Natural Gas Services (NGS) 10-Q 4 Aug 17 2017 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2017	Jul. 31, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	NATURAL GAS SERVICES GROUP INC
Entity Central Index Key	1,084,991
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		12,937,363

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current Assets:
Cash and cash equivalents	$ 73,038	$ 64,094
Trade accounts receivable, net of allowance for doubtful accounts of $646 and $597, respectively	6,171	7,378
Inventory, net	25,431	25,833
Prepaid income taxes	1,944	1,482
Prepaid expenses and other	1,921	972
Total current assets	108,505	99,759
Rental equipment, net of accumulated depreciation of $135,924 and $126,096, respectively	164,553	174,060
Property and equipment, net of accumulated depreciation of $11,184 and $11,267 respectively	7,290	7,753
Goodwill	10,039	10,039
Intangibles, net of accumulated amortization of $1,570 and $1,508, respectively	1,589	1,651
Other assets	798	262
Total assets	292,774	293,524
Current Liabilities:
Line of credit	417	417
Accounts payable	1,309	971
Accrued liabilities	2,846	2,887
Deferred income	376	2,225
Total current liabilities	4,948	6,500
Rental equipment, net of accumulated depreciation of $135,924 and $126,096, respectively	51,136	53,745
Other long-term liabilities	820	325
Total liabilities	56,904	60,570
Commitments and contingencies (Note 9)
Stockholders’ Equity:
Preferred stock, 5,000 shares authorized, no shares issued or outstanding	0	0
Common stock, 30,000 shares authorized, par value $0.01; 12,838 and 12,764 shares issued and outstanding, respectively	128	128
Additional paid-in capital	103,101	100,812
Retained earnings	132,641	132,014
Total stockholders' equity	235,870	232,954
Total liabilities and stockholders' equity	$ 292,774	$ 293,524

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Unaudited) (Parentheticals) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current Assets:
Allowance for doubtful accounts	$ 646	$ 597
Noncurrent Assets:
Accumulated depreciation, rental equipment	135,924	126,096
Accumulated depreciation, property and equipment	11,184	11,267
Accumulated amortization, intangibles	$ 1,570	$ 1,508
Stockholders’ Equity:
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, shares authorized	30,000,000	30,000,000
Common stock, par value (in USD per share)	$ 0.01	$ 0.01
Common stock, shares issued	12,838,000	12,764,000
Common stock, shares outstanding	12,838,000	12,764,000

Condensed Consolidated Income S

Condensed Consolidated Income Statements (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenue:
Rental income	$ 11,420	$ 14,655	$ 23,342	$ 31,063
Sales	4,407	2,300	11,044	7,210
Service and maintenance income	391	239	734	497
Total revenue	16,218	17,194	35,120	38,770
Operating costs and expenses:
Cost of rentals, exclusive of depreciation stated separately below	4,255	5,411	8,923	11,105
Cost of sales, exclusive of depreciation stated separately below	3,745	2,236	9,168	6,168
Cost of service and maintenance	104	85	198	196
Selling, general and administrative expense	2,390	2,152	5,436	4,721
Depreciation and amortization	5,310	5,437	10,638	10,940
Total operating costs and expenses	15,804	15,321	34,363	33,130
Operating income	414	1,873	757	5,640
Other income (expense):
Interest expense	(2)	(2)	(4)	(4)
Other income (expense), net	3	(7)	6	12
Total other income (expense), net	1	(9)	2	8
Income before provision for income taxes	415	1,864	759	5,648
Provision for income taxes	40	605	132	1,848
Net income	$ 375	$ 1,259	$ 627	$ 3,800
Earnings per share:
Basic (in USD per share)	$ 0.03	$ 0.10	$ 0.05	$ 0.30
Diluted (in USD per share)	$ 0.03	$ 0.10	$ 0.05	$ 0.29
Weighted average shares outstanding:
Basic (in shares)	12,831	12,709	12,818	12,678
Diluted (in shares)	13,130	12,936	13,093	12,887

Condensed Consolidated Statemen

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 627	$ 3,800
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	10,638	10,940
Deferred income taxes	(2,609)	(770)
Stock-based compensation	2,416	1,186
Bad debt allowance	60	61
Inventory allowance	0	32
Gain on sale of assets	(49)	(25)
Gain on company owned life insurance	(17)	(4)
Changes in operating assets and liabilities:
Trade accounts receivables	1,147	4,034
Inventory	450	3,179
Prepaid expenses and prepaid income taxes	(1,411)	(1,532)
Accounts payable and accrued liabilities	297	(1,430)
Deferred income	(1,849)	286
Other	512	84
Tax benefit from equity compensation	0	(39)
NET CASH PROVIDED BY OPERATING ACTIVITIES	10,212	19,802
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property and equipment	(654)	(2,618)
Purchase of company owned life insurance	(529)	(105)
Proceeds from sale of property and equipment	49	25
NET CASH USED IN INVESTING ACTIVITIES	(1,134)	(2,698)
CASH FLOWS FROM FINANCING ACTIVITIES:
Payments from other long-term liabilities, net	(7)	(6)
Proceeds from exercise of stock options	517	406
Taxes paid related to net share settlement of equity awards	(644)	(909)
Tax benefit from equity compensation	0	39
NET CASH USED IN FINANCING ACTIVITIES	(134)	(470)
NET CHANGE IN CASH AND CASH EQUIVALENTS	8,944	16,634
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	64,094	35,532
CASH AND CASH EQUIVALENTS AT END OF PERIOD	73,038	52,166
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Interest paid	4	4
Income taxes paid	3,203	4,435
NON-CASH TRANSACTIONS
Transfer of rental equipment components to inventory	$ 48	$ 164

