Energy Recovery (ERII) 10-Q 3 May 18 2018 Q1 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2018	Apr. 27, 2018
Document And Entity Information
Entity Registrant Name	Energy Recovery, Inc.
Entity Central Index Key	1,421,517
Trading Symbol	erii
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		53,503,435
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 32,153	$ 27,780
Restricted cash	1,205	2,664
Short-term investments	58,108	70,020
Accounts receivable, net of allowance for doubtful accounts of $77 and $103 at March 31, 2018 and December 31, 2017, respectively	12,754	12,465
Contract assets	4,948	6,278
Inventories	7,328	5,514
Prepaid expenses and other current assets	1,545	1,342
Total current assets	118,041	126,063
Restricted cash, non-current	85	182
Deferred tax assets, non-current	8,309	7,933
Property and equipment, net	12,742	13,393
Operating lease, right of use asset	2,511	2,843
Goodwill	12,790	12,790
Other intangible assets, net	1,112	1,269
Other assets, non-current	267	12
Total assets	155,857	164,485
Current liabilities:
Accounts payable	2,341	4,091
Accrued expenses and other current liabilities	3,990	7,948
Lease liabilities	1,641	1,603
Income taxes payable	429	432
Accrued warranty reserve	359	366
Contract liabilities	16,831	15,909
Current portion of long-term debt	12	11
Total current liabilities	25,603	30,360
Long-term debt, less current portion	13	16
Lease liabilities, non-current	1,273	1,698
Contract liabilities, non-current	37,239	40,517
Other non-current liabilities	255	0
Total liabilities	64,383	72,591
Commitments and Contingencies (Note 9)
Stockholders’ equity:
Preferred stock, $0.001 par value; 10,000,000 shares authorized; no shares issued or outstanding at March 31, 2018 and December 31, 2017	0	0
Common stock, $0.001 par value; 200,000,000 shares authorized; 58,699,997 shares issued and 54,027,314 shares outstanding at March 31, 2018 and 58,168,433 shares issued and 53,905,600 shares outstanding at December 31, 2017	59	58
Additional paid-in capital	152,850	149,006
Accumulated comprehensive loss	(168)	(125)
Treasury stock, at cost, 4,672,683 shares repurchased at March 31, 2018 and 4,262,833 shares repurchased at December 31, 2017	(23,981)	(20,486)
Accumulated deficit	(37,286)	(36,559)
Total stockholders’ equity	91,474	91,894
Total liabilities and stockholders’ equity	$ 155,857	$ 164,485

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ (77)	$ (103)
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	58,699,997	58,168,433
Common stock, shares outstanding (in shares)	54,027,314	53,905,600
Treasury stock, at cost, shares (in shares)	4,672,683	4,262,833

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Product revenue	$ 11,058	$ 12,245
Product cost of revenue	3,314	4,612
Product gross profit	7,744	7,633
License and development revenue	2,749	2,248
Operating expenses:
General and administrative	5,837	4,408
Sales and marketing	1,912	2,453
Research and development	3,917	2,509
Amortization of intangible assets	158	158
Total operating expenses	11,824	9,528
(Loss) income from operations	(1,331)	353
Other income (expense):
Interest income	301	171
Interest expense	0	(1)
Other non-operating expense, net	(53)	(53)
Total other income, net	248	117
(Loss) income before income taxes	(1,083)	470
(Benefit from) provision for income taxes	(357)	48
Net (loss) income	$ (726)	$ 422
(Loss) income per share:
Basic (in dollars per share)	$ (0.01)	$ 0.01
Diluted (in dollars per share)	$ (0.01)	$ 0.01
Number of shares used in per share calculations:
Basic (in shares)	53,987	53,825
Diluted (in shares)	53,987	56,056

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive (Loss) Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (726)	$ 422
Foreign currency translation adjustments
Foreign currency translation adjustments	21	10
Unrealized (loss) income on investments	(64)	1
Other comprehensive (loss) income, net of tax	(43)	11
Comprehensive (loss) income	$ (769)	$ 433

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash Flows From Operating Activities:
Net (loss) income	$ (726)	$ 422
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Stock-based compensation	2,242	1,113
Depreciation and amortization	1,124	881
Amortization of premiums on investments	90	113
Provision for warranty claims	48	55
Reversal of accruals related to expired warranties	(50)	(63)
Unrealized loss (gain) on foreign currency translation	113	(15)
Provision for doubtful accounts	8	4
Adjustments for excess or obsolete inventory	4	71
Deferred income taxes	(376)	(93)
Loss on disposal of fixed assets	21	0
Other non-cash adjustments	3	(31)
Changes in operating assets and liabilities:
Accounts receivable	(297)	2,581
Contract assets	1,330	(3,556)
Inventories	(1,824)	(343)
Prepaid and other assets	(127)	(553)
Accounts payable	(1,467)	189
Accrued expenses and other liabilities	(4,092)	(3,566)
Income taxes payable	(3)	124
Contract liabilities	(2,354)	(2,157)
Net cash used in operating activities	(6,333)	(4,824)
Cash Flows From Investing Activities:
Maturities of marketable securities	25,623	9,646
Purchases of marketable securities	(13,935)	(9,355)
Capital expenditures	(626)	(532)
Net cash provided by (used in) investing activities	11,062	(241)
Cash Flows From Financing Activities:
Net proceeds from issuance of common stock	1,636	2,992
Tax payment for employee shares withheld	(37)	(153)
Repayment of long-term debt	(2)	(2)
Repurchase of common stock	(3,495)	0
Net cash (used in) provided by financing activities	(1,898)	2,837
Effect of exchange rate differences on cash and cash equivalents	(14)	15
Net change in cash, cash equivalents and restricted cash	2,817	(2,213)
Cash, cash equivalents and restricted cash, beginning of year	30,626	65,748
Cash, cash equivalents and restricted cash, end of period	$ 33,443	$ 63,535

Description of Business and Sig

Description of Business and Significant Accounting Policies	3 Months Ended
	Mar. 31, 2018
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,” “Energy Recovery,” “our,” “us,” or “we”) is an energy solutions provider to industrial fluid flow markets worldwide. The Company’s core competencies are fluid dynamics and advanced material science. The Company’s products make industrial processes more operationally and capital expenditure efficient. The Company’s solutions convert wasted pressure energy into a reusable asset and preserve or eliminate pumping technology in hostile processing environments. The Company’s solutions are marketed and sold in fluid flow markets, such as water, oil & gas, and chemical processing, under the trademarks ERI ® , PX ® , Pressure Exchanger ® , PX Pressure Exchanger ® , VorTeq ™ , MTeq ™ , 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.”) and the Republic of Ireland (“Ireland”). Basis of Presentation The Company’s Condensed Consolidated Financial Statements include the accounts of Energy Recovery, Inc. and its wholly-owned subsidiaries. All significant intercompany accounts and transactions have been eliminated in consolidation. The accompanying Condensed Consolidated Financial Statements have been prepared by the Company, without audit, 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, 2017 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 March 31, 2018 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, 2017 included in the Company’s Annual Report on Form 10-K filed with the SEC on March 8, 2018. In the opinion of management, 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 the Condensed Consolidated Financial Statements in conformity with 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 to Condensed Consolidated Financial Statements. 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 the Company’s reported financial results are revenue recognition; capitalization of research and development assets; allowance for doubtful accounts; allowance for product warranty; valuation of stock options; valuation and impairment of goodwill and acquired intangible assets; useful lives for depreciation and amortization; 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.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	3 Months Ended
	Mar. 31, 2018
Accounting Changes and Error Corrections [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements Recently Adopted Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09 (“ASU 2014-09”), Revenue from Contracts with Customers (Topic 606), referred to as Accounting Standards Codification (“ASC”) 606 (“ASC 606”) or “New Revenue Standard .” ASC 606 supersedes the revenue recognition requirements of ASC 605, Revenue Recognition , and requires entities to recognize revenue when control of promised goods or services is transferred to customers at an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods and services. The update also requires more detailed disclosures to enable readers of financial statements to understand the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. ASC 606 permits the use of either the full retrospective or cumulative effect transition (modified retrospective) method upon adoption. In March and April 2016, the FASB issued ASU No. 2016-08 (“ASU 2016-08”), Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net) and ASU No. 2016-10 (“ASU 2016-10”), Revenue from Contracts with Customers (Topic 606) Identifying Performance Obligations and Licensing, respectively. The amendments in these updates are intended to improve the operability and understandability of the implementation guidance on principal versus agent considerations and to clarify two aspects of ASC 606: identifying performance obligations and the licensing implementation guidance, while retaining the related principles for those areas. The effective date and transition requirements for both ASU 2016-08 and ASU 2016-10 are the same as those for ASU 2014-09, as referred. The Company adopted ASC 606 as of January 1, 2018 using the full retrospective transition method. To assess the impact of and to implement ASC 606, the Company formed a project team, which has operated since 2014, to evaluate internal processes. The Company has implemented changes to its current policies and practices, and internal controls over financial reporting to address the requirements of the standard. Water Segment Revenue . Performance obligations identified under ASC 606, are consistent with deliverables identified under ASC 605. Revenue recognition for performance obligations accounted for under ASC 606 is consistent with ASC 605 given the transfer of control of the promised goods or services follows the same pattern. Adoption of ASC 606 did not have a material impact on the timing of revenue and expense recognition. Oil & Gas Segment - Cost-to-Total Cost (“ CTC ”) Revenue . Performance obligations identified under ASC 606, are consistent with deliverables identified under ASC 605. Revenue recognition for performance obligations accounted for under ASC 606 is consistent with ASC 605 given the transfer of control of the promised goods or services follows the same pattern. Adoption of ASC 606 did not have a material impact on the timing of revenue and expense recognition. Oil & Gas Segment - License and Development Revenue . Under ASC 605, license and development revenue associated with the up-front non-refundable $75.0 million exclusivity payment received in connection with the VorTeq license agreement (the “ VorTeq License Agreement ”) that the Company entered into with Schlumberger Technology Corporation (the “ VorTeq Licensee ”) was recognized on a straight-line basis over the fifteen -year term of the license, while the two substantive milestone payments of $25.0 million each that could be earned under the license agreement were to be recognized in full when achieved under milestone accounting. Under ASC 606, license and development revenue, which includes both the upfront non-refundable $75.0 million exclusivity payment and the two milestone payments of $25.0 million each, when determined probable, is comprised of: • revenue recognition over time based on an input measure of progress based on a cost driver which management has determined is the best estimate of the progress made on the project during the period from inception until full commercialization for the amount allocated to the exclusive Missile (as defined in Note 14 , “ VorTeq Partnership and License Agreement ”) license and research and development services, and • revenue recognition related to stand-ready when and if available upgrades subsequent to full commercialization, recognized over time ratably over the period, which matches the transfer of benefit to the customer on a daily basis, commencing after full commercial launch until the expiration of the contract. The changes in license and development revenue due to the adoption of ASC 606 are as follows. Years Ended December 31, 2017 2016 2015 (In thousands) License and development revenue, as previously reported $ 5,000 $ 5,000 $ 1,042 Change in revenue due to adoption the New Revenue Standard 6,106 3,069 290 License and development revenue, as adjusted $ 11,106 $ 8,069 $ 1,332 The changes in the contract liability balance related to license and development revenue due to the adoption of ASC 606 are as follows. December 31, December 31, (In thousands) License and development contract liability, as previously reported $ 63,958 $ 68,958 Change in contract liability due to adoption the New Revenue Standard 9,465 3,359 License and development contract liability, as adjusted $ 54,493 $ 65,599 Performance obligations identified under ASC 606 differs somewhat from contingent and non-contingent deliverables identified under ASC 605 due to transfer of control considerations. Under ASC 606, the Company concluded that the Missile license represents functional intellectual property and that the license is not distinct from the research and development services to be provided prior to product commercialization. The transaction price allocated to this combined performance obligation of a continually evolving license will be recognized over the estimated period required to result in full commercial launch using an input measure of progress of the cost of salaries and wages related to the project prior to full commercial launch. The milestone method of accounting has been eliminated under ASC 606. Instead of recognizing the full amount of each milestone payment as revenue in the period in which it is achieved, the Company will revise its estimate of the transaction price to include development milestone payments only when they become probable of achievement and revenue will be recognized consistent with the input measure of progress. The Company has concluded that its obligation to provide when and if available updates to its technology in the period subsequent to full commercial launch represents a performance obligation. The transaction price allocated to this stand-ready performance obligation will be recognized ratably over the period commencing after full commercial launch until the expiration of the contract. See Note 14 , “ VorTeq Partnership and License Agreement ” for additional discussion on the VorTeq License Agreement , and Note 3 , “ Revenues ,” for further discussion of revenue recognition. In February 2016, the FASB issued ASU No. 2016-02 (“ASU 2016-02”), Leases (Topic 842), also referred to as “ASC 842” or “New Lease Standard,” which supersedes ASC 840, Leases (Topic 840) and provides principles for the recognition, measurement, presentation and disclosure of leases for both lessees and lessors. The FASB has continued to clarify this guidance through the issuance of additional ASUs. The new standard requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the lessee. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight-line basis over the term of the lease, respectively. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than twelve months regardless of classification. Leases with a term of twelve months or less will be accounted for similar to existing guidance for operating leases. The Company early adopted ASU 2016-02 on January 1, 2018 concurrent with the Company’s adoption of the New Revenue Standard and elected the available practical expedients. The adoption of ASU 2016-02 had no impact on the Company’s Condensed Consolidated Statements of Operations. The most significant impact was the recognition of right of use assets and liabilities for operating leases. Adoption of the standard required the Company to restate certain previously reported results, including the recognition of additional operating lease right of use assets and liabilities. In November 2016, the FASB issued ASU 2016-18 (“ASU 2016-18”), Statement of Cash Flows (Topic 230): Restricted Cash, also referred to as “New Cash Flow Presentation Standard.” ASU 2016-18 is intended to reduce diversity in practice in the classification and presentation of changes in restricted cash on the Consolidated Statement of Cash Flows. ASU 2016-18 requires that the Consolidated Statement of Cash Flows explain the change in total cash and equivalents and amounts generally described as restricted cash or restricted cash equivalents when reconciling the beginning-of-period and end-of-period total amounts. The standard also requires reconciliation between the total cash and equivalents and restricted cash presented on the Consolidated Statement of Cash Flows and the cash and cash equivalents balance presented on the Consolidated Balance Sheet. ASU 2016-18 is effective retrospectively on January 1, 2018. The Company adopted ASU 2016-18 on January 1, 2018. The Company recast its Condensed Consolidated Statements of Cash Flows for the prior period presented based on the restricted cash balance on the balance sheet date and has provided a reconciliation of cash, cash equivalents and restricted cash in Note 5 , “ Other Financial Information .” In January 2016, the FASB issued ASU No. 2016-01 (“ASU 2016-01”), Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. ASU 2016-01 modifies certain aspects of the recognition, measurement, presentation, and disclosure of financial instruments. For public entities, ASU 2016-01 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2017. The Company adopted ASU 2016-01 on January 1, 2018. The adoption ASU 2016-01 did not have a material impact on the Company’s financial position or results of operations. In August 2016, the FASB issued ASU No. 2016-15 (“ASU 2016-15”), Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. ASU 2016-15 impacts all entities that are required to present a statement of cash flows under ASC 230, Statement of Cash Flows . The amendment provides guidance on eight specific cash flow issues. For public entities, ASU 2016-15 is effective for fiscal periods beginning after December 15, 2017 and interim periods within those years. Adoption should be applied using a retrospective transition method to each period presented. The Company adopted ASU 2016-15 on January 1, 2018. The adoption of ASU 2016-15 did not have a material impact on the Company’s financial position or results of operations. In October 2016, the FASB issued ASU 2016-16 (“ASU 2016-16”), Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory. ASU 2016-16 requires recognition of the current and deferred income tax effects of an intra-entity asset transfer, other than inventory, when the transfer occurs, as opposed to legacy GAAP, which requires companies to defer the income tax effects of intra-entity asset transfers until the asset has been sold to an outside party. The income tax effects of intra-entity inventory transfers will continue to be deferred until the inventory is sold. ASU 2016-16 is effective on January 1, 2018, with early adoption permitted. The update is required to be adopted on a modified retrospective basis with the cumulative-effect adjustment recorded to retained earnings as of the beginning of the period of adoption. The Company adopted ASU 2016-16 on January 1, 2018. The adoption of ASU 2016-16 did not have a material impact on the Company’s financial position or results of operations. In May 2017, the FASB issued ASU No. 2017-09, Compensation – Stock Compensation (Topic 718): Scope of Modification Accounting. ASU 2017-09 provides guidance about which changes to the terms or conditions of a share-base payment award require an entity to apply modification accounting under ASC 718, Compensation – Stock Compensation . ASU 2017-09 is effective for annual periods and interim periods within those annual periods, beginning after December 15, 2017. The Company adopted ASU 2017-09 on January 1, 2018. The adoption of ASU 2017-09 did not have an impact on the Company’s financial position or results of operations. Impact of Recently Adopted Accounting Pronouncements The following table illustrates changes in the Condensed Consolidated Balance Sheets as previously reported prior to, and as adjusted subsequent to, the adoption of the New Revenue Standard and New Lease Standard in the first quarter of 2018. December 31, 2017 As Previously Reported Adoption of New Revenue Standard Adoption of New Lease Standard As Adjusted (In thousands) Assets Current assets: Contract assets $ 6,411 $ (133 ) $ — $ 6,278 Total current assets 126,196 (133 ) — 126,063 Non-current assets Deferred tax assets, non-current 7,902 31 — 7,933 Operating lease, right of use asset — — 2,843 2,843 Total assets 161,744 (102 ) 2,843 164,485 Liabilities and Stockholders’ Equity Current liabilities: Accrued expenses and other current liabilities 8,517 (469 ) (100 ) 7,948 Lease liabilities — — 1,603 1,603 Contract liabilities 6,416 9,493 — 15,909 Total current liabilities 19,833 9,024 1,503 30,360 Non-current liabilities Lease liabilities, non-current — — 1,698 1,698 Contract liabilities, non-current 59,006 (18,489 ) — 40,517 Other non-current liabilities 358 — (358 ) — Total liabilities 79,213 (9,465 ) 2,843 72,591 Stockholders’ equity: Accumulated deficit (45,922 ) 9,363 — (36,559 ) Total stockholders’ equity 82,531 9,363 — 91,894 Total liabilities and stockholders’ equity 161,744 (102 ) 2,843 164,485 The following table illustrates changes in the Condensed Consolidated Statement of Operations as previously reported prior to, and as adjusted subsequent to, the adoption of the New Revenue Standard in the first quarter of 2018. Three Months Ended March 31, 2017 As Previously Reported Adoption of New Revenue Standard As Adjusted (In thousands, except for per share data) Product revenue $ 12,261 $ (16 ) $ 12,245 Product cost of revenue 4,610 2 4,612 Product gross profit $ 7,651 $ (18 ) $ 7,633 License and development revenue $ 1,250 $ 998 $ 2,248 Income (loss) from operations (627 ) 980 353 Income (loss) before income taxes (510 ) 980 470 (Benefit from) provision for income taxes (77 ) 125 48 Net income (loss) (433 ) 855 422 Income (loss) per share: Basic $ (0.01 ) $ 0.02 $ 0.01 Diluted $ (0.01 ) $ 0.02 $ 0.01 Number of shares used in per share calculations: Basic 53,825 — 53,825 Diluted 53,825 2,231 56,056 The following table illustrates changes in the Company’s segment activities as previously reported prior to, and as adjusted subsequent to, the adoption of the New Revenue Standard in the first quarter of 2018. Three Months Ended March 31, 2017 As Previously Reported Adoption of New Revenue Standard As Adjusted (In thousands) Water Product revenue $ 10,716 $ — $ 10,716 Product cost of revenue 3,522 2 3,524 Product gross profit $ 7,194 $ (2 ) $ 7,192 Income (loss) from operations $ 4,957 $ (2 ) $ 4,955 Oil & Gas Product revenue $ 1,545 $ (16 ) $ 1,529 Product cost of revenue 1,088 — 1,088 Product gross profit $ 457 $ (16 ) $ 441 License and development revenue $ 1,250 $ 998 $ 2,248 Income (loss) from operations (1,529 ) 982 (547 ) The following table illustrates changes in the Condensed Consolidated Statement of Comprehensive Income (Loss) as previously reported prior to, and as adjusted subsequent to, the adoption of the New Revenue Standard in the first quarter of 2018. Three Months Ended March 31, 2017 As Previously Reported Adoption of New Revenue Standard As Adjusted (In thousands) Net income (loss) $ (433 ) $ 855 $ 422 Comprehensive income (loss) (422 ) 855 433 The following table illustrates changes in the Condensed Consolidated Statement of Cash Flows as previously reported prior to, and as adjusted subsequent to, the adoption of the New Revenue Standard and New Cash Flow Presentation Standard in the first quarter of 2018. Three Months Ended March 31, 2017 As Previously Reported Adoption of New Revenue Standard Adoption of New Cash Flow Presentation Standard As Adjusted (In thousands) Net (loss) income $ (433 ) $ 855 $ — $ 422 Changes in operating assets and liabilities: Accounts receivable 2,571 10 — 2,581 Contract assets (3,572 ) 16 — (3,556 ) Inventories (345 ) 2 — (343 ) Accrued expenses and other liabilities (3,162 ) (404 ) — (3,566 ) Contract liabilities (1,553 ) (604 ) — (2,157 ) Net cash used in operating activities (4,824 ) — — (4,824 ) Restricted cash (460 ) — 460 — Net cash used in investing activities (701 ) — 460 (241 ) Net change in cash, cash equivalents and restricted cash (2,673 ) — 460 (2,213 ) Cash, cash equivalents and restricted cash, beginning of year 61,364 — 4,384 65,748 Cash, cash equivalents and restricted cash, end of period 58,691 — 4,844 63,535 Recently issued accounting pronouncement not yet adopted In January 2017, the FASB issued ASU No. 2017-04 (“ASU 2017-04”), Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment. ASU 2017-04 eliminates Step 2 of the goodwill impairment quantitative test and allows for the determination of impairment by comparing the fair value of the reporting unit with its carrying amount. The amendments in this update should be applied on a prospective basis. For public entities which are SEC filers, this amendment is effective for annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted for testing dates after January 1, 2017. The Company expects to adopt this standard on January 1, 2020 and does not expect the adoption of ASU 2017-04 to have a material impact on its financial statements. In February 2018, the FASB issued ASU No. 2018-02 (“ASU 2018-02”), Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. ASU 2018-02 was issued to address the income tax accounting treatment of the stranded tax effects within other comprehensive income due to the prohibition of backward tracing due to an income tax rate change that was initially recorded in other comprehensive income. This issue came about from the enactment of the U.S. Tax Cuts and Jobs Act of 2017 (the “ Tax Act ”) that changed the Company’s income tax rate from 35% to 21% . ASU 2018-02 changed current accounting whereby an entity may elect to reclassify the stranded tax effect from accumulated other comprehensive income to retained earnings. The ASU 2018-02 is effective for periods beginning after December 15, 2018 although early adoption is permitted. The Company does not expect the adoption of ASU 2018-02 to have a material impact on its financial position or results of operations.

