1) See Note 3―Acquisitions for additional information.
Summary of components of other intangible assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2019 ​ As of December 31, 2018 ​ Gross Accumulated Net Gross Accumulated Net ​ ​ Value ​ Amortization ​ Value ​ Value ​ Amortization ​ Value ​ ​ (in thousands) ​ (in thousands) Definite-lived ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Customer relationships ​ $ 116,554 ​ $ 20,233 ​ $ 96,321 ​ $ 171,245 ​ $ 66,402 ​ $ 104,843 Patents ​ ​ 10,110 ​ ​ 2,420 ​ ​ 7,690 ​ ​ 10,110 ​ ​ 1,417 ​ ​ 8,693 Other ​ ​ 7,234 ​ ​ 4,766 ​ ​ 2,468 ​ 7,234 ​ 2,866 ​ 4,368 Total definite-lived ​ ​ 133,898 ​ ​ 27,419 ​ ​ 106,479 ​ ​ 188,589 ​ ​ 70,685 ​ ​ 117,904 Indefinite-lived ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Water rights ​ ​ 7,031 ​ ​ — ​ ​ 7,031 ​ ​ 7,031 ​ ​ — ​ ​ 7,031 Trademarks ​ ​ 23,442 ​ ​ — ​ ​ 23,442 ​ ​ 23,442 ​ ​ — ​ ​ 23,442 Total indefinite-lived ​ ​ 30,473 ​ ​ — ​ ​ 30,473 ​ ​ 30,473 ​ ​ — ​ ​ 30,473 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total other intangible assets, net ​ $ 164,371 ​ $ 27,419 ​ $ 136,952 ​ $ 219,062 ​ $ 70,685 ​ $ 148,377
Summary of future estimated amortization expense for other intangible assets	​ ​ ​ ​ ​ Year Ending December 31, Amount ​ ​ (in thousands) 2020 ​ $ 11,656 2021 ​ 10,473 2022 ​ 10,259 2023 ​ 10,187 2024 ​ 10,118 Thereafter ​ ​ 53,786 ​ ​ $ 106,479

DEBT (Tables)

DEBT (Tables)	12 Months Ended
	Dec. 31, 2019
DEBT
Summary of Company's leverage ratio	​ ​ ​ ​ ​ ​ ​ ​ Level ​ Average Excess Availability ​ Base Rate Margin ​ Eurocurrency Rate Margin ​ ​ ​ ​ ​ ​ ​ I ​ < 33% of the commitments ​ 1.00% ​ 2.00% II ​ < 66.67% of the commitments and ≥ 33.33% of the commitments ​ 0.75% ​ 1.75% III ​ ≥ 66.67% of the commitments ​ 0.50% ​ 1.50%
Schedule of fee Percentage on unused credit facility	​ ​ ​ ​ ​ ​ Level ​ Average Revolver Usage ​ Unused Line Fee Percentage ​ ​ ​ ​ ​ I ​ ≥ 50% of the commitments ​ 0.250% II ​ < 50% of the commitments ​ 0.375%

EQUITY-BASED COMPENSATION (Tabl

EQUITY-BASED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2019
Schedule of assumptions used in determining the fair value of certain equity options	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, ​ ​ 2018 ​ ​ 2017 ​ Underlying equity $ 20.50 ​ ​ $ 20.00 ​ Strike price $ 20.50 - 30.75 ​ ​ $ 20.00 ​ Dividend yield (%) 0.0 % ​ 0.0 % Risk-free rate (%) 2.3 % ​ 2.0 - 2.7 % Volatility (%) 50.0 % ​ 46.6 - 46.8 % Expected term (years) 10.0 ​ ​ 4.0 6.0 ​
Schedule of equity option activity and related information	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average ​ ​ ​ ​ ​ ​ Weighted-average ​ Weighted-average ​ Grant Date Value Aggregate Intrinsic ​ Stock Options Grant Date Value ​ Exercise Price Term (Years) Value (in thousands) (a) Beginning balance, outstanding 3,865,678 ​ $ 7.95 ​ $ 16.00 ​ 4.9 ​ $ 19 Exercised ​ (5,282) ​ ​ 3.12 ​ ​ 5.68 ​ ​ ​ ​ ​ Forfeited (30,438) ​ ​ 8.33 ​ ​ 17.70 ​ ​ ​ ​ ​ Expired ​ (32,639) ​ ​ 7.45 ​ ​ 21.85 ​ ​ ​ ​ ​ Ending balance, outstanding 3,797,319 ​ $ 8.19 ​ $ 15.95 ​ 4.2 ​ $ 509 Ending balance, exercisable ​ 3,463,549 ​ $ 8.12 ​ $ 15.06 ​ 3.9 ​ $ 510 Nonvested at end of period ​ 333,770 ​ ​ N/A ​ $ 25.22 ​ ​ ​ ​ ​ (a) as of December 31, 2019 and 2018, respectively.
Schedule of percentage of stock settled incentives earned	​ ​ ​ ​ Stock Price at Vesting Date (1) ​ Percentage of Target Amount Earned Less than $20.00 ​ 0% At least $20.00, but less than $25.00 ​ 100% $25.00 or greater ​ 200% (1) The stock price at vesting date equals the greater of (i) the fair market value of a share of the Class A Common Stock on the vesting date, or (ii) the volume weighted average closing price of a share of the Class A Common Stock, as reported on the NYSE, for the 30 trading days preceding the vesting date.
Schedule of stock-settled incentive awards outstanding	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Award Value ​ Value at Target Being Recognized Nonvested as of December 31, 2018 ​ $ 3,147 ​ $ 1,202 Forfeited during 2019 ​ ​ (210) ​ ​ (80) Nonvested as of December 31, 2019 ​ $ 2,937 ​ $ 1,122
summary of ESPP activity	The following table summarizes ESPP activity (in thousands, except shares): ​ ​ ​ ​ ​ ​ For the year ended ​ December 31, 2019 Cash received for shares issued ​ $ 112 Shares issued ​ ​ 13,178
Restricted Stock
Schedule of restricted stock activity	​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2019 ​ ​ ​ ​ Weighted-average ​ Restricted Stock Awards Grant Date Fair Value Nonvested at December 31, 2018 ​ 496,945 ​ $ 19.02 Granted ​ 1,417,458 ​ ​ 8.80 Vested ​ (379,150) ​ ​ 16.69 Forfeited ​ (17,060) ​ ​ 15.97 Nonvested at December 31, 2019 ​ 1,518,193 ​ $ 10.08
Restricted Stock Units
Schedule of restricted stock activity	​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2019 ​ ​ ​ ​ Weighted-average ​ Restricted Stock Units Grant Date Fair Value Nonvested at December 31, 2018 2,500 ​ $ 19.00 Vested (1,250) ​ ​ 19.00 Nonvested at December 31, 2019 1,250 ​ $ 19.00
Performance share units
Schedule of percentage of target PSUs earned	​ ​ ​ ​ Return on Assets at Performance Period End Date ​ Percentage of Target PSUs Earned Less than 9.6% ​ 0% 9.6% ​ 50% 12% ​ 100% 14.4% ​ 175%
Summary of activity related to the units outstanding	​ ​ ​ ​ ​ Performance Share Units Nonvested as of December 31, 2018 ​ 255,364 Target shares granted ​ 778,118 Target shares vested ​ — Target shares forfeited ​ (18,492) Target shares outstanding as of December 31, 2019 ​ 1,014,990

FAIR VALUE MEASUREMENT (Tables)

FAIR VALUE MEASUREMENT (Tables)	12 Months Ended
	Dec. 31, 2019
FAIR VALUE MEASUREMENT
Summary of assets and liabilities measured at fair value on a recurring basis	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value ​ ​ ​ ​ ​ ​ ​ ​ Measurements Using ​ Carrying ​ ​ ​ ​ Level 1 Level 2 Level 3 Value (1) Impairment ​ ​ (in thousands) Year Ended December 31, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Goodwill ​ $ — ​ $ — ​ $ — ​ $ 4,396 ​ $ 4,396 Property and equipment ​ ​ — ​ ​ — ​ ​ 7,325 ​ ​ 11,040 ​ ​ 3,715 Year Ended December 31, 2018 ​ ​ ​ ​ ​ Goodwill ​ $ — ​ $ — ​ $ 7,000 ​ $ 24,894 ​ $ 17,894 Cost-Method Investment ​ — ​ — ​ 500 ​ 2,500 ​ 2,000 Fixed Assets ​ ​ — ​ ​ — ​ ​ 10,262 ​ ​ 16,919 ​ ​ 6,657 Year Ended December 31, 2017 ​ $ — ​ $ — ​ $ — ​ $ — ​ $ — (1) Amount represents carrying value at the date of assessment.

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2019
INCOME TAXES
Summary of components of the federal and state income tax expense (benefit)	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended ​ ​ December 31, ​ 2019 2018 2017 ​ ​ (in thousands) Current tax expense (benefit) ​ ​ ​ Federal income tax expense (benefit) ​ $ 696 ​ $ 1,073 ​ $ (338) State and local income tax expense (benefit) ​ 1,034 ​ 1,077 ​ (77) Total current expense (benefit) ​ 1,730 ​ 2,150 ​ (415) Deferred tax expense (benefit) ​ ​ ​ Federal income tax expense (benefit) ​ 49 ​ (20) ​ (422) State and local income tax expense (benefit) ​ 170 ​ (426) ​ (14) Total deferred expense (benefit) ​ 219 ​ (446) ​ (436) Total income tax expense (benefit) ​ $ 1,949 ​ $ 1,704 ​ $ (851) Tax expense (benefit) attributable to controlling interests ​ $ 1,488 ​ $ 1,425 ​ $ (405) Tax expense (benefit) attributable to noncontrolling interests ​ 461 ​ 279 ​ (446) Total income tax expense (benefit) ​ $ 1,949 ​ $ 1,704 ​ $ (851)
Summary of reconciliation of the provision for income taxes	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, ​ ​ ​ 2019 ​ 2018 ​ 2017 ​ ​ ​ (in thousands) ​ ​ ​ ​ Provision calculated at federal statutory income tax rate: ​ ​ ​ ​ ​ ​ ​ ​ Income (loss) before taxes ​ $ 6,085 ​ ​ $ 56,003 ​ ​ $ (35,978) ​ Statutory rate ​ 21 % ​ 21 % ​ 35 % Income tax expense (benefit) computed at statutory rate ​ 1,278 ​ ​ 11,761 ​ ​ (12,592) ​ Less: noncontrolling interests ​ (284) ​ ​ (3,735) ​ ​ 6,409 ​ Income tax expense (benefit) attributable to controlling interests ​ 994 ​ ​ 8,026 ​ ​ (6,183) ​ State and local income taxes, net of federal benefit ​ 884 ​ ​ 515 ​ ​ (91) ​ Change in enacted tax rate ​ — ​ ​ — ​ ​ 39,166 ​ Change in subsidiary tax status ​ ​ 587 ​ ​ ​ — ​ ​ ​ — ​ Other ​ ​ ​ ​ ​ ​ 580 ​ ​ ​ — ​ Deferred adjustment due to restructuring ​ ​ 856 ​ ​ ​ — ​ ​ ​ — ​ Change in valuation allowance ​ (1,833) ​ ​ (7,696) ​ ​ (33,297) ​ Income tax expense (benefit) attributable to controlling interests ​ 1,488 ​ ​ 1,425 ​ ​ (405) ​ Income tax expense (benefit) attributable to noncontrolling interests ​ 461 ​ ​ 279 ​ ​ (446) ​ Total income tax expense (benefit) ​ $ 1,949 ​ ​ $ 1,704 ​ ​ $ (851) ​
Summary of principal components of the deferred tax assets (liabilities)	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended ​ ​ December 31, ​ 2019 2018 ​ ​ (in thousands) Deferred tax assets ​ ​ Outside basis difference in SES Holdings ​ $ 27,935 ​ $ 38,739 Net operating losses ​ 46,782 ​ 45,927 Credits and other carryforwards ​ 1,451 ​ 1,679 Property and equipment ​ ​ — ​ ​ 150 Intangible assets ​ ​ — ​ ​ 1,284 Other ​ ​ 944 ​ ​ 468 Total deferred tax assets before valuation allowance ​ 77,112 ​ 88,247 Valuation allowance ​ ​ (76,883) ​ ​ (88,247) Total deferred tax assets ​ ​ 229 ​ ​ — Deferred tax liabilities ​ ​ Property and equipment ​ 540 ​ — Other ​ 32 ​ 123 Total deferred tax liabilities ​ 572 ​ 123 Net deferred tax liabilities ​ $ (343) ​ $ (123)