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2017
Accounting Policies [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	Basis of Presentation and Summary of Significant Accounting Policies These notes apply to the unaudited condensed consolidated financial statements of Natural Gas Services Group, Inc. a Colorado corporation (the "Company", “NGSG”, "Natural Gas Services Group", "we" or "our"). The accompanying unaudited condensed consolidated financial statements include all adjustments, consisting of only normal recurring adjustments, which are necessary to make our financial position at June 30, 2017 and the results of our operations for the three and six months ended June 30, 2017 and 2016 not misleading. As permitted by the rules and regulations of the Securities and Exchange Commission (SEC), the accompanying condensed consolidated financial statements do not include all disclosures normally required by generally accepted accounting principles in the United States of America (GAAP). These financial statements should be read in conjunction with the financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2016 on file with the SEC. In our opinion, the condensed consolidated financial statements are a fair presentation of the financial position, results of operations and cash flows for the periods presented. The results of operations for the three and six months ended June 30, 2017 are not necessarily indicative of the results of operations to be expected for the full fiscal year ending December 31, 2017 . Revenue Recognition Revenue from the sales of custom and fabricated compressors, and flare systems is recognized when title passes to the customer, the customer assumes risks and rewards of ownership, collectability is reasonably assured and delivery occurs as directed by our customer. From time to time, we have customers that request units and flares to be built under a bill and hold arrangement. In order to recognize revenue under a bill and hold arrangement the following criteria must be met: risk of ownership was passed to the customer, customer made a fixed commitment to purchase the goods, the customer requested the bill and hold, there was a fixed schedule for delivery, we no longer had any specific performance obligations, the purchase was segregated at our facility and the equipment was complete and ready to ship. For the six months ended June 30, 2017 , we recognized revenue of $3.0 million under these bill and hold arrangements. Exchange and rebuilt compressor revenue is recognized when the replacement compressor has been delivered and the rebuild assessment has been completed. Revenue from compressor service and retrofitting services is recognized upon providing services to the customer. Maintenance agreement revenue is recognized as services are rendered. Rental revenue is recognized over the terms of the respective rental agreements. Deferred income represents payments received before a product is shipped. Revenue from the sale of rental units is included in sales revenue when equipment is shipped or title is transferred to the customer. Fair Value of Financial Instruments Our financial instruments consist principally of cash and cash equivalents, accounts receivable, accounts payable, deferred compensation plan (cash portion) and our line of credit. Pursuant to ASC 820 (Accounting Standards Codification), the fair value of our cash equivalents is determined based on “Level 1” inputs, which consist of quoted prices in active markets for identical assets. We believe that the recorded values of all of our other financial instruments approximate their fair values because of their nature and relatively short maturity dates or durations. Recently Issued Accounting Pronouncements On February 25, 2016, the Financial Accounting Standards Board ("FASB") issued ASU No. 2016-02, Leases (Topic 842). Under the new guidance, a lessee will be required to recognize assets and liabilities for capital and operating leases with lease terms of more than 12 months. Additionally, this ASU will require disclosures to help investors and other financial statement users better understand the amount, timing, and uncertainty of cash flows arising from leases, including qualitative and quantitative requirements. For public business entities, the amendments are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, with early adoption permitted. The new standard will be effective during our first quarter ending March 31, 2019. We are currently determining the impacts of the new standard on our condensed consolidated financial statements and the additional applicable disclosure requirements. On May 28, 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606). This update provides a five-step analysis on how an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This guidance also requires more detailed disclosures to enable users of financial statements to understand the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. In August 2015, the FASB issued an accounting standards update for a one-year deferral of the revenue recognition standard’s effective date for all entities, which changed the effectiveness to interim and annual reporting periods beginning after December 15, 2017. As a result, we expect to adopt this guidance on January 1, 2018. The guidance offers two transition methods: a full retrospective approach to be applied to each prior reporting period presented or a modified retrospective approach where the cumulative effect of initially applying the standard is recognized at the date of initial application. We have not yet selected the transition method. We are currently determining the impacts of the new standard on our consolidated financial statements. Our approach includes performing a detailed review of key contracts that are representative of our various revenue streams and comparing our historical accounting policies and practices to the new standard. Our sales and service and maintenance contracts are more short-term in nature or can usually be completed within the same quarter they are started; but, at this stage in our assessment we are still evaluating the extent to which we will have changes, upon adoption. For the impact related to our rental revenues, we are still in the early stages of our review and have not concluded as to what impact, if any, there may be to our rental revenues. We expect to complete our review by mid-November 2017.