Revenue

Revenue	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue	Revenues Adoption of ASC 606, Revenue from Contracts with Customers On January 1, 2018, the Company adopted ASC 606 using the full retrospective transition method. The Company recorded a net reduction to opening retained earnings of $0.3 million as of January 1, 2016, due to the cumulative impact of adopting ASC 606. The impact to revenues as a result of applying ASC 606 was an increase of $1.0 million for the three months ended March 31, 2017 . Revenue Recognition Revenues are recognized when control of the promised goods or services is transferred to the Company’s customers, in an amount that reflects the consideration the Company expects to be entitled to in exchange for those goods or services. At the inception of each contract, performance obligations are identified and the total transaction price is allocated to the performance obligations. The Company’s payment terms vary based on the credit risk of its customer. For certain customer types, the Company requires payment before the products or services are delivered to the customer. The Company performs an evaluation of customer credit worthiness on an individual contract basis to assess whether collectability is reasonably assured at the inception of the contract. As part of this evaluation, the Company considers many factors about the individual customer, including the underlying financial strength of the customer and/or partnership consortium and the Company’s prior history or industry-specific knowledge about the customer and its supplier relationships. For smaller projects, the Company requires the customer to remit payment generally within 30 to 60 days after product delivery. In some cases, if credit worthiness cannot be determined, prepayment or other security is required. Sales commissions are expensed as incurred when product revenue is earned. These costs are recorded within sales and marketing expenses. The following table presents the Company’s revenues disaggregated by geography, based on the shipped to addresses of the Company’s customers and revenue source. Sales and usage-based taxes are excluded from revenues. Three Months Ended March 31, 2018 Water Oil & Gas Total (In thousands) Primary geographical market Middle East and Africa $ 6,102 $ 10 $ 6,112 Americas 1,101 2,749 3,850 Asia 2,673 — 2,673 Europe 1,172 — 1,172 Total $ 11,048 $ 2,759 $ 13,807 Major product/service line PX, pumps and turbo devices $ 11,048 $ — $ 11,048 License and development — 2,749 2,749 Oil & gas products — 10 10 Total $ 11,048 $ 2,759 $ 13,807 Three Months Ended March 31, 2017 Water Oil & Gas Total (In thousands) Primary geographical market Middle East and Africa $ 6,073 $ 1,530 $ 7,603 Americas 1,073 2,248 3,321 Asia 2,414 — 2,414 Europe 1,155 — 1,155 Total $ 10,715 $ 3,778 $ 14,493 Major product/service line PX, pumps and turbo devices $ 10,715 $ — $ 10,715 License and development — 2,248 2,248 Oil & gas products — 1,530 1,530 Total $ 10,715 $ 3,778 $ 14,493 Arrangements with Multiple Performance Obligations and Termination for Convenience The Company’s contracts with customers may include multiple performance obligations. For such arrangements, the Company allocates revenue to each performance obligation based on its relative stand-alone selling price. The Company generally determines standalone selling prices based on the prices charged to customers. With respect to termination, the Company does not have the ability to cancel the contract for convenience. In general, customers can cancel for convenience upon the payment of a termination fee that covers costs and profit. It is rare for customers to cancel contracts. Practical Expedients and Exemptions In the Water segment, the time period between when the Company transfers control of products to the customer and the payment for the products is, in general, less than one year and, therefore, the practical expedient with respect to a financing component has been adopted by the Company. With respect to taxes, the Company has made the policy election to exclude taxes from the measurement of the transaction price. The Company does not disclose the value of unsatisfied performance obligations for (i) contracts with an original expected length of one year or less and (ii) contracts for which the Company recognizes revenue at the amount to which the Company has the right to invoice for services performed. Contract Balances Contract balances by category are presented in the following table. Prior year amounts have been adjusted for the adoption of ASC 606 in the first quarter of 2018. See Note 2 , “ Recent Accounting Pronouncements ,” for reconciliation of prior year “ As Previously Reported ” and “ As Adjusted ” amounts. March 31, December 31, (In thousands) Trade receivables $ 12,754 $ 12,465 Contract assets: Unbilled receivables $ 1,413 $ 1,413 Unbilled receivables, projects 3,535 4,865 Total contract assets $ 4,948 $ 6,278 Current contract liabilities: Customer deposits $ 894 $ 414 Deferred revenue: Cost and estimated earnings in excess of billings 773 805 License and development 14,568 14,024 Product 469 550 Service 127 116 Total current contract liability 16,831 15,909 Non-current contract liabilities, deferred revenue License and development 37,176 40,469 Product 63 48 Total non-current contract liability 37,239 40,517 Total contract liability $ 54,070 $ 56,426 The Company records unbilled receivables as contract assets. Significant changes in contract assets during the period were as follows. March 31, December 31, (In thousands) Balance, beginning of year $ 6,278 $ 2,015 Transferred to receivables (1,340 ) (2,909 ) Cumulative catch-up adjustments 10 7,172 Balance, end of period $ 4,948 $ 6,278 The Company records contract liabilities when cash payments are received or due in advance of the Company’s performance. Significant changes in contract liabilities during the period were as follows. March 31, December 31, (In thousands) Balance, beginning of year $ 56,426 $ 62,232 Revenue recognized (2,775 ) (5,892 ) Cash received 419 86 Balance, end of period $ 54,070 $ 56,426 Transaction Price Allocated to the Remaining Performance Obligation The following table includes estimated revenue expected to be recognized in the future related to performance obligations that are unsatisfied or partially unsatisfied at March 31, 2018. Estimated Revenue (In thousands) Year: 2018 (remaining nine months) $ 11,815 2019 13,457 2020 14,464 2021 6,871 2022 and thereafter 5,677 Total $ 52,284 The Company applies the practical expedient in ASC 606, paragraph 10-50-14 and does not disclose information about remaining performance obligations that have original expected durations of one year or less. The Company applies the practical expedient in ASC 606 paragraph 10-65-1(f)(3) and does not disclose the amount of the transaction price allocated to the remaining performance obligations and an explanation of when the Company expects to recognize that amount of revenue for the comparative period ended March 31, 2017. Contract Costs The Company recognizes the incremental cost of obtaining contracts as an expense when incurred if the amortization period of the assets that the Company otherwise would have recognized in one year or less. The costs of obtaining contracts are included in sales and marketing expenses. Product and Service Revenue Recognition - Water Segment In the Water segment, a contract is established by a written agreement (executed sales order, executed purchase order or stand-alone contract) with the customer with fixed pricing, and a credit risk assessment is completed prior to the signing of the agreement to ensure that collectability is reasonably assured. The Company does not bundle performance obligations in the Water segment. The Company identifies each performance obligation separately along with its associated relative standalone selling price based on the prices and discounts that the Company would sell a promised good or service separately to a customer. Generally, performance obligations consist of delivery of products, such as PX energy recovery devices, turbochargers, pumps, and spare parts. These service amounts are deferred as contract liabilities until the services are performed. The transfer of control for the Company’s products follows transfer of title which typically occurs upon shipment of the equipment in accordance with International Commercial Terms (commonly referred to as “Incoterms”). The specified product performance criteria for the Company’s products pertain to the ability of the Company’s product to meet its published performance specifications and warranty provisions, which the Company’s products have demonstrated on a consistent basis. This factor, combined with historical performance metrics, provides the Company’s management with a reasonable basis to conclude that the products will perform satisfactorily upon commissioning of the plant. Installation is relatively simple, requires no customization, and is performed by the customer under the supervision of the Company’s personnel. Based on these factors, the Company concluded that performance has been completed upon shipment when title transfers based on the shipping terms, and that product revenue is recognized at a point in time. The Company does not provide its customers with a right of product return; however, the Company will accept returns of products that are deemed to be damaged or defective when delivered that are covered by the terms and conditions of the product warranty. Product warranty is provided consistent with the industry and is considered to be an assurance warranty, not a separate performance obligation. Product returns and warranty charges have not been significant. Revenue allocable to the Company’s product is limited to the amount that is not contingent upon the delivery of additional items or meeting specified performance conditions. The Company adheres to consistent pricing in the stand-alone sale of products and services and the contractual pricing of products and commissioning of services in bundled arrangements. For large projects, stand-alone contracts are utilized. For these contracts, consistent with industry practice, the Company’s customers typically require their suppliers, including the Company, to accept contractual holdback provisions (also referred to as a retention payment) whereby the final amounts due under the sales contract are remitted over extended periods of time or alternatively, stand-by letters of credit are issued. These retention payments are generally 10% or less of the total contract amount and are due and payable upon the passage of time, generally up to 24 to 36 months from the date of product delivery. These retention payments are generally replaced by bank guarantees which have had no history of being exercised, and they align with the product warranty period. Given that they are not material in the context of the contract, they are not considered to be a financing component. The Company has no performance obligation and they are recorded as contract assets. Shipping and handling charges billed to customers is a pass-through from the freight forwarder and is included in product revenue. The cost of shipping to customers is included in cost of revenue. Cost-to-Total Cost (“ CTC ”) Revenue Recognition - Oil & Gas Segment IsoBoost and IsoGen systems are highly engineered, customized solutions that are designed and manufactured over an extended period of time and are built specifically to meet a customer’s specifications. Given the facts and circumstances of these projects, the Company concluded that the CTC method of accounting is appropriate for IsoBoost and IsoGen systems. In the event that a purchase order for an IsoBoost or IsoGen system does not meet these facts and circumstances, then the CTC method of accounting does not apply. The Company had one CTC contract for IsoBoost turbochargers in fiscal years 2016 through 2018, which is expected to be completed and shipped in the second quarter of 2018. A standard assurance type warranty was provided. Revenue from fixed price contracts is recognized with progress measured in the ratio of costs incurred to estimated final costs. Contract costs include all direct material and labor costs related to contract performance. Pre-contract costs with no future benefit were expensed in the period in which they were incurred. Since the financial reporting of these contracts depends on estimates, which are assessed continually during the term of the contract, recognized revenues and profit are subject to revisions as the contract progresses to completion. Revisions in profit estimates are reflected in the period in which the facts that give rise to the revisions become known, using the cumulative catchup method. If material, the effects of any changes in estimates are disclosed in the notes to the consolidated financial statements. When estimates indicate that a loss will be incurred on a contract, a provision for the expected loss is recorded in the period in which the loss becomes evident. No loss has been incurred to date. Revenue is recognized only to the extent costs have been recognized in the same period. Cost and estimated earnings on uncompleted contracts is presented in the following table. December 31, 2017 March 31, As Adjusted Adoption of New Revenue Standard As Previously Reported (In thousands) Estimated earnings to date $ 5,877 $ 5,867 $ (133 ) $ 6,000 Estimated costs to date (4,613 ) (4,525 ) — (4,525 ) Subtotal 1,264 1,342 (133 ) 1,475 Net billings to date 1,498 2,718 — 2,718 Total $ 2,762 $ 4,060 $ (133 ) $ 4,193 Included in accompanying balance sheets: Unbilled project costs $ 3,535 $ 4,865 $ (133 ) $ 4,998 Cost and estimated earnings in excess of billings (773 ) (805 ) — (805 ) Total $ 2,762 $ 4,060 $ (133 ) $ 4,193 Unbilled project costs and Cost and estimated earnings in excess of billings are included in Contract assets and Contract liabilities on the Condensed Consolidated Balance Sheets, respectively. License and Development, and Lease Revenue Recognition - Oil & Gas Segment License and development revenue is comprised of revenue recognition over time of the upfront non-refundable $75.0 million exclusivity fee received in connection with the VorTeq License Agreement , as well as the revenue recognition over time of the two milestone payments of $25.0 million each when uncertainty of receipt is resolved and receipt of each milestone payment is considered probable. The VorTeq License Agreement is comprised of a fifteen -year exclusive license for the Company’s VorTeq technology (“VorTeq”). In performing the obligations under the license, the Company provides research and development services to commercialize the technology in accordance with the Key Performance Indicators (“KPIs”), defined in the license agreement. After commercialization is achieved, payments will be received for the supply and servicing of certain components of the VorTeq. All payments are non-refundable. See Note 14 , “ VorTeq Partnership and License Agreement .” The Company recognizes license and development revenue in accordance with ASC 606. Revenue is recognized when control of the promised goods or services is transferred to customers. Stand-alone selling price was established at the inception of the contract by taking the transaction to market on a non-exclusive basis, and pricing in an exclusivity premium. Since the agreement included an up-front non-refundable payment at the inception of the agreement and future products and services are provided after initial commercialization, the Company completed an analysis and concluded that there was no material right included in the pricing of the agreement. Performance obligations have been identified, i.e. , the exclusive license to the Missile technology and upgrades prior to and subsequent to the date of full commercial launch. Value has been allocated to the performance obligations, and revenue is recognized over time based on the input measure of progress of the cost of salaries and wages related to the project prior to full commercialization, and ratably for the unspecified upgrades for the period subsequent to full commercialization until the expiration of the contract. Once commercial launch is achieved and cartridges are provided under the contract, revenue from those royalty payments will be recognized in accordance with ASC 842, with the Company as the lessor. It is expected that the cartridge leases will be classified as short-term operating leases and revenue will be recognized as earned.

