Energy Recovery (ERII) 10-Q 30 Oct 20 2020 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2020	Oct. 23, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2020
Document Transition Report	false
Entity File Number	001-34112
Entity Registrant Name	Energy Recovery, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	01-0616867
Entity Address, Address Line One	1717 Doolittle Drive
Entity Address, City or Town	San Leandro
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94577
City Area Code	510
Local Phone Number	483-7370
Title of 12(b) Security	Common
Trading Symbol	ERII
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		56,100,279
Entity Central Index Key	0001421517
Document Fiscal Year Focus	2020
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	Q3
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 80,149	$ 26,387
Short-term investments	24,373	58,736
Accounts receivable, net	11,055	12,979
Inventories, net	10,662	10,317
Prepaid expenses and other current assets	4,959	4,548
Total current assets	131,198	112,967
Long-term investments	1,418	15,419
Deferred tax assets, non-current	11,454	16,897
Property and equipment, net	20,535	18,843
Operating lease, right of use asset	16,444	11,195
Goodwill	12,790	12,790
Other intangible assets, net	53	65
Other assets, non-current	645	598
Total assets	194,537	188,774
Current liabilities:
Accounts payable	1,951	1,192
Accrued expenses and other current liabilities	8,654	9,869
Lease liabilities	1,209	1,023
Contract liabilities	1,160	15,746
Total current liabilities	12,974	27,830
Lease liabilities, non-current	16,802	11,533
Contract liabilities, non-current	104	13,120
Other non-current liabilities	672	278
Total liabilities	30,552	52,761
Commitments and contingencies (Note 8)
Stockholders’ equity:
Common stock	61	61
Additional paid-in capital	174,929	170,028
Accumulated other comprehensive income (loss)	100	(37)
Treasury stock	(30,486)	(30,486)
Accumulated earnings (deficit)	19,381	(3,553)
Total stockholders’ equity	163,985	136,013
Total liabilities and stockholders’ equity	$ 194,537	$ 188,774

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue, Product and Service [Extensible List]			us-gaap:ProductMember
Cost, Product and Service [Extensible List]			us-gaap:ProductMember
Revenue	$ 27,408	$ 24,850	$ 92,560	$ 67,441
Operating expenses:
General and administrative	6,271	5,711	18,751	16,790
Sales and marketing	2,141	2,367	5,776	6,710
Research and development	5,098	6,620	18,159	16,354
Amortization of intangible assets	4	156	12	469
Impairment of long-lived assets	0	0	2,332	0
Total operating expenses	13,514	14,854	45,030	40,323
Income from operations	6,078	4,571	27,481	11,275
Other income (expense):
Interest income	134	500	809	1,551
Other non-operating expense, net	(29)	(5)	(59)	(77)
Total other income, net	105	495	750	1,474
Income before income taxes	6,183	5,066	28,231	12,749
Provision for (benefit from) income taxes	796	(83)	5,297	1,227
Net income	$ 5,387	$ 5,149	$ 22,934	$ 11,522
Earnings per share:
Basic (in dollars per share)	$ 0.10	$ 0.09	$ 0.41	$ 0.21
Diluted (in dollars per share)	$ 0.10	$ 0.09	$ 0.41	$ 0.21
Number of shares used in per share calculations:
Basic (in shares)	55,692	54,975	55,573	54,594
Diluted (in shares)	56,471	56,384	56,443	55,971
Product
Revenue	$ 27,408	$ 21,752	$ 65,665	$ 57,050
Product cost of revenue	7,816	5,425	20,049	15,843
Product gross profit	19,592	16,327	45,616	41,207
License and development revenue
Revenue	$ 0	$ 3,098	$ 26,895	$ 10,391

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 5,387	$ 5,149	$ 22,934	$ 11,522
Other comprehensive income (loss), net of tax
Foreign currency translation adjustments	26	(19)	11	(20)
Unrealized gain (loss) on investments	(45)	(5)	126	127
Total other comprehensive income (loss), net of tax	(19)	(24)	137	107
Comprehensive income	$ 5,368	$ 5,125	$ 23,071	$ 11,629

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net income	$ 22,934	$ 11,522
Adjustments to reconcile net income to cash provided by operating activities
Stock-based compensation	3,672	4,425
Depreciation and amortization	3,963	3,440
Amortization (accretion) of premiums and discounts on investments	311	(37)
Deferred income taxes	5,443	1,198
Provision for warranty claims	316	339
Impairment of long-lived assets	2,332	0
Other non-cash adjustments	0	197
Changes in operating assets and liabilities:
Accounts receivable, net	1,862	(10,617)
Contract assets	(747)	2,993
Inventories, net	(506)	(1,885)
Prepaid and other assets	295	383
Accounts payable	656	(94)
Accrued expenses and other liabilities	(2,561)	(1,264)
Income taxes	(18)	30
Contract liabilities	(27,602)	(10,127)
Net cash provided by operating activities	10,350	503
Cash flows from investing activities:
Sales of marketable securities	10,573	3,535
Maturities of marketable securities	50,467	70,040
Purchases of marketable securities	(12,855)	(66,253)
Capital expenditures	(6,019)	(5,501)
Net cash provided by investing activities	42,166	1,821
Cash flows from financing activities:
Net proceeds from issuance of common stock	1,260	5,424
Tax payment for employee shares withheld	(23)	(89)
Net cash provided by financing activities	1,237	5,335
Effect of exchange rate differences on cash and cash equivalents	11	0
Net change in cash, cash equivalents and restricted cash	53,764	7,659
Cash, cash equivalents and restricted cash, beginning of year	26,488	22,138
Cash, cash equivalents and restricted cash, end of period	$ 80,252	$ 29,797

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common stock	Additional paid-in capital	Accumulated other comprehensive income (loss)	Treasury stock	Accumulated earnings (deficit)
Beginning balance (in shares) at Dec. 31, 2018		59,396
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)		1,174
Ending balance (in shares) at Sep. 30, 2019		60,570			5,456
Beginning Balance at Dec. 31, 2018		$ 59	$ 158,404	$ (133)		$ (14,466)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net		1	5,334
Stock-based compensation			4,412
Foreign currency translation adjustments				(20)
Unrealized gain (loss) on investments				127
Total other comprehensive income (loss), net	$ 107			107
Net income	11,522					11,522
Ending Balance at Sep. 30, 2019	134,754	$ 60	168,150	(26)	$ (30,486)	(2,944)
Beginning balance (in shares) at Jun. 30, 2019		60,360
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)		210
Ending balance (in shares) at Sep. 30, 2019		60,570			5,456
Beginning Balance at Jun. 30, 2019		$ 60	165,981	(2)		(8,093)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net		0	815
Stock-based compensation			1,354
Foreign currency translation adjustments				(19)
Unrealized gain (loss) on investments				(5)
Total other comprehensive income (loss), net	(24)			(24)
Net income	5,149					5,149
Ending Balance at Sep. 30, 2019	134,754	$ 60	168,150	(26)	$ (30,486)	(2,944)
Beginning balance (in shares) at Dec. 31, 2019		60,718
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)		452
Ending balance (in shares) at Sep. 30, 2020		61,170			5,456
Beginning Balance at Dec. 31, 2019	136,013	$ 61	170,028	(37)		(3,553)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net		0	1,237
Stock-based compensation			3,664
Foreign currency translation adjustments				11
Unrealized gain (loss) on investments				126
Total other comprehensive income (loss), net	137			137
Net income	22,934					22,934
Ending Balance at Sep. 30, 2020	163,985	$ 61	174,929	100	$ (30,486)	19,381
Beginning balance (in shares) at Jun. 30, 2020		61,133
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)		37
Ending balance (in shares) at Sep. 30, 2020		61,170			5,456
Beginning Balance at Jun. 30, 2020		$ 61	173,729	119		13,994
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net		0	132
Stock-based compensation			1,068
Foreign currency translation adjustments				26
Unrealized gain (loss) on investments				(45)
Total other comprehensive income (loss), net	(19)			(19)
Net income	5,387					5,387
Ending Balance at Sep. 30, 2020	$ 163,985	$ 61	$ 174,929	$ 100	$ (30,486)	$ 19,381