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	Stock-Based Compensation Stock Options: A summary of option activity under our 1998 Stock Option Plan as of December 31, 2016 , and changes during the six months ended June 30, 2017 is presented below. Number of Stock Options Weighted Average Exercise Price Weighted Average Remaining Contractual Life (years) Aggregate Intrinsic Value (in thousands) Outstanding, December 31, 2016 350,186 $ 19.45 4.25 $ 4,453 Granted 32,750 28.15 Exercised (25,580 ) 20.19 271 Outstanding, June 30, 2017 357,356 $ 20.19 4.43 $ 2,071 Exercisable, June 30, 2017 305,441 $ 19.11 3.67 $ 2,038 The following table summarizes information about our stock options outstanding at June 30, 2017 : Range of Exercise Prices Options Outstanding Options Exercisable Shares Weighted Average Remaining Contractual Life (years) Weighted Average Exercise Price Shares Weighted Average Exercise Price $0.01-15.70 65,852 2.06 $ 9.82 65,852 $ 9.82 $15.71-17.81 72,750 2.29 17.53 72,750 17.53 $17.82-20.48 86,836 2.84 19.60 86,836 19.60 $20.49-33.36 131,918 7.84 27.23 80,003 27.67 357,356 4.43 $ 20.19 305,441 $ 19.11 The summary of the status of our unvested stock options as of December 31, 2016 and changes during the six months ended June 30, 2017 is presented below. Unvested stock options: Shares Weighted Average Grant Date Fair Value Per Share Unvested at December 31, 2016 50,833 $ 12.67 Granted 32,750 11.93 Vested (31,668 ) 13.56 Unvested at June 30, 2017 51,915 $ 11.66 As of June 30, 2017 , there was $418,151 of unrecognized compensation cost related to unvested options. Such cost is expected to be recognized over a weighted-average period of two years. Total compensation expense for stock options was $207,560 and $277,549 for the six months ended June 30, 2017 and 2016 , respectively. Restricted Shares/Units: In accordance with the Company's employment agreement with Stephen Taylor, the Company's Chief Executive Officer, the Compensation Committee reviewed his performance in determining the issuance of restricted common stock. Based on this review which included consideration of the Company's 2016 performance, Mr. Taylor, was awarded 70,464 restricted shares/units on February 14, 2017 , which vest over three years , in equal installments, beginning February 14, 2018. On March 23, 2017 , the Compensation Committee awarded 20,000 restricted shares/units to each of G. Larry Lawrence, our CFO, and James Hazlett, our Vice President of Technical Services. The restricted shares to Messrs. Lawrence and Hazlett vest over three years , in equal installments, beginning March 23, 2018. We also awarded and issued 15,968 shares of restricted common stock to our Board of Directors as partial payment for 2017 directors' fees. The restricted stock issued to our directors vests over one year, in quarterly installments, beginning March 31, 2018. Total compensation expense related to restricted awards was $2,209,455 and $908,879 for the six months ended June 30, 2017 and 2016 , respectively. As of June 30, 2017 , there was a total of $2,848,876 of unrecognized compensation expense related to these shares/units which is expected to be recognized over the next two years.

Inventory

Inventory	6 Months Ended
	Jun. 30, 2017
Inventory Disclosure [Abstract]
Inventory	Inventory Our inventory, net of allowance for obsolescence of $ 16,458 and $15,000 at June 30, 2017 and December 31, 2016 , respectively, consisted of the following amounts: June 30, 2017 December 31, 2016 (in thousands) Raw materials $ 19,098 $ 18,365 Finished Goods 1,006 2,558 Work in process 5,327 4,910 $ 25,431 $ 25,833 During the six months ended June 30, 2017 and 2016, there were no write-offs of obsolete inventory against the allowance for obsolescence.

Retirement of Long-Lived Assets

Retirement of Long-Lived Assets	6 Months Ended
	Jun. 30, 2017
Property, Plant and Equipment [Abstract]
Retirement of Long-Lived Assets	Retirement of Long-Lived Assets During the review of our rental compressor units, management looks for any units that are not of the type, configuration, make or model that our customers are demanding or that were not cost efficient to refurbish, maintain and/or operate. From our review in 2016, we determined 63 units should be retired from our rental fleet with key components from those units being re-utilized in future unit builds and/or repairs. We performed an optimization review and recorded a $545,000 loss on retirement of rental equipment to reduce the book value of each unit to the estimated fair value of approximately $242,000 for key components being kept. This retirement was recorded in the 2016 consolidated income statement under loss on retirement of rental equipment. No retirements have been made in 2017.

Deferred Compensation Plans

Deferred Compensation Plans	6 Months Ended
	Jun. 30, 2017
Postemployment Benefits [Abstract]
Deferred Compensation Plans	Deferred Compensation Plans Effective January 1, 2016, the Company established a non-qualified deferred compensation plan for executive officers, directors and certain eligible employees. The assets of the deferred compensation plan are held in a rabbi trust and are subject to additional risk of loss in the event of bankruptcy or insolvency of the Company. The plan allows for deferral of up to 90% of a participant’s base salary, bonus, commissions, director fees and restricted stock awards. A Company owned life insurance policy held in a rabbi trust is utilized as a source of funding for the plan. The cash surrender value of the life insurance policy is $ 754,000 and $109,000 as of June 30, 2017 and 2016, respectively, with a gain related to the policy of approximately $17,000 and $4,000 reported in other income in the condensed consolidated income statement for the six months ending June 30, 2017 and 2016, respectively. For deferrals of base salary, bonus, commissions and director fees, settlement payments are made to participants in cash, either in a lump sum or in periodic installments. The obligation to pay the deferred compensation and the deferred director fees is adjusted to reflect the positive or negative performance of investment measurement options selected by each participant and was $713,000 and $109,000 as of June 30, 2017 and 2016, respectively. The deferred obligation is included in other long-term liabilities in the condensed consolidated balance sheet. For deferrals of restricted stock units, the plan does not allow for diversification, therefore, distributions are paid in shares of common stock and the obligation is carried at grant value. As of June 30, 2017 , 97,011 unvested restricted stock units have been deferred.