(Loss) Income Per Share

(Loss) Income Per Share	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
(Loss) Income Per Share	(Loss) Income Per Share Net (loss) income is divided by the weighted average number of common shares outstanding during the year to calculate basic net (loss) income per common share. Basic earnings per share exclude any dilutive effects of stock options and restricted stock units (“RSUs”). Diluted net (loss) income per common share reflects the potential dilution that would occur if outstanding stock options to purchase common stock were exercised for common stock, using the treasury stock method, and the common stock underlying outstanding RSU was issued. Diluted earnings per share for the three months ended March 31, 2018 and 2017 , includes the dilutive effects of stock options and RSUs. Certain common stock issuable under stock options and RSUs have been omitted from the three months ended March 31, 2018 and 2017 diluted net income per share calculations because their inclusion is considered anti-dilutive. The computation of basic and diluted net (loss) income per share is presented in the following table. Prior year amounts have been adjusted for the adoption of ASC 606 in the first quarter of 2018. See Note 2 , Recent Accounting Pronouncements , for reconciliation of prior year “ As Previously Reported ” and “ As Adjusted ” amounts. Three Months Ended March 31, 2018 2017 (In thousands, except per share amounts) Numerator: Net (loss) income $ (726 ) $ 422 Denominator: Basic weighted average common shares outstanding 53,987 53,825 Weighted average effect of dilutive stock awards — 2,231 Diluted weighted average common shares outstanding 53,987 56,056 Net (loss) income per share: Basic $ (0.01 ) $ 0.01 Diluted $ (0.01 ) $ 0.01 The potential common shares were excluded from the computation of diluted net (loss) income per share as their effect would have been anti-dilutive is presented in the following table. Three Months Ended March 31, 2018 2017 (In thousands) Anti-dilutive shares excluded from net (loss) income per share calculation 5,414 1,279

Other Financial Information

Other Financial Information	3 Months Ended
	Mar. 31, 2018
Other Financial Information [Abstract]
Other Financial Information	Other Financial Information Cash, Cash Equivalents and Restricted Cash The Company’s Condensed Consolidated Statement of Cash Flows explains the change in the total of cash, cash equivalents, and restricted cash. The following table provides a reconciliation of cash and cash equivalents, and restricted cash reported within the Condensed Consolidated Balance Sheets that sum to the total of such amounts in the Condensed Consolidated Statements of Cash Flows. March 31, December 31, (In thousands) Cash and cash equivalents $ 32,153 $ 27,780 Restricted cash 1,290 2,846 Total cash, cash equivalents, and restricted cash $ 33,443 $ 30,626 The Company pledged cash in connection with certain stand-by letters of credit and company credit cards. The Company deposited corresponding amounts into accounts at several financial institutions. See Note 8 , “ Long-term Debt and Lines of Credit ,” for additional discussion related to the Company’s stand-by letters of credit and restricted cash requirements. Inventories Inventories are stated at the lower of cost (using the first-in, first-out method) or net realizable value and are presented by category in the following table. March 31, December 31, (In thousands) Raw materials $ 2,342 $ 1,899 Work in process 2,889 2,191 Finished goods 2,097 1,424 Inventories, net $ 7,328 $ 5,514 Valuation adjustments for excess and obsolete inventory, reflected as a reduction of inventory at March 31, 2018 and December 31, 2017 was $0.6 million and $0.7 million , respectively. Prepaid and Other Current Assets Prepaid expenses and other current assets by category are presented in the following table. March 31, December 31, (In thousands) Insurance $ 205 $ 256 Interest receivable 443 439 Property taxes 255 189 Supplier advances 113 124 Software license 267 193 Other prepaid expenses and current assets 262 141 Total prepaid and other current assets $ 1,545 $ 1,342 Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities by category are presented in the following table. March 31, December 31, (In thousands) Payroll and commissions payable $ 2,800 $ 6,071 Other accrued expenses and current liabilities 1,190 1,877 Total accrued expenses and other current liabilities $ 3,990 $ 7,948 Lease Liabilities Lease liabilities are presented in the following table. March 31, December 31, (In thousands) Lease liabilities $ 1,641 $ 1,603 Lease liabilities, non-current 1,273 1,698 Total lease liabilities $ 2,914 $ 3,301 Accumulated Other Comprehensive Loss Changes in accumulated other comprehensive loss by component are presented in the following table. Foreign Currency Translation Adjustments Unrealized Losses on Investments Total Accumulated Other Comprehensive Loss (In thousands) Balance, December 31, 2017 $ (33 ) $ (92 ) $ (125 ) Other comprehensive income (loss), net 21 (64 ) (43 ) Balance, March 31, 2018 $ (12 ) $ (156 ) $ (168 ) There were no reclassifications of amounts out of accumulated other comprehensive loss , as there have been no sales of securities or translation adjustments that impacted other comprehensive loss during the years presented. The tax impact of the changes in accumulated other comprehensive loss was not material.

Investments and Fair Value Meas

Investments and Fair Value Measurements	3 Months Ended
	Mar. 31, 2018
Investments, Fair Value Disclosure [Abstract]
Investments and Fair Value Measurements	Investments and Fair Value Measurements The Company’s cash, cash equivalents and short-term investments are presented in the following table. March 31, December 31, (In thousands) Cash and cash equivalents $ 32,153 $ 27,780 Short-term investments 58,108 70,020 Total cash, cash equivalents and marketable securities $ 90,261 $ 97,800 As of March 31, 2018 , there were no available-for-sale investments reported in Cash and cash equivalents on the Condensed Consolidated Balance Sheets. As of December 31, 2017 , available-for-sale investments of $0.3 million were reported in Cash and cash equivalents on the Condensed Consolidated Balance Sheets. Available-for-Sale Investments The Company’s investments are all classified as available-for-sale. As of March 31, 2018 and December 31, 2017 , all available-for-sale investments were classified as short-term, with maturities less than 12 months. There were no sales of available-for-sale investments during the three months ended March 31, 2018 and 2017 . Available-for-sale investments as of March 31, 2018 and December 31, 2017 are presented in the following tables. March 31, 2018 Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Fair Value (In thousands) U.S. Treasury securities $ 11,626 $ — $ (21 ) $ 11,605 Corporate notes and bonds 46,390 — (135 ) 46,255 Municipal notes and bonds 248 — — 248 Total available-for-sale investments $ 58,264 $ — $ (156 ) $ 58,108 December 31, 2017 Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Fair Value (In thousands) U.S. Treasury securities $ 16,755 $ — $ (14 ) $ 16,741 Corporate notes and bonds 53,367 — (77 ) 53,290 Municipal notes and bonds 247 — — 247 Total available-for-sale investments $ 70,369 $ — $ (91 ) $ 70,278 The Company monitors investments for other-than-temporary impairment. It was determined that unrealized gains and losses at March 31, 2018 and December 31, 2017 , are 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 maturity, it is expected that the realized gains or losses, if any, will be immaterial. Expected maturities can differ from contractual maturities because borrowers may have the right to prepay obligations without prepayment penalties. The amortized cost and fair value of available-for-sale securities that had stated maturities are shown by contractual maturity in the following table. March 31, 2018 Amortized Cost Fair Value (In thousands) Due in one year or less $ 58,264 $ 58,108 Fair Value of Financial Instruments Financial assets and liabilities that are remeasured and reported at fair value at each reporting period are classified and disclosed in one of the following three 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. For the Company’s investments in available-for-sale securities, if quoted prices in active markets for identical investments are not available to determine fair value (Level 1), then the Company uses quoted prices for similar assets or inputs other than quoted prices that are observable either directly or indirectly (Level 2). The investments included in Level 2 consist of corporate notes and bonds, municipal notes and bonds and U.S. Treasury securities. Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis The fair value of financial assets and liabilities measured on a recurring basis is presented in the following tables. March 31, 2018 Total Level 1 Inputs Level 2 Inputs Level 3 Inputs (In thousands) Assets: Short-term investments U.S. Treasury securities $ 11,605 $ — $ 11,605 $ — Corporate notes and bonds 46,255 — 46,255 — Municipal notes and bonds 248 — 248 — Total short-term investments 58,108 — 58,108 — Total assets $ 58,108 $ — $ 58,108 $ — December 31, 2017 Total Level 1 Inputs Level 2 Inputs Level 3 Inputs (In thousands) Assets: Cash equivalents Corporate notes and bonds $ 258 $ — $ 258 $ — Total cash equivalents 258 — 258 — Short-term investments U.S. Treasury securities 16,741 — 16,741 — Corporate notes and bonds 53,032 — 53,032 — Municipal notes and bonds 247 — 247 — Total short-term investments 70,020 — 70,020 — Total assets $ 70,278 $ — $ 70,278 $ — During the three months ended March 31, 2018 , the Company had no transfers of financial assets and liabilities between Level 1 and Level 2. The fair value and gross unrealized losses on the available-for-sale securities that have been in a continuous unrealized loss position, aggregated by type of investment instrument as of March 31, 2018 and December 31, 2017 are summarized in the following table. All of the Company’s available-for-sale investments were short-term with maturities less than 12 months. Available-for-sale investments that were in an unrealized gain position have been excluded from the following table. March 31, 2018 December 31, 2017 Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses (In thousands) U.S. Treasury securities $ 11,605 $ (21 ) $ 10,162 $ (14 ) Corporate notes and bonds 46,255 (135 ) 53,222 (77 ) Municipal notes and bonds 248 — 247 — Total available-for-sale investments $ 58,108 $ (156 ) $ 63,631 $ (91 )

Goodwill and Intangible Assets

Goodwill and Intangible Assets	3 Months Ended
	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill The net carrying amount of goodwill as of March 31, 2018 and December 31, 2017 was $12.8 million . As of March 31, 2018 and December 31, 2017 , no impairment of goodwill was recorded in the accompanying Condensed Consolidated Financial Statements. Other Intangible Assets The components of identifiable intangible assets, all of which are finite-lived, as of the date indicated were as follows in the table below. All intangible assets are amortized on a straight-line basis over their useful life. March 31, December 31, (In thousands) Finite-lived intangible assets $ 6,643 $ 6,643 Accumulated amortization (5,531 ) (5,374 ) Intangible assets, net $ 1,112 $ 1,269

Long-term Debt and Lines of Cre

Long-term Debt and Lines of Credit	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Long-term Debt and Lines of Credit	Long-term Debt and Lines of Credit Loans and Stand-by Letters of Credit Loan and Pledge Agreement On January 27, 2017 , the Company entered into a loan and pledge agreement (the “ Loan and Pledge Agreement ”) with a financial institution (“ Financial Institution 2 ”). The Loan and Pledge Agreement provides for a committed revolving credit line of $16.0 million and an uncommitted revolving credit line of $4.0 million . The Loan and Pledge Agreement was amended on March 30, 2018 to extend the termination date of the Loan and Pledge Agreement from March 31, 2018 to March 31, 2020 , of which the Company paid closing fees of $16 thousand . No other provisions of the Loan and Pledge Agreement was amended. As of March 31, 2018 , no amount under the Loan and Pledge Agreement was outstanding. Stand-by Letters of Credit The financial institutions where the outstanding amounts of stand-by letters of credit are collateralized by pledged U.S. investments or restricted cash are presented in the following table. March 31, December 31, (In thousands) Financial Institution 1 $ 1,148 $ 1,687 Financial Institution 2 7,309 7,745 Financial Institution 3 — 990 Total $ 8,457 $ 10,422 The Company’s total restricted cash balances by financial institution are presented in the following table. Financial Institution 2 requires pledged U.S. investments in lieu of restricted cash balances. March 31, December 31, (In thousands) Financial Institution 1 $ 1,205 $ 1,771 Financial Institution 3 — 990 Financial Institution 4 85 85 Total $ 1,290 $ 2,846

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2018
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 2021 . At March 31, 2018, the Company’s corporate office, research and development lab and manufacturing facilities lease (“ Doolittle Lease ”), had a renewal term of two additional periods of five years each. In April 2018 , the Company renegotiated the Doolittle Lease with the lessor (“ New Doolittle Lease ”). The New Doolittle Lease is effective from April 2018 through December 2028 and has a renewal term of one additional period of five years. The Company will incur an annual base facility lease payment of $0.8 million in the first year and $19.0 million over the term of the New Doolittle Lease . The components of lease expense are presented in the following table. Three Months Ended March 31, 2018 (In thousands) Operating Lease Cost $ 380 Other information related to the operating leases are presented in the following table. Three Months Ended March 31, 2018 (In thousands, except for discount rate and lease term) Cash payments $ 435 Weighted average remaining lease term 20 months Weighted average discount rate 6.19 % Maturities of lease liabilities as of March 31, 2018 are presented in the following table. Lease Amounts (In thousands) Year: 2018 (remaining nine months) $ 1,319 2019 1,564 2020 148 2021 37 Total 3,068 Less imputed lease interest (154 ) Total lease liabilities $ 2,914 Warranty Changes in the Company’s accrued product warranty reserve are presented in the following table. Three Months Ended March 31, 2018 2017 (In thousands) Balance, beginning of year $ 366 $ 406 Warranty costs charged to cost of revenue 48 55 Utilization charges against reserve (50 ) (36 ) Release of accrual related to expired warranties (5 ) (27 ) Balance, end of period $ 359 $ 398 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 March 31, 2018 . These arrangements are subject to change based on the Company’s sales demand forecasts, and the Company has the right to cancel the arrangements prior to the date of delivery. The majority of these purchase order arrangements were related to various raw materials and components parts. As of March 31, 2018 , the Company had approximately $3.5 million of open cancellable purchase order arrangements related primarily to materials and parts. Guarantees The Company enters into indemnification provisions under its agreements with other companies in the ordinary course of business, typically with customers. Under these provisions, the Company generally indemnifies and holds harmless the indemnified party for losses suffered or incurred by the indemnified party as a result of the Company’s activities, generally limited to personal injury and property damage caused by the Company’s employees at a customer’s desalination plant in proportion to the employee’s percentage of fault for the accident. Damages incurred for these indemnifications would be covered by the Company’s general liability insurance to the extent provided by the policy limitations. The Company has not incurred material costs to defend lawsuits or settle claims related to these indemnification agreements. As a result, the estimated fair value of these agreements is not material. Accordingly, the Company had no liabilities recorded for these agreements as of March 31, 2018 and December 31, 2017 . In certain cases, the Company issues warranty and product performance guarantees to its customers for amounts generally equal to 10% or less of the total sales agreement to endorse the execution of product delivery and the warranty of design work, fabrication, and operating performance of our devices. These guarantees are generally stand-by letters of credit that typically remain in place in general for periods of 24 to 36 months , and in some cases up to 68 months . All stand-by letters of credit at March 31, 2018 and December 31, 2017 , were in the aggregate for amounts of $8.5 million and $10.4 million , respectively. See Note 8 , “ Long-term Debt and Lines of Credit ,” for additional information about the Company’s stand-by letters of credit arrangements. Litigation The Company is named in and subject to various proceedings and claims in connection with our business. The Company is contesting the allegations in these claims, and the Company believes that there are meritorious defenses in each of these matters. The outcome of matters the Company has been, and currently are, 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 our results of operations in any future period and a significant judgment could have a material adverse 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 its 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 adjusted to reflect the impacts of negotiations, settlements, rulings, advice of legal counsel and other information and events pertaining to a particular case. On September 10, 2014, the Company terminated the employment of its Senior Vice President, Sales, Borja Blanco, on the basis of breach of duty of trust and conduct leading to conflict of interest. On October 24, 2014, Mr. Blanco filed a labor claim against ERI Iberia in Madrid, Spain, challenging the fairness of his dismissal and seeking compensation (“Case 1”). A hearing was held on November 13, 2015, after which the labor court ruled that it did not have jurisdiction over the matter. Mr. Blanco appealed and the appeals court reversed the labor court’s finding and instructed the labor court to make a ruling on the merits on November 21, 2017. On February 14, 2018, the Company received notice that the labor court issued a ruling in favor of Mr. Blanco declaring the termination an unjustified dismissal and ordered the Company to pay a dismissed severance. The Company appealed the decision on February 21, 2018. The Company denies any allegations of wrongdoing and intends to continue to vigorously defend against this lawsuit. Based on currently available information and review with outside counsel, the Company has estimated and accrued a potential loss. On November 24, 2014, Mr. Blanco filed a second action based on breach of contract theories in the same court as Case 1 (“Case 2”), but the cases are separate. In Case 2, Mr. Blanco seeks payment of an unpaid bonus, stock options, and non-compete compensation. The court ruled that this case is stayed until a final ruling is issued in Case 1. The Company denies any allegations of wrongdoing and intends to continue to vigorously defend against this lawsuit. Based on currently available information and review with outside counsel, the Company has determined that an award to Mr. Blanco is not probable. While a loss may be reasonably possible, an estimate of loss, if any, cannot reasonably be determined at this time. On February 18, 2016 and July 27, 2016, two derivative action complaints were filed in connection with the Company’s previously reported stockholder class action lawsuit in the Superior Court for the State of California, County of Alameda where the Company was named as a nominal defendant under the captions, Goldberg v. Rooney, et al ., HG 16804359, and Gerald McManiman v. Gay, et al ., RG 16824960. The complaints have been consolidated under the caption, In Re Energy Recovery, Inc. Derivative Litigation , HG16804359. The consolidated complaint is styled as a derivative action being brought on behalf of the Company and generally alleges breach of fiduciary duty, waste of corporate assets, and unjust enrichment causes of action against the individually named defendants. In March 2018, the Company and the attorneys representing the plaintiffs reached an agreement in principle to settle all outstanding claims in the case. As part of the settlement agreement, the Company has agreed to certain changes to the Company’s corporate governance policies and procedures, and to pay the attorneys representing the plaintiffs legal fees, which will be paid entirely by the Company’s insurer.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes For the three months ended March 31, 2018 , the Company recognized income tax benefit of $0.4 million , which included a discrete tax benefit related to tax deductions from stock-based compensation. For the three months ended March 31, 2017 , the Company recognized income tax expense of approximately $48 thousand . The effective tax rate for the three months ended March 31, 2018 and 2017 was 33.0% and 10.2% , respectively. Excluding the discrete tax income tax items, the effective tax rate for the three months ended March 31, 2018 and 2017 was (3.5%) and 24.0% , respectively. The effective tax rate for March 31, 2018 was adversely impacted by the full valuation allowance related to the losses in the Company’s Irish operations.