NONCONTROLLING INTERESTS (Table

NONCONTROLLING INTERESTS (Tables)	12 Months Ended
	Dec. 31, 2019
NONCONTROLLING INTERESTS
Schedule of Non Controlling Interests Categories	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31 ​ ​ 2019 2018 ​ ​ ​ (in thousands) Noncontrolling interests attributable to joint ventures formed for water-related services ​ ​ $ 2,674 $ 3,273 Noncontrolling interests attributable to holders of Class B Common Stock ​ ​ ​ 172,961 274,566 Total noncontrolling interests ​ ​ $ 175,635 $ 277,839
Summary of the effects of changes in noncontrolling interests	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, ​ 2019 2018 2017 ​ ​ (in thousands) Net income (loss) attributable to Select Energy Services, Inc. ​ $ 2,784 $ 36,512 $ (16,816) Transfers (to) from noncontrolling interests: ​ ​ ​ ​ ​ Decrease in additional paid-in capital as a result of the contribution of proceeds from the IPO to SES Holdings, LLC in exchange for common units ​ ​ — ​ ​ — ​ ​ (41,135) Decrease in additional paid-in capital as a result of the contribution of net assets acquired to SES Holdings, LLC in exchange for common units ​ ​ — ​ ​ — ​ ​ (4,879) Decrease in additional paid-in capital as a result of the contribution of net assets from the Rockwater Merger to SES Holdings, LLC in exchange for common units ​ ​ — ​ ​ — ​ ​ (170,276) Increase in additional paid-in capital as a result of stock option exercises ​ 54 374 — Increase in additional paid-in capital as a result of restricted stock issuance, net of forfeitures ​ 3,614 1,942 — Increase in additional paid-in capital as a result of issuance of common stock due to vesting of restricted stock units ​ ​ 4 ​ ​ 104 ​ ​ — (Decrease) increase in additional paid-in capital as a result of the repurchase of SES Holdings LLC Units ​ (3,362) (576) 113 Increase in additional paid-in capital as a result of exchanges of SES Holdings LLC Units (an equivalent number of shares of Class B Common Stock) for shares of Class A Common Stock ​ ​ 107,062 ​ ​ 146,865 ​ ​ — Increase in additional paid-in capital as a result of the Employee Stock Purchase Plan shares issued ​ ​ 42 ​ ​ 15 ​ ​ — Change to equity from net income (loss) attributable to Select Energy Services, Inc. and transfers from noncontrolling interests ​ $ 110,198 $ 185,236 $ (232,993)

EARNINGS (LOSS) PER SHARE (Tabl

EARNINGS (LOSS) PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2019
EARNINGS (LOSS) PER SHARE
Summary of calculation of basic and diluted earnings per share	The following tables present the Company’s calculation of basic and diluted earnings per share for the years ended December 31, 2019, 2018 and 2017 (dollars in thousands, except share and per share amounts): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, 2019 ​ ​ Select Energy ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Services, Inc. Class A Class A-2 Class B Numerator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income ​ $ 4,136 ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to noncontrolling interests ​ ​ (1,352) ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to Select Energy Services, Inc. — basic ​ ​ 2,784 ​ $ 2,784 ​ $ — ​ $ — Add: Reallocation of net income attributable to noncontrolling interests for the dilutive effect of restricted stock ​ ​ 7 ​ ​ 7 ​ ​ — ​ ​ — Add: Reallocation of net income attributable to noncontrolling interests for the dilutive effect of performance share units ​ ​ 2 ​ ​ 2 ​ ​ — ​ ​ — Add: Reallocation of net income attributable to noncontrolling interests for the dilutive effect of stock options ​ ​ 1 ​ ​ 1 ​ ​ — ​ ​ — Net income attributable to Select Energy Services, Inc. — diluted ​ $ 2,794 ​ $ 2,794 ​ $ — ​ $ — Denominator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average shares of common stock outstanding — basic ​ ​ ​ ​ ​ 80,176,323 ​ ​ — ​ ​ 23,806,646 Dilutive effect of restricted stock ​ ​ ​ ​ ​ 373,366 ​ ​ — ​ ​ — Dilutive effect of performance share units ​ ​ ​ ​ ​ 80,979 ​ ​ ​ ​ ​ — Dilutive effect of stock options ​ ​ ​ ​ ​ 40,215 ​ ​ — ​ ​ — Dilutive effect of ESPP ​ ​ ​ ​ ​ 446 ​ ​ — ​ ​ — Weighted-average shares of common stock outstanding — diluted ​ ​ ​ ​ ​ 80,671,330 ​ ​ — ​ ​ 23,806,646 Earnings per share: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic ​ ​ ​ ​ $ 0.03 ​ $ — ​ $ — Diluted ​ ​ ​ ​ $ 0.03 ​ $ — ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, 2018 ​ ​ Select Energy Services, Inc. ​ Class A ​ Class A-1 ​ Class A-2 ​ Class B Numerator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income ​ $ 54,299 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to noncontrolling interests ​ ​ (17,787) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to Select Energy Services, Inc. — basic ​ ​ 36,512 ​ $ 35,720 ​ $ ​ ​ $ 792 ​ $ — Add: Reallocation of net income attributable to noncontrolling interests for the dilutive effect of restricted stock ​ ​ 13 ​ ​ 13 ​ ​ — ​ ​ ​ ​ ​ — Add: Reallocation of net income attributable to noncontrolling interests for the dilutive effect of stock options ​ ​ 30 ​ ​ 30 ​ ​ — ​ ​ ​ ​ ​ — Net loss attributable to Select Energy Services, Inc. — diluted ​ $ 36,555 ​ $ 35,763 ​ $ — ​ $ 792 ​ $ — Denominator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average shares of common stock outstanding — basic ​ ​ ​ ​ ​ 72,403,318 ​ ​ ​ ​ ​ 1,604,575 ​ ​ 31,986,438 Dilutive effect of restricted stock ​ ​ ​ ​ ​ 71,718 ​ ​ — ​ ​ — ​ ​ — Dilutive effect of stock options ​ ​ ​ ​ ​ 166,999 ​ ​ — ​ ​ — ​ ​ — Dilutive effect of ESPP ​ ​ ​ ​ ​ 112 ​ ​ — ​ ​ — ​ ​ — Weighted-average shares of common stock outstanding — diluted ​ ​ ​ ​ ​ 72,642,147 ​ ​ — ​ ​ 1,604,575 ​ ​ 31,986,438 Earnings per share: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic ​ ​ ​ ​ $ 0.49 ​ $ — ​ $ 0.49 ​ $ — Diluted ​ ​ ​ ​ $ 0.49 ​ $ — ​ $ 0.49 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, 2017 ​ ​ Select Energy Services, Inc. ​ Class A ​ Class A-1 ​ Class A-2 ​ Class B Numerator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss ​ $ (35,127) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss attributable to noncontrolling interests ​ ​ 18,311 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss attributable to Select Energy Services, Inc. — basic ​ ​ (16,816) ​ $ (12,560) ​ $ (3,691) ​ $ (565) ​ $ — Net loss attributable to Select Energy Services, Inc. — diluted ​ $ (16,816) ​ $ (12,560) ​ $ (3,691) ​ $ (565) ​ $ — Denominator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average shares of common stock outstanding — basic ​ ​ ​ ​ ​ 24,612,853 ​ ​ 7,233,973 ​ ​ 1,106,605 ​ ​ 38,768,156 Dilutive effect of restricted stock ​ ​ ​ ​ ​ — ​ ​ — ​ ​ — ​ ​ — Dilutive effect of stock options ​ ​ ​ ​ ​ — ​ ​ — ​ ​ — ​ ​ — Dilutive effect of ESPP ​ ​ ​ ​ ​ — ​ ​ — ​ ​ — ​ ​ — Weighted-average shares of common stock outstanding — diluted ​ ​ ​ ​ ​ 24,612,853 ​ ​ 7,233,973 ​ ​ 1,106,605 ​ ​ 38,768,156 Loss per share: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Basic ​ ​ ​ ​ $ (0.51) ​ $ (0.51) ​ $ (0.51) ​ $ — Diluted ​ ​ ​ ​ $ (0.51) ​ $ (0.51) ​ $ (0.51) ​ $ —

SEGMENT INFORMATION (Tables)