Credit Facility

Credit Facility	6 Months Ended
	Jun. 30, 2017
Debt Disclosure [Abstract]
Credit Facility	Credit Facility We have a senior secured revolving credit agreement the ("Amended Credit Agreement") with JP Morgan Chase Bank, N.A (the "Lender") with an aggregate commitment of $30 million , subject to collateral availability. We also have a right to request from the Lender, on an uncommitted basis, an increase of up to $20 million on the aggregate commitment (which could potentially increase the commitment amount to $50 million ). Borrowing Base . At any time before the maturity of the Amended Credit Agreement, we may draw, repay and re-borrow amounts available under the borrowing base up to the maximum aggregate availability discussed above. Generally, the borrowing base equals the sum of (a) 80% of our eligible accounts receivable plus (b) 50% of the book value of our eligible general inventory (not to exceed 50% of the commitment amount at the time) plus (c) 75% of the book value of our eligible equipment inventory. The Lender may adjust the borrowing base components if material deviations in the collateral are discovered in future audits of the collateral. We had $ 29.5 million borrowing base availability at June 30, 2017 under the terms of our Amended Credit Agreement. Interest and Fees . Under the terms of the Amended Credit Agreement, we have the option of selecting the applicable variable rate for each revolving loan, or portion thereof, of either (a) LIBOR multiplied by the Statutory Reserve Rate (as defined in the Amended Credit Agreement), with respect to this rate, for Eurocurrency funding, plus the Applicable Margin (“LIBOR-based”), or (b) CB Floating Rate, which is the Lender's Prime Rate less the Applicable Margin; provided, however, that no more than three LIBOR-based borrowings under the agreement may be outstanding at any one time. For purposes of the LIBOR-based interest rate, the Applicable Margin is 1.50% . For purposes of the CB Floating Rate, the Applicable Margin is 1.50% . For the half month period ended June 30, 2017 , our weighted average interest rate was 2.49% . Accrued interest is payable monthly on outstanding principal amounts, provided that accrued interest on LIBOR-based loans is payable at the end of each interest period, but in no event less frequently than quarterly. In addition, fees and expenses are payable in connection with our requests for letters of credit (generally equal to the Applicable Margin for LIBOR-related borrowings multiplied by the face amount of the requested letter of credit) and administrative and legal costs. Maturity . The maturity date of the Amended Credit Agreement is December 31, 2017 , at which time all amounts borrowed under the agreement will be due and outstanding letters of credit must be cash collateralized. The agreement may be terminated early upon our request or the occurrence of an event of default. Due to our debt maturing in less than twelve months, the debt was classified as current on the condensed consolidated balance sheet. Security . The obligations under the Amended Credit Agreement are secured by a first priority lien on all of our inventory and accounts and leases receivables, along with a first priority lien on a variable number of our leased compressor equipment the book value of which must be maintained at a minimum of 2.00 to 1.00 commitment coverage ratio (such ratio being equal to (i) the amount of the borrowing base as of such date to (ii) the amount of the commitment as of such date.) Covenants. The Amended Credit Agreement contains customary representations and warranties, as well as covenants which, among other things, limit our ability to incur additional indebtedness and liens; enter into transactions with affiliates; make acquisitions in excess of certain amounts; pay dividends; redeem or repurchase capital stock or senior notes; make investments or loans; make negative pledges; consolidate, merge or effect asset sales; or change the nature of our business. In addition, we also have certain financial covenants that require us to maintain on a consolidated basis a leverage ratio less than or equal to 2.50 to 1.00 as of the last day of each fiscal quarter. Events of Default and Acceleration. The Amended Credit Agreement contains customary events of default for credit facilities of this size and type, and includes, without limitation, payment defaults; defaults in performance of covenants or other agreements contained in the loan documents; inaccuracies in representations and warranties; certain defaults, termination events or similar events; certain defaults with respect to any other Company indebtedness in excess of $50,000 ; certain bankruptcy or insolvency events; the rendering of certain judgments in excess of $150,000 ; certain ERISA events; certain change in control events and the defectiveness of any liens under the secured revolving credit facility. Obligations under the Amended Credit Agreement may be accelerated upon the occurrence of an event of default. As of June 30, 2017 , we were in compliance with all covenants in our Amended Credit Agreement. A default under our Credit Agreement could trigger the acceleration of our bank debt so that it is immediately due and payable. Such default would likely limit our ability to access other credit. At June 30, 2017 and December 31, 2016 our outstanding balance on the line of credit was $417,000 .

Earnings per Share

Earnings per Share	6 Months Ended
	Jun. 30, 2017
Earnings Per Share [Abstract]
Earnings per Share	Earnings per Share The following table reconciles the numerators and denominators of the basic and diluted earnings per share computation (in thousands, except per share data) . Three months ended Six months ended June 30, June 30, 2017 2016 2017 2016 Numerator: Net income $ 375 $ 1,259 $ 627 $ 3,800 Denominator for basic net income per common share: Weighted average common shares outstanding 12,831 12,709 12,818 12,678 Denominator for diluted net income per share: Weighted average common shares outstanding 12,831 12,709 12,818 12,678 Dilutive effect of stock options and restricted stock 299 227 275 209 Diluted weighted average shares 13,130 12,936 13,093 12,887 Earnings per common share: Basic $ 0.03 $ 0.10 $ 0.05 $ 0.30 Diluted $ 0.03 $ 0.10 $ 0.05 $ 0.29 In the three and six months ended June 30, 2017 , options to purchase 83,917 shares of common stock with exercise prices ranging from $28.15 to $33.36 were not included in the computation of dilutive income per share, due to their antidilutive effect. In the three and six months ended June 30, 2016, options to purchase 107,500 shares of common stock with exercise prices ranging from $22.90 to $33.36 were not included in the computation of dilutive income per share, due to their antidilutive effect.