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2018
Stockholders' Equity Note [Abstract]
Stockholders' Equity	Stockholder’s Equity Stock Repurchase Program On March 7, 2018 , the Board of Directors authorized a stock repurchase program under which the Company, at the discretion of management, may repurchase up to $10.0 million in aggregate cost of the Company’s outstanding common stock (the “ March 2018 Authorization ”). Under the March 2018 Authorization , purchases of shares of common stock may be made through September 30, 2018, from time to time in the open market, or in privately negotiated transactions, in compliance with applicable state and federal securities laws. The timing and amounts of any purchases will be based on market conditions and other factors including price, regulatory requirements, and capital availability. The March 2018 Authorization does not obligate the Company to acquire any specific number of shares in any period, and may be expanded, extended, modified or discontinued at any time without prior notice. Under the March 2018 Authorization , as of March 31, 2018 , the Company repurchased 409,850 shares at an aggregate cost of $3.5 million . The Company accounts for stock repurchases using the cost method. The aggregate cost includes fees charged in connection with acquiring the outstanding common stock.

Stock-based Compensation

Stock-based Compensation	3 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-based Compensation	Stock-based Compensation Stock-based Compensation Expense Stock-based compensation expense related to the fair value measurement of awards granted to employees by financial line and by type of award is presented in the following table. Three Months Ended March 31, 2018 2017 (In thousands) Stock-based compensation expense by financial line: Cost of revenue $ 24 $ 49 General and administrative (1) 1,676 567 Sales and marketing 262 237 Research and development 281 260 Total stock-based compensation expense $ 2,243 $ 1,113 Stock-based compensation expense by type of award: Options (1) $ 1,664 $ 889 RSUs (1) 579 224 Total stock-based compensation expense $ 2,243 $ 1,113 (1) First quarter of 2018 amounts include modifications of equity awards. The Company estimates forfeitures at the time of grant and revise those estimates periodically in subsequent periods if actual forfeitures differ from those estimates. The Company uses historical data to estimate pre-vesting option forfeitures and record stock-based compensation expense only for those awards that are expected to vest. All stock-based payment awards are amortized on a straight-line basis over the requisite service periods of the awards, which are generally the vesting periods. If the Company’s actual forfeiture rate is materially different from its estimate, the stock-based compensation expense could be significantly different from what the Company has recorded in the current period. Modifications of Equity Awards In the first quarter of 2018, the Company recorded additional stock-based compensation expense of $0.9 million due to an equity award modification charge chiefly related to the modification of certain equity awards held by the Company’s former President and Chief Executive Officer , who resigned on February 24, 2018, in consideration for his entering into a Settlement Agreement and Release. Unamortized Stock-based Compensation Costs Stock-based compensation cost related to unvested stock options and RSUs will generally be amortized on a straight-line basis over the remaining average service period of each award. The following table presents the unamortized compensation cost and weighted average service period of all unvested outstanding awards as of March 31, 2018 . Unamortized Compensation Costs Weighted Average Service Period (In thousands) (In years) Stock options $ 6,760 2.9 RSUs 3,518 2.9 Total $ 10,278 Vested Stock Options and RSUs The total grant date fair value of stock options and RSUs vested during the period are presented in the following table. Three Months Ended March 31, 2018 2017 (In thousands) Stock options $ 1,261 $ 1,172 RSUs 509 436 Total grant date fair value of stock options and RSUs vested during the period $ 1,770 $ 1,608 Stock Option Activities The following table summarizes the stock option activities under the Company’s 2016 Incentive Plan (“ 2016 Plan ”) and Amended and Restated 2008 Equity Incentive Plan . Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Life (in Years) Aggregate Intrinsic Value (1) (In thousands, except for weighted average exercise price and weighted average remaining contractual life) Balance, December 31, 2017 5,092 $ 5.43 6.6 $ 17,735 Granted 828 7.51 Exercised (484 ) 3.38 2,509 Forfeited (447 ) 6.94 Balance, March 31, 2018 4,989 $ 5.84 6.5 $ 13,067 Vested and exercisable as of March 31, 2018 3,260 $ 5.07 5.3 $ 10,763 Vested and exercisable as of March 31, 2018 and expected to vest thereafter 4,680 $ 5.71 6.3 $ 12,791 (1) The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying options and the fair value of the Company’s common stock at the time of exercise. The aggregate intrinsic value at March 31, 2018 is calculated as the difference between the exercise price of the underlying options and the fair value of the Company’s common stock as of March 31, 2018 or the last trading day prior to March 31, 2018 . The aggregate intrinsic value at December 31, 2017 is calculated as the difference between the exercise price of the underlying options and the fair value of the Company’s common stock as of December 31, 2017 or the last trading day prior to December 31, 2017 . Restricted Stock Unit Activities The following table summarizes the RSU activities under the 2016 Plan . Shares Weighted (In thousands, except for weighted average grant-date fair value) Balance, December 31, 2017 274 $ 9.54 Awarded 280 7.74 Vested (52 ) 9.82 Forfeited (77 ) 8.42 Balance, March 31, 2018 425 8.52

Business Segment

Business Segment	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Business Segment	Business Segment The Company is an energy solutions provider to industrial fluid flow markets worldwide. The Company manufactures and sells high-efficiency energy recovery devices (“ERDs”) and pumps as well as related products and services. The Company’s chief operating decision-maker (“CODM”) is the chief executive officer. The Company’s reportable operating 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 energy recovery device sold, and the related products and services. The Water segment consists of revenue associated with products sold for use in reverse osmosis water desalination, as well as the related identifiable expenses. The Oil & Gas segment consists of product revenue associated with products sold for use in gas processing, chemical processing, and hydraulic fracturing and license and development revenue associated with hydraulic fracturing, as well as related identifiable expenses. Operating income (loss) for each segment excludes other income and expenses and certain expenses managed outside the operating segment. Costs excluded from Operating income (loss) include various corporate expenses 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 (loss) . The summary of financial information by segment is presented in the following tables. Three Months Ended March 31, 2018 Water Oil & Gas Total (In thousands) Product revenue $ 11,048 $ 10 $ 11,058 Product cost of revenue 3,228 86 3,314 Product gross profit 7,820 (76 ) 7,744 License and development revenue — 2,749 2,749 Operating expenses: General and administrative 305 651 956 Sales and marketing 1,445 344 1,789 Research and development 244 3,665 3,909 Amortization of intangibles 158 — 158 Operating expenses 2,152 4,660 6,812 Operating income (loss) $ 5,668 $ (1,987 ) 3,681 Less: Corporate operating expenses 5,012 Consolidated operating loss (1,331 ) Non-operating income 248 Loss before income taxes $ (1,083 ) Prior year amounts in the following table have been adjusted for the adoption of ASC 606 in the first quarter of 2018. See Note 2 , Recent Accounting Pronouncements , for reconciliation of prior year “As Previously Reported” and “As Reported” amounts. Three Months Ended March 31, 2017 Water Oil & Gas Total (In thousands) Product revenue $ 10,716 $ 1,529 $ 12,245 Product cost of revenue 3,524 1,088 4,612 Product gross profit 7,192 441 7,633 License and development revenue — 2,248 2,248 Operating expenses: General and administrative 318 349 667 Sales and marketing 1,499 641 2,140 Research and development 262 2,246 2,508 Amortization of intangibles 158 — 158 Operating expenses 2,237 3,236 5,473 Operating income (loss) $ 4,955 $ (547 ) 4,408 Less: Corporate operating expenses 4,055 Consolidated operating income 353 Non-operating income 117 Income before income taxes $ 470

VorTeq Partnership and License

VorTeq Partnership and License Agreement	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
VorTeq Partnership and License Agreement	VorTeq Partnership and License Agreement The Company’s VorTeq technology enables oilfield service hydraulic fracturing operators to isolate their high-pressure hydraulic fracturing pumps from fracturing fluid thereby reducing operating and capital costs. In 2014, the Company entered into a strategic partnership with Liberty Oil Field Services (“Liberty”) to pilot and conduct field trials with the VorTeq. Through this agreement, Liberty has the rights to lease up to twenty VorTeq Missiles (defined below) for a period of up to five years following commercialization. On October 14, 2015, the Company and the VorTeq Licensee entered into the VorTeq License Agreement , which provides the VorTeq Licensee with exclusive worldwide rights to the Company’s VorTeq technology for use in hydraulic fracturing onshore applications. The VorTeq License Agreement provides an exception for Liberty’s contractual rights to utilize the VorTeq. In performing the obligations under the agreement, the Company provides research and development services to commercialize the technology in accordance with the KPIs, defined in the license agreement. After commercialization is achieved, royalty payments will be received for the supply and servicing of cartridges. All payments are non-refundable. The VorTeq is made up of Pressure Exchanger cartridges, housed in a high-pressure manifold (the “Missile”) though which a motive fluid is used to pressurize hydraulic fracturing fluid, which is processed and sent down the well bore. The VorTeq License Agreement includes up to $125.0 million in upfront consideration paid in stages: (i) a $75.0 million non-refundable upfront exclusivity payment; and (ii) two milestone payments of $25.0 million each upon achievement of successful tests in accord with KPIs specified in the agreement (“Milestone Payment 1 and 2”). Milestone Payment 1 of $25.0 million is payable upon a successful five stage yard test at the VorTeq Licensee’s test facility. The Milestone Payment 2 of $25.0 million is payable upon a successful twenty stage hydraulic fracturing at one of the VorTeq Licensee’s customer’s live well. The achievement of each milestone and the receipt of each of the related payments are subject to a high degree of uncertainty. After initial commercialization, the VorTeq Licensee will begin paying ongoing recurring royalty fees to the Company for supply and service of the cartridges based on the number of VorTeqs in operation which is subject to the greater of a minimum adoption curve or the adoption rate of the technology. During the period, from initial commercialization to full commercialization, the technology will be deployed commercially; and through continuous improvement and cost refinement, the efficiency and effectiveness of the product will fully stabilize. The exclusive nature of the agreement terminates if the VorTeq Licensee does not meet the specified minimum adoption curves. In the event the Company is not able to achieve full commercialization under the terms of the VorTeq License Agreement , the exclusivity right of the VorTeq Licensee under the VorTeq License Agreement continues throughout the term. See Note 2 , “ Recent Accounting Pronouncements ,” and Note 3 , “ Revenues ,” for further discussion of revenue recognition.

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On May 2, 2018, the Board appointed Chris Gannon as the Company’s President and Chief Executive Officer, effective immediately. In addition, Mr. Gannon was also elected to the Company’s Board of Directors.