SEGMENT INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2019
SEGMENT INFORMATION
Summary of financial information by segment	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2019 ​ ​ ​ Income (loss) Depreciation and Capital ​ ​ Revenue ​ before taxes ​ Amortization ​ Expenditures ​ ​ (in thousands) Water services ​ $ 773,946 ​ $ 51,185 ​ $ 80,664 ​ $ 37,692 Water infrastructure ​ ​ 221,661 ​ ​ 15,103 ​ ​ 25,665 ​ ​ 53,839 Oilfield chemicals ​ ​ 268,963 ​ ​ 17,942 ​ ​ 8,766 ​ ​ 11,110 Other ​ ​ 33,365 ​ ​ (8,066) ​ ​ 1,714 ​ ​ 64 Eliminations ​ (6,346) ​ — ​ — ​ — Income from operations ​ ​ ​ 76,164 ​ ​ ​ ​ Corporate ​ — ​ (53,090) ​ 3,860 ​ — Interest expense, net ​ — ​ (2,688) ​ — ​ — Other income, net ​ — ​ (14,301) ​ — ​ — ​ ​ $ 1,291,589 ​ $ 6,085 ​ $ 120,669 ​ $ 102,705 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2018 ​ ​ ​ Income (loss) Depreciation and Capital ​ ​ Revenue ​ before taxes ​ Amortization ​ Expenditures ​ ​ (in thousands) Water services ​ $ 897,160 ​ $ 89,826 ​ $ 82,875 ​ $ 120,883 Water infrastructure ​ ​ 230,130 ​ ​ 31,579 ​ ​ 23,042 ​ ​ 33,372 Oilfield chemicals ​ ​ 260,281 ​ ​ (7,107) ​ ​ 10,496 ​ ​ 10,832 Other ​ ​ 144,499 ​ ​ (14,021) ​ ​ 14,124 ​ ​ 7,045 Eliminations ​ (3,140) ​ — ​ — ​ — Income from operations ​ ​ ​ 100,277 ​ ​ ​ ​ Corporate ​ — ​ (38,603) ​ 3,176 ​ — Interest expense, net ​ — ​ (5,311) ​ — ​ — Other income, net ​ — ​ (360) ​ — ​ — ​ ​ $ 1,528,930 ​ $ 56,003 ​ $ 133,713 ​ $ 172,132 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2017 ​ ​ ​ Income (loss) Depreciation and Capital ​ ​ Revenue ​ before taxes ​ Amortization ​ Expenditures ​ ​ (in thousands) Water Services ​ $ 420,757 ​ $ 1,823 ​ $ 70,839 ​ $ 82,127 Water Infrastructure ​ ​ 163,386 ​ ​ 11,723 ​ ​ 22,481 ​ ​ 15,264 Oilfield Chemicals ​ ​ 41,586 ​ ​ 663 ​ ​ 2,040 ​ ​ 3,063 Other ​ ​ 69,382 ​ ​ (2,649) ​ ​ 6,286 ​ ​ 7,823 Eliminations ​ (2,620) ​ — ​ — ​ — Loss from operations ​ ​ ​ 11,560 ​ ​ ​ ​ Corporate ​ — ​ (41,559) ​ 1,803 ​ — Interest expense, net ​ — ​ (6,629) ​ — ​ — Other income, net ​ — ​ 650 ​ — ​ — ​ ​ $ 692,491 ​ $ (35,978) ​ $ 103,449 ​ $ 108,277 ​ Total assets by segment as of December 31, 2019 and 2018 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ ​ 2019 ​ 2018 ​ ​ (in thousands) Water services ​ $ 831,123 ​ $ 865,992 Water infrastructure ​ ​ 314,026 ​ 250,207 Oilfield chemicals ​ ​ 192,224 ​ 173,762 Other ​ ​ 10,247 ​ ​ 70,644 ​ ​ $ 1,347,620 ​ $ 1,360,605 ​ Revenue by groups of similar products and services are as follows:
Revenue from External Customers by Products and Services	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, ​ 2019 2018 ​ 2017 ​ ​ (in thousands) Water transfer ​ $ 355,535 ​ $ 443,650 ​ $ 193,314 Oilfield chemicals ​ ​ 268,963 ​ 260,281 ​ ​ 41,586 Flowback and well testing ​ 208,572 ​ 223,828 ​ ​ 90,107 Accommodations and rentals ​ 150,793 ​ ​ 153,013 ​ ​ 63,107 Water sourcing ​ 120,517 ​ 129,958 ​ ​ 97,898 Pipeline logistics and disposal ​ ​ 101,145 ​ ​ 100,172 ​ ​ 65,488 Fluid hauling ​ ​ 63,156 ​ ​ 79,568 ​ ​ 75,273 Other ​ 22,908 ​ 138,460 ​ ​ 65,718 ​ ​ $ 1,291,589 ​ $ 1,528,930 ​ $ 692,491

QUARTERLY RESULTS OF OPERATIO_2

QUARTERLY RESULTS OF OPERATIONS (UNAUDITED) (Tables)	12 Months Ended
	Dec. 31, 2019
QUARTERLY RESULTS OF OPERATIONS (UNAUDITED)
Schedule of quarterly results of operations	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2019 ​ ​ First ​ Second ​ Third ​ Fourth ​ ​ Quarter ​ Quarter ​ Quarter Quarter ​ ​ (in thousands) Revenue ​ $ 362,646 ​ $ 323,887 ​ $ 328,968 ​ $ 276,088 Gross profit ​ 45,997 ​ 39,939 ​ 40,994 ​ 21,810 Income (loss) from operations ​ 6,633 ​ 11,179 ​ 12,475 ​ (7,213) Net income (loss) ​ 1,400 ​ 8,068 ​ 7,172 ​ (12,504) Net income (loss) attributable to Select Energy Services, Inc. ​ 1,135 ​ 6,200 ​ 5,379 ​ (9,930) Net income (loss) per share attributable to common stockholders: ​ ​ ​ ​ ​ ​ ​ ​ Class A-Basic & Diluted ​ $ 0.01 ​ $ 0.08 ​ $ 0.07 ​ $ (0.12) Class A-1-Basic & Diluted ​ $ — ​ $ — ​ $ — ​ $ — Class A-2-Basic & Diluted ​ $ — ​ $ — ​ $ — ​ $ — Class B-Basic & Diluted ​ $ — ​ $ — ​ $ — ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2018 ​ ​ First ​ Second ​ Third ​ Fourth ​ ​ Quarter ​ Quarter ​ Quarter Quarter ​ ​ (in thousands) Revenue ​ $ 376,395 ​ $ 393,247 ​ $ 396,970 ​ $ 362,318 Gross profit ​ 47,949 ​ 56,728 ​ 59,397 ​ 34,408 Income (loss) from operations ​ 18,603 ​ 24,795 ​ 32,258 ​ (13,982) Net income (loss) ​ 16,132 ​ 25,023 ​ 31,267 ​ (18,123) Net income (loss) attributable to Select Energy Services, Inc. ​ 10,099 ​ 16,963 ​ 22,951 ​ (13,501) Net income (loss) per share attributable to common stockholders: ​ ​ ​ ​ ​ ​ ​ ​ Class A-Basic & Diluted ​ $ 0.15 ​ $ 0.24 ​ $ 0.29 ​ $ (0.17) Class A-1-Basic & Diluted ​ $ — ​ $ — ​ $ — ​ $ — Class A-2-Basic & Diluted ​ $ 0.15 ​ $ — ​ $ — ​ $ — Class B-Basic & Diluted ​ $ — ​ $ — ​ $ — ​ $ —

BUSINESS AND BASIS OF PRESENT_2

BUSINESS AND BASIS OF PRESENTATION (Details) $ / shares in Units, $ in Thousands	Jan. 12, 2018shares	Nov. 01, 2017USD ($)shares	Sep. 15, 2017USD ($)shares	Apr. 26, 2017shares	Mar. 10, 2017USD ($)shares	Dec. 20, 2016USD ($)$ / sharesshares	Dec. 31, 2019USD ($)segmentitemagreement$ / sharesshares	Dec. 31, 2018USD ($)segmentitem$ / sharesshares	Dec. 31, 2017segment$ / sharesshares	Mar. 31, 2018USD ($)	Mar. 28, 2018shares	Dec. 31, 2016shares
Share Price | $ / shares								$ 20.50	$ 20
Convertible Common Stock, Shares Issued upon Conversion												1
Common units issued						16,100,000
Financial Designation, Predecessor and Successor [Fixed List]						Predecessor
Number of tax receivable agreements | agreement							2
Impairment of cost-method investment | $								$ 2,000
Number of equity method investee | item							0	0
Number of cost-method investee | item							1	1
Number of operating segments | segment							3	3	3
Number of reportable segments | segment							3	3	3
Fair value of cost method investee | $										$ 500
Cumulative translation adjustment | $							$ 400
Revolving line of credit
Maximum borrowing capacity | $		$ 300,000				$ 300,000
Class A-1 Common Stock
Par value | $ / shares						$ 0.01
Common stock issued												16,100,000
Class A-1 Common Stock | Private Placement
Shares issued						16,100,000
Conversion rate per share												1
Class A Common Stock
Shares issued									10,005,000
Par value | $ / shares						$ 0.01	$ 0.01	$ 0.01
Common stock issued							87,893,525	78,956,555
Common Stock, Shares, Outstanding							87,893,525	78,956,555
Class A Common Stock | IPO
Shares issued				8,700,000
Class B Common Stock
Par value | $ / shares						$ 0.01	$ 0.01	$ 0.01
Common stock issued						38,462,541	16,221,101	26,026,843
Common Stock, Shares, Outstanding							16,221,101	26,026,843
Class A-2 Common Stock
Par value | $ / shares							$ 0.01	$ 0.01
Common stock issued							0	0
Common Stock, Shares, Outstanding							0	0
GRR Acquisition
Total consideration transferred | $					$ 59,638
Number of shares resold					274,998
Resource Water Acquisition
Total consideration transferred | $			$ 8,966
Resource Water Acquisition | Class A Common Stock
Number of shares resold			156,909
Rockwater Merger
Total consideration transferred | $		$ 620,201
Rockwater Merger | Class A Common Stock
Shares issued		25,900,000
Number of shares resold		25,914,260
Rockwater Merger | Class B Common Stock
Shares issued		4,400,000
Number of shares resold		4,356,477
Rockwater Merger | Class A-2 Common Stock
Shares issued		6,700,000
Conversion rate per share											1
Common Stock, Shares, Outstanding							0
Number of shares resold	6,653,777	6,731,845
Rockwater Merger | SES Holdings
Common units issued		37,300,000
Rockwater Merger | SES Holdings | Class B Common Stock
Number of shares resold		4,356,477

SIGNIFICANT ACCOUNTING POLICI_4

SIGNIFICANT ACCOUNTING POLICIES - Allowance activity (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)customer	Dec. 31, 2018USD ($)customer	Dec. 31, 2017USD ($)customer
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year	$ 5,329	$ 2,979	$ 2,144
Provisions for bad debts, included in selling, general and administrative	2,553	2,210	1,542
Uncollectible receivable (write-offs) recoveries	(2,109)	140	(707)
Balance at end of year	$ 5,773	$ 5,329	$ 2,979
Concentrations of credit and customer risk
Number of customers accounting for more than 10% of consolidated revenues | customer	0	0	0
Debt issuance costs
Unamortized Debt issuance Costs			$ 2,900
Agreement Debt Issuance Cost			3,442
Amortization of debt issuance costs	$ 688	$ 688	$ 4,031