Segment Information

Segment Information	6 Months Ended
	Jun. 30, 2017
Segment Reporting [Abstract]
Segment Information	Segment Information ASC 280-10-50, “Operating Segments", defines the characteristics of an operating segment as: a) being engaged in business activity from which it may earn revenue and incur expenses, b) being reviewed by the Company's chief operating decision maker (CODM) for decisions about resources to be allocated and assess its performance and c) having discrete financial information. Although we look at our products to analyze the nature of our revenue, other financial information, such as certain costs and expenses, net income and EBITDA are not captured or analyzed by these categories. Our CODM does not make resource allocation decisions or access the performance of the business based on these categories, but rather in the aggregate. Based on this, management believes that it operates in one business segment. In their analysis of product lines as potential operating segments, management also considered ASC 280-10-50-11, “Aggregation Criteria”, which allows for the aggregation of operating segments if the segments have similar economic characteristics and if the segments are similar in each of the following areas: • The nature of the products and services; • The nature of the production processes; • The type or class of customer for their products and services; • The methods used to distribute their products or provide their services; and • The nature of the regulatory environment, if applicable. We are engaged in the business of designing and manufacturing compressors and flares. Our compressors and flares are sold and rented to our customers. In addition, we provide service and maintenance on compressors in our fleet and to third parties. These business activities are similar in all geographic areas. Our manufacturing process is essentially the same for the entire Company and is performed in-house at our facilities in Midland, Texas and Tulsa, Oklahoma. Our customers primarily consist of entities in the business of producing natural gas and crude oil. The maintenance and service of our products is consistent across the entire Company and is performed via an internal fleet of vehicles. The regulatory environment is similar in every jurisdiction in that the most impacting regulations and practices are the result of federal energy policy. In addition, the economic characteristics of each customer arrangement are similar in that we maintain policies at the corporate level. For the three months ended June 30, 2017 (in thousands): Rental Sales Service & Maintenance Corporate Total Revenue $ 11,420 $ 4,407 $ 391 $ — $ 16,218 Operating costs and corporate expenses 4,255 3,745 104 7,700 15,804 Total other expense, net — — 1 1 Income before provision for income taxes $ 7,165 $ 662 $ 287 $ (7,699 ) $ 415 For the three months ended June 30, 2016 (in thousands): Rental Sales Service & Maintenance Corporate Total Revenue $ 14,655 $ 2,300 $ 239 $ — $ 17,194 Operating costs and corporate expenses 5,411 2,236 85 7,589 15,321 Total other expense, net — — (9 ) (9 ) Income before provision for income taxes $ 9,244 $ 64 $ 154 $ (7,598 ) $ 1,864 For the six months ended June 30, 2017 (in thousands): Rental Sales Service & Maintenance Corporate Total Revenue $ 23,342 $ 11,044 $ 734 $ — $ 35,120 Operating costs and expenses 8,923 9,168 198 16,074 34,363 Total other income, net — — — 2 2 Income before provision for income taxes $ 14,419 $ 1,876 $ 536 $ (16,072 ) $ 759 For the six months ended June 30, 2016 (in thousands): Rental Sales Service & Maintenance Corporate Total Revenue $ 31,063 $ 7,210 $ 497 $ — $ 38,770 Operating costs and expenses 11,105 6,168 196 15,661 33,130 Total other income, net — — — 8 8 Income before provision for income taxes $ 19,958 $ 1,042 $ 301 $ (15,653 ) $ 5,648

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies From time to time, we are a party to various legal proceedings in the ordinary course of our business. While management is unable to predict the ultimate outcome of these actions, it believes that any ultimate liability arising from these actions will not have a material adverse effect on our financial position, results of operations or cash flow. We are not currently a party to any material legal proceedings, and we are not aware of any threatened material litigation.