Description of Business and S22

Description of Business and Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The Company’s Condensed Consolidated Financial Statements include the accounts of Energy Recovery, Inc. and its wholly-owned subsidiaries. All significant intercompany accounts and transactions have been eliminated in consolidation. The accompanying Condensed Consolidated Financial Statements have been prepared by the Company, without audit, 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, 2017 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 March 31, 2018 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, 2017 included in the Company’s Annual Report on Form 10-K filed with the SEC on March 8, 2018. In the opinion of management, 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 the Condensed Consolidated Financial Statements in conformity with 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 to Condensed Consolidated Financial Statements. 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 the Company’s reported financial results are revenue recognition; capitalization of research and development assets; allowance for doubtful accounts; allowance for product warranty; valuation of stock options; valuation and impairment of goodwill and acquired intangible assets; useful lives for depreciation and amortization; 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.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Financial assets and liabilities that are remeasured and reported at fair value at each reporting period are classified and disclosed in one of the following three 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. For the Company’s investments in available-for-sale securities, if quoted prices in active markets for identical investments are not available to determine fair value (Level 1), then the Company uses quoted prices for similar assets or inputs other than quoted prices that are observable either directly or indirectly (Level 2). The investments included in Level 2 consist of corporate notes and bonds, municipal notes and bonds and U.S. Treasury securities.
New Accounting Pronouncements	In February 2016, the FASB issued ASU No. 2016-02 (“ASU 2016-02”), Leases (Topic 842), also referred to as “ASC 842” or “New Lease Standard,” which supersedes ASC 840, Leases (Topic 840) and provides principles for the recognition, measurement, presentation and disclosure of leases for both lessees and lessors. The FASB has continued to clarify this guidance through the issuance of additional ASUs. The new standard requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the lessee. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight-line basis over the term of the lease, respectively. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than twelve months regardless of classification. Leases with a term of twelve months or less will be accounted for similar to existing guidance for operating leases. The Company early adopted ASU 2016-02 on January 1, 2018 concurrent with the Company’s adoption of the New Revenue Standard and elected the available practical expedients. The adoption of ASU 2016-02 had no impact on the Company’s Condensed Consolidated Statements of Operations. The most significant impact was the recognition of right of use assets and liabilities for operating leases. Adoption of the standard required the Company to restate certain previously reported results, including the recognition of additional operating lease right of use assets and liabilities. In November 2016, the FASB issued ASU 2016-18 (“ASU 2016-18”), Statement of Cash Flows (Topic 230): Restricted Cash, also referred to as “New Cash Flow Presentation Standard.” ASU 2016-18 is intended to reduce diversity in practice in the classification and presentation of changes in restricted cash on the Consolidated Statement of Cash Flows. ASU 2016-18 requires that the Consolidated Statement of Cash Flows explain the change in total cash and equivalents and amounts generally described as restricted cash or restricted cash equivalents when reconciling the beginning-of-period and end-of-period total amounts. The standard also requires reconciliation between the total cash and equivalents and restricted cash presented on the Consolidated Statement of Cash Flows and the cash and cash equivalents balance presented on the Consolidated Balance Sheet. ASU 2016-18 is effective retrospectively on January 1, 2018. The Company adopted ASU 2016-18 on January 1, 2018. The Company recast its Condensed Consolidated Statements of Cash Flows for the prior period presented based on the restricted cash balance on the balance sheet date and has provided a reconciliation of cash, cash equivalents and restricted cash in Note 5 , “ Other Financial Information .” In January 2016, the FASB issued ASU No. 2016-01 (“ASU 2016-01”), Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. ASU 2016-01 modifies certain aspects of the recognition, measurement, presentation, and disclosure of financial instruments. For public entities, ASU 2016-01 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2017. The Company adopted ASU 2016-01 on January 1, 2018. The adoption ASU 2016-01 did not have a material impact on the Company’s financial position or results of operations. In August 2016, the FASB issued ASU No. 2016-15 (“ASU 2016-15”), Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. ASU 2016-15 impacts all entities that are required to present a statement of cash flows under ASC 230, Statement of Cash Flows . The amendment provides guidance on eight specific cash flow issues. For public entities, ASU 2016-15 is effective for fiscal periods beginning after December 15, 2017 and interim periods within those years. Adoption should be applied using a retrospective transition method to each period presented. The Company adopted ASU 2016-15 on January 1, 2018. The adoption of ASU 2016-15 did not have a material impact on the Company’s financial position or results of operations. In October 2016, the FASB issued ASU 2016-16 (“ASU 2016-16”), Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory. ASU 2016-16 requires recognition of the current and deferred income tax effects of an intra-entity asset transfer, other than inventory, when the transfer occurs, as opposed to legacy GAAP, which requires companies to defer the income tax effects of intra-entity asset transfers until the asset has been sold to an outside party. The income tax effects of intra-entity inventory transfers will continue to be deferred until the inventory is sold. ASU 2016-16 is effective on January 1, 2018, with early adoption permitted. The update is required to be adopted on a modified retrospective basis with the cumulative-effect adjustment recorded to retained earnings as of the beginning of the period of adoption. The Company adopted ASU 2016-16 on January 1, 2018. The adoption of ASU 2016-16 did not have a material impact on the Company’s financial position or results of operations. In May 2017, the FASB issued ASU No. 2017-09, Compensation – Stock Compensation (Topic 718): Scope of Modification Accounting. ASU 2017-09 provides guidance about which changes to the terms or conditions of a share-base payment award require an entity to apply modification accounting under ASC 718, Compensation – Stock Compensation . ASU 2017-09 is effective for annual periods and interim periods within those annual periods, beginning after December 15, 2017. The Company adopted ASU 2017-09 on January 1, 2018. The adoption of ASU 2017-09 did not have an impact on the Company’s financial position or results of operations. Recently issued accounting pronouncement not yet adopted In January 2017, the FASB issued ASU No. 2017-04 (“ASU 2017-04”), Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment. ASU 2017-04 eliminates Step 2 of the goodwill impairment quantitative test and allows for the determination of impairment by comparing the fair value of the reporting unit with its carrying amount. The amendments in this update should be applied on a prospective basis. For public entities which are SEC filers, this amendment is effective for annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted for testing dates after January 1, 2017. The Company expects to adopt this standard on January 1, 2020 and does not expect the adoption of ASU 2017-04 to have a material impact on its financial statements. In February 2018, the FASB issued ASU No. 2018-02 (“ASU 2018-02”), Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. ASU 2018-02 was issued to address the income tax accounting treatment of the stranded tax effects within other comprehensive income due to the prohibition of backward tracing due to an income tax rate change that was initially recorded in other comprehensive income. This issue came about from the enactment of the U.S. Tax Cuts and Jobs Act of 2017 (the “ Tax Act ”) that changed the Company’s income tax rate from 35% to 21% . ASU 2018-02 changed current accounting whereby an entity may elect to reclassify the stranded tax effect from accumulated other comprehensive income to retained earnings. The ASU 2018-02 is effective for periods beginning after December 15, 2018 although early adoption is permitted. The Company does not expect the adoption of ASU 2018-02 to have a material impact on its financial position or results of operations. Recently Adopted Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09 (“ASU 2014-09”), Revenue from Contracts with Customers (Topic 606), referred to as Accounting Standards Codification (“ASC”) 606 (“ASC 606”) or “New Revenue Standard .” ASC 606 supersedes the revenue recognition requirements of ASC 605, Revenue Recognition , and requires entities to recognize revenue when control of promised goods or services is transferred to customers at an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods and services. The update also requires more detailed disclosures to enable readers of financial statements to understand the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. ASC 606 permits the use of either the full retrospective or cumulative effect transition (modified retrospective) method upon adoption. In March and April 2016, the FASB issued ASU No. 2016-08 (“ASU 2016-08”), Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net) and ASU No. 2016-10 (“ASU 2016-10”), Revenue from Contracts with Customers (Topic 606) Identifying Performance Obligations and Licensing, respectively. The amendments in these updates are intended to improve the operability and understandability of the implementation guidance on principal versus agent considerations and to clarify two aspects of ASC 606: identifying performance obligations and the licensing implementation guidance, while retaining the related principles for those areas. The effective date and transition requirements for both ASU 2016-08 and ASU 2016-10 are the same as those for ASU 2014-09, as referred. The Company adopted ASC 606 as of January 1, 2018 using the full retrospective transition method. To assess the impact of and to implement ASC 606, the Company formed a project team, which has operated since 2014, to evaluate internal processes. The Company has implemented changes to its current policies and practices, and internal controls over financial reporting to address the requirements of the standard.
Revenue Recognition	Performance obligations identified under ASC 606 differs somewhat from contingent and non-contingent deliverables identified under ASC 605 due to transfer of control considerations. Under ASC 606, the Company concluded that the Missile license represents functional intellectual property and that the license is not distinct from the research and development services to be provided prior to product commercialization. The transaction price allocated to this combined performance obligation of a continually evolving license will be recognized over the estimated period required to result in full commercial launch using an input measure of progress of the cost of salaries and wages related to the project prior to full commercial launch. The milestone method of accounting has been eliminated under ASC 606. Instead of recognizing the full amount of each milestone payment as revenue in the period in which it is achieved, the Company will revise its estimate of the transaction price to include development milestone payments only when they become probable of achievement and revenue will be recognized consistent with the input measure of progress. The Company has concluded that its obligation to provide when and if available updates to its technology in the period subsequent to full commercial launch represents a performance obligation. The transaction price allocated to this stand-ready performance obligation will be recognized ratably over the period commencing after full commercial launch until the expiration of the contract. The Company adopted ASC 606 as of January 1, 2018 using the full retrospective transition method. To assess the impact of and to implement ASC 606, the Company formed a project team, which has operated since 2014, to evaluate internal processes. The Company has implemented changes to its current policies and practices, and internal controls over financial reporting to address the requirements of the standard. Water Segment Revenue . Performance obligations identified under ASC 606, are consistent with deliverables identified under ASC 605. Revenue recognition for performance obligations accounted for under ASC 606 is consistent with ASC 605 given the transfer of control of the promised goods or services follows the same pattern. Adoption of ASC 606 did not have a material impact on the timing of revenue and expense recognition. Oil & Gas Segment - Cost-to-Total Cost (“ CTC ”) Revenue . Performance obligations identified under ASC 606, are consistent with deliverables identified under ASC 605. Revenue recognition for performance obligations accounted for under ASC 606 is consistent with ASC 605 given the transfer of control of the promised goods or services follows the same pattern. Adoption of ASC 606 did not have a material impact on the timing of revenue and expense recognition. Oil & Gas Segment - License and Development Revenue . Under ASC 605, license and development revenue associated with the up-front non-refundable $75.0 million exclusivity payment received in connection with the VorTeq license agreement (the “ VorTeq License Agreement ”) that the Company entered into with Schlumberger Technology Corporation (the “ VorTeq Licensee ”) was recognized on a straight-line basis over the fifteen -year term of the license, while the two substantive milestone payments of $25.0 million each that could be earned under the license agreement were to be recognized in full when achieved under milestone accounting. Under ASC 606, license and development revenue, which includes both the upfront non-refundable $75.0 million exclusivity payment and the two milestone payments of $25.0 million each, when determined probable, is comprised of: • revenue recognition over time based on an input measure of progress based on a cost driver which management has determined is the best estimate of the progress made on the project during the period from inception until full commercialization for the amount allocated to the exclusive Missile (as defined in Note 14 , “ VorTeq Partnership and License Agreement ”) license and research and development services, and • revenue recognition related to stand-ready when and if available upgrades subsequent to full commercialization, recognized over time ratably over the period, which matches the transfer of benefit to the customer on a daily basis, commencing after full commercial launch until the expiration of the contract. Contract Costs The Company recognizes the incremental cost of obtaining contracts as an expense when incurred if the amortization period of the assets that the Company otherwise would have recognized in one year or less. The costs of obtaining contracts are included in sales and marketing expenses. Product and Service Revenue Recognition - Water Segment In the Water segment, a contract is established by a written agreement (executed sales order, executed purchase order or stand-alone contract) with the customer with fixed pricing, and a credit risk assessment is completed prior to the signing of the agreement to ensure that collectability is reasonably assured. The Company does not bundle performance obligations in the Water segment. The Company identifies each performance obligation separately along with its associated relative standalone selling price based on the prices and discounts that the Company would sell a promised good or service separately to a customer. Generally, performance obligations consist of delivery of products, such as PX energy recovery devices, turbochargers, pumps, and spare parts. These service amounts are deferred as contract liabilities until the services are performed. The transfer of control for the Company’s products follows transfer of title which typically occurs upon shipment of the equipment in accordance with International Commercial Terms (commonly referred to as “Incoterms”). The specified product performance criteria for the Company’s products pertain to the ability of the Company’s product to meet its published performance specifications and warranty provisions, which the Company’s products have demonstrated on a consistent basis. This factor, combined with historical performance metrics, provides the Company’s management with a reasonable basis to conclude that the products will perform satisfactorily upon commissioning of the plant. Installation is relatively simple, requires no customization, and is performed by the customer under the supervision of the Company’s personnel. Based on these factors, the Company concluded that performance has been completed upon shipment when title transfers based on the shipping terms, and that product revenue is recognized at a point in time. The Company does not provide its customers with a right of product return; however, the Company will accept returns of products that are deemed to be damaged or defective when delivered that are covered by the terms and conditions of the product warranty. Product warranty is provided consistent with the industry and is considered to be an assurance warranty, not a separate performance obligation. Product returns and warranty charges have not been significant. Revenue allocable to the Company’s product is limited to the amount that is not contingent upon the delivery of additional items or meeting specified performance conditions. The Company adheres to consistent pricing in the stand-alone sale of products and services and the contractual pricing of products and commissioning of services in bundled arrangements. For large projects, stand-alone contracts are utilized. For these contracts, consistent with industry practice, the Company’s customers typically require their suppliers, including the Company, to accept contractual holdback provisions (also referred to as a retention payment) whereby the final amounts due under the sales contract are remitted over extended periods of time or alternatively, stand-by letters of credit are issued. These retention payments are generally 10% or less of the total contract amount and are due and payable upon the passage of time, generally up to 24 to 36 months from the date of product delivery. These retention payments are generally replaced by bank guarantees which have had no history of being exercised, and they align with the product warranty period. Given that they are not material in the context of the contract, they are not considered to be a financing component. The Company has no performance obligation and they are recorded as contract assets. Shipping and handling charges billed to customers is a pass-through from the freight forwarder and is included in product revenue. The cost of shipping to customers is included in cost of revenue. Cost-to-Total Cost (“ CTC ”) Revenue Recognition - Oil & Gas Segment IsoBoost and IsoGen systems are highly engineered, customized solutions that are designed and manufactured over an extended period of time and are built specifically to meet a customer’s specifications. Given the facts and circumstances of these projects, the Company concluded that the CTC method of accounting is appropriate for IsoBoost and IsoGen systems. In the event that a purchase order for an IsoBoost or IsoGen system does not meet these facts and circumstances, then the CTC method of accounting does not apply. The Company had one CTC contract for IsoBoost turbochargers in fiscal years 2016 through 2018, which is expected to be completed and shipped in the second quarter of 2018. A standard assurance type warranty was provided. Revenue from fixed price contracts is recognized with progress measured in the ratio of costs incurred to estimated final costs. Contract costs include all direct material and labor costs related to contract performance. Pre-contract costs with no future benefit were expensed in the period in which they were incurred. Since the financial reporting of these contracts depends on estimates, which are assessed continually during the term of the contract, recognized revenues and profit are subject to revisions as the contract progresses to completion. Revisions in profit estimates are reflected in the period in which the facts that give rise to the revisions become known, using the cumulative catchup method. If material, the effects of any changes in estimates are disclosed in the notes to the consolidated financial statements. When estimates indicate that a loss will be incurred on a contract, a provision for the expected loss is recorded in the period in which the loss becomes evident. No loss has been incurred to date. Revenue is recognized only to the extent costs have been recognized in the same period. License and Development, and Lease Revenue Recognition - Oil & Gas Segment License and development revenue is comprised of revenue recognition over time of the upfront non-refundable $75.0 million exclusivity fee received in connection with the VorTeq License Agreement , as well as the revenue recognition over time of the two milestone payments of $25.0 million each when uncertainty of receipt is resolved and receipt of each milestone payment is considered probable. The VorTeq License Agreement is comprised of a fifteen -year exclusive license for the Company’s VorTeq technology (“VorTeq”). In performing the obligations under the license, the Company provides research and development services to commercialize the technology in accordance with the Key Performance Indicators (“KPIs”), defined in the license agreement. After commercialization is achieved, payments will be received for the supply and servicing of certain components of the VorTeq. All payments are non-refundable. See Note 14 , “ VorTeq Partnership and License Agreement .” The Company recognizes license and development revenue in accordance with ASC 606. Revenue is recognized when control of the promised goods or services is transferred to customers. Stand-alone selling price was established at the inception of the contract by taking the transaction to market on a non-exclusive basis, and pricing in an exclusivity premium. Since the agreement included an up-front non-refundable payment at the inception of the agreement and future products and services are provided after initial commercialization, the Company completed an analysis and concluded that there was no material right included in the pricing of the agreement. Performance obligations have been identified, i.e. , the exclusive license to the Missile technology and upgrades prior to and subsequent to the date of full commercial launch. Value has been allocated to the performance obligations, and revenue is recognized over time based on the input measure of progress of the cost of salaries and wages related to the project prior to full commercialization, and ratably for the unspecified upgrades for the period subsequent to full commercialization until the expiration of the contract. Once commercial launch is achieved and cartridges are provided under the contract, revenue from those royalty payments will be recognized in accordance with ASC 842, with the Company as the lessor. It is expected that the cartridge leases will be classified as short-term operating leases and revenue will be recognized as earned. Revenue Recognition Revenues are recognized when control of the promised goods or services is transferred to the Company’s customers, in an amount that reflects the consideration the Company expects to be entitled to in exchange for those goods or services. At the inception of each contract, performance obligations are identified and the total transaction price is allocated to the performance obligations. The Company’s payment terms vary based on the credit risk of its customer. For certain customer types, the Company requires payment before the products or services are delivered to the customer. The Company performs an evaluation of customer credit worthiness on an individual contract basis to assess whether collectability is reasonably assured at the inception of the contract. As part of this evaluation, the Company considers many factors about the individual customer, including the underlying financial strength of the customer and/or partnership consortium and the Company’s prior history or industry-specific knowledge about the customer and its supplier relationships. For smaller projects, the Company requires the customer to remit payment generally within 30 to 60 days after product delivery. In some cases, if credit worthiness cannot be determined, prepayment or other security is required. Sales commissions are expensed as incurred when product revenue is earned. These costs are recorded within sales and marketing expenses. Arrangements with Multiple Performance Obligations and Termination for Convenience The Company’s contracts with customers may include multiple performance obligations. For such arrangements, the Company allocates revenue to each performance obligation based on its relative stand-alone selling price. The Company generally determines standalone selling prices based on the prices charged to customers. With respect to termination, the Company does not have the ability to cancel the contract for convenience. In general, customers can cancel for convenience upon the payment of a termination fee that covers costs and profit. It is rare for customers to cancel contracts. Practical Expedients and Exemptions In the Water segment, the time period between when the Company transfers control of products to the customer and the payment for the products is, in general, less than one year and, therefore, the practical expedient with respect to a financing component has been adopted by the Company. With respect to taxes, the Company has made the policy election to exclude taxes from the measurement of the transaction price. The Company does not disclose the value of unsatisfied performance obligations for (i) contracts with an original expected length of one year or less and (ii) contracts for which the Company recognizes revenue at the amount to which the Company has the right to invoice for services performed.

Recent Accounting Pronounceme23

Recent Accounting Pronouncements (Tables)	3 Months Ended
	Mar. 31, 2018
Accounting Changes and Error Corrections [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	Impact of Recently Adopted Accounting Pronouncements The following table illustrates changes in the Condensed Consolidated Balance Sheets as previously reported prior to, and as adjusted subsequent to, the adoption of the New Revenue Standard and New Lease Standard in the first quarter of 2018. December 31, 2017 As Previously Reported Adoption of New Revenue Standard Adoption of New Lease Standard As Adjusted (In thousands) Assets Current assets: Contract assets $ 6,411 $ (133 ) $ — $ 6,278 Total current assets 126,196 (133 ) — 126,063 Non-current assets Deferred tax assets, non-current 7,902 31 — 7,933 Operating lease, right of use asset — — 2,843 2,843 Total assets 161,744 (102 ) 2,843 164,485 Liabilities and Stockholders’ Equity Current liabilities: Accrued expenses and other current liabilities 8,517 (469 ) (100 ) 7,948 Lease liabilities — — 1,603 1,603 Contract liabilities 6,416 9,493 — 15,909 Total current liabilities 19,833 9,024 1,503 30,360 Non-current liabilities Lease liabilities, non-current — — 1,698 1,698 Contract liabilities, non-current 59,006 (18,489 ) — 40,517 Other non-current liabilities 358 — (358 ) — Total liabilities 79,213 (9,465 ) 2,843 72,591 Stockholders’ equity: Accumulated deficit (45,922 ) 9,363 — (36,559 ) Total stockholders’ equity 82,531 9,363 — 91,894 Total liabilities and stockholders’ equity 161,744 (102 ) 2,843 164,485 The following table illustrates changes in the Condensed Consolidated Statement of Operations as previously reported prior to, and as adjusted subsequent to, the adoption of the New Revenue Standard in the first quarter of 2018. Three Months Ended March 31, 2017 As Previously Reported Adoption of New Revenue Standard As Adjusted (In thousands, except for per share data) Product revenue $ 12,261 $ (16 ) $ 12,245 Product cost of revenue 4,610 2 4,612 Product gross profit $ 7,651 $ (18 ) $ 7,633 License and development revenue $ 1,250 $ 998 $ 2,248 Income (loss) from operations (627 ) 980 353 Income (loss) before income taxes (510 ) 980 470 (Benefit from) provision for income taxes (77 ) 125 48 Net income (loss) (433 ) 855 422 Income (loss) per share: Basic $ (0.01 ) $ 0.02 $ 0.01 Diluted $ (0.01 ) $ 0.02 $ 0.01 Number of shares used in per share calculations: Basic 53,825 — 53,825 Diluted 53,825 2,231 56,056 The following table illustrates changes in the Company’s segment activities as previously reported prior to, and as adjusted subsequent to, the adoption of the New Revenue Standard in the first quarter of 2018. Three Months Ended March 31, 2017 As Previously Reported Adoption of New Revenue Standard As Adjusted (In thousands) Water Product revenue $ 10,716 $ — $ 10,716 Product cost of revenue 3,522 2 3,524 Product gross profit $ 7,194 $ (2 ) $ 7,192 Income (loss) from operations $ 4,957 $ (2 ) $ 4,955 Oil & Gas Product revenue $ 1,545 $ (16 ) $ 1,529 Product cost of revenue 1,088 — 1,088 Product gross profit $ 457 $ (16 ) $ 441 License and development revenue $ 1,250 $ 998 $ 2,248 Income (loss) from operations (1,529 ) 982 (547 ) The following table illustrates changes in the Condensed Consolidated Statement of Comprehensive Income (Loss) as previously reported prior to, and as adjusted subsequent to, the adoption of the New Revenue Standard in the first quarter of 2018. Three Months Ended March 31, 2017 As Previously Reported Adoption of New Revenue Standard As Adjusted (In thousands) Net income (loss) $ (433 ) $ 855 $ 422 Comprehensive income (loss) (422 ) 855 433 The following table illustrates changes in the Condensed Consolidated Statement of Cash Flows as previously reported prior to, and as adjusted subsequent to, the adoption of the New Revenue Standard and New Cash Flow Presentation Standard in the first quarter of 2018. Three Months Ended March 31, 2017 As Previously Reported Adoption of New Revenue Standard Adoption of New Cash Flow Presentation Standard As Adjusted (In thousands) Net (loss) income $ (433 ) $ 855 $ — $ 422 Changes in operating assets and liabilities: Accounts receivable 2,571 10 — 2,581 Contract assets (3,572 ) 16 — (3,556 ) Inventories (345 ) 2 — (343 ) Accrued expenses and other liabilities (3,162 ) (404 ) — (3,566 ) Contract liabilities (1,553 ) (604 ) — (2,157 ) Net cash used in operating activities (4,824 ) — — (4,824 ) Restricted cash (460 ) — 460 — Net cash used in investing activities (701 ) — 460 (241 ) Net change in cash, cash equivalents and restricted cash (2,673 ) — 460 (2,213 ) Cash, cash equivalents and restricted cash, beginning of year 61,364 — 4,384 65,748 Cash, cash equivalents and restricted cash, end of period 58,691 — 4,844 63,535 The changes in the contract liability balance related to license and development revenue due to the adoption of ASC 606 are as follows. December 31, December 31, (In thousands) License and development contract liability, as previously reported $ 63,958 $ 68,958 Change in contract liability due to adoption the New Revenue Standard 9,465 3,359 License and development contract liability, as adjusted $ 54,493 $ 65,599 The changes in license and development revenue due to the adoption of ASC 606 are as follows. Years Ended December 31, 2017 2016 2015 (In thousands) License and development revenue, as previously reported $ 5,000 $ 5,000 $ 1,042 Change in revenue due to adoption the New Revenue Standard 6,106 3,069 290 License and development revenue, as adjusted $ 11,106 $ 8,069 $ 1,332