SIGNIFICANT ACCOUNTING POLICI_5

SIGNIFICANT ACCOUNTING POLICIES - Property and Equipment (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of Current Period				$ 1,898				$ 1,846	$ 1,898	$ 1,846
Accretion expense from asset retirement obligations									115	183	$ 178
Change in estimate										377
Disposals									(486)
Divestitures										(508)
Balance at end of Current Period	$ 1,527				$ 1,898				1,527	1,898	1,846
PROPERTY AND EQUIPMENT
Depreciation									107,738	119,114	92,402
Net Income (Loss) Attributable to Parent	(9,930)	$ 5,379	$ 6,200	1,135	(13,501)	$ 22,951	$ 16,963	$ 10,099	2,784	36,512	(16,816)
Goodwill and Intangible Asset Impairment
Depreciation and amortization									3,860	3,176	1,804
Goodwill, Impairment Loss				$ 0					4,396	17,894
Goodwill	266,934				273,801				266,934	273,801	273,421
Impairment of property and equipment									3,715	6,657
Fluid Disposal Equipment
Goodwill and Intangible Asset Impairment
Impaired asset carrying value	2,300				2,300				2,300	2,300
Estimated fair value	$ 0				0				0	0
Canadian Assets
Goodwill and Intangible Asset Impairment
Impairment of property and equipment									900	4,400
Layflat Hose
Goodwill and Intangible Asset Impairment
Impairment of property and equipment									1,000
Pipeline Assets
Goodwill and Intangible Asset Impairment
Impairment of property and equipment									1,100
Owned Facility
Goodwill and Intangible Asset Impairment
Impairment of property and equipment									$ 600
Water Solutions
Goodwill and Intangible Asset Impairment
Goodwill					266,801					266,801	245,542
Wellsite Services
Goodwill and Intangible Asset Impairment
Goodwill, Impairment Loss										5,242
Goodwill					$ 7,000					7,000	12,242
Buildings and leasehold improvements
PROPERTY AND EQUIPMENT
Estimated useful lives of the assets									30 years
Vehicles and equipment | Minimum
PROPERTY AND EQUIPMENT
Estimated useful lives of the assets									4 years
Vehicles and equipment | Maximum
PROPERTY AND EQUIPMENT
Estimated useful lives of the assets									7 years
Machinery and equipment
Goodwill and Intangible Asset Impairment
Depreciation and amortization									$ 108,700	120,400	$ 92,600
Machinery and equipment | Minimum
PROPERTY AND EQUIPMENT
Estimated useful lives of the assets									2 years
Machinery and equipment | Maximum
PROPERTY AND EQUIPMENT
Estimated useful lives of the assets									15 years
Computer equipment and software | Minimum
PROPERTY AND EQUIPMENT
Estimated useful lives of the assets									3 years
Computer equipment and software | Maximum
PROPERTY AND EQUIPMENT
Estimated useful lives of the assets									4 years
Office furniture and equipment
PROPERTY AND EQUIPMENT
Estimated useful lives of the assets									7 years
Disposal wells | Minimum
PROPERTY AND EQUIPMENT
Estimated useful lives of the assets									7 years
Disposal wells | Maximum
PROPERTY AND EQUIPMENT
Estimated useful lives of the assets									10 years
Change in useful life estimate and increased salvage value
PROPERTY AND EQUIPMENT
Depreciation										12,600
Net Income (Loss) Attributable to Parent										$ 10,900
Earnings Per Share, Basic and Diluted										$ 0.15
Change in useful life estimate and increased salvage value | Vehicles and equipment
PROPERTY AND EQUIPMENT
Depreciation										$ 3,900
Change in useful life estimate and increased salvage value | Vehicles and equipment | Minimum
PROPERTY AND EQUIPMENT
Estimated useful lives of the assets									6 years
Change in useful life estimate and increased salvage value | Vehicles and equipment | Maximum
PROPERTY AND EQUIPMENT
Estimated useful lives of the assets									8 years 1 month 6 days
Change in useful life estimate and increased salvage value | Machinery and equipment | Minimum
PROPERTY AND EQUIPMENT
Estimated useful lives of the assets									5 years 6 months
Change in useful life estimate and increased salvage value | Machinery and equipment | Maximum
PROPERTY AND EQUIPMENT
Estimated useful lives of the assets									6 years 10 months 24 days

SIGNIFICANT ACCOUNTING POLICI_6

SIGNIFICANT ACCOUNTING POLICIES - Self Insurance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Self insurance reserve towards deductible for general liability	$ 1,000
Self insurance reserve towards deductible for workers compensation and employers liability	1,000
Self insurance reserve towards deductible for vehicle liability	1,000
Excess loss policy limit	100,000
Self insured group medical claim plan deductible	300
Workers' Compensation Liability, Current	13,400
Accrued insurance	$ 8,843	$ 14,849
Employee benefit plans
Matching contribution as a percentage of employee contributions	100.00%
Matching contribution as a percentage of employee compensation	4.00%
Company 401k contribution	$ 4,200	$ 3,600
First year
Employee benefit plans
Annual vesting matching contribution as a percentage of employee compensation	25.00%
Second year
Employee benefit plans
Annual vesting matching contribution as a percentage of employee compensation	50.00%
Third year
Employee benefit plans
Annual vesting matching contribution as a percentage of employee compensation	75.00%
Fourth year
Employee benefit plans
Annual vesting matching contribution as a percentage of employee compensation	100.00%
Minimum
Class of Stock [Line Items]
Estimated exposure amount of workers compensation claims	$ 13,900
Maximum
Class of Stock [Line Items]
Estimated exposure amount of workers compensation claims	$ 15,900

ACQUISITIONS AND DIVESTITURES -

ACQUISITIONS AND DIVESTITURES - Pro Well Acquisition (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Nov. 20, 2018	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Less: identified assets acquired and liabilities assumed
Goodwill				$ 266,934	$ 273,801	$ 273,421
Well Chemical Services Acquisition
Consideration transferred
Cash paid	$ 10,000
Total consideration transferred	10,000
Less: identified assets acquired and liabilities assumed
Inventory	5,221
Property and equipment	4,473
Current liabilities	(170)
Total identifiable net assets acquired	10,000
Fair value allocated to net assets acquired	10,000
Well Chemical Services Acquisition | Customer relationships
Less: identified assets acquired and liabilities assumed
Intangible assets	$ 476
Pro Well Acquisition
Consideration transferred
Cash paid		$ 11,754
Total consideration transferred		11,754	$ 11,800
Less: identified assets acquired and liabilities assumed
Working capital		1,051
Property and equipment		6,588
Total identifiable net assets acquired		10,639
Goodwill		1,115
Fair value allocated to net assets acquired		11,754
Initial payment		12,400
Pro Well Acquisition | Customer relationships
Less: identified assets acquired and liabilities assumed
Intangible assets		$ 3,000

ACQUISITIONS - Rockwater Merger

ACQUISITIONS - Rockwater Merger (Details) - USD ($) $ in Thousands	Nov. 01, 2018	Jan. 12, 2018	Nov. 01, 2017	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019
Less: identified assets acquired and liabilities assumed
Goodwill				$ 273,421	$ 273,801	$ 273,421	$ 266,934
SES Holdings
Business Acquisition [Line Items]
Gain on remeasurement of investment				1,200
Water Solutions
Less: identified assets acquired and liabilities assumed
Goodwill				245,542	266,801	245,542
Oilfield chemicals
Less: identified assets acquired and liabilities assumed
Goodwill				$ 15,637		15,637
Rockwater Merger
Business Acquisition [Line Items]
Transaction-related costs					$ 6,300	$ 8,900
Consideration transferred
Fair value of previously held interest in Rockwater	$ 2,300		$ 2,310
Fair value of Rockwater share-based awards attributed to pre-acquisition service			12,529
Total consideration transferred			620,201
Less: identified assets acquired and liabilities assumed
Working capital			141,720
Property and equipment			172,650
Other long-term assets			88
Deferred tax liabilities			(408)
Long-term debt			(80,555)
Other long-term liabilities			(2,517)
Total identifiable net assets acquired			355,673
Goodwill			264,528
Fair value allocated to net assets acquired			620,201
Rockwater Merger | Customer relationships
Less: identified assets acquired and liabilities assumed
Intangible assets			89,661
Rockwater Merger | Trademarks and patents
Less: identified assets acquired and liabilities assumed
Intangible assets			31,223
Rockwater Merger | Noncompete agreements
Less: identified assets acquired and liabilities assumed
Intangible assets			3,811
Rockwater Merger | Water Solutions
Less: identified assets acquired and liabilities assumed
Goodwill			251,800
Rockwater Merger | Oilfield chemicals
Less: identified assets acquired and liabilities assumed
Goodwill			12,700
Class A Common Stock | Rockwater Merger
Consideration transferred
Common stock issued			$ 423,957
Less: identified assets acquired and liabilities assumed
Shares issued in Merger Agreement			25,914,260
Class A-2 Common Stock | Rockwater Merger
Consideration transferred
Common stock issued			$ 110,133
Less: identified assets acquired and liabilities assumed
Shares issued in Merger Agreement		6,653,777	6,731,845
Class B Common Stock | Rockwater Merger
Consideration transferred
Common stock issued			$ 71,272
Less: identified assets acquired and liabilities assumed
Shares issued in Merger Agreement			4,356,477
Class B Common Stock | Rockwater Merger | SES Holdings
Less: identified assets acquired and liabilities assumed
Shares issued in Merger Agreement			4,356,477

ACQUISITIONS - Resource Water A

ACQUISITIONS - Resource Water Acquisition - Purchase price allocation (Details) - USD ($) $ / shares in Units, $ in Thousands	Sep. 15, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Less: identified assets acquired and liabilities assumed
Goodwill		$ 266,934	$ 273,801	$ 273,421
Resource Water Acquisition
Consideration transferred
Miles Of Layflat Hose	24
Class A Common stock issued, Share Price	$ 15.17
Cash paid	$ 6,586
Common stock issued	2,380
Total consideration transferred	8,966
Less: identified assets acquired and liabilities assumed
Working capital	1,189
Fixed assets	3,485
Total identifiable net assets acquired	7,072
Goodwill	1,894
Fair value allocated to net assets acquired	8,966
Cash on hand	$ 6,600
Resource Water Acquisition | Class A Common Stock
Less: identified assets acquired and liabilities assumed
Shares issued in Merger Agreement	156,909
Resource Water Acquisition | Customer relationships
Less: identified assets acquired and liabilities assumed
Intangible assets	$ 1,933
Resource Water Acquisition | Other intangibles
Less: identified assets acquired and liabilities assumed
Intangible assets	$ 465

ACQUISITIONS - GRR Acquisition

ACQUISITIONS - GRR Acquisition (Details) - USD ($) $ / shares in Units, $ in Thousands	Mar. 10, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
ACQUISITION
Goodwill		$ 266,934	$ 273,801	$ 273,421
GRR Acquisition
ACQUISITION
Miles of layflat hose	1,000
Cash paid	$ 53,032
Assumed liabilities	1,106
Class A Common Stock (274,998 shares)	5,500
Total consideration paid	59,638
Goodwill	$ 12,049
Class A Common stock issued, Share Price	$ 20
Cash on hand	$ 19,000
Proceeds from credit facility	34,000
Transaction cost	$ 1,000

ACQUISITIONS - GRR Acquisitio_2

ACQUISITIONS - GRR Acquisition - Purchase price allocation (Details) - USD ($) $ in Thousands	Mar. 10, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Less: identified assets acquired and liabilities assumed
Goodwill		$ 266,934	$ 273,801	$ 273,421
GRR Acquisition
Consideration transferred
Cash paid	$ 53,032
Class A Common Stock (274,998 shares)	5,500
Assumed liabilities	1,106
Total consideration transferred	59,638
Less: identified assets acquired and liabilities assumed
Working capital	7,728
Fixed assets	13,225
Total identifiable net assets acquired	47,589
Goodwill	12,049
Fair value allocated to net assets acquired	$ 59,638
Shares issued in Merger Agreement	274,998
GRR Acquisition | Customer relationships
Less: identified assets acquired and liabilities assumed
Intangible assets	$ 21,484
GRR Acquisition | Other intangibles
Less: identified assets acquired and liabilities assumed
Intangible assets	$ 5,152

ACQUISITIONS - Proforma (Detail

ACQUISITIONS - Proforma (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Pro forma information
Revenue	$ 1,270,736
Net loss	(13,079)
Less: net loss attributable to noncontrolling interests	5,299
Net loss attributable to Select Energy Services, Inc	$ (7,780)