Basis of Presentation and Sum15

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2017
Accounting Policies [Abstract]
Basis of Accounting	These notes apply to the unaudited condensed consolidated financial statements of Natural Gas Services Group, Inc. a Colorado corporation (the "Company", “NGSG”, "Natural Gas Services Group", "we" or "our"). The accompanying unaudited condensed consolidated financial statements include all adjustments, consisting of only normal recurring adjustments, which are necessary to make our financial position at June 30, 2017 and the results of our operations for the three and six months ended June 30, 2017 and 2016 not misleading. As permitted by the rules and regulations of the Securities and Exchange Commission (SEC), the accompanying condensed consolidated financial statements do not include all disclosures normally required by generally accepted accounting principles in the United States of America (GAAP). These financial statements should be read in conjunction with the financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2016 on file with the SEC. In our opinion, the condensed consolidated financial statements are a fair presentation of the financial position, results of operations and cash flows for the periods presented. The results of operations for the three and six months ended June 30, 2017 are not necessarily indicative of the results of operations to be expected for the full fiscal year ending December 31, 2017 .
Revenue Recognition	Revenue Recognition Revenue from the sales of custom and fabricated compressors, and flare systems is recognized when title passes to the customer, the customer assumes risks and rewards of ownership, collectability is reasonably assured and delivery occurs as directed by our customer. From time to time, we have customers that request units and flares to be built under a bill and hold arrangement. In order to recognize revenue under a bill and hold arrangement the following criteria must be met: risk of ownership was passed to the customer, customer made a fixed commitment to purchase the goods, the customer requested the bill and hold, there was a fixed schedule for delivery, we no longer had any specific performance obligations, the purchase was segregated at our facility and the equipment was complete and ready to ship. For the six months ended June 30, 2017 , we recognized revenue of $3.0 million under these bill and hold arrangements. Exchange and rebuilt compressor revenue is recognized when the replacement compressor has been delivered and the rebuild assessment has been completed. Revenue from compressor service and retrofitting services is recognized upon providing services to the customer. Maintenance agreement revenue is recognized as services are rendered. Rental revenue is recognized over the terms of the respective rental agreements. Deferred income represents payments received before a product is shipped. Revenue from the sale of rental units is included in sales revenue when equipment is shipped or title is transferred to the customer.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Our financial instruments consist principally of cash and cash equivalents, accounts receivable, accounts payable, deferred compensation plan (cash portion) and our line of credit. Pursuant to ASC 820 (Accounting Standards Codification), the fair value of our cash equivalents is determined based on “Level 1” inputs, which consist of quoted prices in active markets for identical assets. We believe that the recorded values of all of our other financial instruments approximate their fair values because of their nature and relatively short maturity dates or durations.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements On February 25, 2016, the Financial Accounting Standards Board ("FASB") issued ASU No. 2016-02, Leases (Topic 842). Under the new guidance, a lessee will be required to recognize assets and liabilities for capital and operating leases with lease terms of more than 12 months. Additionally, this ASU will require disclosures to help investors and other financial statement users better understand the amount, timing, and uncertainty of cash flows arising from leases, including qualitative and quantitative requirements. For public business entities, the amendments are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, with early adoption permitted. The new standard will be effective during our first quarter ending March 31, 2019. We are currently determining the impacts of the new standard on our condensed consolidated financial statements and the additional applicable disclosure requirements. On May 28, 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606). This update provides a five-step analysis on how an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This guidance also requires more detailed disclosures to enable users of financial statements to understand the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. In August 2015, the FASB issued an accounting standards update for a one-year deferral of the revenue recognition standard’s effective date for all entities, which changed the effectiveness to interim and annual reporting periods beginning after December 15, 2017. As a result, we expect to adopt this guidance on January 1, 2018. The guidance offers two transition methods: a full retrospective approach to be applied to each prior reporting period presented or a modified retrospective approach where the cumulative effect of initially applying the standard is recognized at the date of initial application. We have not yet selected the transition method. We are currently determining the impacts of the new standard on our consolidated financial statements. Our approach includes performing a detailed review of key contracts that are representative of our various revenue streams and comparing our historical accounting policies and practices to the new standard. Our sales and service and maintenance contracts are more short-term in nature or can usually be completed within the same quarter they are started; but, at this stage in our assessment we are still evaluating the extent to which we will have changes, upon adoption. For the impact related to our rental revenues, we are still in the early stages of our review and have not concluded as to what impact, if any, there may be to our rental revenues. We expect to complete our review by mid-November 2017.
Segment Information	ASC 280-10-50, “Operating Segments", defines the characteristics of an operating segment as: a) being engaged in business activity from which it may earn revenue and incur expenses, b) being reviewed by the Company's chief operating decision maker (CODM) for decisions about resources to be allocated and assess its performance and c) having discrete financial information. Although we look at our products to analyze the nature of our revenue, other financial information, such as certain costs and expenses, net income and EBITDA are not captured or analyzed by these categories. Our CODM does not make resource allocation decisions or access the performance of the business based on these categories, but rather in the aggregate. Based on this, management believes that it operates in one business segment. In their analysis of product lines as potential operating segments, management also considered ASC 280-10-50-11, “Aggregation Criteria”, which allows for the aggregation of operating segments if the segments have similar economic characteristics and if the segments are similar in each of the following areas: • The nature of the products and services; • The nature of the production processes; • The type or class of customer for their products and services; • The methods used to distribute their products or provide their services; and • The nature of the regulatory environment, if applicable. We are engaged in the business of designing and manufacturing compressors and flares. Our compressors and flares are sold and rented to our customers. In addition, we provide service and maintenance on compressors in our fleet and to third parties. These business activities are similar in all geographic areas. Our manufacturing process is essentially the same for the entire Company and is performed in-house at our facilities in Midland, Texas and Tulsa, Oklahoma. Our customers primarily consist of entities in the business of producing natural gas and crude oil. The maintenance and service of our products is consistent across the entire Company and is performed via an internal fleet of vehicles. The regulatory environment is similar in every jurisdiction in that the most impacting regulations and practices are the result of federal energy policy. In addition, the economic characteristics of each customer arrangement are similar in that we maintain policies at the corporate level.

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Option Activity	A summary of option activity under our 1998 Stock Option Plan as of December 31, 2016 , and changes during the six months ended June 30, 2017 is presented below. Number of Stock Options Weighted Average Exercise Price Weighted Average Remaining Contractual Life (years) Aggregate Intrinsic Value (in thousands) Outstanding, December 31, 2016 350,186 $ 19.45 4.25 $ 4,453 Granted 32,750 28.15 Exercised (25,580 ) 20.19 271 Outstanding, June 30, 2017 357,356 $ 20.19 4.43 $ 2,071 Exercisable, June 30, 2017 305,441 $ 19.11 3.67 $ 2,038
Summary of Stock Options Outstanding	The following table summarizes information about our stock options outstanding at June 30, 2017 : Range of Exercise Prices Options Outstanding Options Exercisable Shares Weighted Average Remaining Contractual Life (years) Weighted Average Exercise Price Shares Weighted Average Exercise Price $0.01-15.70 65,852 2.06 $ 9.82 65,852 $ 9.82 $15.71-17.81 72,750 2.29 17.53 72,750 17.53 $17.82-20.48 86,836 2.84 19.60 86,836 19.60 $20.49-33.36 131,918 7.84 27.23 80,003 27.67 357,356 4.43 $ 20.19 305,441 $ 19.11
Status of Unvested Stock Options	The summary of the status of our unvested stock options as of December 31, 2016 and changes during the six months ended June 30, 2017 is presented below. Unvested stock options: Shares Weighted Average Grant Date Fair Value Per Share Unvested at December 31, 2016 50,833 $ 12.67 Granted 32,750 11.93 Vested (31,668 ) 13.56 Unvested at June 30, 2017 51,915 $ 11.66