Description of Business and Sig

Description of Business and Significant Accounting Policies	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Description of Business and Significant Accounting Policies	Description of Business and Significant Accounting Policies Energy Recovery, Inc. and its wholly-owned subsidiaries (the “Company” or “Energy Recovery”) has, for more than 20 years, created technologies that solve complex challenges for industrial fluid flow markets worldwide . The Company design s and manufacture s solutions that reduce waste, improve operational efficiency, and lower the production costs of clean water and oil & gas . The Company’s solutions are marketed and sold in fluid flow markets such as water, oil & gas and chemical processing under the trademarks ERI ® , Ultra PX ™ , PX ® , Pressure Exchanger ® , PX Pressure Exchanger ® , Powertrain ™ , VorTeq ™ , IsoBoost ® , IsoGen ® , AT ™ and AquaBold ™ . The Company owns, manufactures and/or develops its solutions, in whole or in part, in the United States of America (“U.S.”). Basis of Presentation The Company’s Condensed Consolidated Financial Statements include the accounts of the Company and its wholly-owned subsidiaries. All significant inter-company accounts and transactions have been eliminated in consolidation. The accompanying Condensed Consolidated Financial Statements have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and footnote disclosures normally included in the financial statements prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) have been condensed or omitted pursuant to such rules and regulations. The December 31, 2019 Condensed Consolidated Balance Sheet was derived from audited financial statements and may not include all disclosures required by GAAP; however, the Company believes that the disclosures are adequate to make the information presented not misleading. The September 30, 2020 unaudited Condensed Consolidated Financial Statements should be read in conjunction with the audited Consolidated Financial Statements and the notes thereto for the fiscal year ended December 31, 2019 included in the Company’s Annual Report on Form 10-K filed with the SEC on March 6, 2020, as amended on June 10, 2020 (the “ 2019 Annual Report ”). All adjustments consisting of normal recurring adjustments that are necessary to present fairly the financial position, results of operations and cash flows for the interim periods have been made. The results of operations for the interim periods are not necessarily indicative of the operating results for the full fiscal year or any future periods. Use of Estimates The preparation of Condensed Consolidated Financial Statements, in conformity with U.S. GAAP, requires the Company’s management to make judgments, assumptions and estimates that affect the amounts reported in the Condensed Consolidated Financial Statements and accompanying notes. The accounting policies that reflect the Company’s more significant estimates and judgments and that the Company believes are the most critical to aid in fully understanding and evaluating its reported financial results are revenue recognition; capitalization of research and development (“R&D”) assets; valuation of stock options; valuation and impairment of goodwill and acquired intangible assets; valuation adjustments for excess and obsolete inventory; deferred taxes and valuation allowances on deferred tax assets; and evaluation and measurement of contingencies. Those estimates could change, and as a result, actual results could differ materially from those estimates. Due to the novel coronavirus (“ COVID-19”) pandemic, and the impact on our customers due to the reduced demand for oil and gas, as well as the oversupply of oil, there has been uncertainty and disruption in the global economy and financial markets. The Company is not aware of any specific event or circumstance that would require an update to its estimates or judgments or a revision of the carrying value of its assets or liabilities as of October 30, 2020 , the date of issuance of this Quarterly Report on Form 10-Q. These estimates may change, as new events occur and additional information is obtained. Actual results could differ materially from these estimates under different assumptions or conditions. The Company undertakes no obligation to update publicly these estimates for any reason after the date of this Quarterly Report on Form 10-Q, except as required by law. Significant Accounting Policies Except for adopting new accounting pronouncements, as noted under “ Recently Adopted Accounting Pronouncements ,” there have been no material changes to the Company’s significant accounting policies in Note 1, “ Description of Business and Significant Accounting Policies ,” of the Notes to Consolidated Financial Statements included in the 2019 Annual Report . Recently Adopted Accounting Pronouncements In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-13, Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which amends Accounting Standards Codification (“ASC”) No. 326, Financial Instruments-Credit Losses (“ASC 326”). Subsequent to the issuance of ASU 2016-13, ASC 326 was amended by various updates that amend and clarify the impact and implementation of the aforementioned update. The new guidance introduces the current expected credit loss (“CECL”) model, which requires an entity to record an allowance for credit losses for certain financial instruments and financial assets, including trade receivables, based on expected losses rather than incurred losses. Under this update, on initial recognition and at each reporting period, an entity is required to recognize an allowance that reflects the entity’s current estimate of credit losses expected to be incurred over the life of the financial instrument. In February 2020, the FASB issued ASU No. 2020-02, Financial Instruments-Credit Losses (Topic 326) and Leases (Topic 842)-Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 119 and Update to SEC Section on Effective Date Related to Accounting Standards Update No. 2016-02, Leases (Topic 842) (“ASU 2020-02”), which amended the language in Subtopic 326-20 and addressed questions primarily regarding documentation and company policies. ASU 2016-13 and its amendments are effective for the Company for interim and annual periods in fiscal years beginning after December 15, 2019, on a modified retrospective basis. The adoption of ASU 2016-13 and its amendments on January 1, 2020 did not have a material impact on the Company’s Condensed Consolidated Financial Statements and related disclosures. The Company will continue to actively monitor the impact of the recent COVID-19 pandemic, and the impact on our customers due to the reduced demand for oil and gas, as well as the oversupply of oil, on expected credit losses. In March 2020, the FASB issued ASU No. 2020-03, Codification Improvements to Financial Instruments (“ASU 2020-03”). This ASU improves and clarifies various financial instruments topics, including the CECL standard issued in 2016. ASU 2020-03 included seven different issues that describe the areas of improvement and the related amendments to GAAP, intended to make the standards easier to understand and apply by eliminating inconsistencies and providing clarifications. The adoption of ASU 2020-03 on January 1, 2020 did not have a material impact on the Company’s Condensed Consolidated Financial Statements and related disclosures. Recently Issued Accounting Pronouncements Not Yet Adopted In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848) (“ASU 2020-04”), which provided optional expedients and exceptions for applying U.S. GAAP to contracts, hedging relationships, and other transactions affected by the discontinuation of the London Interbank Offered Rate (“LIBOR”) or by another reference rate expected to be discontinued. Entities may apply the provisions of the new standard as of the beginning of the reporting period when the election is made (i.e., as early as the first quarter of 2020). Unlike other topics, the provisions of this update are only available until December 31, 2022, when the reference rate replacement activity is expected to have been completed. The Company is currently evaluating the impact of the provisions of ASU 2020-04 on its financial condition, results of operation, and cash flows.

Revenue

Revenue	9 Months Ended
	Sep. 30, 2020
Revenue from Contract with Customer [Abstract]
Revenue	Revenue On June 24, 2020 , the Company entered into an agreement with Schlumberger Technology Corporation (“ Schlumberger ”) to terminate the existing agreement to license the VorTeq technology (the “ VorTeq License Agreement ”). Pursuant to the terms of the agreement , each party’s rights, duties and obligations under the VorTeq License Agreement have been terminated effective June 1, 2020 . Accordingly, the Company (i) is entitled to retain all of the non-refundable upfront exclusivity payment, (ii) is not entitled to any further payments from Schlumberger , and (iii) has no future performance obligations under the VorTeq License Agreement . The Company accounted for the termination as a contract modification, which resulted in the Company recognizing the remaining amounts of the original $75.0 million non-refundable upfront exclusivity payment of $24.4 million during the second quarter of fiscal year 2020 as license and development revenue in the Condensed Consolidated Statements of Operations for such quarter. See Note 12 , “ VorTeq Partnership and License Agreement ,” for additional discussion regarding the termination of the VorTeq License Agreement . Disaggregation of Revenue The following tables present the Company’s revenues disaggregated by geography based on the “shipped to” addresses of the Company’s customers and by major product/service line. Sales and usage-based taxes are excluded from revenues. Three Months Ended September 30, 2020 Nine Months Ended September 30, 2020 Water Oil & Gas Total Water Oil & Gas Total (In thousands) Primary geographical market Middle East and Africa $ 22,667 $ — $ 22,667 $ 55,402 $ — $ 55,402 Americas 1,157 — 1,157 3,519 26,895 30,414 Asia 2,226 — 2,226 3,618 — 3,618 Europe 1,358 — 1,358 3,126 — 3,126 Total revenue $ 27,408 $ — $ 27,408 $ 65,665 $ 26,895 $ 92,560 Major product/service line PX Pressure Exchangers, pumps and turbo devices, and other $ 27,408 $ — $ 27,408 $ 65,665 — $ 65,665 License and development — — — — 26,895 26,895 Total revenue $ 27,408 $ — $ 27,408 $ 65,665 $ 26,895 $ 92,560 Three Months Ended September 30, 2019 Nine Months Ended September 30, 2019 Water Oil & Gas Total Water Oil & Gas Total (In thousands) Primary geographical market Middle East and Africa $ 16,691 $ — $ 16,691 $ 36,193 $ 104 $ 36,297 Americas 2,227 3,098 5,325 7,978 10,391 18,369 Asia 2,188 — 2,188 9,364 — 9,364 Europe 646 — 646 3,411 — 3,411 Total revenue $ 21,752 $ 3,098 $ 24,850 $ 56,946 $ 10,495 $ 67,441 Major product/service line PX Pressure Exchangers, pumps and turbo devices, and other $ 21,752 $ — $ 21,752 $ 56,946 $ 104 $ 57,050 License and development — 3,098 3,098 — 10,391 10,391 Total revenue $ 21,752 $ 3,098 $ 24,850 $ 56,946 $ 10,495 $ 67,441 Contract Balances The following table presents contract balances by category. September 30, December 31, (In thousands) Accounts receivable, net $ 11,055 $ 12,979 Contract assets: Contract assets, current (included in prepaid expenses and other current assets) $ 1,198 $ 501 Contract assets, non-current (included in other assets, non-current) 241 191 Total contract assets $ 1,439 $ 692 Current contract liabilities: Customer deposits $ 792 $ 1,506 Deferred revenue: License and development — 13,846 Product 78 78 Service 290 316 Total deferred revenue 368 14,240 Total current contract liabilities 1,160 15,746 Non-current contract liabilities, deferred revenue: License and development — 13,048 Service 104 72 Total non-current contract liabilities 104 13,120 Total contract liabilities $ 1,264 $ 28,866 The Company records unbilled receivables as contract assets. The following table presents significant changes in contract assets during the period. Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (In thousands) Contract assets balance, beginning of period $ 890 $ 1,936 $ 692 $ 4,083 Transferred to trade receivables (9,619 ) (4,773 ) (19,464 ) (8,371 ) Additions to contract assets 10,168 3,927 20,211 5,378 Contract assets balance, end of period $ 1,439 $ 1,090 $ 1,439 $ 1,090 The Company records contract liabilities when cash payments are received in advance of the Company’s performance. The following table presents significant changes in contract liabilities during the period. Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (In thousands) Contract liabilities balance, beginning of period $ 1,077 $ 35,079 $ 28,866 $ 42,809 Revenue recognized (19 ) (3,582 ) (29,750 ) (10,901 ) Cash received, excluding amounts recognized as revenue during the period 206 1,185 2,148 774 Contract liabilities balance, end of period $ 1,264 $ 32,682 $ 1,264 $ 32,682 Transaction Price Allocated to the Remaining Performance Obligation The following table presents the estimated revenue expected to be recognized in the future related to performance obligations that are unsatisfied or partially unsatisfied. September 30, (In thousands) Year: 2020 (remaining three months) $ 4,619 2021 17,964 2022 15 Total performance obligation $ 22,598

Earnings per Share

Earnings per Share	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Earnings per Share	Earnings per Share Net income for the reported period is divided by the weighted average number of common shares outstanding during the reported period to calculate basic earnings per common share . Basic earnings per share exclude any dilutive effect of stock options and restricted stock units (“RSU”). Diluted earnings per common share reflects the potential dilution that would occur if outstanding stock options to purchase common stock were exercised for shares of common stock, using the treasury stock method, and the shares of common stock underlying each outstanding RSU were issued (outstanding stock options to purchase common stock and RSUs collectively referred to as, “stock awards”). Certain shares of common stock issuable under stock awards have been omitted from the diluted earnings per share calculations because their inclusion is considered anti-dilutive. The following table presents the computation of basic and diluted earnings per share . Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (In thousands, except per share amounts) Numerator: Net income $ 5,387 $ 5,149 $ 22,934 $ 11,522 Denominator (weighted average shares): Basic common shares outstanding 55,692 54,975 55,573 54,594 Dilutive stock awards 779 1,409 870 1,377 Diluted common shares outstanding 56,471 56,384 56,443 55,971 Earnings per share: Basic $ 0.10 $ 0.09 $ 0.41 $ 0.21 Diluted $ 0.10 $ 0.09 $ 0.41 $ 0.21 The following table presents the potential common shares issuable under stock awards that were excluded from the computation of diluted earnings per share , as their effect would have been anti-dilutive. Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (In thousands) Anti-dilutive stock awards 3,033 1,610 2,700 1,964