Revenue (Tables)

Revenue (Tables)	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The following table presents the Company’s revenues disaggregated by geography, based on the shipped to addresses of the Company’s customers and revenue source. Sales and usage-based taxes are excluded from revenues. Three Months Ended March 31, 2018 Water Oil & Gas Total (In thousands) Primary geographical market Middle East and Africa $ 6,102 $ 10 $ 6,112 Americas 1,101 2,749 3,850 Asia 2,673 — 2,673 Europe 1,172 — 1,172 Total $ 11,048 $ 2,759 $ 13,807 Major product/service line PX, pumps and turbo devices $ 11,048 $ — $ 11,048 License and development — 2,749 2,749 Oil & gas products — 10 10 Total $ 11,048 $ 2,759 $ 13,807 Three Months Ended March 31, 2017 Water Oil & Gas Total (In thousands) Primary geographical market Middle East and Africa $ 6,073 $ 1,530 $ 7,603 Americas 1,073 2,248 3,321 Asia 2,414 — 2,414 Europe 1,155 — 1,155 Total $ 10,715 $ 3,778 $ 14,493 Major product/service line PX, pumps and turbo devices $ 10,715 $ — $ 10,715 License and development — 2,248 2,248 Oil & gas products — 1,530 1,530 Total $ 10,715 $ 3,778 $ 14,493
Contract with Customer, Asset and Liability	Contract balances by category are presented in the following table. Prior year amounts have been adjusted for the adoption of ASC 606 in the first quarter of 2018. See Note 2 , “ Recent Accounting Pronouncements ,” for reconciliation of prior year “ As Previously Reported ” and “ As Adjusted ” amounts. March 31, December 31, (In thousands) Trade receivables $ 12,754 $ 12,465 Contract assets: Unbilled receivables $ 1,413 $ 1,413 Unbilled receivables, projects 3,535 4,865 Total contract assets $ 4,948 $ 6,278 Current contract liabilities: Customer deposits $ 894 $ 414 Deferred revenue: Cost and estimated earnings in excess of billings 773 805 License and development 14,568 14,024 Product 469 550 Service 127 116 Total current contract liability 16,831 15,909 Non-current contract liabilities, deferred revenue License and development 37,176 40,469 Product 63 48 Total non-current contract liability 37,239 40,517 Total contract liability $ 54,070 $ 56,426 The Company records unbilled receivables as contract assets. Significant changes in contract assets during the period were as follows. March 31, December 31, (In thousands) Balance, beginning of year $ 6,278 $ 2,015 Transferred to receivables (1,340 ) (2,909 ) Cumulative catch-up adjustments 10 7,172 Balance, end of period $ 4,948 $ 6,278 The Company records contract liabilities when cash payments are received or due in advance of the Company’s performance. Significant changes in contract liabilities during the period were as follows. March 31, December 31, (In thousands) Balance, beginning of year $ 56,426 $ 62,232 Revenue recognized (2,775 ) (5,892 ) Cash received 419 86 Balance, end of period $ 54,070 $ 56,426
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction	The following table includes estimated revenue expected to be recognized in the future related to performance obligations that are unsatisfied or partially unsatisfied at March 31, 2018. Estimated Revenue (In thousands) Year: 2018 (remaining nine months) $ 11,815 2019 13,457 2020 14,464 2021 6,871 2022 and thereafter 5,677 Total $ 52,284
Contract With Customer, Cost And Estimated Earnings On Uncompleted Contracts	Cost and estimated earnings on uncompleted contracts is presented in the following table. December 31, 2017 March 31, As Adjusted Adoption of New Revenue Standard As Previously Reported (In thousands) Estimated earnings to date $ 5,877 $ 5,867 $ (133 ) $ 6,000 Estimated costs to date (4,613 ) (4,525 ) — (4,525 ) Subtotal 1,264 1,342 (133 ) 1,475 Net billings to date 1,498 2,718 — 2,718 Total $ 2,762 $ 4,060 $ (133 ) $ 4,193 Included in accompanying balance sheets: Unbilled project costs $ 3,535 $ 4,865 $ (133 ) $ 4,998 Cost and estimated earnings in excess of billings (773 ) (805 ) — (805 ) Total $ 2,762 $ 4,060 $ (133 ) $ 4,193

(Loss) Income Per Share (Tables

(Loss) Income Per Share (Tables)	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The computation of basic and diluted net (loss) income per share is presented in the following table. Prior year amounts have been adjusted for the adoption of ASC 606 in the first quarter of 2018. See Note 2 , Recent Accounting Pronouncements , for reconciliation of prior year “ As Previously Reported ” and “ As Adjusted ” amounts. Three Months Ended March 31, 2018 2017 (In thousands, except per share amounts) Numerator: Net (loss) income $ (726 ) $ 422 Denominator: Basic weighted average common shares outstanding 53,987 53,825 Weighted average effect of dilutive stock awards — 2,231 Diluted weighted average common shares outstanding 53,987 56,056 Net (loss) income per share: Basic $ (0.01 ) $ 0.01 Diluted $ (0.01 ) $ 0.01
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The potential common shares were excluded from the computation of diluted net (loss) income per share as their effect would have been anti-dilutive is presented in the following table. Three Months Ended March 31, 2018 2017 (In thousands) Anti-dilutive shares excluded from net (loss) income per share calculation 5,414 1,279

Other Financial Information (Ta

Other Financial Information (Tables)	3 Months Ended
	Mar. 31, 2018
Other Financial Information [Abstract]
Restrictions on Cash and Cash Equivalents	The Company’s Condensed Consolidated Statement of Cash Flows explains the change in the total of cash, cash equivalents, and restricted cash. The following table provides a reconciliation of cash and cash equivalents, and restricted cash reported within the Condensed Consolidated Balance Sheets that sum to the total of such amounts in the Condensed Consolidated Statements of Cash Flows. March 31, December 31, (In thousands) Cash and cash equivalents $ 32,153 $ 27,780 Restricted cash 1,290 2,846 Total cash, cash equivalents, and restricted cash $ 33,443 $ 30,626
Schedule of Inventory, Current	Inventories are stated at the lower of cost (using the first-in, first-out method) or net realizable value and are presented by category in the following table. March 31, December 31, (In thousands) Raw materials $ 2,342 $ 1,899 Work in process 2,889 2,191 Finished goods 2,097 1,424 Inventories, net $ 7,328 $ 5,514
Schedule of Other Current Assets	Prepaid expenses and other current assets by category are presented in the following table. March 31, December 31, (In thousands) Insurance $ 205 $ 256 Interest receivable 443 439 Property taxes 255 189 Supplier advances 113 124 Software license 267 193 Other prepaid expenses and current assets 262 141 Total prepaid and other current assets $ 1,545 $ 1,342
Schedule of Accrued Liabilities	Accrued expenses and other current liabilities by category are presented in the following table. March 31, December 31, (In thousands) Payroll and commissions payable $ 2,800 $ 6,071 Other accrued expenses and current liabilities 1,190 1,877 Total accrued expenses and other current liabilities $ 3,990 $ 7,948
Schedule Of Lease Liabilities	Lease liabilities are presented in the following table. March 31, December 31, (In thousands) Lease liabilities $ 1,641 $ 1,603 Lease liabilities, non-current 1,273 1,698 Total lease liabilities $ 2,914 $ 3,301 The components of lease expense are presented in the following table. Three Months Ended March 31, 2018 (In thousands) Operating Lease Cost $ 380 Other information related to the operating leases are presented in the following table. Three Months Ended March 31, 2018 (In thousands, except for discount rate and lease term) Cash payments $ 435 Weighted average remaining lease term 20 months Weighted average discount rate 6.19 % Maturities of lease liabilities as of March 31, 2018 are presented in the following table. Lease Amounts (In thousands) Year: 2018 (remaining nine months) $ 1,319 2019 1,564 2020 148 2021 37 Total 3,068 Less imputed lease interest (154 ) Total lease liabilities $ 2,914
Schedule of Accumulated Other Comprehensive Income (Loss)	Changes in accumulated other comprehensive loss by component are presented in the following table. Foreign Currency Translation Adjustments Unrealized Losses on Investments Total Accumulated Other Comprehensive Loss (In thousands) Balance, December 31, 2017 $ (33 ) $ (92 ) $ (125 ) Other comprehensive income (loss), net 21 (64 ) (43 ) Balance, March 31, 2018 $ (12 ) $ (156 ) $ (168 )

Investments and Fair Value Me27

Investments and Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2018
Investments, Fair Value Disclosure [Abstract]
Cash, Cash Equivalents and Investments	The Company’s cash, cash equivalents and short-term investments are presented in the following table. March 31, December 31, (In thousands) Cash and cash equivalents $ 32,153 $ 27,780 Short-term investments 58,108 70,020 Total cash, cash equivalents and marketable securities $ 90,261 $ 97,800
Available-for-sale Securities	Available-for-sale investments as of March 31, 2018 and December 31, 2017 are presented in the following tables. March 31, 2018 Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Fair Value (In thousands) U.S. Treasury securities $ 11,626 $ — $ (21 ) $ 11,605 Corporate notes and bonds 46,390 — (135 ) 46,255 Municipal notes and bonds 248 — — 248 Total available-for-sale investments $ 58,264 $ — $ (156 ) $ 58,108 December 31, 2017 Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Fair Value (In thousands) U.S. Treasury securities $ 16,755 $ — $ (14 ) $ 16,741 Corporate notes and bonds 53,367 — (77 ) 53,290 Municipal notes and bonds 247 — — 247 Total available-for-sale investments $ 70,369 $ — $ (91 ) $ 70,278
Schedule Of Amortized Cost And Fair Value Of Available For Sale Securities	The amortized cost and fair value of available-for-sale securities that had stated maturities are shown by contractual maturity in the following table. March 31, 2018 Amortized Cost Fair Value (In thousands) Due in one year or less $ 58,264 $ 58,108
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The fair value of financial assets and liabilities measured on a recurring basis is presented in the following tables. March 31, 2018 Total Level 1 Inputs Level 2 Inputs Level 3 Inputs (In thousands) Assets: Short-term investments U.S. Treasury securities $ 11,605 $ — $ 11,605 $ — Corporate notes and bonds 46,255 — 46,255 — Municipal notes and bonds 248 — 248 — Total short-term investments 58,108 — 58,108 — Total assets $ 58,108 $ — $ 58,108 $ — December 31, 2017 Total Level 1 Inputs Level 2 Inputs Level 3 Inputs (In thousands) Assets: Cash equivalents Corporate notes and bonds $ 258 $ — $ 258 $ — Total cash equivalents 258 — 258 — Short-term investments U.S. Treasury securities 16,741 — 16,741 — Corporate notes and bonds 53,032 — 53,032 — Municipal notes and bonds 247 — 247 — Total short-term investments 70,020 — 70,020 — Total assets $ 70,278 $ — $ 70,278 $ —
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	The fair value and gross unrealized losses on the available-for-sale securities that have been in a continuous unrealized loss position, aggregated by type of investment instrument as of March 31, 2018 and December 31, 2017 are summarized in the following table. All of the Company’s available-for-sale investments were short-term with maturities less than 12 months. Available-for-sale investments that were in an unrealized gain position have been excluded from the following table. March 31, 2018 December 31, 2017 Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses (In thousands) U.S. Treasury securities $ 11,605 $ (21 ) $ 10,162 $ (14 ) Corporate notes and bonds 46,255 (135 ) 53,222 (77 ) Municipal notes and bonds 248 — 247 — Total available-for-sale investments $ 58,108 $ (156 ) $ 63,631 $ (91 )

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets	The components of identifiable intangible assets, all of which are finite-lived, as of the date indicated were as follows in the table below. All intangible assets are amortized on a straight-line basis over their useful life. March 31, December 31, (In thousands) Finite-lived intangible assets $ 6,643 $ 6,643 Accumulated amortization (5,531 ) (5,374 ) Intangible assets, net $ 1,112 $ 1,269

Long-term Debt and Lines of C29

Long-term Debt and Lines of Credit (Tables)	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Schedule Of Outstanding Amounts Of Standby Letters Of Credit By Financial Institution	The financial institutions where the outstanding amounts of stand-by letters of credit are collateralized by pledged U.S. investments or restricted cash are presented in the following table. March 31, December 31, (In thousands) Financial Institution 1 $ 1,148 $ 1,687 Financial Institution 2 7,309 7,745 Financial Institution 3 — 990 Total $ 8,457 $ 10,422
Schedule Of Outstanding Amounts Collateralized By Restricted Cash By Financial institution	The Company’s total restricted cash balances by financial institution are presented in the following table. Financial Institution 2 requires pledged U.S. investments in lieu of restricted cash balances. March 31, December 31, (In thousands) Financial Institution 1 $ 1,205 $ 1,771 Financial Institution 3 — 990 Financial Institution 4 85 85 Total $ 1,290 $ 2,846

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule Of Lease Liabilities	Lease liabilities are presented in the following table. March 31, December 31, (In thousands) Lease liabilities $ 1,641 $ 1,603 Lease liabilities, non-current 1,273 1,698 Total lease liabilities $ 2,914 $ 3,301 The components of lease expense are presented in the following table. Three Months Ended March 31, 2018 (In thousands) Operating Lease Cost $ 380 Other information related to the operating leases are presented in the following table. Three Months Ended March 31, 2018 (In thousands, except for discount rate and lease term) Cash payments $ 435 Weighted average remaining lease term 20 months Weighted average discount rate 6.19 % Maturities of lease liabilities as of March 31, 2018 are presented in the following table. Lease Amounts (In thousands) Year: 2018 (remaining nine months) $ 1,319 2019 1,564 2020 148 2021 37 Total 3,068 Less imputed lease interest (154 ) Total lease liabilities $ 2,914
Schedule of Product Warranty Liability	Changes in the Company’s accrued product warranty reserve are presented in the following table. Three Months Ended March 31, 2018 2017 (In thousands) Balance, beginning of year $ 366 $ 406 Warranty costs charged to cost of revenue 48 55 Utilization charges against reserve (50 ) (36 ) Release of accrual related to expired warranties (5 ) (27 ) Balance, end of period $ 359 $ 398

Stock-based Compensation (Table

Stock-based Compensation (Tables)	3 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs	Stock-based compensation expense related to the fair value measurement of awards granted to employees by financial line and by type of award is presented in the following table. Three Months Ended March 31, 2018 2017 (In thousands) Stock-based compensation expense by financial line: Cost of revenue $ 24 $ 49 General and administrative (1) 1,676 567 Sales and marketing 262 237 Research and development 281 260 Total stock-based compensation expense $ 2,243 $ 1,113 Stock-based compensation expense by type of award: Options (1) $ 1,664 $ 889 RSUs (1) 579 224 Total stock-based compensation expense $ 2,243 $ 1,113 (1) First quarter of 2018 amounts include modifications of equity awards.
Schedule of Unamortized Compensation Cost and Weighted Average Service Period	The following table presents the unamortized compensation cost and weighted average service period of all unvested outstanding awards as of March 31, 2018 . Unamortized Compensation Costs Weighted Average Service Period (In thousands) (In years) Stock options $ 6,760 2.9 RSUs 3,518 2.9 Total $ 10,278
Schedule of Grant Date Fair Value of Equity Instruments Vested	The total grant date fair value of stock options and RSUs vested during the period are presented in the following table. Three Months Ended March 31, 2018 2017 (In thousands) Stock options $ 1,261 $ 1,172 RSUs 509 436 Total grant date fair value of stock options and RSUs vested during the period $ 1,770 $ 1,608
Share-based Compensation, Stock Options, Activity	The following table summarizes the stock option activities under the Company’s 2016 Incentive Plan (“ 2016 Plan ”) and Amended and Restated 2008 Equity Incentive Plan . Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Life (in Years) Aggregate Intrinsic Value (1) (In thousands, except for weighted average exercise price and weighted average remaining contractual life) Balance, December 31, 2017 5,092 $ 5.43 6.6 $ 17,735 Granted 828 7.51 Exercised (484 ) 3.38 2,509 Forfeited (447 ) 6.94 Balance, March 31, 2018 4,989 $ 5.84 6.5 $ 13,067 Vested and exercisable as of March 31, 2018 3,260 $ 5.07 5.3 $ 10,763 Vested and exercisable as of March 31, 2018 and expected to vest thereafter 4,680 $ 5.71 6.3 $ 12,791 (1) The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying options and the fair value of the Company’s common stock at the time of exercise. The aggregate intrinsic value at March 31, 2018 is calculated as the difference between the exercise price of the underlying options and the fair value of the Company’s common stock as of March 31, 2018 or the last trading day prior to March 31, 2018 .
Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity	The following table summarizes the RSU activities under the 2016 Plan . Shares Weighted (In thousands, except for weighted average grant-date fair value) Balance, December 31, 2017 274 $ 9.54 Awarded 280 7.74 Vested (52 ) 9.82 Forfeited (77 ) 8.42 Balance, March 31, 2018 425 8.52