Inventory (Tables)

Inventory (Tables)	6 Months Ended
	Jun. 30, 2017
Inventory Disclosure [Abstract]
Schedule of Inventory	Our inventory, net of allowance for obsolescence of $ 16,458 and $15,000 at June 30, 2017 and December 31, 2016 , respectively, consisted of the following amounts: June 30, 2017 December 31, 2016 (in thousands) Raw materials $ 19,098 $ 18,365 Finished Goods 1,006 2,558 Work in process 5,327 4,910 $ 25,431 $ 25,833

Earnings per Share (Tables)

Earnings per Share (Tables)	6 Months Ended
	Jun. 30, 2017
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table reconciles the numerators and denominators of the basic and diluted earnings per share computation (in thousands, except per share data) . Three months ended Six months ended June 30, June 30, 2017 2016 2017 2016 Numerator: Net income $ 375 $ 1,259 $ 627 $ 3,800 Denominator for basic net income per common share: Weighted average common shares outstanding 12,831 12,709 12,818 12,678 Denominator for diluted net income per share: Weighted average common shares outstanding 12,831 12,709 12,818 12,678 Dilutive effect of stock options and restricted stock 299 227 275 209 Diluted weighted average shares 13,130 12,936 13,093 12,887 Earnings per common share: Basic $ 0.03 $ 0.10 $ 0.05 $ 0.30 Diluted $ 0.03 $ 0.10 $ 0.05 $ 0.29

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2017
Segment Reporting [Abstract]
Schedule of Segment Reporting Information	For the three months ended June 30, 2017 (in thousands): Rental Sales Service & Maintenance Corporate Total Revenue $ 11,420 $ 4,407 $ 391 $ — $ 16,218 Operating costs and corporate expenses 4,255 3,745 104 7,700 15,804 Total other expense, net — — 1 1 Income before provision for income taxes $ 7,165 $ 662 $ 287 $ (7,699 ) $ 415 For the three months ended June 30, 2016 (in thousands): Rental Sales Service & Maintenance Corporate Total Revenue $ 14,655 $ 2,300 $ 239 $ — $ 17,194 Operating costs and corporate expenses 5,411 2,236 85 7,589 15,321 Total other expense, net — — (9 ) (9 ) Income before provision for income taxes $ 9,244 $ 64 $ 154 $ (7,598 ) $ 1,864 For the six months ended June 30, 2017 (in thousands): Rental Sales Service & Maintenance Corporate Total Revenue $ 23,342 $ 11,044 $ 734 $ — $ 35,120 Operating costs and expenses 8,923 9,168 198 16,074 34,363 Total other income, net — — — 2 2 Income before provision for income taxes $ 14,419 $ 1,876 $ 536 $ (16,072 ) $ 759 For the six months ended June 30, 2016 (in thousands): Rental Sales Service & Maintenance Corporate Total Revenue $ 31,063 $ 7,210 $ 497 $ — $ 38,770 Operating costs and expenses 11,105 6,168 196 15,661 33,130 Total other income, net — — — 8 8 Income before provision for income taxes $ 19,958 $ 1,042 $ 301 $ (15,653 ) $ 5,648

Basis of Presentation and Sum20

Basis of Presentation and Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenue from External Customer [Line Items]
Revenue recognized	$ 16,218	$ 17,194	$ 35,120	$ 38,770
Bill and Hold Arrangement
Revenue from External Customer [Line Items]
Revenue recognized			$ 3,000

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Number of Stock Options
Outstanding, beginning of period (in shares)	350,186
Granted (in shares)	32,750
Exercised (in shares)	(25,580)
Outstanding, end of period (in shares)	357,356	350,186
Exercisable (in shares)	305,441
Weighted Average Exercise Price
Outstanding, beginning of period (in USD per share)	$ 19.45
Granted (in USD per share)	28.15
Exercised (in USD per share)	20.19
Outstanding, end of period (in USD per share)	20.19	$ 19.45
Exercisable (in USD per share)	$ 19.11
Weighted Average Remaining Contractual Life (years)
Outstanding	4 years 5 months 6 days	4 years 2 months 29 days
Exercisable	3 years 6 months 63 days
Aggregate Intrinsic Value
Outstanding, beginning of period	$ 4,453
Exercised	271
Outstanding, end of period	2,071	$ 4,453
Exercisable	$ 2,038