ACQUISITIONS AND DIVESTITURES_2

ACQUISITIONS AND DIVESTITURES - Affirm and Canadian Operations Divestitures (Details) $ in Thousands	3 Months Ended	6 Months Ended	9 Months Ended		10 Months Ended	12 Months Ended
	Mar. 31, 2019USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2019USD ($)item	Dec. 31, 2018USD ($)	Jun. 28, 2019USD ($)	Apr. 01, 2019USD ($)	Mar. 19, 2019USD ($)	Feb. 26, 2019USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of sales transactions						4
Reduction in goodwill						$ 2,604
Impairment of Goodwill	$ 0					$ 4,396	$ 17,894
Affirm Crane Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Initial Net Proceeds								$ 6,968			$ 10,982
Working Capital True Up											(208)
Adjusted Net Proceeds								$ 6,968			$ 10,774
Gain or loss		$ (1,646)			$ 208
Canadian Business
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Initial Net Proceeds									$ 2,242	$ 4,975
Working Capital True Up										(302)
Adjusted Net Proceeds									$ 2,242	$ 4,673
Gain or loss			$ 5,013	$ 101
Sale | Affirm Crane Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain or loss	0
Number of transactions assigned for working capital | item						2
Reduction in goodwill	2,600
Impairment of Goodwill	$ 4,400
Sale | Affirm and Canadian Operations Divestitures [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of sales transactions						4
Net book value		$ 18,600	$ 18,600	$ 18,600	$ 18,600	$ 18,600

REVENUE (Details)

REVENUE (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2019USD ($)region	Dec. 31, 2018USD ($)region	Dec. 31, 2017USD ($)region
REVENUE
Revenue	$ 276,088	$ 328,968	$ 323,887	$ 362,646	$ 362,318	$ 396,970	$ 393,247	$ 376,395	$ 1,291,589	$ 1,528,930	$ 692,491
Permian Basin
REVENUE
Revenue									610,528	606,591	243,482
MidCon
REVENUE
Revenue									176,216	243,524	96,844
Eagle Ford
REVENUE
Revenue									156,621	171,942	104,934
Bakken
REVENUE
Revenue									92,956	153,212	74,543
Marcellus/Utica
REVENUE
Revenue									96,454	134,984	32,805
Rockies
REVENUE
Revenue									85,339	111,901	80,180
Haynesville/E. Texas
REVENUE
Revenue									73,658	59,969	49,600
All other
REVENUE
Revenue									$ (183)	$ 46,807	$ 10,103
Permian Basin, MidCon and Eagle Ford | Water services
REVENUE
Number of revenue producing regions | region									3	3	3
Percentage of revenue									74.00%	72.00%	71.00%
Permian Basin and Bakken | Water infrastructure
REVENUE
Number of revenue producing regions | region									2	2	2
Percentage of revenue									84.00%	85.00%	80.00%
Permian Basin and MidCon | Oilfield chemicals
REVENUE
Number of revenue producing regions | region									2	2	2
Percentage of revenue									77.00%	77.00%	72.00%

LEASES - Description (Details)

LEASES - Description (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)lease	Dec. 31, 2018USD ($)facility
LEASES
Number of operating leases | lease	593
Number of subleases | lease	15
Number of finance leases | lease	25
Number of lessor owned properties | lease	3
Lessee Operating Lease Existence Of Option To Extend	true
Renewal option for lease facility (Number) | lease	1
Exit-disposal cease use liability		$ 16,752
Operating lease liabilities	$ 72,143
Long-term operating lease liabilities		16,800
Variable Lease, Cost	1,600
Property tax expense	$ 800
Minimum
LEASES
Lessee operating lease renewal term	1 year
Maximum
LEASES
Lessee operating lease renewal term	5 years
Exit and disposal activities
LEASES
Exit-disposal cease use liability		$ 18,800
Number of abandoned facility leases | facility		17

LEASES - Financial Impact of Le

LEASES - Financial Impact of Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position
Operating lease assets	$ 70,635
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:LongTermRightOfUseAssetsMember
Finance lease assets	$ 213
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Property Plant And Equipment [Member]
Operating lease liabilities	$ 19,315
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	wttr:CurrentOperatingLeaseLiabilitiesMember
Operating lease liabilities	$ 72,143
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	wttr:LongTermOperatingLeaseLiabilitiesMember
Finance lease liabilities	$ 128	$ 938
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Finance Lease, Liability
Finance lease liabilities	$ 87
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	wttr:OtherLongTermLliabilitiesMember
Operating lease cost:
Impairment of lease	$ 16,800
Finance lease, accumulated amortization	1,600
Operating lease cost - fixed	27,856
Lease abandonment costs	2,073
Short-term agreements:	93,949
Finance lease cost:
Amortization of leased assets	916	1,314	$ 168
Interest on lease liabilities	32
Sublease income	1,544
Lessor income	478
Statement of cash flows
Cash paid for operating leases	30,670
Cash paid for finance leases lease interest	32
Cash paid for finance leases	$ 883	$ 1,881

LEASES - Lease Term and Discoun

LEASES - Lease Term and Discount Rate (Details)	Dec. 31, 2019
LEASES
Operating leases, weighted average remaining lease term	7 years 10 months 24 days
Finance leases, weighted average remaining lease term	1 year 7 months 6 days
Operating Leases, Weighted-average discount rate	5.30%
Finance leases, Weighted average discount rate	5.10%

LEASES - Lease Commitments (Det

LEASES - Lease Commitments (Details) $ in Thousands	Dec. 31, 2019USD ($)
Operating Leases
2020	$ 24,742
2021	16,592
2022	13,231
2023	11,074
2024	10,589
Thereafter	44,094
Total minimum lease payments	120,322
Operating lease, Less reconciling items to reconcile undiscounted cash flows to lease liabilities:
Leases commencing in the future	5,793
Short-term leases excluded from balance sheet	693
Imputed interest	22,378
Total reconciling items	28,864
Total liabilities per balance sheet	$ 91,458
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Operating Lease, Liability, Current
Finance Leases
2020	$ 135
2021	88
Total minimum lease payments	223
Finance Lease, Less reconciling items to reconcile undiscounted cash flows to lease liabilities:
Imputed interest	8
Total reconciling items	8
Total liabilities per balance sheet	215
Total
2020	24,877
2021	16,680
2022	13,231
2023	11,074
2024	10,589
Thereafter	44,094
Total minimum lease payments	120,545
Leases Total , Less reconciling items to reconcile undiscounted cash flows to lease liabilities:
Leases commencing in the future	5,793
Short-term leases excluded from balance sheet	693
Imputed interest	22,386
Total reconciling items	28,872
Total liabilities per balance sheet	91,673
2020	1,600
2021	600
2022	$ 300

INVENTORIES (Details)

INVENTORIES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Significant components of inventory
Raw materials	$ 12,365	$ 15,219
Finished goods	24,724	28,540
Materials and supplies	453	1,233
Inventory net	37,542	44,992
Inventory write-downs	250	442
Inventory Valuation Reserves	4,100	$ 4,800
Well Chemical Services Acquisition
Significant components of inventory
Finished goods	$ 5,200

PROPERTY AND EQUIPMENT (Details

PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property and equipment
Property and equipment	$ 1,015,379	$ 1,114,378
Accumulated depreciation	(562,986)	(611,530)
Property and equipment held-for-sale, net	885
Total property and equipment, net	453,278	502,848
Accumulated depreciation related to finance leases	1,600	1,300
depreciation and amortization expense
Depreciation expense from property and equipment	107,738	119,114	$ 92,402
Amortization expense from finance lease	916	1,314	168
Amortization expense from intangible assets	11,900	13,102	10,701
Accretion expense from asset retirement obligations	115	183	178
Total depreciation and amortization	120,669	133,713	103,449
Property and Equipment Held-for-Sale and Impairments
Impairment of property and equipment	3,715	6,657
Net loss on divestitures and sales of property and equipment held-for-sale	(7,950)	3,803	$ 2,726
Canadian Business
Property and Equipment Held-for-Sale and Impairments
Impairment of property and equipment	900
Net loss on divestitures and sales of property and equipment held-for-sale	3,900
Canadian Assets
Property and Equipment Held-for-Sale and Impairments
Impairment of property and equipment	900	4,400
Fluid Disposal Equipment
Property and Equipment Held-for-Sale and Impairments
Impaired Assets to be Disposed of by Method Other than Sale, Carrying Value of Asset	2,300	2,300
Property and equipment	0	0
Land
Property and equipment
Property and equipment	16,030	17,799
Buildings and leasehold improvements
Property and equipment
Property and equipment	97,426	106,626
Vehicles and equipment
Property and equipment
Property and equipment	53,819	83,435
Vehicles and equipment - finance lease
Property and equipment
Property and equipment	1,291	1,833
Machinery and equipment
Property and equipment
Property and equipment	729,162	758,528
Machinery and equipment - finance lease
Property and equipment
Property and equipment	162	532
Computer equipment and software
Property and equipment
Property and equipment	8,051	15,775
Computer equipment and software - finance lease
Property and equipment
Property and equipment	356	356
Office furniture and equipment
Property and equipment
Property and equipment	1,157	4,612
Disposal wells
Property and equipment
Property and equipment	64,149	64,038
Other
Property and equipment
Property and equipment	497	497
Construction in progress
Property and equipment
Property and equipment	$ 43,279	$ 60,347

PROPERTY AND EQUIPMENT- Sold An

PROPERTY AND EQUIPMENT- Sold And Divested (Details) $ in Thousands	Dec. 31, 2019USD ($)
Property, Plant and Equipment [Line Items]
Property and equipment held-for-sale	$ 885
Total property and equipment sold and divested	23,409
Affirm Crane Operations [Member]
Property, Plant and Equipment [Line Items]
Business divestitures	11,275
Property and equipment sales	1,339
Canadian Business
Property, Plant and Equipment [Line Items]
Business divestitures	7,372
Property and equipment sales	393
Sand Hauling Operations
Property, Plant and Equipment [Line Items]
Property and equipment sales	$ 3,030

GOODWILL AND OTHER INTANGIBLE_3

GOODWILL AND OTHER INTANGIBLE ASSETS - Goodwill (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)segment
Goodwill
Number of Reporting Units | segment				1
Balance at the beginning of the period	$ 273,801		$ 273,801	$ 273,421
Additions				982
Measurement period adjustment			133	17,292
Affirm crane business divestiture			2,604
Impairment	0		(4,396)	(17,894)
Balance at the end of the period		$ 273,801	266,934	273,801
Oilfield chemicals
Goodwill
Balance at the beginning of the period				15,637
Measurement period adjustment				(2,985)
Impairment		(12,700)		(12,652)
Water Solutions
Goodwill
Balance at the beginning of the period	266,801		266,801	245,542
Additions				982
Resegmentation			(266,801)
Measurement period adjustment				20,277
Balance at the end of the period		266,801		266,801
Wellsite Services
Goodwill
Balance at the beginning of the period	$ 7,000		7,000	12,242
Resegmentation			(7,000)
Impairment				(5,242)
Balance at the end of the period		$ 7,000		$ 7,000
Water services
Goodwill
Resegmentation			186,335
Measurement period adjustment			133
Balance at the end of the period			186,468
Water infrastructure
Goodwill
Resegmentation			80,466
Balance at the end of the period			80,466
Other
Goodwill
Resegmentation			7,000
Affirm crane business divestiture			2,604
Impairment			$ (4,396)