Other Financial Information

Other Financial Information	9 Months Ended
	Sep. 30, 2020
Other Financial Information [Abstract]
Other Financial Information	Other Financial Information Cash, Cash Equivalents and Restricted Cash The Company’s Condensed Consolidated Statements of Cash Flows explain the changes in the total of cash, cash equivalents and restricted cash. The following table presents a reconciliation of cash, cash equivalents and restricted cash reported within the Condensed Consolidated Balance Sheets that sum to the total of such amounts presented. September 30, December 31, September 30, (In thousands) Cash and cash equivalents $ 80,149 $ 26,387 $ 29,696 Restricted cash, non-current (included in other assets, non-current) 103 101 101 Total cash, cash equivalents and restricted cash $ 80,252 $ 26,488 $ 29,797 The Company pledged cash in connection with the Company’s credit cards. The Company deposited corresponding amounts into restricted accounts at several financial institutions. Accounts Receivable, net September 30, December 31, (In thousands) Accounts receivable, gross $ 11,425 $ 13,287 Allowance for doubtful accounts (370 ) (308 ) Accounts receivable, net $ 11,055 $ 12,979 Inventories September 30, December 31, (In thousands) Raw materials $ 4,345 $ 3,742 Work in process 2,877 2,141 Finished goods 3,440 4,434 Inventories, net $ 10,662 $ 10,317 Inventories are stated at the lower of cost or net realizable value, using the first-in, first-out method. Valuation adjustments for excess and obsolete inventory reflected as a reduction of inventory was $0.5 million and $0.4 million at September 30, 2020 and December 31, 2019 , respectively. During the three and nine months ended September 30, 2020 , due to the COVID-19 pandemic, the Company expensed $0.3 million and $1.5 million , respectively, to product cost of revenue related to the reduced utilization of the Company’s manufacturing facilities. Property and Equipment Estimated useful lives are periodically reviewed, and when appropriate, changes are made prospectively. When certain events or changes in operating conditions occur, asset lives may be adjusted and an impairment assessment may be performed on the recoverability of the carrying amounts. The Company evaluates the recoverability of long-lived assets by comparing the carrying amount of an asset to estimated future net undiscounted cash flows generated by the asset (asset group). If such assets are considered to be impaired, the impairment recognized is measured as the amount by which the carrying amount of the assets exceeds the fair value of the assets. The evaluation of recoverability involves estimates of future operating cash flows based upon certain forecasted assumptions, including, but not limited to, revenue growth rates, gross profit margins, and operating expenses. On June 24, 2020 , the Company entered into an agreement with Schlumberger to terminate the existing VorTeq License Agreement effective June 1, 2020 . As a result, the Company conducted an analysis on certain VorTeq long-lived assets that were directly related to obligations under the VorTeq License Agreement and determined that certain of those assets were impaired. The net carrying value of the impaired long-lived assets of $2.3 million was recognized in the nine months ended September 30, 2020 as impairment of long-lived assets in the Condensed Consolidated Statements of Operations . See Note 12 , “ VorTeq Partnership and License Agreement ,” for additional discussion regarding the termination of the VorTeq License Agreement . Accrued Expenses and Other Current Liabilities September 30, December 31, (In thousands) Payroll, incentives and commissions payable $ 6,270 $ 6,040 Warranty reserve 747 631 Other accrued expenses and current liabilities 1,637 3,198 Total accrued expenses and other current liabilities $ 8,654 $ 9,869

Investments and Fair Value Meas

Investments and Fair Value Measurements	9 Months Ended
	Sep. 30, 2020
Investments, Fair Value Disclosure [Abstract]
Investments and Fair Value Measurements	Investments and Fair Value Measurements Available-for-Sale Investments The Company’s investments in U.S. treasury securities and corporate notes and bonds are classified as available-for-sale. As of September 30, 2020 and December 31, 2019 , all available-for-sale investments were either classified as cash equivalents with contractual maturities less than or equal to 90 days, short-term with contractual maturities over 90 days but less than or equal to 12 months, or long-term with contractual maturities over 12 months. Expected maturities can differ from contractual maturities because borrowers may have the right to prepay obligations without prepayment penalties. The Company generally holds available-for-sale investments until maturity; however, from time-to-time, the Company may elect to sell certain available-for-sale investments prior to contractual maturity. The Company monitors investments for impairment. It was determined that unrealized gains and losses at September 30, 2020 and December 31, 2019 , were temporary in nature, because the changes in market value for these securities resulted from fluctuating interest rates, rather than a deterioration of the credit worthiness of the issuers. The Company is unlikely to experience gains or losses if these securities are held to maturity. In the event that the Company disposes of these securities before contractual maturity, it is expected that the realized gains or losses, if any, will be immaterial. Fair Value of Financial Instruments All of the Company’s financial assets and liabilities are remeasured and reported at fair value at each reporting period; and are classified and disclosed in one of the following three pricing category levels: Level 1 — Quoted prices (unadjusted) in active markets for identical assets or liabilities; Level 2 — Inputs other than quoted prices included within Level 1 that are either directly or indirectly observable; and Level 3 — Unobservable inputs in which little or no market activity exists, therefore requiring an entity to develop its own assumptions that market participants would use in pricing. The following table presents the Company’s financial assets measured on a recurring basis by contractual maturity, including their pricing category, amortized cost, gross unrealized holding gains and losses, and fair value, as of September 30, 2020 and December 31, 2019 . September 30, 2020 December 31, 2019 Pricing Category Amortized Gross Gross Fair Amortized Gross Gross Fair (In thousands) Cash equivalents Money market securities Level 1 $ 53,695 $ — $ — $ 53,695 $ 86 $ — $ — $ 86 U.S. treasury securities Level 2 — — — — 11,582 — — 11,582 Total cash equivalents 53,695 — — 53,695 11,668 — — 11,668 Short-term investments U.S. treasury securities Level 2 3,084 16 — 3,100 2,746 1 — 2,747 Corporate notes and bonds Level 2 21,108 167 (2 ) 21,273 55,951 49 (11 ) 55,989 Total short-term investments 24,192 183 (2 ) 24,373 58,697 50 (11 ) 58,736 Long-term investments Corporate notes and bonds Level 2 1,395 23 — 1,418 15,415 9 (5 ) 15,419 Total long-term investments 1,395 23 — 1,418 15,415 9 (5 ) 15,419 Total $ 79,282 $ 206 $ (2 ) $ 79,486 $ 85,780 $ 59 $ (16 ) $ 85,823 As of September 30, 2020 and December 31, 2019 , the Company had no financial liabilities and no Level 3 financial assets. During the nine months ended September 30, 2020 and year ended December 31, 2019 , the Company had no transfers of financial assets between any levels. The following table presents a summary of the fair value and gross unrealized holding losses on the available-for-sale securities that have been in a continuous unrealized loss position, aggregated by type of investment instrument as of September 30, 2020 and December 31, 2019 . The available-for-sale for investments that were in an unrealized gain position have been excluded from the table. September 30, 2020 December 31, 2019 Fair Gross Fair Gross (In thousands) U.S. treasury securities $ — $ — $ 2,027 $ — Corporate notes and bonds 938 (2 ) 18,754 (16 ) Total available-for-sale investments with unrealized loss positions $ 938 $ (2 ) $ 20,781 $ (16 ) Sales of Available-for-Sale Investments The following table presents the sales of available-for-sale investments. Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (In thousands) U.S. treasury securities $ — $ 998 $ — $ 998 Corporate notes and bonds 806 2,537 10,573 2,537 Total sales of securities $ 806 $ 3,535 $ 10,573 $ 3,535 Realized gain on sales of securities was immaterial during the three and nine months ended September 30, 2020 and 2019 .

Goodwill Goodwill

Goodwill Goodwill	9 Months Ended
	Sep. 30, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	Goodwill The net carrying amount of goodwill as of September 30, 2020 and December 31, 2019 was $12.8 million . Goodwill is tested for impairment annually in the third quarter (July 1) of the Company’s fiscal year or more frequently if indicators of potential impairment exist. The recoverability of goodwill is measured at the reporting unit level, which represents the operating segment. On July 1, 2020, the Company estimated the fair value of its reporting units using both the discounted cash flow and market approaches. The forecast of future cash flows, which is the result of the Company’s best estimates of future net sales and operating expenses, are based primarily on expected category expansion, pricing, market segment, and general economic conditions. The Company incorporated other significant inputs to its fair value calculations, including discount rate and market multiples, to reflect current market conditions, and also considered the impact of the COVID-19 pandemic and the termination of the VorTeq License Agreement in its calculations. The analysis performed indicated that the fair value of each reporting unit that is allocated to goodwill significantly exceeded its carrying value. As a result, no impairment charge was recorded during the quarter ended September 30, 2020. The Company continues to actively monitor the industries in which it operates and its businesses’ performance for indicators of potential impairment.

Lines of Credit

Lines of Credit	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Lines of Credit	Lines of Credit Loan and Pledge Agreement The Company entered into a loan and pledge agreement with a financial institution on January 27, 2017 . Since inception, this loan and pledge agreement has been amended multiple times to accommodate the growth of the Company (the as amended loan and pledge agreement is hereinafter referred to as the “ Loan and Pledge Agreement ”). The Loan and Pledge Agreement , which will expire on June 30, 2022 , currently provides for a committed revolving credit line of $16.0 million and an uncommitted revolving credit line of $4.0 million . The covenants of the Loan and Pledge Agreement allow the Company to incur indebtedness owed to a foreign subsidiary in an aggregate amount not to exceed $66.0 million , which amount is subordinated to any amounts outstanding under the Loan and Pledge Agreement . As of September 30, 2020 and December 31, 2019 , there was no debt outstanding under the Loan and Pledge Agreement . Stand-By Letters of Credit Under the Loan and Pledge Agreement , the Company is allowed to issue stand-by letters of credit (“ SBLCs ”) up to one year past the expiration date of the Loan and Pledge Agreement and to hold SBLCs with other financial institutions up to $5.1 million . SBLCs have a term limit of three years , are secured by pledged U.S. investments, and do not have any cash collateral balance requirements. SBLCs are deducted from the total revolving credit line under the Loan and Pledge Agreement and are subject to a non-refundable quarterly fee that is in an amount equal to 0.7% per annum of the face amount of the outstanding SBLCs . As of September 30, 2020 and December 31, 2019 , there were $12.5 million and $11.8 million , respectively, of outstanding SBLCs .