Business Segment (Tables)

Business Segment (Tables)	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Reconciliation of Operating Profit (Loss) from Segments to Consolidated	The summary of financial information by segment is presented in the following tables. Three Months Ended March 31, 2018 Water Oil & Gas Total (In thousands) Product revenue $ 11,048 $ 10 $ 11,058 Product cost of revenue 3,228 86 3,314 Product gross profit 7,820 (76 ) 7,744 License and development revenue — 2,749 2,749 Operating expenses: General and administrative 305 651 956 Sales and marketing 1,445 344 1,789 Research and development 244 3,665 3,909 Amortization of intangibles 158 — 158 Operating expenses 2,152 4,660 6,812 Operating income (loss) $ 5,668 $ (1,987 ) 3,681 Less: Corporate operating expenses 5,012 Consolidated operating loss (1,331 ) Non-operating income 248 Loss before income taxes $ (1,083 ) Prior year amounts in the following table have been adjusted for the adoption of ASC 606 in the first quarter of 2018. See Note 2 , Recent Accounting Pronouncements , for reconciliation of prior year “As Previously Reported” and “As Reported” amounts. Three Months Ended March 31, 2017 Water Oil & Gas Total (In thousands) Product revenue $ 10,716 $ 1,529 $ 12,245 Product cost of revenue 3,524 1,088 4,612 Product gross profit 7,192 441 7,633 License and development revenue — 2,248 2,248 Operating expenses: General and administrative 318 349 667 Sales and marketing 1,499 641 2,140 Research and development 262 2,246 2,508 Amortization of intangibles 158 — 158 Operating expenses 2,237 3,236 5,473 Operating income (loss) $ 4,955 $ (547 ) 4,408 Less: Corporate operating expenses 4,055 Consolidated operating income 353 Non-operating income 117 Income before income taxes $ 470

Recent Accounting Pronounceme33

Recent Accounting Pronouncements - Additional Details (Details) $ in Thousands	Oct. 14, 2015USD ($)payment	Mar. 31, 2018USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
License and development revenue		$ 2,749	$ 2,248	$ 11,106	$ 8,069	$ 1,332
License and development contract liability				54,493	65,599
As Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
License and development revenue			1,250	5,000	5,000	1,042
License and development contract liability				63,958	68,958
Accounting Standards Update 2014-09 | Restatement Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
License and development revenue			$ 998	6,106	3,069	$ 290
License and development contract liability				$ 9,465	$ 3,359
VorTeq License Agreement
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Up front non-refundable payment	$ 75,000
License term	15 years
Number of milestone payments | payment	2
Milestone Payment One Upon Successful Yard Test | VorTeq License Agreement
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
VorTeq milestone payment to be received	$ 25,000

Recent Accounting Pronounceme34

Recent Accounting Pronouncements - Balance Sheet (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Contract assets	$ 4,948	$ 6,278
Total current assets	118,041	126,063
Deferred tax assets, non-current	8,309	7,933
Operating lease, right of use asset	2,511	2,843
Total assets	155,857	164,485
Accrued expenses and other current liabilities	3,990	7,948
Lease liabilities	1,641	1,603
Contract liabilities	16,831	15,909
Total current liabilities	25,603	30,360
Lease liabilities, non-current	1,273	1,698
Contract liabilities, non-current	37,239	40,517
Other non-current liabilities	255	0
Total liabilities	64,383	72,591
Accumulated deficit	(37,286)	(36,559)
Total stockholders’ equity	91,474	91,894
Total liabilities and stockholders’ equity	$ 155,857	164,485
As Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Contract assets		6,411
Total current assets		126,196
Deferred tax assets, non-current		7,902
Operating lease, right of use asset		0
Total assets		161,744
Accrued expenses and other current liabilities		8,517
Lease liabilities		0
Contract liabilities		6,416
Total current liabilities		19,833
Lease liabilities, non-current		0
Contract liabilities, non-current		59,006
Other non-current liabilities		358
Total liabilities		79,213
Accumulated deficit		(45,922)
Total stockholders’ equity		82,531
Total liabilities and stockholders’ equity		161,744
Restatement Adjustment | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Contract assets		(133)
Total current assets		(133)
Deferred tax assets, non-current		31
Operating lease, right of use asset		0
Total assets		(102)
Accrued expenses and other current liabilities		(469)
Lease liabilities		0
Contract liabilities		9,493
Total current liabilities		9,024
Lease liabilities, non-current		0
Contract liabilities, non-current		(18,489)
Other non-current liabilities		0
Total liabilities		(9,465)
Accumulated deficit		9,363
Total stockholders’ equity		9,363
Total liabilities and stockholders’ equity		(102)
Restatement Adjustment | Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Contract assets		0
Total current assets		0
Deferred tax assets, non-current		0
Operating lease, right of use asset		2,843
Total assets		2,843
Accrued expenses and other current liabilities		(100)
Lease liabilities		1,603
Contract liabilities		0
Total current liabilities		1,503
Lease liabilities, non-current		1,698
Contract liabilities, non-current		0
Other non-current liabilities		(358)
Total liabilities		2,843
Accumulated deficit		0
Total stockholders’ equity		0
Total liabilities and stockholders’ equity		$ 2,843

Recent Accounting Pronounceme35

Recent Accounting Pronouncements - Income Statement (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Product revenue	$ 11,058	$ 12,245
Product cost of revenue	3,314	4,612
Product gross profit	7,744	7,633
License and development revenue	2,749	2,248	$ 11,106	$ 8,069	$ 1,332
(Loss) income from operations	(1,331)	353
(Loss) income before income taxes	(1,083)	470
(Benefit from) provision for income taxes	(357)	48
Net (loss) income	$ (726)	$ 422
Basic (in dollars per share)	$ (0.01)	$ 0.01
Diluted (in dollars per share)	$ (0.01)	$ 0.01
Basic (in shares)	53,987	53,825
Diluted (in shares)	53,987	56,056
As Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Product revenue		$ 12,261
Product cost of revenue		4,610
Product gross profit		7,651
License and development revenue		1,250	5,000	5,000	1,042
(Loss) income from operations		(627)
(Loss) income before income taxes		(510)
(Benefit from) provision for income taxes		(77)
Net (loss) income		$ (433)
Basic (in dollars per share)		$ (0.01)
Diluted (in dollars per share)		$ (0.01)
Basic (in shares)		53,825
Diluted (in shares)		53,825
Accounting Standards Update 2014-09 | Restatement Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Product revenue		$ (16)
Product cost of revenue		2
Product gross profit		(18)
License and development revenue		998	$ 6,106	$ 3,069	$ 290
(Loss) income from operations		980
(Loss) income before income taxes		980
(Benefit from) provision for income taxes		125
Net (loss) income		$ 855
Basic (in dollars per share)		$ 0.02
Diluted (in dollars per share)		$ 0.02
Basic (in shares)		0
Diluted (in shares)		2,231
Operating Segments
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Product revenue	$ 11,058	$ 12,245
Product cost of revenue	3,314	4,612
Product gross profit	7,744	7,633
License and development revenue	2,749	2,248
(Loss) income from operations	3,681	4,408
Operating Segments | Water
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Product revenue	11,048	10,716
Product cost of revenue	3,228	3,524
Product gross profit	7,820	7,192
License and development revenue	0	0
(Loss) income from operations	5,668	4,955
Operating Segments | Water | As Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Product revenue		10,716
Product cost of revenue		3,522
Product gross profit		7,194
(Loss) income from operations		4,957
Operating Segments | Water | Accounting Standards Update 2014-09 | Restatement Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Product revenue		0
Product cost of revenue		2
Product gross profit		(2)
(Loss) income from operations		(2)
Operating Segments | Oil & Gas
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Product revenue	10	1,529
Product cost of revenue	86	1,088
Product gross profit	(76)	441
License and development revenue	2,749	2,248
(Loss) income from operations	$ (1,987)	(547)
Operating Segments | Oil & Gas | As Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Product revenue		1,545
Product cost of revenue		1,088
Product gross profit		457
License and development revenue		1,250
(Loss) income from operations		(1,529)
Operating Segments | Oil & Gas | Accounting Standards Update 2014-09 | Restatement Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Product revenue		(16)
Product cost of revenue		0
Product gross profit		(16)
License and development revenue		998
(Loss) income from operations		$ 982

Recent Accounting Pronounceme36

Recent Accounting Pronouncements - Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net (loss) income	$ (726)	$ 422
Comprehensive (loss) income	$ (769)	433
As Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net (loss) income		(433)
Comprehensive (loss) income		(422)
Accounting Standards Update 2014-09 | Restatement Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net (loss) income		855
Comprehensive (loss) income		$ 855

Recent Accounting Pronounceme37

Recent Accounting Pronouncements - Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net (loss) income	$ (726)	$ 422
Accounts receivable	(297)	2,581
Contract assets	1,330	(3,556)
Inventories	(1,824)	(343)
Accrued expenses and other liabilities	(4,092)	(3,566)
Contract liabilities	(2,354)	(2,157)
Net cash used in operating activities	(6,333)	(4,824)
Restricted cash		0
Net cash provided by (used in) investing activities	11,062	(241)
Net change in cash, cash equivalents and restricted cash	2,817	(2,213)
Cash, cash equivalents and restricted cash, beginning of year	30,626	65,748
Cash, cash equivalents and restricted cash, end of period	$ 33,443	63,535
As Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net (loss) income		(433)
Accounts receivable		2,571
Contract assets		(3,572)
Inventories		(345)
Accrued expenses and other liabilities		(3,162)
Contract liabilities		(1,553)
Net cash used in operating activities		(4,824)
Restricted cash		(460)
Net cash provided by (used in) investing activities		(701)
Net change in cash, cash equivalents and restricted cash		(2,673)
Cash, cash equivalents and restricted cash, beginning of year		61,364
Cash, cash equivalents and restricted cash, end of period		58,691
Accounting Standards Update 2014-09 | Restatement Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net (loss) income		855
Accounts receivable		10
Contract assets		16
Inventories		2
Accrued expenses and other liabilities		(404)
Contract liabilities		(604)
Net cash used in operating activities		0
Restricted cash		0
Net cash provided by (used in) investing activities		0
Net change in cash, cash equivalents and restricted cash		0
Cash, cash equivalents and restricted cash, beginning of year		0
Cash, cash equivalents and restricted cash, end of period		0
Accounting Standards Update 2016-18 | Restatement Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net (loss) income		0
Accounts receivable		0
Contract assets		0
Inventories		0
Accrued expenses and other liabilities		0
Contract liabilities		0
Net cash used in operating activities		0
Restricted cash		460
Net cash provided by (used in) investing activities		460
Net change in cash, cash equivalents and restricted cash		460
Cash, cash equivalents and restricted cash, beginning of year		4,384
Cash, cash equivalents and restricted cash, end of period		$ 4,844

Revenue Narrative (Details)

Revenue Narrative (Details) $ in Thousands	Oct. 14, 2015USD ($)payment	Mar. 31, 2018USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Licenses Revenue		$ 2,749	$ 2,248	$ 11,106	$ 8,069	$ 1,332
Retention payments, percentage (or less)		10.00%
Minimum
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Customer payment period after product delivery		24 months
Maximum
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Customer payment period after product delivery		36 months
VorTeq License Agreement
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Up front non-refundable payment	$ 75,000
Number of milestone payments | payment	2
License term	15 years
VorTeq License Agreement | Milestone Payment One Upon Successful Yard Test
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
VorTeq milestone payment to be received	$ 25,000
Accounting Standards Update 2014-09 | Restatement Adjustment
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Licenses Revenue			$ 998	$ 6,106	$ 3,069	$ 290

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disaggregation of Revenue [Line Items]
Revenues	$ 13,807	$ 14,493
PX, pumps and turbo devices
Disaggregation of Revenue [Line Items]
Revenues	11,048	10,715
License and development
Disaggregation of Revenue [Line Items]
Revenues	2,749	2,248
Oil & gas products
Disaggregation of Revenue [Line Items]
Revenues	10	1,530
Middle East and Africa
Disaggregation of Revenue [Line Items]
Revenues	6,112	7,603
Americas
Disaggregation of Revenue [Line Items]
Revenues	3,850	3,321
Asia
Disaggregation of Revenue [Line Items]
Revenues	2,673	2,414
Europe
Disaggregation of Revenue [Line Items]
Revenues	1,172	1,155
Water
Disaggregation of Revenue [Line Items]
Revenues	11,048	10,715
Water | PX, pumps and turbo devices
Disaggregation of Revenue [Line Items]
Revenues	11,048	10,715
Water | License and development
Disaggregation of Revenue [Line Items]
Revenues	0	0
Water | Oil & gas products
Disaggregation of Revenue [Line Items]
Revenues	0	0
Water | Middle East and Africa
Disaggregation of Revenue [Line Items]
Revenues	6,102	6,073
Water | Americas
Disaggregation of Revenue [Line Items]
Revenues	1,101	1,073
Water | Asia
Disaggregation of Revenue [Line Items]
Revenues	2,673	2,414
Water | Europe
Disaggregation of Revenue [Line Items]
Revenues	1,172	1,155
Oil & gas products
Disaggregation of Revenue [Line Items]
Revenues	2,759	3,778
Oil & gas products | PX, pumps and turbo devices
Disaggregation of Revenue [Line Items]
Revenues	0	0
Oil & gas products | License and development
Disaggregation of Revenue [Line Items]
Revenues	2,749	2,248
Oil & gas products | Oil & gas products
Disaggregation of Revenue [Line Items]
Revenues	10	1,530
Oil & gas products | Middle East and Africa
Disaggregation of Revenue [Line Items]
Revenues	10	1,530
Oil & gas products | Americas
Disaggregation of Revenue [Line Items]
Revenues	2,749	2,248
Oil & gas products | Asia
Disaggregation of Revenue [Line Items]
Revenues	0	0
Oil & gas products | Europe
Disaggregation of Revenue [Line Items]
Revenues	$ 0	$ 0

Revenue - Contract Assets and L

Revenue - Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue from Contract with Customer [Abstract]
Trade receivables	$ 12,754	$ 12,465
Contract assets:
Unbilled receivables	1,413	1,413
Unbilled receivables, projects	3,535	4,865
Total contract assets	4,948	6,278
Current contract liabilities:
Customer deposits	894	414
Deferred revenue:
Cost and estimated earnings in excess of billings	773	805
License and development	14,568	14,024
Product	469	550
Service	127	116
Contract with Customer, Liability, Current	16,831	15,909
Non-current contract liabilities, deferred revenue
License and development	37,176	40,469
Product	63	48
Total non-current contract liability	37,239	40,517
Contract with Customer, Liability	$ 54,070	$ 56,426	$ 62,232

Revenue - Significant Changes i

Revenue - Significant Changes in Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Change In Contract With Customer, Asset [Roll Forward]
Balance, beginning of year	$ 6,278	$ 2,015
Transferred to receivables	(1,340)	(2,909)
Cumulative catch-up adjustments	10	7,172
Balance, end of period	4,948	6,278
Change In Contract With Customer, Liability [Roll Forward]
Balance, beginning of year	56,426	62,232
Revenue recognized	(2,775)	(5,892)
Cash received	419	86
Balance, end of period	$ 54,070	$ 56,426

Revenue - Remaining Performance

Revenue - Remaining Performance Obligation (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 11,815
Performance obligations expected to be satisfied, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 13,457
Performance obligations expected to be satisfied, expected timing	2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 14,464
Performance obligations expected to be satisfied, expected timing	3 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 6,871
Performance obligations expected to be satisfied, expected timing	4 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 52,284
Performance obligations expected to be satisfied, expected timing	5 years

Revenue - Cost and Estimated Ea

Revenue - Cost and Estimated Earnings on Uncompleted Contracts (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated earnings to date	$ 5,877	$ 5,867
Estimated costs to date	(4,613)	(4,525)
Subtotal	1,264	1,342
Net billings to date	1,498	2,718
Unbilled project costs	3,535	4,865
Cost and estimated earnings in excess of billings	(773)	(805)
Total	$ 2,762	4,060
As Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated earnings to date		6,000
Estimated costs to date		(4,525)
Subtotal		1,475
Net billings to date		2,718
Unbilled project costs		4,998
Cost and estimated earnings in excess of billings		(805)
Total		4,193
Accounting Standards Update 2014-09 | Restatement Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated earnings to date		(133)
Estimated costs to date		0
Subtotal		(133)
Net billings to date		0
Unbilled project costs		(133)
Cost and estimated earnings in excess of billings		0
Total		$ (133)