GOODWILL AND OTHER INTANGIBLE_4

GOODWILL AND OTHER INTANGIBLE ASSETS - Other Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other intangible assets
Gross Value	$ 133,898	$ 188,589
Accumulated Amortization	27,419	70,685
Net Value	106,479	117,904
Intangible assets	30,473	30,473
Intangible Assets, Gross (Excluding Goodwill)	164,371	219,062
Intangible Assets, Net (Excluding Goodwill)	136,952	148,377
Amortization of Intangible Assets	11,900	13,102	$ 10,701
Water rights
Other intangible assets
Intangible assets	$ 7,031	7,031
Indefinite-lived intangible assets added		1,800
Water rights | Minimum
Other intangible assets
Renewal term	5 years
Water rights | Maximum
Other intangible assets
Renewal term	10 years
Trademarks
Other intangible assets
Intangible assets	$ 23,442	23,442
Trademarks | Minimum
Other intangible assets
Renewal term	5 years
Trademarks | Maximum
Other intangible assets
Renewal term	10 years
Customer relationships
Other intangible assets
Gross Value	$ 116,554	171,245
Accumulated Amortization	20,233	66,402
Net Value	96,321	104,843
Definite-lived intangible asset acquired	$ 500	3,000
Weighted average amortization period	10 years 8 months 12 days
Patents
Other intangible assets
Gross Value	$ 10,110	10,110
Accumulated Amortization	2,420	1,417
Net Value	$ 7,690	8,693
Weighted average amortization period	7 years 8 months 12 days
Other intangibles
Other intangible assets
Gross Value	$ 7,234	7,234
Accumulated Amortization	4,766	2,866
Net Value	$ 2,468	$ 4,368
Weighted average amortization period	2 years 2 months 12 days

GOODWILL AND OTHER INTANGIBLE_5

GOODWILL AND OTHER INTANGIBLE ASSETS - Annual Amortization of Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Annual amortization of intangible assets
2020	$ 11,656
2021	10,473
2022	10,259
2023	10,187
2024	10,118
Thereafter	53,786
Net Value	$ 106,479	$ 117,904

DEBT (Details)

DEBT (Details) - USD ($) $ in Thousands	Nov. 01, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 20, 2016
DEBT
Unamortized Debt issuance Costs				$ 2,900
Amortization of debt issuance costs		$ 688	$ 688	$ 4,031
Average excess availability, less than 33% of the commitments | Base Rate Advances
DEBT
Variable interest rate (as a percent)		1.00%
Average excess availability, less than 33% of the commitments | LIBOR
DEBT
Variable interest rate (as a percent)		2.00%
Average excess availability, less than 66.67% of the commitments and more than or equal to 33.33% of the commitments | Base Rate Advances
DEBT
Variable interest rate (as a percent)		0.75%
Average excess availability, less than 66.67% of the commitments and more than or equal to 33.33% of the commitments | LIBOR
DEBT
Variable interest rate (as a percent)		1.75%
Average excess availability, more than or equal to 66.67% of the commitments | Base Rate Advances
DEBT
Variable interest rate (as a percent)		0.50%
Average excess availability, more than or equal to 66.67% of the commitments | LIBOR
DEBT
Variable interest rate (as a percent)		1.50%
Average excess availability more than or equal to fifty percent
DEBT
Unused line fee (as a percent)		0.25%
Average excess availability less than fifty percent
DEBT
Unused line fee (as a percent)		0.375%
Eligible unbilled receivables
DEBT
Borrowing base (as a percent)	75.00%
Letter of credit
DEBT
Amount outstanding		$ 0	45,000
Revolving line of credit
DEBT
Maximum borrowing capacity	$ 300,000				$ 300,000
Revolving line of credit | Letter of credit
DEBT
Unused portion of available borrowing		214,600	$ 270,500
Senior secured credit facility
DEBT
Additional borrowing capacity	$ 150,000
Time frame for increasing borrowing capacity	3 years
Percentage of borrowing base allowed	35.00%
Margin (as a percent)	2.00%
Weighted average interest rate (as a percent)			4.256%
Reduction in borrowing capacity		19,900	$ 20,800
Unused portion of available borrowing		194,700
Unamortized Debt issuance Costs		$ 2,000	$ 2,600
Senior secured credit facility | Minimum
DEBT
Percentage of borrowing base allowed	30.00%
Variable interest rate (as a percent)		1.50%
Senior secured credit facility | Maximum
DEBT
Variable interest rate (as a percent)		2.00%
Senior secured credit facility | Base Rate Advances | Minimum
DEBT
Margin (as a percent)	0.50%
Senior secured credit facility | Base Rate Advances | Maximum
DEBT
Margin (as a percent)	1.00%
Senior secured credit facility | LIBOR
DEBT
Margin (as a percent)	1.00%
Senior secured credit facility | LIBOR | Minimum
DEBT
Margin (as a percent)	1.50%
Senior secured credit facility | LIBOR | Maximum
DEBT
Margin (as a percent)	2.00%
Senior secured credit facility | Federal Funds Rate
DEBT
Margin (as a percent)	0.50%
Senior secured credit facility | Eligible billed receivables
DEBT
Borrowing base (as a percent)	85.00%
Senior secured credit facility | Eligible inventory
DEBT
Borrowing base (as a percent)	70.00%
Senior secured credit facility | Net recovery percentage
DEBT
Borrowing base (as a percent)	85.00%
Senior secured credit facility | Criteria for distributions, scenario one
DEBT
Lookback period	30 days
Percentage outstanding	25.00%
Base amount	$ 37,500
Senior secured credit facility | Criteria for distributions, scenario two
DEBT
Lookback period	30 days
Percentage outstanding	20.00%
Base amount	$ 30,000
Fixed charge coverage ratio	1.00%
Senior secured credit facility | Coverage Ratio Criteria
DEBT
Lookback period	60 days
Percentage outstanding	10.00%
Base amount	$ 15,000
Fixed charge coverage ratio	1.00%
Senior secured credit facility | Letter of credit
DEBT
Maximum borrowing capacity	$ 40,000
Senior secured credit facility | Swingline loan
DEBT
Maximum borrowing capacity	$ 30,000
Previous Credit Facility
DEBT
Maximum borrowing capacity					$ 100,000

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Details)	12 Months Ended
	Dec. 31, 2019
COMMITMENTS AND CONTINGENCIES
Percentage of vehicles in which certain employees at some of the facilities altered emissions controls systems	4.00%

EQUITY-BASED COMPENSATION (Deta

EQUITY-BASED COMPENSATION (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2019	Nov. 01, 2017
EQUITY-BASED COMPENSATION
offering period	3 years
2016 plan | Maximum
EQUITY-BASED COMPENSATION
Equity options term	10 years
Rockwater Equity Plan
EQUITY-BASED COMPENSATION
Maximum number of shares		9.3

EQUITY-BASED COMPENSATION - Ass

EQUITY-BASED COMPENSATION - Assumptions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
EQUITY-BASED COMPENSATION
Granted (in shares)	0
Weighted-average grant date fair value of equity options granted		$ 8.98	$ 7.85
Assumptions for equity options granted:
Underlying equity		$ 20.50	20
Strike price			$ 20
Dividend yield (%)		0.00%	0.00%
Risk free rate(%)		2.30%
Volatility (%)		50.00%
Expected term (years)		10 years
Equity options | Minimum
Assumptions for equity options granted:
Strike price		$ 20.50
Expected term (years)			4 years
Risk free rate(%), minimum			2.00%
Volatility (%), minimum			46.60%
Equity options | Maximum
Assumptions for equity options granted:
Strike price		$ 30.75
Expected term (years)			6 years
Risk free rate(%), maximum			2.70%
Volatility (%), maximum			46.80%

EQUITY-BASED COMPENSATION - Equ

EQUITY-BASED COMPENSATION - Equity Options Changed During Period (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Equity Options
Granted (in shares)	0
Equity options
Equity Options
Beginning balance (in shares)	3,865,678
Exercised (in shares)	(5,282)
Forfeited (in shares)	(30,438)
Expired (in shares)	(32,639)
Ending balance (in shares)	3,797,319	3,865,678
Ending balance, exercisable (in shares)	3,463,549
Nonvested at end of period (in shares)	333,770
Weighted-average Grant Date Value
Beginning balance (in dollars per share)	$ 7.95
Exercised (in dollars per share)	3.12
Forfeited (in dollars per share)	8.33
Expired (in dollars per share)	7.45
Ending balance (in dollars per share)	8.19	$ 7.95
Ending balance, exercisable	8.12
Weighted-average Exercise Price
Beginning balance (in dollars per share)	16
Exercised (in dollars per share)	5.68
Forfeited (in dollars per share)	17.70
Expired (in dollars per share)	21.85
Ending balance (in dollars per share)	15.95	$ 16
Ending balance, exercisable	15.06
Nonvested at end of period (in dollar per share)	$ 25.22
Weighted-average Remaining Contractual Term (Years)
Outstanding	4 years 2 months 12 days	4 years 10 months 24 days
Ending balance, exercisable	3 years 10 months 24 days
Aggregate Intrinsic Value
Beginning balance, outstanding	$ 19
Ending balance, outstanding	509	$ 19
Ending balance, exercisable	$ 510

EQUITY-BASED COMPENSATION - E_2

EQUITY-BASED COMPENSATION - Equity Options (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Price		$ 20.50	$ 20
Equity options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 4.3	$ 5.2	$ 1.9
Unrecognized compensation expense	$ 0.2
Weighted-average period for recognition (in years)	1 year
Class A Common Stock | Equity options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Price	$ 9.28	$ 6.32

EQUITY-BASED COMPENSATION - Res

EQUITY-BASED COMPENSATION - Restricted stock (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
EQUITY-BASED COMPENSATION
offering period	3 years
Payments for repurchase of common stock	$ 18,600	$ 16,562	$ 297
Restricted Stock
EQUITY-BASED COMPENSATION
Compensation expense	8,500	4,300
Unrecognized compensation expense	9,200
Payments for repurchase of common stock	$ 1,000	$ 900
Weighted-average remaining life	1 year 4 months 24 days
Restricted Stock | Minimum
EQUITY-BASED COMPENSATION
offering period	1 year
Restricted Stock | Maximum
EQUITY-BASED COMPENSATION
offering period	3 years
Restricted Stock Awards
Restricted stock
Beginning balance (in shares)	496,945
Granted (in shares)	1,417,458
Vested (in shares)	(379,150)
Forfeited (in shares)	(17,060)
Ending balance (in shares)	1,518,193	496,945
Grant Date Fair Value
Beginning balance (in dollars per share)	$ 19.02
Granted (in dollars per share)	8.80
Vested (in dollars per share)	16.69
Forfeited	15.97
Ending balance (in dollars per share)	$ 10.08	$ 19.02
Restricted Stock Units
Restricted stock
Beginning balance (in shares)	2,500
Vested (in shares)	(1,250)
Ending balance (in shares)	1,250	2,500
Grant Date Fair Value
Beginning balance (in dollars per share)	$ 19
Vested (in dollars per share)	19
Ending balance (in dollars per share)	$ 19	$ 19