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Operating Lease Obligations The Company leases office facilities and equipment under operating leases that expire on various dates through fiscal year 2030 . On January 10, 2019 , the Company entered into an industrial lease agreement, which commenced on January 1, 2020 . This lease for a commercial development center for oil & gas field testing, manufacturing, and training, located in Katy, Texas (the “ Katy Lease ”), included an office and warehouse space of approximately 25,200 square feet (“sqft.”) and land of approximately 4.5 acres. The Company’s annual base rent obligation, paid monthly, is approximately $0.3 million with an increase of approximately 3% annually thereafter, totaling approximately $3.6 million , over the term of the lease. The initial term of the Katy Lease is 120 months after the commencement date, and the Company has two options to extend the lease by an additional five -year term per option, which must be exercised by written notice by the Company at least six months prior to the end of the relevant term. On February 10, 2020 , the Company entered into a lease agreement, that commenced on March 1, 2020 , for an additional manufacturing and warehousing space of approximately 54,429 sqft., located in Tracy, California (the “ Tracy Lease ”). This lease supplements the existing manufacturing, warehousing and distribution of the Company’s energy recovery devices (“ ERDs ”) and other products. The Company’s annual base rent obligation, paid monthly, is approximately $0.4 million , with an increase of approximately 3% annually thereafter, totaling approximately $5.0 million , over the term of the lease. The initial term of the Tracy Lease is 122 months after the commencement date, and the Company has one option to extend the lease by an additional five -year term, which must be exercised by written notice by the Company at least nine months prior to the end of the original lease term. The following table presents operating lease activities related to all leased properties. Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (In thousands) Operating lease expense $ 669 $ 471 $ 1,940 $ 1,421 Cash payments 655 459 1,763 1,365 Non-cash lease liabilities arising from obtaining right-of-use assets — — 6,384 — The following table presents other information related to outstanding operating leases as of September 30, 2020 . Weighted average remaining lease term 8.7 years Weighted average discount rate 7.0% The following table presents the minimum lease payments under noncancelable operating leases, exclusive of executory costs as of September 30, 2020 . Lease Amounts (In thousands) Year: 2020 (remaining three months) $ 635 2021 2,431 2022 2,650 2023 2,580 2024 2,812 2025 and thereafter 13,197 Total 24,305 Less imputed lease interest (6,294 ) Total lease liabilities $ 18,011 Warranty The following table presents the changes in the Company’s accrued product warranty reserve. Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (In thousands) Warranty reserve balance, beginning of period $ 673 $ 599 $ 631 $ 478 Warranty costs charged to cost of revenue 143 97 316 339 Utilization charges against reserve (5 ) (15 ) (7 ) (53 ) Release of accrual related to expired warranties (64 ) (48 ) (193 ) (131 ) Warranty reserve balance, end of period $ 747 $ 633 $ 747 $ 633 Purchase Obligations The Company has purchase order arrangements with its vendors for which the Company has not received the related goods or services as of September 30, 2020 . These arrangements are subject to change based on the Company’s sales demand forecasts. The Company has the right to cancel the arrangements prior to the date of delivery. The purchase order arrangements are related to various raw materials and component parts, as well as capital equipment. As of September 30, 2020 , the Company had approximately $5.2 million of such open cancellable purchase order arrangements. Litigation The Company is named in and subject to various proceedings and claims in connection with its business. The outcome of matters the Company has been, and currently is, involved in cannot be determined at this time, and the results cannot be predicted with certainty. There can be no assurance that these matters will not have a material adverse effect on the Company’s results of operations in any future period, and a significant judgment could have a material impact on the Company’s financial condition, results of operations and cash flows. The Company may in the future become involved in additional litigation in the ordinary course of business, including litigation that could be material to its business. The Company considers all claims on a quarterly basis and, based on known facts, assesses whether potential losses are considered reasonably possible, probable and estimable. Based upon this assessment, the Company then evaluates disclosure requirements and whether to accrue for such claims in its consolidated financial statements. The Company records a provision for a liability when it is both probable that a liability has been incurred and the amount of the loss can be reasonably estimated. These provisions are reviewed at least quarterly and are adjusted to reflect the impacts of negotiations, settlements, rulings, advice of legal counsel and other information and events pertaining to a particular case. Other than matters discussed below, as of September 30, 2020 , there were no material losses which were probable or reasonably possible. On July 21, 2020, a purported securities class action lawsuit was filed in the United States District Court for the Southern District of New York ( Visser, et al. v. Energy Recovery, Inc., et al. , Case No. 1:20-cv-05647-VM (S.D.N.Y.)), naming as defendants the Company and certain of the Company’s present and former executive officers. The Complaint alleges that the defendants violated Section 10(b) and 20 (a) of the Securities Exchange Act of 1934, as amended, and Rule 10b-5 promulgated thereunder, by making materially false and misleading statements, and failed to disclose material adverse facts concerning, the commercialization of VorTeq and expectations of future license revenue . The Complaint further alleges unspecified damages based on a decline in the market price of the Company’s shares following the announcement of the termination of the VorTeq License Agreement . The Company believes the complaint is without merit and intends to defend the case vigorously. At this time, the Company is not able to estimate any reasonable possible loss, if any, due to the early state of this matter.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (In thousands, except percentages) Provision for (benefit from) income taxes $ 796 $ (83 ) $ 5,297 $ 1,227 Effective tax rate 12.9 % (1.6 %) 18.8 % 9.6 % Effective tax rate, excluding discrete items 13.4 % 11.8 % 18.6 % 17.7 % The Company’s tax provision for interim periods is determined using an estimate of its annual effective tax rate, adjusted for discrete items, if any, that arise during the period . Each quarter, the Company update s its estimate of the annual effective tax rate, and if the estimated annual effective tax rate changes, the Company makes a cumulative adjustment in such period . The Company’s quarterly tax provision and estimate of its annual effective tax rate are subject to variation due to several factors, including variability in accurately predicting its pre-tax income or loss and the mix of jurisdictions to which they relate, intercompany transactions, the applicability of special tax regimes, and changes in how the Company does business . For the nine months ended September 30, 2020 , the recognized income tax expense included a discrete tax charge due primarily to the termination of the VorTeq License Agreement , partially offset by a discrete tax benefit related to stock-based compensation windfalls . For the nine months ended September 30, 2019 , the recognized income tax expense included a discrete tax benefit related to an increase in prior year U.S. federal research and development credits and a discrete tax benefit related to tax deductions from stock-based compensation windfalls, partially offset by deferred tax charge primarily related to a remeasurement of the Company’s state deferred tax assets due to an adjustment to the Company’s estimated blended state effective tax rate . The effective tax rate, excluding the discrete items, for the nine months ended September 30, 2020 , compared to the nine months ended September 30, 2019 , was consistent year over year .

Segment Reporting

Segment Reporting	9 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
Segment Reporting	Segment Reporting The Company’s chief operating decision-maker (“CODM”) is its chief executive officer. The Company’s reportable segments consist of the Water segment and the Oil & Gas segment. These segments are based on the industries in which the products are sold, the type of products sold and the related products and services. The Water segment consists of revenue associated with products sold for use in reverse osmosis desalination as well as the related identifiable expenses. The Oil & Gas segment consists of revenue associated with products sold for use in gas processing, chemical processing and hydraulic fracturing as well as license and development revenue associated therewith. Operating income (loss) for each segment excludes other income and expenses and certain corporate expenses managed outside the operating segment such as income taxes and other separately managed general and administrative expenses not related to the identified segments. Assets and liabilities are reviewed at the consolidated level by the CODM and are not accounted for by segment. The CODM allocates resources to and assesses the performance of each operating segment using information about its revenue and operating income . The following tables present a summary of the Company’s financial information by segment and corporate operating expenses. Three Months Ended September 30, 2020 Nine Months Ended September 30, 2020 Water Oil & Gas Total Water Oil & Gas Total (In thousands) Product revenue $ 27,408 $ — $ 27,408 $ 65,665 $ — $ 65,665 Product cost of revenue 7,816 — 7,816 20,049 — 20,049 Product gross profit 19,592 — 19,592 45,616 — 45,616 License and development revenue (1) — — — — 26,895 26,895 Operating expenses General and administrative 606 439 1,045 1,467 1,601 3,068 Sales and marketing 1,507 30 1,537 4,307 106 4,413 Research and development 723 2,956 3,679 2,585 12,720 15,305 Amortization of intangible assets 4 — 4 12 — 12 Impairment of long-lived assets (2) — — — — 2,332 2,332 Total operating expenses 2,840 3,425 6,265 8,371 16,759 25,130 Operating income (loss) $ 16,752 $ (3,425 ) 13,327 $ 37,245 $ 10,136 47,381 Less: Corporate operating expenses 7,249 19,900 Income from operations 6,078 27,481 Other income, net 105 750 Income before income taxes $ 6,183 $ 28,231 (1) See Note 12 , “ VorTeq Partnership and License Agreement ,” for additional discussion regarding the termination of the VorTeq License Agreement . (2) See Note 4 , “ Other Financial Information – Property and Equipment ,” for additional discussion regarding the impairment of certain VorTeq long-lived assets that were directly related to obligations under the VorTeq License Agreement . Three Months Ended September 30, 2019 Nine Months Ended September 30, 2019 Water Oil & Gas Total Water Oil & Gas Total (In thousands) Product revenue $ 21,752 $ — $ 21,752 $ 56,946 $ 104 $ 57,050 Product cost of revenue 5,425 — 5,425 15,655 188 15,843 Product gross profit (loss) 16,327 — 16,327 41,291 (84 ) 41,207 License and development revenue — 3,098 3,098 — 10,391 10,391 Operating expenses General and administrative 359 431 790 1,456 1,207 2,663 Sales and marketing 1,850 92 1,942 5,058 674 5,732 Research and development 886 5,667 6,553 2,794 13,335 16,129 Amortization of intangible assets 156 — 156 469 — 469 Total operating expenses 3,251 6,190 9,441 9,777 15,216 24,993 Operating income (loss) $ 13,076 $ (3,092 ) 9,984 $ 31,514 $ (4,909 ) 26,605 Less: Corporate operating expenses 5,413 15,330 Income from operations 4,571 11,275 Other income, net 495 1,474 Income before income taxes $ 5,066 $ 12,749

Concentrations

Concentrations	9 Months Ended
	Sep. 30, 2020
Risks and Uncertainties [Abstract]
Concentrations	Concentrations Product Revenue The following table presents customers accounting for 10% or more of the Company’s product revenue by segment. Although certain customers might account for greater than 10% of the Company’s revenue at any one point in time, the concentration of revenue between a limited number of large engineering, procurement and construction (“EPC”) firms shifts regularly, depending on contract negotiations. The percentages by customer reflect specific relationships or contracts that would concentrate the Company’s revenue for the periods presented and does not indicate a trend specific to any one customer. Three Months Ended September 30, Nine Months Ended September 30, Segment 2020 2019 2020 2019 Customer A Water 30% ** 27% ** Customer B Water 28% ** 24% 17% Customer C Water ** 11% 12% ** Customer D Water ** 26% ** 10% ** Zero or less than 10%. License and Development Revenue One international Oil & Gas segment customer accounted for 100% of the Company’s license and development revenue for the nine months ended September 30, 2020 and the three and nine months ended September 30, 2019 .

VorTeq Partnership and License

VorTeq Partnership and License Agreement	9 Months Ended
	Sep. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
VorTeq Partnership and License Agreement	VorTeq Partnership and License Agreement On October 14, 2015, the Company and Schlumberger entered into the VorTeq License Agreement , which provided Schlumberger with exclusive worldwide rights to the Company’s VorTeq technology for use in hydraulic fracturing onshore applications. In performing the obligations under the agreement, the Company provided research and development services to commercialize the technology in accordance with the Key Performance Indicators (“ KPIs ”), as defined in the VorTeq License Agreement . The VorTeq License Agreement included up to $125.0 million in upfront consideration paid in the following stages: (i) a $75.0 million non-refundable upfront exclusivity payment; and (ii) two non-refundable milestone payments of $25.0 million each made upon achievement of successful tests in accordance with the KPIs specified in the VorTeq License Agreement (“ M1 ” and “ M2 ”). On June 24, 2020 , prior to activating the M1 test, the Company and Schlumberger entered into an agreement to terminate the VorTeq License Agreement effective June 1, 2020 . Prior to the termination of the VorTeq License Agreement , the Company had been recognizing license and development revenue related to the non-refundable exclusivity payment under the cost to total cost method of accounting. Pursuant to the terms of the agreement , each party’s rights, duties and obligations under the VorTeq License Agreement have been terminated . Accordingly, the Company (i) is entitled to retain all of the non-refundable upfront exclusivity payment, (ii) is not entitled to any further payments from Schlumberger , and (iii) has no future performance obligations under the VorTeq License Agreement . The Company accounted for the termination as a contract modification, which resulted in the Company recognizing the remaining amounts of the original $75.0 million non-refundable upfront exclusivity payment of $24.4 million during the second quarter of fiscal year 2020 as license and development revenue in the Condensed Consolidated Statements of Operations