(Loss) Income Per Share - Compu

(Loss) Income Per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Numerator:
Net (loss) income	$ (726)	$ 422
Denominator:
Basic weighted average common shares outstanding (in shares)	53,987	53,825
Weighted average effect of dilutive stock awards (in shares)	0	2,231
Diluted weighted average common shares outstanding (in shares)	53,987	56,056
Net income (loss) per share - basic (in dollars per share)	$ (0.01)	$ 0.01
Net income (loss) per share - diluted (in dollars per share)	$ (0.01)	$ 0.01

(Loss) Income Per Share - Antid

(Loss) Income Per Share - Antidilutive Securities Excluded From Computation of Diluted Earnings Per Share (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Anti-dilutive shares excluded from net income (loss) per share calculation (in shares)	5,414	1,279

Other Financial Information - A

Other Financial Information - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Other Financial Information [Abstract]
Inventory valuation reserves	$ 600,000		$ 700,000
Reclassification from AOCI, current period	$ 0	$ 0

Other Financial Information - R

Other Financial Information - Restricted Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Other Financial Information [Abstract]
Cash and cash equivalents	$ 32,153	$ 27,780
Restricted cash	1,290	2,846
Total cash, cash equivalents, and restricted cash	$ 33,443	$ 30,626	$ 63,535	$ 65,748

Other Financial Information - I

Other Financial Information - Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Other Financial Information [Abstract]
Raw materials	$ 2,342	$ 1,899
Work in process	2,889	2,191
Finished goods	2,097	1,424
Inventories, net	$ 7,328	$ 5,514

Other Financial Information - P

Other Financial Information - Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Other Financial Information [Abstract]
Insurance	$ 205	$ 256
Interest receivable	443	439
Property taxes	255	189
Supplier advances	113	124
Software license	267	193
Other prepaid expenses and current assets	262	141
Total prepaid and other current assets	$ 1,545	$ 1,342

Other Financial Information -50

Other Financial Information - Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Other Financial Information [Abstract]
Payroll and commissions payable	$ 2,800	$ 6,071
Other accrued expenses and current liabilities	1,190	1,877
Total accrued expenses and other current liabilities	$ 3,990	$ 7,948

Other Financial Information - L

Other Financial Information - Lease Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Other Financial Information [Abstract]
Lease liabilities	$ 1,641	$ 1,603
Lease liabilities, non-current	1,273	1,698
Total lease liabilities	$ 2,914	$ 3,301

Other Financial Information -52

Other Financial Information - Accumulated Other Comprehensive Loss (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 91,894
Other comprehensive income (loss), net	(43)
Ending Balance	91,474
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(33)
Other comprehensive income (loss), net	21
Ending Balance	(12)
Unrealized Losses on Investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(92)
Other comprehensive income (loss), net	(64)
Ending Balance	(156)
Total Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(125)
Ending Balance	$ (168)

Investments and Fair Value Me53

Investments and Fair Value Measurements - Additional Information (Details)	Mar. 31, 2018USD ($)
Investments, Fair Value Disclosure [Abstract]
Transfer between Level 1 and Level 2	$ 0
Transfers between Level 2 and Level 1	$ 0

Investments and Fair Value Me54

Investments and Fair Value Measurements - Cash, Cash Equivalents and Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Investments, Fair Value Disclosure [Abstract]
Cash and cash equivalents	$ 32,153	$ 27,780
Short-term investments	58,108	70,020
Total cash, cash equivalents and marketable securities	$ 90,261	97,800
Cash equivalents		$ 258

Investments and Fair Value Me55

Investments and Fair Value Measurements - Available-for-sale Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 58,264	$ 70,369
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	(156)	(91)
Fair Value	58,108	70,278
Short-term Investments [Member] | U.S. Treasury securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	11,626	16,755
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	(21)	(14)
Fair Value	11,605	16,741
Short-term Investments [Member] | Corporate notes and bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	46,390	53,367
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	(135)	(77)
Fair Value	46,255	53,290
Short-term Investments [Member] | Municipal notes and bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	248	247
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	0	0
Fair Value	$ 248	$ 247

Investments and Fair Value Me56

Investments and Fair Value Measurements - Amortized Cost and Fair Value of Available-for-sale Securities (Details) $ in Thousands	Mar. 31, 2018USD ($)
Investments, Fair Value Disclosure [Abstract]
Due in one year or less, amortized cost	$ 58,264
Due in one year or less, fair value	$ 58,108

Investments and Fair Value Me57

Investments and Fair Value Measurements - Fair Value of Financial Assets and Liabilities Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets:
Cash equivalents		$ 258
Short-term investments	$ 58,108	70,020
Total assets	58,108	70,278
Fair Value, Measurements, Recurring | Level 1 Inputs
Assets:
Cash equivalents		0
Short-term investments	0	0
Total assets	0	0
Fair Value, Measurements, Recurring | Level 2 Inputs
Assets:
Cash equivalents		258
Short-term investments	58,108	70,020
Total assets	58,108	70,278
Fair Value, Measurements, Recurring | Level 3 Inputs
Assets:
Cash equivalents		0
Short-term investments	0	0
Total assets	0	0
U.S. Treasury securities
Assets:
Short-term investments	11,605	16,741
U.S. Treasury securities | Fair Value, Measurements, Recurring | Level 1 Inputs
Assets:
Short-term investments	0	0
U.S. Treasury securities | Fair Value, Measurements, Recurring | Level 2 Inputs
Assets:
Short-term investments	11,605	16,741
U.S. Treasury securities | Fair Value, Measurements, Recurring | Level 3 Inputs
Assets:
Short-term investments	0	0
Corporate notes and bonds
Assets:
Short-term investments	46,255	53,032
Corporate notes and bonds | Fair Value, Measurements, Recurring | Level 1 Inputs
Assets:
Short-term investments	0	0
Corporate notes and bonds | Fair Value, Measurements, Recurring | Level 2 Inputs
Assets:
Short-term investments	46,255	53,032
Corporate notes and bonds | Fair Value, Measurements, Recurring | Level 3 Inputs
Assets:
Short-term investments	0	0
Municipal notes and bonds
Assets:
Short-term investments	248	247
Municipal notes and bonds | Fair Value, Measurements, Recurring | Level 1 Inputs
Assets:
Short-term investments	0	0
Municipal notes and bonds | Fair Value, Measurements, Recurring | Level 2 Inputs
Assets:
Short-term investments	248	247
Municipal notes and bonds | Fair Value, Measurements, Recurring | Level 3 Inputs
Assets:
Short-term investments	0	0
Corporate notes and bonds
Assets:
Cash equivalents	$ 0	258
Corporate notes and bonds | Fair Value, Measurements, Recurring | Level 1 Inputs
Assets:
Cash equivalents		0
Corporate notes and bonds | Fair Value, Measurements, Recurring | Level 2 Inputs
Assets:
Cash equivalents		258
Corporate notes and bonds | Fair Value, Measurements, Recurring | Level 3 Inputs
Assets:
Cash equivalents		$ 0

Investments and Fair Value Me58

Investments and Fair Value Measurements - Gross Unrealized Losses and Fair Values of Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Fair Value	$ 58,108	$ 63,631
Gross Unrealized Losses	(156)	(91)
U.S. Treasury securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	11,605	10,162
Gross Unrealized Losses	(21)	(14)
Corporate notes and bonds
Schedule of Available-for-sale Securities [Line Items]
Fair Value	46,255	53,222
Gross Unrealized Losses	(135)	(77)
Municipal notes and bonds
Schedule of Available-for-sale Securities [Line Items]
Fair Value	248	247
Gross Unrealized Losses	$ 0	$ 0

Goodwill and Intangible Asset59

Goodwill and Intangible Assets - Additional Information (Details) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 12,790,000	$ 12,790,000
Accumulated impairment loss	$ 0

Goodwill and Intangible Asset60

Goodwill and Intangible Assets - Identifiable Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Gross Carrying Amount	$ 6,643	$ 6,643
Accumulated Amortization	(5,531)	(5,374)
Net Carrying Amount	$ 1,112	$ 1,269

Long-term Debt and Lines of C61

Long-term Debt and Lines of Credit - Loan Agreements and Stand-by Letters of Credit (Details) - Loan and Pledge Agreement - Financial Institution 2 - USD ($)	Mar. 30, 2018	Jan. 27, 2017
Line of Credit Facility [Line Items]
Payments of closing fees	$ 16,000
Committed Revolving Credit Line
Line of Credit Facility [Line Items]
Maximum borrowing capacity		$ 16,000,000
Uncommitted Revolving Credit Line
Line of Credit Facility [Line Items]
Maximum borrowing capacity		$ 4,000,000

Long-term Debt and Lines of C62

Long-term Debt and Lines of Credit - Stand-by Letters of Credit Outstanding by Financial Institution (Details) - Standby Letters of Credit - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Line of Credit Facility [Line Items]
Letters of credit outstanding, amount	$ 8,500	$ 10,400
Financial Institution 1
Line of Credit Facility [Line Items]
Letters of credit outstanding, amount	1,148	1,687
Financial Institution 2
Line of Credit Facility [Line Items]
Letters of credit outstanding, amount	7,309	7,745
Financial Institution 3
Line of Credit Facility [Line Items]
Letters of credit outstanding, amount	$ 0	$ 990

Long-term Debt and Lines of C63

Long-term Debt and Lines of Credit - Restricted Cash Requirements (Details) - Collateral for stand-by letters of credit - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	$ 1,290	$ 2,846
Financial Institution 1
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	1,205	1,771
Financial Institution 3
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	0	990
Financial Institution 4
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	$ 85	$ 85

Commitments and Contingencies -

Commitments and Contingencies - Operating Lease Obligations (Details) $ in Thousands	1 Months Ended	3 Months Ended
	Apr. 30, 2018USD ($)term	Mar. 31, 2018USD ($)term	Dec. 31, 2017USD ($)
Loss Contingencies [Line Items]
Operating Lease Cost		$ 380
Cash payments		$ 435
Weighted average remaining lease term		20 months
Weighted average discount rate		6.19%
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2018 (remaining nine months)		$ 1,319
2,019		1,564
2,020		148
2,021		37
Total		3,068
Less imputed lease interest		(154)
Total lease liabilities		$ 2,914	$ 3,301
Doolittle Lease
Loss Contingencies [Line Items]
Operating lease, number of renewal terms | term		2
Operating lease, renewal term		5 years
New Doolittle Lease | Subsequent Event
Loss Contingencies [Line Items]
Operating lease, number of renewal terms | term	1
Operating lease, renewal term	5 years
Operating lease, annual base facility lease payment	$ 800
Operating lease, liability, payments, due	$ 19,000

Commitments and Contingencies65

Commitments and Contingencies - Product Warranty Liability (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance, beginning of year	$ 366	$ 406
Warranty costs charged to cost of revenue	48	55
Utilization charges against reserve	(50)	(36)
Release of accrual related to expired warranties	(5)	(27)
Balance, end of period	$ 359	$ 398

Commitments and Contingencies66

Commitments and Contingencies - Additional Information (Details)	3 Months Ended	5 Months Ended
	Mar. 31, 2018USD ($)	Jul. 27, 2016complaint	Dec. 31, 2017USD ($)
Loss Contingencies [Line Items]
Long-term purchase commitment	$ 3,500,000
Warranty and product performance guarantees as percentage of total sales agreement	10.00%
Warranty and product performance guarantees, period	36 months
Loss contingency, new claims filed, number | complaint		2
Indemnification Agreement
Loss Contingencies [Line Items]
Guarantor obligations, current carrying value	$ 0		$ 0
Minimum
Loss Contingencies [Line Items]
Warranty and product performance guarantees, period	24 months
Maximum
Loss Contingencies [Line Items]
Warranty and product performance guarantees, period	68 months
Standby Letters of Credit
Loss Contingencies [Line Items]
Letters of credit outstanding, amount	$ 8,500,000		$ 10,400,000

Income Taxes (Detail)

Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Provision for (benefit from) income taxes	$ (357)	$ 48
Effective tax rate	33.00%	10.20%
Effective tax rate, excluding discrete tax income tax items	(3.50%)	24.00%

Stockholders' Equity - Stock Re

Stockholders' Equity - Stock Repurchase Program (Details) - March 2018 Authorization - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 07, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock repurchase program, authorized amount		$ 10,000,000
Treasury stock, shares, acquired (in shares)	409,850
Treasury stock, value, acquired, cost method	$ 3,500,000

Stock-based Compensation - Shar

Stock-based Compensation - Share-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 2,243	$ 1,113
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	1,664	889
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	579	224
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	24	49
General and administrative (1)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	1,676	567
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	262	237
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	281	$ 260
Former President and Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 900

Stock-based Compensation - Unam

Stock-based Compensation - Unamortized Compensation Cost and Grant Date Fair Value (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unamortized Compensation Costs	$ 10,278
Grant date fair value	1,770	$ 1,608
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unamortized Compensation Costs	$ 6,760
Weighted Average Service Period	2 years 11 months
Grant date fair value	$ 1,261	1,172
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unamortized Compensation Costs	$ 3,518
Weighted Average Service Period	2 years 11 months
Grant date fair value	$ 509	$ 436

Stock-based Compensation - Stoc

Stock-based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Granted (in shares)	828
Exercised (in shares)	(484)
Forfeited (in shares)	(447)
Ending balance (in shares)	4,989
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Beginning balance, Weighted Average Exercise Price (in dollars per share)	$ 5.43
Granted, weighted average exercise price (in dollars per share)	7.51
Exercised, weighted average exercise price (in dollars per share)	3.38
Forfeited, weighted average exercise price (in dollars per share)	6.94
Ending balance, Weighted average exercise price (in dollars per share)	$ 5.84	$ 5.43
Weighted Average Remaining Contractual Life	6 years 6 months	6 years 7 months
Aggregate Intrinsic Value	$ 13,067	$ 17,735
Aggregate intrinsic value, exercised	$ 2,509
Vested and exercisable options (in shares)	3,260
Vested and exercisable options, weighted average exercise price (in dollars per share)	$ 5.07
Vested and exercisable options, weighted average remaining contractual term	5 years 3 months 18 days
Vested and exercisable options, Aggregate Intrinsic Value	$ 10,763
Vested and exercisable, and expected to vest options (in shares)	4,680
Vested and exercisable, and expected to vest options, weighted average exercise price (in dollars per share)	$ 5.71
Vested and exercisable, and expected to vest options, weighted average remaining contractual life	6 years 3 months 18 days
Vested and exercisable, and expected to vest options, Aggregate Intrinsic Value	$ 12,791

Stock-based Compensation - Rest

Stock-based Compensation - Restricted Stock Units Activity (Details) - Restricted Stock Units shares in Thousands	3 Months Ended
	Mar. 31, 2018$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Beginning balance (in shares) | shares	274
Awarded (in shares) | shares	280
Vested (in shares) | shares	(52)
Forfeited (in shares) | shares	(77)
Ending balance (in shares) | shares	425
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Beginning balance, Weighted average grant-date fair value (in dollars per share) | $ / shares	$ 9.54
Awarded, Weighted average grant-date fair value (in dollars per share) | $ / shares	7.74
Vested, Weighted average grant-date fair value, (in dollars per share) | $ / shares	9.82
Forfeited, Weighted average grant-date fair value (in dollars per share) | $ / shares	8.42
Ending balance, Weighted average grant-date fair value (in dollars per share) | $ / shares	$ 8.52

Business Segment - Summary of F

Business Segment - Summary of Financial Information by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Product revenue	$ 11,058	$ 12,245
Product cost of revenue	3,314	4,612
Product gross profit	7,744	7,633
License and development revenue	2,749	2,248	$ 11,106	$ 8,069	$ 1,332
General and administrative	5,837	4,408
Sales and marketing	1,912	2,453
Research and development	3,917	2,509
Amortization of intangibles	158	158
Total operating expenses	11,824	9,528
(Loss) income from operations	(1,331)	353
Non-operating income	248	117
(Loss) income before income taxes	(1,083)	470
Operating Segments
Segment Reporting Information [Line Items]
Product revenue	11,058	12,245
Product cost of revenue	3,314	4,612
Product gross profit	7,744	7,633
License and development revenue	2,749	2,248
General and administrative	956	667
Sales and marketing	1,789	2,140
Research and development	3,909	2,508
Amortization of intangibles	158	158
Total operating expenses	6,812	5,473
(Loss) income from operations	3,681	4,408
Operating Segments | Water
Segment Reporting Information [Line Items]
Product revenue	11,048	10,716
Product cost of revenue	3,228	3,524
Product gross profit	7,820	7,192
License and development revenue	0	0
General and administrative	305	318
Sales and marketing	1,445	1,499
Research and development	244	262
Amortization of intangibles	158	158
Total operating expenses	2,152	2,237
(Loss) income from operations	5,668	4,955
Operating Segments | Oil & Gas
Segment Reporting Information [Line Items]
Product revenue	10	1,529
Product cost of revenue	86	1,088
Product gross profit	(76)	441
License and development revenue	2,749	2,248
General and administrative	651	349
Sales and marketing	344	641
Research and development	3,665	2,246
Amortization of intangibles	0	0
Total operating expenses	4,660	3,236
(Loss) income from operations	(1,987)	(547)
Corporate
Segment Reporting Information [Line Items]
Total operating expenses	$ 5,012	$ 4,055

VorTeq Partnership and Licens74

VorTeq Partnership and License Agreement (Details) - VorTeq License Agreement	Oct. 14, 2015USD ($)payment	Mar. 31, 2018USD ($)	Dec. 31, 2015missile
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
VorTeq license agreement payments	$ 125,000,000
Up front non-refundable payment	$ 75,000,000
Number of milestone payments | payment	2
Milestone Payment One Upon Successful Yard Test
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
VorTeq milestone payment to be received	$ 25,000,000
Milestone Payment Two Upon Successful Fracing of ALive Well
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
VorTeq milestone payment to be received		$ 25,000,000
Affiliated Entity | Liberty Oil Field Services
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of missiles available for lease | missile			20
License agreement term			5 years