EQUITY-BASED COMPENSATION - Per

EQUITY-BASED COMPENSATION - Performance share units (Details) - Performance share units	12 Months Ended
	Dec. 31, 2019USD ($)$ / shares	Dec. 31, 2018USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of times shares issued for each performance share settlement | $ / shares	1
Grant date fair value of PSUs	$ 7,000,000	$ 5,900,000
Compensation expense	2,100,000	$ 500,000
Unrecognized compensation expense	$ 4,200,000
Weighted-average remaining life	1 year 4 months 24 days
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of times shares issued for each performance share settlement	0
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of times shares issued for each performance share settlement	1.75
Return on assets Less than 9.6%
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of Target PSUs Earned	0.00%
Return on assets 9.6%
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of Target PSUs Earned	50.00%
Return on assets 12%
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of Target PSUs Earned	100.00%
Return on assets 14.4%
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of Target PSUs Earned	175.00%

EQUITY-BASED COMPENSATION - P_2

EQUITY-BASED COMPENSATION - Performance share units outstanding (Details) - Performance share units - 2019	12 Months Ended
	Dec. 31, 2019shares
Performance share units
Beginning balance (in shares)	255,364
Target shares granted	778,118
Target shares forfeited	(18,492)
Ending balance (in shares)	1,014,990

EQUITY-BASED COMPENSATION - Sto

EQUITY-BASED COMPENSATION - Stock-Settled Incentive Awards (Details) - USD ($) $ in Millions	May 17, 2018	Dec. 31, 2018	Dec. 31, 2019
EQUITY-BASED COMPENSATION
offering period			3 years
Stock-Settled Incentive Awards
EQUITY-BASED COMPENSATION
offering period	2 years
Vesting date		30 days
Target amount of stock settled incentive awards granted		$ 3.9
Compensation expense		$ 0.4	$ 0.5
Unrecognized compensation expense			$ 0.2
Weighted-average period for recognition (in years)			5 months
Stock-Settled Incentive Awards | Minimum
EQUITY-BASED COMPENSATION
Pay out percentage	0.00%
Stock-Settled Incentive Awards | Maximum
EQUITY-BASED COMPENSATION
Pay out percentage	200.00%
Stock-Settled Incentive Awards | Less than $20.00
EQUITY-BASED COMPENSATION
Percentage of Target Amount Earned		0.00%
Stock-Settled Incentive Awards | At least $20.00, but less than $25.00
EQUITY-BASED COMPENSATION
Percentage of Target Amount Earned		100.00%
Stock-Settled Incentive Awards | $25.00 or greater
EQUITY-BASED COMPENSATION
Percentage of Target Amount Earned		200.00%

EQUITY-BASED COMPENSATION - S_2

EQUITY-BASED COMPENSATION - Stock-settled incentive awards outstanding (Details) - Stock-Settled Incentive Awards $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Value at Target
Non-vested at beginning of period	$ 3,147
Forfeited during 2019	(210)
Non-vested at end of period	2,937
Award Value Being Recognized
Non-vested at beginning of period	1,202
Forfeited during 2019	(80)
Non-vested at end of period	$ 1,122

EQUITY-BASED COMPENSATION - Emp

EQUITY-BASED COMPENSATION - Employee Stock Purchase Plan (ESPP) (Details) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
offering period	3 years
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
offering period	4 years
Issue price (percentage)	95.00%
Maximum annual employees contribution	$ 15,000
Cash received for shares issued	$ 112
Shares issued | shares	13,178
Minimum | ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee service period	1 year

EQUITY-BASED COMPENSATION - Pha

EQUITY-BASED COMPENSATION - Phantom unit awards (Details) - USD ($) $ / shares in Units, $ in Thousands	May 05, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Underlying equity		$ 20		$ 20.50
Phantom unit awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Settlement of phantom units	$ 7,800
Underlying equity	$ 14
Cash payment (in dollars per share)	$ 5.53
Compensation expense		$ 7,800	$ 0

EQUITY-BASED COMPENSATION - Sha

EQUITY-BASED COMPENSATION - Share-repurchases (Details) - 2016 plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares repurchased in open market	2,180,806	1,703,651
Number of shares repurchased with employee minimum tax withholding requirements	108,074	62,777
Decrease in paid in-capital	$ 21.9
Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Decrease in Class A common stock	23,000

FAIR VALUE MEASUREMENT (Details

FAIR VALUE MEASUREMENT (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfers into Level3		$ 0	$ 0	$ 0
Transfers out of Level3		0	0	$ 0
Impairment of Goodwill	$ 0	4,396	17,894
Impairment of property and equipment		3,715	6,657
Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill		4,396	17,894
Cost-Method Investment			2,000
Property and equipment		3,715	6,657
Nonrecurring | Carrying value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill		4,396	24,894
Cost-Method Investment			2,500
Property and equipment		11,040	16,919
Level 3 | Nonrecurring | Fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill			7,000
Cost-Method Investment			500
Property and equipment		$ 7,325	$ 10,262

RELATED PARTY TRANSACTIONS (Det

RELATED PARTY TRANSACTIONS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
RELATED PARTY TRANSACTIONS
Sales to related parties	$ 16.8	$ 8.3	$ 9
Purchases from related party vendors	$ 18.8	16.7	10.4
Minimum
RELATED PARTY TRANSACTIONS
Beneficial ownership (as a percent)	5.00%
Tax Receivable Agreement | Legacy Owner Holdco and Crestview GP
RELATED PARTY TRANSACTIONS
Percentage of net tax savings for payment to TRA Holders	85.00%
Tax Receivable Agreement | Contributing Legacy Owners
RELATED PARTY TRANSACTIONS
Percentage of net tax savings for payment to TRA Holders	85.00%
Property and equipment
RELATED PARTY TRANSACTIONS
Purchases from related party vendors	$ 3	4.7	3.8
Inventory and consumables
RELATED PARTY TRANSACTIONS
Purchases from related party vendors	0.2	0.3	0.3
Rent of certain equipment or other services
RELATED PARTY TRANSACTIONS
Purchases from related party vendors	14.3	10.3	2.7
Management, consulting and other services
RELATED PARTY TRANSACTIONS
Purchases from related party vendors	$ 1.3	$ 1.4	$ 3.6

INCOME TAXES (Details)

INCOME TAXES (Details) - USD ($) $ in Thousands	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
INCOME TAXES
Effective Income tax (as percent)			32.00%	3.00%	2.40%
Statutory tax rate (as a percent)	21.00%	35.00%	21.00%	21.00%	35.00%
Tax expense (benefit)			$ 1,949	$ 1,704	$ (851)
Current tax expense (benefit)
Federal income tax expense (benefit)			696	1,073	(338)
State and local income tax expense (benefit)			1,034	1,077	(77)
Total current expense (benefit)			1,730	2,150	(415)
Deferred tax expense (benefit)
Federal income tax expense (benefit)			49	(20)	(422)
State and local income tax expense (benefit)			170	(426)	(14)
Total deferred expense (benefit)			219	(446)	(436)
Total income tax expense (benefit)			1,949	1,704	(851)
Tax expense (benefit) attributable to controlling interests			1,488	1,425	(405)
Tax expense (benefit) attributable to noncontrolling interests			461	279	(446)
Provision calculated at federal statutory income tax rate:
Income (loss) before taxes			$ 6,085	$ 56,003	$ (35,978)
Statutory rate	21.00%	35.00%	21.00%	21.00%	35.00%
Income tax expense (benefit) computed at statutory rate			$ 1,278	$ 11,761	$ (12,592)
Less: noncontrolling interests			(284)	(3,735)	6,409
Income tax expense (benefit) attributable to controlling interests			994	8,026	(6,183)
State and local income taxes, net of federal benefit			884	515	(91)
Change in enacted tax rate					39,166
Change in subsidiary tax status			587
Other				580
Deferred adjsutment due to restructuring			856
Change in valuation allowance			(1,833)	(7,696)	(33,297)
Income tax expense (benefit) attributable to controlling interests			1,488	1,425	(405)
Tax expense (benefit) attributable to noncontrolling interests			461	279	(446)
Total income tax expense (benefit)			$ 1,949	$ 1,704	$ (851)

INCOME TAXES - Deferred tax ass

INCOME TAXES - Deferred tax assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets
Outside basis difference in SES Holdings	$ 27,935	$ 38,739
Federal net operating loss carryforward	46,782	45,927
Federal net operating loss carryforward expires begining in 2031	133,800
Federal net operating loss carry forward with no expiration	56,600
State NOLs	102,000
Foreign NOLs	5,500
Credits and other carryforwards	1,451	1,679
Property and equipment		150
Intangible assets		1,284
Other	944	468
Total deferred tax assets before valuation allowance	77,112	88,247
Valuation allowance	(76,883)	(88,247)
Total deferred tax assets	229
Deferred tax liabilities
Property and equipment	540
Other	32	123
Total deferred tax liabilities	572	123
Net deferred tax (liabilities)	$ (343)	$ (123)

INCOME TAXES - Valuation allowa

INCOME TAXES - Valuation allowance (Details) - USD ($) $ in Millions	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Change in valuation allowance
Change during the year			$ 11.4
Net operating loss carryforward			$ 190.4
Statutory rate	21.00%	35.00%	21.00%	21.00%	35.00%
Liability or expense			$ 0	$ 0

NONCONTROLLING INTERESTS (Detai

NONCONTROLLING INTERESTS (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
NONCONTROLLING INTERESTS
Noncontrolling interests attributable to joint ventures formed for water-related services	$ 2,674	$ 3,273
Noncontrolling interests attributable to holders of Class B Common Stock	172,961	274,566
Total noncontrolling interests	$ 175,635	$ 277,839

NONCONTROLLING INTERESTS - Effe

NONCONTROLLING INTERESTS - Effect of Changes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Effects of changes in noncontrolling interests on equity
Net income (loss) attributable to Select Energy Services, Inc.	$ (9,930)	$ 5,379	$ 6,200	$ 1,135	$ (13,501)	$ 22,951	$ 16,963	$ 10,099	$ 2,784	$ 36,512	$ (16,816)
Transfers (to) from noncontrolling interests:
Decrease in additional paid-in capital as a result of the contribution of proceeds from the IPO to SES Holdings, LLC in exchange for common units											(41,135)
Decrease in additional paid-in capital as a result of the contribution of net assets acquired to SES Holdings, LLC in exchange for common units											(4,879)
Decrease in additional paid-in capital as a result of the contribution of net assets from the Rockwater Merger to SES Holdings, LLC in exchange for common units											170,276
Increase in additional paid-in capital as a result of stock option exercises									54	374
Increase in additional paid-in capital as a result of restricted stock issuance, net of forfeitures									3,614	1,942
Increase in additional paid-in capital as a result of issuance of common stock due to vesting of restricted stock units									4	104
(Decrease) increase in additional paid-in capital as a result of the repurchase of SES Holdings LLC Units									(3,362)	(576)	113
Increase in additional paid-in capital as a result of exchanges of SES Holdings LLC Units (an equivalent number of shares of Class B Common Stock) for shares of Class A Common Stock									107,062	146,865
Increase in additional paid-in capital as a result of the Employee Stock Purchase Plan shares issued									42	15
Change to equity from net income attributable to Select Energy Services, Inc. and transfers from noncontrolling interests									$ 110,198	$ 185,236	$ (232,993)