Description of Business and S_2

Description of Business and Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The Company’s Condensed Consolidated Financial Statements include the accounts of the Company and its wholly-owned subsidiaries. All significant inter-company accounts and transactions have been eliminated in consolidation. The accompanying Condensed Consolidated Financial Statements have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and footnote disclosures normally included in the financial statements prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) have been condensed or omitted pursuant to such rules and regulations. The December 31, 2019 Condensed Consolidated Balance Sheet was derived from audited financial statements and may not include all disclosures required by GAAP; however, the Company believes that the disclosures are adequate to make the information presented not misleading. The September 30, 2020 unaudited Condensed Consolidated Financial Statements should be read in conjunction with the audited Consolidated Financial Statements and the notes thereto for the fiscal year ended December 31, 2019 included in the Company’s Annual Report on Form 10-K filed with the SEC on March 6, 2020, as amended on June 10, 2020 (the “ 2019 Annual Report ”). All adjustments consisting of normal recurring adjustments that are necessary to present fairly the financial position, results of operations and cash flows for the interim periods have been made. The results of operations for the interim periods are not necessarily indicative of the operating results for the full fiscal year or any future periods.
Use of Estimates	Use of Estimates The preparation of Condensed Consolidated Financial Statements, in conformity with U.S. GAAP, requires the Company’s management to make judgments, assumptions and estimates that affect the amounts reported in the Condensed Consolidated Financial Statements and accompanying notes. The accounting policies that reflect the Company’s more significant estimates and judgments and that the Company believes are the most critical to aid in fully understanding and evaluating its reported financial results are revenue recognition; capitalization of research and development (“R&D”) assets; valuation of stock options; valuation and impairment of goodwill and acquired intangible assets; valuation adjustments for excess and obsolete inventory; deferred taxes and valuation allowances on deferred tax assets; and evaluation and measurement of contingencies. Those estimates could change, and as a result, actual results could differ materially from those estimates. Due to the novel coronavirus (“ COVID-19”) pandemic, and the impact on our customers due to the reduced demand for oil and gas, as well as the oversupply of oil, there has been uncertainty and disruption in the global economy and financial markets. The Company is not aware of any specific event or circumstance that would require an update to its estimates or judgments or a revision of the carrying value of its assets or liabilities as of October 30, 2020 , the date of issuance of this Quarterly Report on Form 10-Q. These estimates may change, as new events occur and additional information is obtained. Actual results could differ materially from these estimates under different assumptions or conditions. The Company undertakes no obligation to update publicly these estimates for any reason after the date of this Quarterly Report on Form 10-Q, except as required by law.
New Accounting Pronouncements	Recently Adopted Accounting Pronouncements In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-13, Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which amends Accounting Standards Codification (“ASC”) No. 326, Financial Instruments-Credit Losses (“ASC 326”). Subsequent to the issuance of ASU 2016-13, ASC 326 was amended by various updates that amend and clarify the impact and implementation of the aforementioned update. The new guidance introduces the current expected credit loss (“CECL”) model, which requires an entity to record an allowance for credit losses for certain financial instruments and financial assets, including trade receivables, based on expected losses rather than incurred losses. Under this update, on initial recognition and at each reporting period, an entity is required to recognize an allowance that reflects the entity’s current estimate of credit losses expected to be incurred over the life of the financial instrument. In February 2020, the FASB issued ASU No. 2020-02, Financial Instruments-Credit Losses (Topic 326) and Leases (Topic 842)-Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 119 and Update to SEC Section on Effective Date Related to Accounting Standards Update No. 2016-02, Leases (Topic 842) (“ASU 2020-02”), which amended the language in Subtopic 326-20 and addressed questions primarily regarding documentation and company policies. ASU 2016-13 and its amendments are effective for the Company for interim and annual periods in fiscal years beginning after December 15, 2019, on a modified retrospective basis. The adoption of ASU 2016-13 and its amendments on January 1, 2020 did not have a material impact on the Company’s Condensed Consolidated Financial Statements and related disclosures. The Company will continue to actively monitor the impact of the recent COVID-19 pandemic, and the impact on our customers due to the reduced demand for oil and gas, as well as the oversupply of oil, on expected credit losses. In March 2020, the FASB issued ASU No. 2020-03, Codification Improvements to Financial Instruments (“ASU 2020-03”). This ASU improves and clarifies various financial instruments topics, including the CECL standard issued in 2016. ASU 2020-03 included seven different issues that describe the areas of improvement and the related amendments to GAAP, intended to make the standards easier to understand and apply by eliminating inconsistencies and providing clarifications. The adoption of ASU 2020-03 on January 1, 2020 did not have a material impact on the Company’s Condensed Consolidated Financial Statements and related disclosures. Recently Issued Accounting Pronouncements Not Yet Adopted In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848) (“ASU 2020-04”), which provided optional expedients and exceptions for applying U.S. GAAP to contracts, hedging relationships, and other transactions affected by the discontinuation of the London Interbank Offered Rate (“LIBOR”) or by another reference rate expected to be discontinued. Entities may apply the provisions of the new standard as of the beginning of the reporting period when the election is made (i.e., as early as the first quarter of 2020). Unlike other topics, the provisions of this update are only available until December 31, 2022, when the reference rate replacement activity is expected to have been completed. The Company is currently evaluating the impact of the provisions of ASU 2020-04 on its financial condition, results of operation, and cash flows.
Fair Value of Financial Instruments	Fair Value of Financial Instruments All of the Company’s financial assets and liabilities are remeasured and reported at fair value at each reporting period; and are classified and disclosed in one of the following three pricing category levels: Level 1 — Quoted prices (unadjusted) in active markets for identical assets or liabilities; Level 2 — Inputs other than quoted prices included within Level 1 that are either directly or indirectly observable; and Level 3 — Unobservable inputs in which little or no market activity exists, therefore requiring an entity to develop its own assumptions that market participants would use in pricing.
Property and Equipment	Property and Equipment Estimated useful lives are periodically reviewed, and when appropriate, changes are made prospectively. When certain events or changes in operating conditions occur, asset lives may be adjusted and an impairment assessment may be performed on the recoverability of the carrying amounts. The Company evaluates the recoverability of long-lived assets by comparing the carrying amount of an asset to estimated future net undiscounted cash flows generated by the asset (asset group). If such assets are considered to be impaired, the impairment recognized is measured as the amount by which the carrying amount of the assets exceeds the fair value of the assets. The evaluation of recoverability involves estimates of future operating cash flows based upon certain forecasted assumptions, including, but not limited to, revenue growth rates, gross profit margins, and operating expenses.
Goodwill	Goodwill is tested for impairment annually in the third quarter (July 1) of the Company’s fiscal year or more frequently if indicators of potential impairment exist. The recoverability of goodwill is measured at the reporting unit level, which represents the operating segment. On July 1, 2020, the Company estimated the fair value of its reporting units using both the discounted cash flow and market approaches. The forecast of future cash flows, which is the result of the Company’s best estimates of future net sales and operating expenses, are based primarily on expected category expansion, pricing, market segment, and general economic conditions. The Company incorporated other significant inputs to its fair value calculations, including discount rate and market multiples, to reflect current market conditions, and also considered the impact of the COVID-19 pandemic and the termination of the VorTeq License Agreement in its calculations. The analysis performed indicated that the fair value of each reporting unit that is allocated to goodwill significantly exceeded its carrying value. As a result, no impairment charge was recorded during the quarter ended September 30, 2020. The Company continues to actively monitor the industries in which it operates and its businesses’ performance for indicators of potential impairment.
Litigation	The Company considers all claims on a quarterly basis and, based on known facts, assesses whether potential losses are considered reasonably possible, probable and estimable. Based upon this assessment, the Company then evaluates disclosure requirements and whether to accrue for such claims in its consolidated financial statements. The Company records a provision for a liability when it is both probable that a liability has been incurred and the amount of the loss can be reasonably estimated. These provisions are reviewed at least quarterly and are adjusted to reflect the impacts of negotiations, settlements, rulings, advice of legal counsel and other information and events pertaining to a particular case.
Income Taxes	The Company’s tax provision for interim periods is determined using an estimate of its annual effective tax rate, adjusted for discrete items, if any, that arise during the period . Each quarter, the Company update s its estimate of the annual effective tax rate, and if the estimated annual effective tax rate changes, the Company makes a cumulative adjustment in such period . The Company’s quarterly tax provision and estimate of its annual effective tax rate are subject to variation due to several factors, including variability in accurately predicting its pre-tax income or loss and the mix of jurisdictions to which they relate, intercompany transactions, the applicability of special tax regimes, and changes in how the Company does business .

Revenue (Tables)

Revenue (Tables)	9 Months Ended
	Sep. 30, 2020
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	Three Months Ended September 30, 2020 Nine Months Ended September 30, 2020 Water Oil & Gas Total Water Oil & Gas Total (In thousands) Primary geographical market Middle East and Africa $ 22,667 $ — $ 22,667 $ 55,402 $ — $ 55,402 Americas 1,157 — 1,157 3,519 26,895 30,414 Asia 2,226 — 2,226 3,618 — 3,618 Europe 1,358 — 1,358 3,126 — 3,126 Total revenue $ 27,408 $ — $ 27,408 $ 65,665 $ 26,895 $ 92,560 Major product/service line PX Pressure Exchangers, pumps and turbo devices, and other $ 27,408 $ — $ 27,408 $ 65,665 — $ 65,665 License and development — — — — 26,895 26,895 Total revenue $ 27,408 $ — $ 27,408 $ 65,665 $ 26,895 $ 92,560 Three Months Ended September 30, 2019 Nine Months Ended September 30, 2019 Water Oil & Gas Total Water Oil & Gas Total (In thousands) Primary geographical market Middle East and Africa $ 16,691 $ — $ 16,691 $ 36,193 $ 104 $ 36,297 Americas 2,227 3,098 5,325 7,978 10,391 18,369 Asia 2,188 — 2,188 9,364 — 9,364 Europe 646 — 646 3,411 — 3,411 Total revenue $ 21,752 $ 3,098 $ 24,850 $ 56,946 $ 10,495 $ 67,441 Major product/service line PX Pressure Exchangers, pumps and turbo devices, and other $ 21,752 $ — $ 21,752 $ 56,946 $ 104 $ 57,050 License and development — 3,098 3,098 — 10,391 10,391 Total revenue $ 21,752 $ 3,098 $ 24,850 $ 56,946 $ 10,495 $ 67,441
Contract with Customer, Asset and Liability	The following table presents contract balances by category. September 30, December 31, (In thousands) Accounts receivable, net $ 11,055 $ 12,979 Contract assets: Contract assets, current (included in prepaid expenses and other current assets) $ 1,198 $ 501 Contract assets, non-current (included in other assets, non-current) 241 191 Total contract assets $ 1,439 $ 692 Current contract liabilities: Customer deposits $ 792 $ 1,506 Deferred revenue: License and development — 13,846 Product 78 78 Service 290 316 Total deferred revenue 368 14,240 Total current contract liabilities 1,160 15,746 Non-current contract liabilities, deferred revenue: License and development — 13,048 Service 104 72 Total non-current contract liabilities 104 13,120 Total contract liabilities $ 1,264 $ 28,866
Contract With Customer, Contract Asset, Contract Liability, Activity	The Company records unbilled receivables as contract assets. The following table presents significant changes in contract assets during the period. Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (In thousands) Contract assets balance, beginning of period $ 890 $ 1,936 $ 692 $ 4,083 Transferred to trade receivables (9,619 ) (4,773 ) (19,464 ) (8,371 ) Additions to contract assets 10,168 3,927 20,211 5,378 Contract assets balance, end of period $ 1,439 $ 1,090 $ 1,439 $ 1,090 The Company records contract liabilities when cash payments are received in advance of the Company’s performance. The following table presents significant changes in contract liabilities during the period. Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (In thousands) Contract liabilities balance, beginning of period $ 1,077 $ 35,079 $ 28,866 $ 42,809 Revenue recognized (19 ) (3,582 ) (29,750 ) (10,901 ) Cash received, excluding amounts recognized as revenue during the period 206 1,185 2,148 774 Contract liabilities balance, end of period $ 1,264 $ 32,682 $ 1,264 $ 32,682
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction	The following table presents the estimated revenue expected to be recognized in the future related to performance obligations that are unsatisfied or partially unsatisfied. September 30, (In thousands) Year: 2020 (remaining three months) $ 4,619 2021 17,964 2022 15 Total performance obligation $ 22,598