EARNINGS (LOSS) PER SHARE (Deta

EARNINGS (LOSS) PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Calculation of basic and diluted earnings per share:
Antidilutive shares									2,961,439	2,706,159
Net income	$ (12,504)	$ 7,172	$ 8,068	$ 1,400	$ (18,123)	$ 31,267	$ 25,023	$ 16,132	$ 4,136	$ 54,299	$ (35,127)
Net income attributable to noncontrolling interests									(1,352)	(17,787)	18,311
Net income (loss) attributable to Select Energy Services, Inc.	$ (9,930)	$ 5,379	$ 6,200	$ 1,135	$ (13,501)	$ 22,951	$ 16,963	$ 10,099	2,784	36,512	(16,816)
Add: Reallocation of net income attributable to noncontrolling interests for the dilutive effect of restricted stock									7	13
Add: Reallocation of net income attributable to noncontrolling interests for the dilutive effect of performance share units									2
Add: Reallocation of net income attributable to noncontrolling interests for the dilutive effect of stock options									1	30
Net income attributable to Select Energy Services, Inc. - diluted									2,794	36,555	(16,816)
Class A Common Stock
Calculation of basic and diluted earnings per share:
Net income (loss) attributable to Select Energy Services, Inc.									2,784	35,720	(12,560)
Add: Reallocation of net income attributable to noncontrolling interests for the dilutive effect of restricted stock									7	13
Add: Reallocation of net income attributable to noncontrolling interests for the dilutive effect of performance share units									2
Add: Reallocation of net income attributable to noncontrolling interests for the dilutive effect of stock options									1	30
Net income attributable to Select Energy Services, Inc. - diluted									$ 2,794	$ 35,763	$ (12,560)
Weighted-average shares of common stock outstanding - basic									80,176,323	72,403,318	24,612,853
Dilutive effect of restricted stock									373,366	71,718
Dilutive effect of stock options									40,215	166,999
Dilutive effect of ESPP									446	112
Weighted-average shares of common stock outstanding - diluted									80,671,330	72,642,147	24,612,853
Earnings (loss) per share, Basic (in dollars per share)									$ 0.03	$ 0.49	$ (0.51)
Earnings (loss) per share, Diluted (in dollars per share)									$ 0.03	$ 0.49	$ (0.51)
Basic & Diluted	$ (0.12)	$ 0.07	$ 0.08	$ 0.01	$ (0.17)	$ 0.29	$ 0.24	$ 0.15
Class A Common Stock | Performance share units
Calculation of basic and diluted earnings per share:
Dilutive effect of stock options									80,979
Class A-1 Common Stock
Calculation of basic and diluted earnings per share:
Net income (loss) attributable to Select Energy Services, Inc.											$ (3,691)
Net income attributable to Select Energy Services, Inc. - diluted											$ (3,691)
Weighted-average shares of common stock outstanding - basic											7,233,973
Weighted-average shares of common stock outstanding - diluted											7,233,973
Earnings (loss) per share, Basic (in dollars per share)											$ (0.51)
Earnings (loss) per share, Diluted (in dollars per share)											$ (0.51)
Class A-2 Common Stock
Calculation of basic and diluted earnings per share:
Net income (loss) attributable to Select Energy Services, Inc.										$ 792	$ (565)
Net income attributable to Select Energy Services, Inc. - diluted										$ 792	$ (565)
Weighted-average shares of common stock outstanding - basic										1,604,575	1,106,605
Weighted-average shares of common stock outstanding - diluted										1,604,575	1,106,605
Earnings (loss) per share, Basic (in dollars per share)										$ 0.49	$ (0.51)
Earnings (loss) per share, Diluted (in dollars per share)										$ 0.49	$ (0.51)
Basic & Diluted								$ 0.15
Class B Common Stock
Calculation of basic and diluted earnings per share:
Weighted-average shares of common stock outstanding - basic									23,806,646	31,986,438	38,768,156
Weighted-average shares of common stock outstanding - diluted									23,806,646	31,986,438	38,768,156

SEGMENT INFORMATION (Details)

SEGMENT INFORMATION (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2019USD ($)segment	Dec. 31, 2018USD ($)segment	Dec. 31, 2017USD ($)segment
SEGMENT INFORMATION
Number of operating segments | segment									3	3	3
Number of reportable segments | segment									3	3	3
Segment information
Revenue	$ 276,088	$ 328,968	$ 323,887	$ 362,646	$ 362,318	$ 396,970	$ 393,247	$ 376,395	$ 1,291,589	$ 1,528,930	$ 692,491
Income (loss) before taxes									6,085	56,003	(35,978)
Depreciation and Amortization									120,669	133,713	103,449
Capital Expenditures									102,705	172,132	108,277
Income (loss) from operations	$ (7,213)	$ 12,475	$ 11,179	$ 6,633	$ (13,982)	$ 32,258	$ 24,795	$ 18,603	23,074	61,674	(29,999)
Other income, net									(2,948)	(2,872)	(2,357)
Other
Segment information
Revenue									33,365	144,499	69,382
Income (loss) before taxes									(8,066)	(14,021)	(2,649)
Depreciation and Amortization									1,714	14,124	6,286
Capital Expenditures									64	7,045	7,823
Operating segment | Water services
Segment information
Revenue									773,946	897,160	420,757
Income (loss) before taxes									51,185	89,826	1,823
Depreciation and Amortization									80,664	82,875	70,839
Capital Expenditures									37,692	120,883	82,127
Operating segment | Water infrastructure
Segment information
Revenue									221,661	230,130	163,386
Income (loss) before taxes									15,103	31,579	11,723
Depreciation and Amortization									25,665	23,042	22,481
Capital Expenditures									53,839	33,372	15,264
Operating segment | Oilfield chemicals
Segment information
Revenue									268,963	260,281	41,586
Income (loss) before taxes									17,942	(7,107)	663
Depreciation and Amortization									8,766	10,496	2,040
Capital Expenditures									11,110	10,832	3,063
Elimination
Segment information
Revenue									(6,346)	(3,140)	(2,620)
Corporate
Segment information
Income (loss) before taxes									(53,090)	(38,603)	(41,559)
Depreciation and Amortization									3,860	3,176	1,803
Material reconciling items
Segment information
Income (loss) from operations									76,164	100,277	11,560
Interest expense, net									(2,688)	(5,311)	(6,629)
Other income, net									$ (14,301)	$ (360)	$ 650

SEGMENT INFORMATION - Total Ass

SEGMENT INFORMATION - Total Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Assets	$ 1,347,620	$ 1,360,605
Operating segment | Water services
Segment Reporting Information [Line Items]
Assets	831,123	865,992
Operating segment | Water infrastructure
Segment Reporting Information [Line Items]
Assets	314,026	250,207
Operating segment | Oilfield chemicals
Segment Reporting Information [Line Items]
Assets	192,224	173,762
Operating segment | Other
Segment Reporting Information [Line Items]
Assets	$ 10,247	$ 70,644

SEGMENT INFORMATION - Revenue b

SEGMENT INFORMATION - Revenue by product (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenue	$ 276,088	$ 328,968	$ 323,887	$ 362,646	$ 362,318	$ 396,970	$ 393,247	$ 376,395	$ 1,291,589	$ 1,528,930	$ 692,491
Water transfer
Segment Reporting Information [Line Items]
Revenue									355,535	443,650	193,314
Oilfield chemicals
Segment Reporting Information [Line Items]
Revenue									268,963	260,281	41,586
Flowback and well testing
Segment Reporting Information [Line Items]
Revenue									208,572	223,828	90,107
Accommodations and rentals
Segment Reporting Information [Line Items]
Revenue									150,793	153,013	63,107
Water Sourcing
Segment Reporting Information [Line Items]
Revenue									120,517	129,958	97,898
Pipeline logistics and disposal
Segment Reporting Information [Line Items]
Revenue									101,145	100,172	65,488
Fluid hauling
Segment Reporting Information [Line Items]
Revenue									63,156	79,568	75,273
Other
Segment Reporting Information [Line Items]
Revenue									$ 22,908	$ 138,460	$ 65,718

SEGMENT INFORMATION - Other dis

SEGMENT INFORMATION - Other disclosures (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Concentration Risk [Line Items]
Revenue	$ 276,088	$ 328,968	$ 323,887	$ 362,646	$ 362,318	$ 396,970	$ 393,247	$ 376,395	$ 1,291,589	$ 1,528,930	$ 692,491
Geographic concentration risk | UNITED STATES | Revenue
Concentration Risk [Line Items]
Revenue									$ 1,283,400	$ 1,480,400	$ 680,900
Concentration risk (as a percent)									99.40%	96.80%	98.30%
Geographic concentration risk | UNITED STATES | Long Lived Asset
Concentration Risk [Line Items]
Long-lived assets	452,400				492,400				$ 452,400	$ 492,400	$ 451,700
Concentration risk (as a percent)									99.80%	97.90%	95.30%
Geographic concentration risk | CANADA | Revenue
Concentration Risk [Line Items]
Revenue									$ 8,200	$ 48,600	$ 11,600
Concentration risk (as a percent)									0.60%	3.20%	1.70%
Geographic concentration risk | CANADA | Long Lived Asset
Concentration Risk [Line Items]
Long-lived assets	$ 900				$ 10,500				$ 900	$ 10,500	$ 22,400
Concentration risk (as a percent)									0.20%	2.10%	4.70%

QUARTERLY RESULTS OF OPERATIO_3

QUARTERLY RESULTS OF OPERATIONS (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Data [Abstract]
Revenue	$ 276,088	$ 328,968	$ 323,887	$ 362,646	$ 362,318	$ 396,970	$ 393,247	$ 376,395	$ 1,291,589	$ 1,528,930	$ 692,491
Gross profit	21,810	40,994	39,939	45,997	34,408	59,397	56,728	47,949	148,740	198,482	57,780
Income (loss) from operations	(7,213)	12,475	11,179	6,633	(13,982)	32,258	24,795	18,603	23,074	61,674	(29,999)
Net income (loss)	(12,504)	7,172	8,068	1,400	(18,123)	31,267	25,023	16,132	4,136	54,299	(35,127)
Net income (loss) attributable to Select Energy Services, Inc.	$ (9,930)	$ 5,379	$ 6,200	$ 1,135	$ (13,501)	$ 22,951	$ 16,963	$ 10,099	2,784	36,512	(16,816)
Class A Common Stock
Quarterly Financial Data [Abstract]
Net income (loss) attributable to Select Energy Services, Inc.									$ 2,784	35,720	(12,560)
Net income (loss) per share attributable to common stockholders (Note 16):
Basic & Diluted	$ (0.12)	$ 0.07	$ 0.08	$ 0.01	$ (0.17)	$ 0.29	$ 0.24	$ 0.15
Class A-1 Common Stock
Quarterly Financial Data [Abstract]
Net income (loss) attributable to Select Energy Services, Inc.											(3,691)
Class A-2 Common Stock
Quarterly Financial Data [Abstract]
Net income (loss) attributable to Select Energy Services, Inc.										$ 792	$ (565)
Net income (loss) per share attributable to common stockholders (Note 16):
Basic & Diluted								$ 0.15