Earnings per Share (Tables)

Earnings per Share (Tables)	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table presents the computation of basic and diluted earnings per share . Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (In thousands, except per share amounts) Numerator: Net income $ 5,387 $ 5,149 $ 22,934 $ 11,522 Denominator (weighted average shares): Basic common shares outstanding 55,692 54,975 55,573 54,594 Dilutive stock awards 779 1,409 870 1,377 Diluted common shares outstanding 56,471 56,384 56,443 55,971 Earnings per share: Basic $ 0.10 $ 0.09 $ 0.41 $ 0.21 Diluted $ 0.10 $ 0.09 $ 0.41 $ 0.21
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following table presents the potential common shares issuable under stock awards that were excluded from the computation of diluted earnings per share , as their effect would have been anti-dilutive. Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (In thousands) Anti-dilutive stock awards 3,033 1,610 2,700 1,964

Other Financial Information (Ta

Other Financial Information (Tables)	9 Months Ended
	Sep. 30, 2020
Other Financial Information [Abstract]
Restrictions on Cash and Cash Equivalents	The Company’s Condensed Consolidated Statements of Cash Flows explain the changes in the total of cash, cash equivalents and restricted cash. The following table presents a reconciliation of cash, cash equivalents and restricted cash reported within the Condensed Consolidated Balance Sheets that sum to the total of such amounts presented. September 30, December 31, September 30, (In thousands) Cash and cash equivalents $ 80,149 $ 26,387 $ 29,696 Restricted cash, non-current (included in other assets, non-current) 103 101 101 Total cash, cash equivalents and restricted cash $ 80,252 $ 26,488 $ 29,797
Schedule of Accounts, Notes, Loans and Financing Receivable	Accounts Receivable, net September 30, December 31, (In thousands) Accounts receivable, gross $ 11,425 $ 13,287 Allowance for doubtful accounts (370 ) (308 ) Accounts receivable, net $ 11,055 $ 12,979
Schedule of Inventory, Current	Inventories September 30, December 31, (In thousands) Raw materials $ 4,345 $ 3,742 Work in process 2,877 2,141 Finished goods 3,440 4,434 Inventories, net $ 10,662 $ 10,317
Schedule of Accrued Liabilities	Accrued Expenses and Other Current Liabilities September 30, December 31, (In thousands) Payroll, incentives and commissions payable $ 6,270 $ 6,040 Warranty reserve 747 631 Other accrued expenses and current liabilities 1,637 3,198 Total accrued expenses and other current liabilities $ 8,654 $ 9,869

Investments and Fair Value Me_2

Investments and Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2020
Investments, Fair Value Disclosure [Abstract]
Schedule Of Amortized Cost And Fair Value Of Available For Sale Securities	The following table presents the Company’s financial assets measured on a recurring basis by contractual maturity, including their pricing category, amortized cost, gross unrealized holding gains and losses, and fair value, as of September 30, 2020 and December 31, 2019 . September 30, 2020 December 31, 2019 Pricing Category Amortized Gross Gross Fair Amortized Gross Gross Fair (In thousands) Cash equivalents Money market securities Level 1 $ 53,695 $ — $ — $ 53,695 $ 86 $ — $ — $ 86 U.S. treasury securities Level 2 — — — — 11,582 — — 11,582 Total cash equivalents 53,695 — — 53,695 11,668 — — 11,668 Short-term investments U.S. treasury securities Level 2 3,084 16 — 3,100 2,746 1 — 2,747 Corporate notes and bonds Level 2 21,108 167 (2 ) 21,273 55,951 49 (11 ) 55,989 Total short-term investments 24,192 183 (2 ) 24,373 58,697 50 (11 ) 58,736 Long-term investments Corporate notes and bonds Level 2 1,395 23 — 1,418 15,415 9 (5 ) 15,419 Total long-term investments 1,395 23 — 1,418 15,415 9 (5 ) 15,419 Total $ 79,282 $ 206 $ (2 ) $ 79,486 $ 85,780 $ 59 $ (16 ) $ 85,823
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	The following table presents a summary of the fair value and gross unrealized holding losses on the available-for-sale securities that have been in a continuous unrealized loss position, aggregated by type of investment instrument as of September 30, 2020 and December 31, 2019 . The available-for-sale for investments that were in an unrealized gain position have been excluded from the table. September 30, 2020 December 31, 2019 Fair Gross Fair Gross (In thousands) U.S. treasury securities $ — $ — $ 2,027 $ — Corporate notes and bonds 938 (2 ) 18,754 (16 ) Total available-for-sale investments with unrealized loss positions $ 938 $ (2 ) $ 20,781 $ (16 )
Debt Securities, Available-For-Sale, Proceeds From Sale	The following table presents the sales of available-for-sale investments. Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (In thousands) U.S. treasury securities $ — $ 998 $ — $ 998 Corporate notes and bonds 806 2,537 10,573 2,537 Total sales of securities $ 806 $ 3,535 $ 10,573 $ 3,535

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Lease, Cost	The following table presents operating lease activities related to all leased properties. Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (In thousands) Operating lease expense $ 669 $ 471 $ 1,940 $ 1,421 Cash payments 655 459 1,763 1,365 Non-cash lease liabilities arising from obtaining right-of-use assets — — 6,384 —
Lease, Term And Discount Rate	The following table presents other information related to outstanding operating leases as of September 30, 2020 . Weighted average remaining lease term 8.7 years Weighted average discount rate 7.0%
Lessee, Operating Lease, Liability, Maturity	The following table presents the minimum lease payments under noncancelable operating leases, exclusive of executory costs as of September 30, 2020 . Lease Amounts (In thousands) Year: 2020 (remaining three months) $ 635 2021 2,431 2022 2,650 2023 2,580 2024 2,812 2025 and thereafter 13,197 Total 24,305 Less imputed lease interest (6,294 ) Total lease liabilities $ 18,011
Schedule of Product Warranty Liability	The following table presents the changes in the Company’s accrued product warranty reserve. Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (In thousands) Warranty reserve balance, beginning of period $ 673 $ 599 $ 631 $ 478 Warranty costs charged to cost of revenue 143 97 316 339 Utilization charges against reserve (5 ) (15 ) (7 ) (53 ) Release of accrual related to expired warranties (64 ) (48 ) (193 ) (131 ) Warranty reserve balance, end of period $ 747 $ 633 $ 747 $ 633

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit)	Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (In thousands, except percentages) Provision for (benefit from) income taxes $ 796 $ (83 ) $ 5,297 $ 1,227 Effective tax rate 12.9 % (1.6 %) 18.8 % 9.6 % Effective tax rate, excluding discrete items 13.4 % 11.8 % 18.6 % 17.7 %

Segment Reporting (Tables)

Segment Reporting (Tables)	9 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
Reconciliation of Operating Profit (Loss) from Segments to Consolidated	The following tables present a summary of the Company’s financial information by segment and corporate operating expenses. Three Months Ended September 30, 2020 Nine Months Ended September 30, 2020 Water Oil & Gas Total Water Oil & Gas Total (In thousands) Product revenue $ 27,408 $ — $ 27,408 $ 65,665 $ — $ 65,665 Product cost of revenue 7,816 — 7,816 20,049 — 20,049 Product gross profit 19,592 — 19,592 45,616 — 45,616 License and development revenue (1) — — — — 26,895 26,895 Operating expenses General and administrative 606 439 1,045 1,467 1,601 3,068 Sales and marketing 1,507 30 1,537 4,307 106 4,413 Research and development 723 2,956 3,679 2,585 12,720 15,305 Amortization of intangible assets 4 — 4 12 — 12 Impairment of long-lived assets (2) — — — — 2,332 2,332 Total operating expenses 2,840 3,425 6,265 8,371 16,759 25,130 Operating income (loss) $ 16,752 $ (3,425 ) 13,327 $ 37,245 $ 10,136 47,381 Less: Corporate operating expenses 7,249 19,900 Income from operations 6,078 27,481 Other income, net 105 750 Income before income taxes $ 6,183 $ 28,231 (1) See Note 12 , “ VorTeq Partnership and License Agreement ,” for additional discussion regarding the termination of the VorTeq License Agreement . (2) See Note 4 , “ Other Financial Information – Property and Equipment ,” for additional discussion regarding the impairment of certain VorTeq long-lived assets that were directly related to obligations under the VorTeq License Agreement . Three Months Ended September 30, 2019 Nine Months Ended September 30, 2019 Water Oil & Gas Total Water Oil & Gas Total (In thousands) Product revenue $ 21,752 $ — $ 21,752 $ 56,946 $ 104 $ 57,050 Product cost of revenue 5,425 — 5,425 15,655 188 15,843 Product gross profit (loss) 16,327 — 16,327 41,291 (84 ) 41,207 License and development revenue — 3,098 3,098 — 10,391 10,391 Operating expenses General and administrative 359 431 790 1,456 1,207 2,663 Sales and marketing 1,850 92 1,942 5,058 674 5,732 Research and development 886 5,667 6,553 2,794 13,335 16,129 Amortization of intangible assets 156 — 156 469 — 469 Total operating expenses 3,251 6,190 9,441 9,777 15,216 24,993 Operating income (loss) $ 13,076 $ (3,092 ) 9,984 $ 31,514 $ (4,909 ) 26,605 Less: Corporate operating expenses 5,413 15,330 Income from operations 4,571 11,275 Other income, net 495 1,474 Income before income taxes $ 5,066 $ 12,749

Concentrations (Tables)

Concentrations (Tables)	9 Months Ended
	Sep. 30, 2020
Risks and Uncertainties [Abstract]
Schedules of Concentration of Risk, by Risk Factor	The following table presents customers accounting for 10% or more of the Company’s product revenue by segment. Although certain customers might account for greater than 10% of the Company’s revenue at any one point in time, the concentration of revenue between a limited number of large engineering, procurement and construction (“EPC”) firms shifts regularly, depending on contract negotiations. The percentages by customer reflect specific relationships or contracts that would concentrate the Company’s revenue for the periods presented and does not indicate a trend specific to any one customer. Three Months Ended September 30, Nine Months Ended September 30, Segment 2020 2019 2020 2019 Customer A Water 30% ** 27% ** Customer B Water 28% ** 24% 17% Customer C Water ** 11% 12% ** Customer D Water ** 26% ** 10% ** Zero or less than 10%.

Revenue - Schlumberger Technolo

Revenue - Schlumberger Technology Corporation (Details) - USD ($) $ in Thousands	Oct. 14, 2015	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue from External Customer [Line Items]
Revenue		$ 27,408		$ 24,850	$ 92,560	$ 67,441
License and development revenue
Revenue from External Customer [Line Items]
Revenue		$ 0		$ 3,098	26,895	$ 10,391
VorTeq License Agreement | Affiliated Entity | License and development revenue | Schlumberger Technology Corporation
Revenue from External Customer [Line Items]
Up front non-refundable payment	$ 75,000
Revenue			$ 24,400		$ 24,400

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 27,408	$ 24,850	$ 92,560	$ 67,441
PX Pressure Exchangers, pumps and turbo devices, and other
Disaggregation of Revenue [Line Items]
Revenue	27,408	21,752	65,665	57,050
License and development revenue
Disaggregation of Revenue [Line Items]
Revenue	0	3,098	26,895	10,391
Product
Disaggregation of Revenue [Line Items]
Revenue	27,408	21,752	65,665	57,050
Middle East and Africa
Disaggregation of Revenue [Line Items]
Revenue	22,667	16,691	55,402	36,297
Americas
Disaggregation of Revenue [Line Items]
Revenue	1,157	5,325	30,414	18,369
Asia
Disaggregation of Revenue [Line Items]
Revenue	2,226	2,188	3,618	9,364
Europe
Disaggregation of Revenue [Line Items]
Revenue	1,358	646	3,126	3,411
Water
Disaggregation of Revenue [Line Items]
Revenue	27,408	21,752	65,665	56,946
Water | PX Pressure Exchangers, pumps and turbo devices, and other
Disaggregation of Revenue [Line Items]
Revenue	27,408	21,752	65,665	56,946
Water | License and development revenue
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Water | Middle East and Africa
Disaggregation of Revenue [Line Items]
Revenue	22,667	16,691	55,402	36,193
Water | Americas
Disaggregation of Revenue [Line Items]
Revenue	1,157	2,227	3,519	7,978
Water | Asia
Disaggregation of Revenue [Line Items]
Revenue	2,226	2,188	3,618	9,364
Water | Europe
Disaggregation of Revenue [Line Items]
Revenue	1,358	646	3,126	3,411
Oil & Gas
Disaggregation of Revenue [Line Items]
Revenue	0	3,098	26,895	10,495
Oil & Gas | PX Pressure Exchangers, pumps and turbo devices, and other
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	104
Oil & Gas | License and development revenue
Disaggregation of Revenue [Line Items]
Revenue	0	3,098	26,895	10,391
Oil & Gas | Middle East and Africa
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	104
Oil & Gas | Americas
Disaggregation of Revenue [Line Items]
Revenue	0	3,098	26,895	10,391
Oil & Gas | Asia
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Oil & Gas | Europe
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Operating Segments | License and development revenue
Disaggregation of Revenue [Line Items]
Revenue	0	3,098	26,895	10,391
Operating Segments | Product
Disaggregation of Revenue [Line Items]
Revenue	27,408	21,752	65,665	57,050
Operating Segments | Water | License and development revenue
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Operating Segments | Water | Product
Disaggregation of Revenue [Line Items]
Revenue	27,408	21,752	65,665	56,946
Operating Segments | Oil & Gas | License and development revenue
Disaggregation of Revenue [Line Items]
Revenue	0	3,098	26,895	10,391
Operating Segments | Oil & Gas | Product
Disaggregation of Revenue [Line Items]
Revenue	$ 0	$ 0	$ 0	$ 104

Revenue - Contract Assets and L

Revenue - Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Accounts receivable, net	$ 11,055		$ 12,979
Contract assets, current (included in prepaid expenses and other current assets)	1,198		501
Contract assets, non-current (included in other assets, non-current)	241		191
Total contract assets	1,439	$ 890	692	$ 1,090	$ 1,936	$ 4,083
Current contract liabilities:
Customer deposits	792		1,506
Deferred revenue:
License and development	0		13,846
Product	78		78
Service	290		316
Total deferred revenue	368		14,240
Total current contract liabilities	1,160		15,746
Non-current contract liabilities, deferred revenue:
License and development	0		13,048
Service	104		72
Total non-current contract liabilities	104		13,120
Total contract liabilities	$ 1,264	$ 1,077	$ 28,866	$ 32,682	$ 35,079	$ 42,809

Revenue - Significant Changes i

Revenue - Significant Changes in Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Change In Contract With Customer, Asset [Roll Forward]
Contract assets balance, beginning of period	$ 890	$ 1,936	$ 692	$ 4,083
Transferred to trade receivables	(9,619)	(4,773)	(19,464)	(8,371)
Additions to contract assets	10,168	3,927	20,211	5,378
Contract assets balance, end of period	1,439	1,090	1,439	1,090
Change In Contract With Customer, Liability [Roll Forward]
Contract liabilities balance, beginning of period	1,077	35,079	28,866	42,809
Revenue recognized	(19)	(3,582)	(29,750)	(10,901)
Increase due to cash received, excluding amounts recognized as revenue during the period	206	1,185	2,148	774
Contract liabilities balance, end of period	$ 1,264	$ 32,682	$ 1,264	$ 32,682

Revenue - Remaining Performance

Revenue - Remaining Performance Obligation (Details) $ in Thousands	Sep. 30, 2020USD ($)
Revenue from Contract with Customer [Abstract]
Performance obligations expected to be satisfied	$ 22,598
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-10-01
Revenue from Contract with Customer [Abstract]
Performance obligations expected to be satisfied	$ 4,619
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied, expected timing	3 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue from Contract with Customer [Abstract]
Performance obligations expected to be satisfied	$ 17,964
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue from Contract with Customer [Abstract]
Performance obligations expected to be satisfied	$ 15
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied, expected timing	1 year

Earnings per Share - Computatio

Earnings per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net income	$ 5,387	$ 5,149	$ 22,934	$ 11,522
Denominator (weighted average shares):
Basic common shares outstanding (in shares)	55,692	54,975	55,573	54,594
Dilutive stock awards (in shares)	779	1,409	870	1,377
Diluted common shares outstanding (in shares)	56,471	56,384	56,443	55,971
Earnings per share - Basic (in dollars per share)	$ 0.10	$ 0.09	$ 0.41	$ 0.21
Earnings per share - Diluted (in dollars per share)	$ 0.10	$ 0.09	$ 0.41	$ 0.21

Earnings per Share - Antidiluti

Earnings per Share - Antidilutive Securities Excluded From Computation of Diluted Earnings Per Share (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Anti-dilutive shares excluded from net income per share calculation (in shares)	3,033	1,610	2,700	1,964

Other Financial Information - C

Other Financial Information - Cash and Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018
Other Financial Information [Abstract]
Cash and cash equivalents	$ 80,149	$ 26,387	$ 29,696
Restricted cash, non-current	103	101	101
Total cash, cash equivalents and restricted cash	$ 80,252	$ 26,488	$ 29,797	$ 22,138

Other Financial Information - A

Other Financial Information - Accounts Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Other Financial Information [Abstract]
Accounts receivable, gross	$ 11,425	$ 13,287
Allowance for doubtful accounts	(370)	(308)
Accounts receivable, net	$ 11,055	$ 12,979

Other Financial Information - I

Other Financial Information - Inventories (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Other Financial Information [Abstract]
Raw materials	$ 4,345	$ 3,742
Work in process	2,877	2,141
Finished goods	3,440	4,434
Inventories, net	$ 10,662	$ 10,317

Other Financial Information -_2

Other Financial Information - Inventory Valuation Reserves (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Dec. 31, 2019
Loss Contingencies [Line Items]
Inventory valuation reserves	$ 0.5	$ 0.5	$ 0.4
COVID-19
Loss Contingencies [Line Items]
Expense to product cost of revenue	$ 0.3	$ 1.5

Other Financial Information - P

Other Financial Information - Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Property, Plant and Equipment [Line Items]
Impairment of long-lived assets	$ 0	$ 0	$ 2,332	$ 0
Schlumberger Technology Corporation | VorTeq License Agreement | Affiliated Entity
Property, Plant and Equipment [Line Items]
Impairment of long-lived assets			$ 2,300

Other Financial Information -_3

Other Financial Information - Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Other Financial Information [Abstract]
Payroll, incentives and commissions payable	$ 6,270		$ 6,040
Warranty reserve	747	$ 673	631	$ 633	$ 599	$ 478
Other accrued expenses and current liabilities	1,637		3,198
Total accrued expenses and other current liabilities	$ 8,654		$ 9,869

Investments and Fair Value Me_3

Investments and Fair Value Measurements - Financial Assets Measured on Recurring Basis (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Total fair value of financial assets	$ 0		$ 0
Transfer between Level 1 and Level 2					$ 0
Transfers between Level 2 and Level 1	0		0		0
Debt Securities, Available-for-sale, Unrealized Gain (Loss) [Abstract]
Amortized Cost	79,282,000		79,282,000		85,780,000
Gross Unrealized Gains	206,000		206,000		59,000
Gross Unrealized Losses	(2,000)		(2,000)		(16,000)
Fair Value	79,486,000		79,486,000		85,823,000
Proceeds from Sale and Maturity of Debt Securities, Available-for-sale
Proceeds from sale of available-for sale securities	806,000	$ 3,535,000	10,573,000	$ 3,535,000
U.S. Treasury securities
Proceeds from Sale and Maturity of Debt Securities, Available-for-sale
Proceeds from sale of available-for sale securities	0	998,000	0	998,000
Corporate notes and bonds
Proceeds from Sale and Maturity of Debt Securities, Available-for-sale
Proceeds from sale of available-for sale securities	806,000	$ 2,537,000	10,573,000	$ 2,537,000
Cash equivalents
Debt Securities, Available-for-sale, Unrealized Gain (Loss) [Abstract]
Amortized Cost	53,695,000		53,695,000		11,668,000
Gross Unrealized Gains	0		0		0
Gross Unrealized Losses	0		0		0
Fair Value	53,695,000		53,695,000		11,668,000
Short-term investments
Debt Securities, Available-for-sale, Unrealized Gain (Loss) [Abstract]
Amortized Cost	24,192,000		24,192,000		58,697,000
Gross Unrealized Gains	183,000		183,000		50,000
Gross Unrealized Losses	(2,000)		(2,000)		(11,000)
Fair Value	24,373,000		24,373,000		58,736,000
Long-term investments
Debt Securities, Available-for-sale, Unrealized Gain (Loss) [Abstract]
Amortized Cost	1,395,000		1,395,000		15,415,000
Gross Unrealized Gains	23,000		23,000		9,000
Gross Unrealized Losses	0		0		(5,000)
Fair Value	1,418,000		1,418,000		15,419,000
Level 1 | Cash equivalents | Money Market Funds
Debt Securities, Available-for-sale, Unrealized Gain (Loss) [Abstract]
Amortized Cost	53,695,000		53,695,000		86,000
Gross Unrealized Gains	0		0		0
Gross Unrealized Losses	0		0		0
Fair Value	53,695,000		53,695,000		86,000
Level 2 | Cash equivalents | U.S. Treasury securities
Debt Securities, Available-for-sale, Unrealized Gain (Loss) [Abstract]
Amortized Cost	0		0		11,582,000
Gross Unrealized Gains	0		0		0
Gross Unrealized Losses	0		0		0
Fair Value	0		0		11,582,000
Level 2 | Short-term investments | U.S. Treasury securities
Debt Securities, Available-for-sale, Unrealized Gain (Loss) [Abstract]
Amortized Cost	3,084,000		3,084,000		2,746,000
Gross Unrealized Gains	16,000		16,000		1,000
Gross Unrealized Losses	0		0		0
Fair Value	3,100,000		3,100,000		2,747,000
Level 2 | Short-term investments | Corporate notes and bonds
Debt Securities, Available-for-sale, Unrealized Gain (Loss) [Abstract]
Amortized Cost	21,108,000		21,108,000		55,951,000
Gross Unrealized Gains	167,000		167,000		49,000
Gross Unrealized Losses	(2,000)		(2,000)		(11,000)
Fair Value	21,273,000		21,273,000		55,989,000
Level 2 | Long-term investments | Corporate notes and bonds
Debt Securities, Available-for-sale, Unrealized Gain (Loss) [Abstract]
Amortized Cost	1,395,000		1,395,000		15,415,000
Gross Unrealized Gains	23,000		23,000		9,000
Gross Unrealized Losses	0		0		(5,000)
Fair Value	1,418,000		1,418,000		15,419,000
Measured On Recurring Basis
Debt Securities, Available-for-sale [Line Items]
Total fair value of financial liabilities					0
Measured On Recurring Basis | Level 3
Debt Securities, Available-for-sale [Line Items]
Total fair value of financial liabilities	0		0
Total fair value of financial assets	$ 0		$ 0		$ 0

Investments and Fair Value Me_4

Investments and Fair Value Measurements - Gross Unrealized Losses and Fair Values of Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Fair Value	$ 938	$ 20,781
Gross Unrealized Losses	(2)	(16)
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Fair Value	0	2,027
Gross Unrealized Losses	0	0
Corporate notes and bonds
Debt Securities, Available-for-sale [Line Items]
Fair Value	938	18,754
Gross Unrealized Losses	$ (2)	$ (16)

Goodwill - Goodwill (Details)

Goodwill - Goodwill (Details) - USD ($)	3 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 12,790,000	$ 12,790,000
Goodwill impairment charge	$ 0

Lines of Credit - Loan Agreemen

Lines of Credit - Loan Agreements and Stand-by Letters of Credit (Details) - USD ($)	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019	Jan. 27, 2017
Standby Letters of Credit
Line of Credit Facility [Line Items]
Letters of credit outstanding, amount	$ 12,500,000	$ 11,800,000
Loan and Pledge Agreement
Line of Credit Facility [Line Items]
Long-term debt	$ 0	$ 0
Loan and Pledge Agreement | Standby Letters of Credit
Line of Credit Facility [Line Items]
Term past expiration of agreement	1 year
Debt instrument, term	3 years
Line of Credit | Loan and Pledge Agreement | Committed Revolving Credit Line
Line of Credit Facility [Line Items]
Maximum borrowing capacity			$ 16,000,000
Line of Credit | Loan and Pledge Agreement | Uncommitted Revolving Credit Line
Line of Credit Facility [Line Items]
Maximum borrowing capacity			4,000,000
Line of Credit | Loan and Pledge Agreement | Standby Letters of Credit
Line of Credit Facility [Line Items]
Commitment fee percentage	0.70%
Line of Credit | Foreign Subsidiary | Loan and Pledge Agreement
Line of Credit Facility [Line Items]
Maximum borrowing capacity			$ 66,000,000
Other Financial Institution | Line of Credit | Loan and Pledge Agreement
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 5,100,000

- Operating Lease Obligations (

- Operating Lease Obligations (Details) $ in Millions	Mar. 01, 2020USD ($)ft²term	Jan. 01, 2020USD ($)ft²aterm
Office And Warehouse, Katy, TX
Loss Contingencies [Line Items]
Area of leased space | ft²		25,200
Area of land | a		4.5
Operating leases, rent expense (per month)		$ 0.3
Operating leases, rent expense, annual increase, percent		3.00%
Operating leases, rent expense, term of contract		$ 3.6
Lease initial term		120 months
Operating lease, number of renewal terms | term		2
Operating lease, renewal term		5 years
Operating lease, renewal to extend lease, written notice period		6 months
Tracy, California | Office And Warehouse Space, Tracy Lease
Loss Contingencies [Line Items]
Area of leased space | ft²	54,429
Operating leases, rent expense (per month)	$ 0.4
Operating leases, rent expense, annual increase, percent	3.00%
Operating leases, rent expense, term of contract	$ 5
Lease initial term	122 months
Operating lease, number of renewal terms | term	1
Operating lease, renewal term	5 years
Operating lease, renewal to extend lease, written notice period	9 months

Commitments and Contingencies -

Commitments and Contingencies - Lease Cost and Terms (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Operating lease expense	$ 669	$ 471	$ 1,940	$ 1,421
Cash payments	655	459	1,763	1,365
Non-cash lease liabilities arising from obtaining right-of-use assets	$ 0	$ 0	$ 6,384	$ 0
Weighted average remaining lease term	8 years 8 months 12 days		8 years 8 months 12 days
Weighted average discount rate	7.00%		7.00%

Commitments and Contingencies_2

Commitments and Contingencies - Maturities of Lease Liabilities (Details) $ in Thousands	Sep. 30, 2020USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2020 (remaining three months)	$ 635
2021	2,431
2022	2,650
2023	2,580
2024	2,812
2025 and thereafter	13,197
Total	24,305
Less imputed lease interest	(6,294)
Total lease liabilities	$ 18,011

Commitments and Contingencies_3

Commitments and Contingencies - Product Warranty Liability (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Provision for warranty claims			$ 316	$ 339
Movement in Standard Product Warranty Accrual [Roll Forward]
Warranty reserve balance, beginning of period	$ 673	$ 599	631	478
Warranty costs charged to cost of revenue	143	97	316	339
Utilization charges against reserve	(5)	(15)	(7)	(53)
Release of accrual related to expired warranties	(64)	(48)	(193)	(131)
Warranty reserve balance, end of period	$ 747	$ 633	$ 747	$ 633

Commitments and Contingencies_4

Commitments and Contingencies - Purchase Obligations (Details) $ in Millions	9 Months Ended
	Sep. 30, 2020USD ($)
Commitments and Contingencies Disclosure [Abstract]
Long-term purchase commitment	$ 5.2

Income Taxes - Provision and Ef

Income Taxes - Provision and Effective Tax Rate (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Provision for (benefit from) income taxes	$ 796	$ (83)	$ 5,297	$ 1,227
Effective tax rate	12.90%	(1.60%)	18.80%	9.60%
Effective tax rate, excluding discrete items	13.40%	11.80%	18.60%	17.70%

Segment Reporting - Summary of

Segment Reporting - Summary of Financial Information by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Revenue	$ 27,408	$ 24,850	$ 92,560	$ 67,441
General and administrative	6,271	5,711	18,751	16,790
Sales and marketing	2,141	2,367	5,776	6,710
Research and development	5,098	6,620	18,159	16,354
Amortization of intangible assets	4	156	12	469
Impairment of long-lived assets	0	0	2,332	0
Total operating expenses	13,514	14,854	45,030	40,323
Income from operations	6,078	4,571	27,481	11,275
Other income	105	495	750	1,474
Income before income taxes	6,183	5,066	28,231	12,749
Water
Segment Reporting Information [Line Items]
Revenue	27,408	21,752	65,665	56,946
Oil & Gas
Segment Reporting Information [Line Items]
Revenue	0	3,098	26,895	10,495
Operating Segments
Segment Reporting Information [Line Items]
General and administrative	1,045	790	3,068	2,663
Sales and marketing	1,537	1,942	4,413	5,732
Research and development	3,679	6,553	15,305	16,129
Amortization of intangible assets	4	156	12	469
Impairment of long-lived assets	0		2,332
Total operating expenses	6,265	9,441	25,130	24,993
Income from operations	13,327	9,984	47,381	26,605
Operating Segments | Water
Segment Reporting Information [Line Items]
General and administrative	606	359	1,467	1,456
Sales and marketing	1,507	1,850	4,307	5,058
Research and development	723	886	2,585	2,794
Amortization of intangible assets	4	156	12	469
Impairment of long-lived assets	0		0
Total operating expenses	2,840	3,251	8,371	9,777
Income from operations	16,752	13,076	37,245	31,514
Operating Segments | Oil & Gas
Segment Reporting Information [Line Items]
General and administrative	439	431	1,601	1,207
Sales and marketing	30	92	106	674
Research and development	2,956	5,667	12,720	13,335
Amortization of intangible assets	0	0	0	0
Impairment of long-lived assets	0		2,332
Total operating expenses	3,425	6,190	16,759	15,216
Income from operations	(3,425)	(3,092)	10,136	(4,909)
Corporate
Segment Reporting Information [Line Items]
Total operating expenses	7,249	5,413	19,900	15,330
Product
Segment Reporting Information [Line Items]
Revenue	27,408	21,752	65,665	57,050
Product cost of revenue	7,816	5,425	20,049	15,843
Product gross profit	19,592	16,327	45,616	41,207
Product | Operating Segments
Segment Reporting Information [Line Items]
Revenue	27,408	21,752	65,665	57,050
Product cost of revenue	7,816	5,425	20,049	15,843
Product gross profit	19,592	16,327	45,616	41,207
Product | Operating Segments | Water
Segment Reporting Information [Line Items]
Revenue	27,408	21,752	65,665	56,946
Product cost of revenue	7,816	5,425	20,049	15,655
Product gross profit	19,592	16,327	45,616	41,291
Product | Operating Segments | Oil & Gas
Segment Reporting Information [Line Items]
Revenue	0	0	0	104
Product cost of revenue	0	0	0	188
Product gross profit	0	0	0	(84)
License and development revenue
Segment Reporting Information [Line Items]
Revenue	0	3,098	26,895	10,391
License and development revenue | Water
Segment Reporting Information [Line Items]
Revenue	0	0	0	0
License and development revenue | Oil & Gas
Segment Reporting Information [Line Items]
Revenue	0	3,098	26,895	10,391
License and development revenue | Operating Segments
Segment Reporting Information [Line Items]
Revenue	0	3,098	26,895	10,391
License and development revenue | Operating Segments | Water
Segment Reporting Information [Line Items]
Revenue	0	0	0	0
License and development revenue | Operating Segments | Oil & Gas
Segment Reporting Information [Line Items]
Revenue	$ 0	$ 3,098	$ 26,895	$ 10,391

Concentrations - Product Revenu

Concentrations - Product Revenue Concentrations (Details) - Product Revenue - Customer Concentration Risk	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Water | Customer A
Concentration Risk [Line Items]
Percentage of product revenue	30.00%		27.00%
Water | Customer B
Concentration Risk [Line Items]
Percentage of product revenue	28.00%		24.00%	17.00%
Water | Customer C
Concentration Risk [Line Items]
Percentage of product revenue		11.00%	12.00%
Water | Customer D
Concentration Risk [Line Items]
Percentage of product revenue		26.00%		10.00%
License and Development Revenue | One Customer
Concentration Risk [Line Items]
Percentage of product revenue		100.00%	100.00%	100.00%

VorTeq Partnership and Licens_2

VorTeq Partnership and License Agreement (Details) $ in Thousands	Oct. 14, 2015USD ($)payment	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue		$ 27,408		$ 24,850	$ 92,560	$ 67,441
VorTeq License Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
VorTeq license agreement payments	$ 125,000
Number of milestone payments | payment	2
VorTeq milestone payment to be received	$ 25,000
License and development revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue		$ 0		$ 3,098	26,895	$ 10,391
License and development revenue | Affiliated Entity | Schlumberger Technology Corporation | VorTeq License Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Up front non-refundable payment	$ 75,000
Revenue			$ 24,400		$ 24,400