Stock-Based Compensation - St22

Stock-Based Compensation - Stock Options Outstanding (Details)	6 Months Ended
	Jun. 30, 2017$ / sharesshares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding, shares | shares	357,356
Options outstanding, weighted average remaining contractual life (years)	4 years 4 months 36 days
Options outstanding, weighted average exercise price (in USD per share) | $ / shares	$ 20.19
Options exercisable, shares | shares	305,441
Options exercisable, weighted average exercise price (in USD per share) | $ / shares	$ 19.11
$0.01-15.70
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding, shares | shares	65,852
Options outstanding, weighted average remaining contractual life (years)	2 years 22 days
Options outstanding, weighted average exercise price (in USD per share) | $ / shares	$ 9.82
Options exercisable, shares | shares	65,852
Options exercisable, weighted average exercise price (in USD per share) | $ / shares	$ 9.82
$15.71-17.81
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding, shares | shares	72,750
Options outstanding, weighted average remaining contractual life (years)	2 years 2 months 44 days
Options outstanding, weighted average exercise price (in USD per share) | $ / shares	$ 17.53
Options exercisable, shares | shares	72,750
Options exercisable, weighted average exercise price (in USD per share) | $ / shares	$ 17.53
$17.82-20.48
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding, shares | shares	86,836
Options outstanding, weighted average remaining contractual life (years)	2 years 9 months 34 days
Options outstanding, weighted average exercise price (in USD per share) | $ / shares	$ 19.60
Options exercisable, shares | shares	86,836
Options exercisable, weighted average exercise price (in USD per share) | $ / shares	$ 19.60
$20.49-33.36
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding, shares | shares	131,918
Options outstanding, weighted average remaining contractual life (years)	7 years 8 months 65 days
Options outstanding, weighted average exercise price (in USD per share) | $ / shares	$ 27.23
Options exercisable, shares | shares	80,003
Options exercisable, weighted average exercise price (in USD per share) | $ / shares	$ 27.67

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Unvested Stock Options (Details) - USD ($)	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Shares
Unvested, beginning of period (in shares)	50,833
Granted (in shares)	32,750
Vested (in shares)	(31,668)
Unvested, end of period (in shares)	51,915
Weighted Average Grant Date Fair Value Per Share
Unvested, weighted average grant date fair value, beginning of period (in USD per share)	$ 12.67
Granted (in USD per share)	11.93
Vested, weighted average grant date fair value (in USD per share)	13.56
Unvested, weighted average grant date fair value, end of period (in USD per share)	$ 11.66
Stock Options
Weighted Average Grant Date Fair Value Per Share
Unrecognized compensation cost related to unvested options	$ 418,151
Unrecognized compensation cost related to awards, weighted average period for recognition	2 years
Share-based compensation expense	$ 207,560	$ 277,549

Stock-Based Compensation - Rest

Stock-Based Compensation - Restricted Stock (Details) - Restricted Stock - USD ($)	Mar. 23, 2017	Feb. 14, 2017	Jun. 30, 2017	Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense			$ 2,209,455	$ 908,879
Total unrecognized compensation expense			$ 2,848,876
Unrecognized compensation cost related to awards, vesting period			2 years
Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period		70,464
Award vesting period		3 years
Chief Financial Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period	20,000
Award vesting period	3 years
Vice President of Technical Services
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period			15,968
Award vesting period			1 year

Inventory (Details)

Inventory (Details) - USD ($)	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Allowance for inventory obsolescence	$ 16,458	$ 15,000
Raw materials	19,098,000	18,365,000
Finished Goods	1,006,000	2,558,000
Work in process	5,327,000	4,910,000
Inventory, net	25,431,000	$ 25,833,000
Write-offs of obsolete inventory against allowance	$ 0

Retirement of Long-Lived Asse26

Retirement of Long-Lived Assets (Details)	6 Months Ended	12 Months Ended
	Jun. 30, 2017USD ($)	Dec. 31, 2016USD ($)compressor
Impaired Assets to be Disposed of by Method Other than Sale [Line Items]
Loss on retirement of rental equipment	$ 0
Rental Compressor Unit
Impaired Assets to be Disposed of by Method Other than Sale [Line Items]
Number of rental compressors to be retired | compressor		63
Estimated fair value of long-lived assets		$ 242,000
Rental Compressor Unit | Loss on Retirement of Rental Equipment
Impaired Assets to be Disposed of by Method Other than Sale [Line Items]
Loss on retirement of rental equipment		$ 545,000

Deferred Compensation Plans (De

Deferred Compensation Plans (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2017USD ($)	Jun. 30, 2016USD ($)
Postemployment Benefits [Abstract]
Participant's maximum compensation deferral percentage	90.00%
Company owned life insurance	$ 754	$ 109
Gain on company owned life insurance	17	4
Deferred compensation obligation	$ 713	$ 109
Deferred restricted stock shares	97,011

Credit Facility (Details)

Credit Facility (Details) - Revolving Credit Facility	6 Months Ended
	Jun. 30, 2017USD ($)loan
Line of Credit Facility [Line Items]
Aggregate credit agreement commitment	$ 30,000,000
Potential increase in borrowing capacity	20,000,000
Potential maximum borrowing capacity	$ 50,000,000
Borrowing base, component, % of eligible accounts receivable	80.00%
Borrowing base, component, % of eligible inventory	50.00%
Borrowing base, allowable share of total commitment amount attributable to inventory component	50.00%
Borrowing base, component, % of eligible equipment inventory	75.00%
Borrowing base amount available	$ 29,500,000
Weighted average interest rate	2.49%
Default trigger, certain defaults of other company indebtedness, amount	$ 50,000
Default trigger, rendering of certain judgments, amount	150,000
Line of credit balance	$ 417,000
LIBOR Rate
Line of Credit Facility [Line Items]
Reference rate, number of allowable LIBOR-based borrowings outstanding | loan	3
Variable rate, applicable margin	1.50%
CB Floating Rate
Line of Credit Facility [Line Items]
Variable rate, applicable margin	1.50%
Minimum
Line of Credit Facility [Line Items]
Minimum commitment coverage ratio allowed	2
Maximum
Line of Credit Facility [Line Items]
Maximum leverage ratio allowed	2.50

Earnings per Share - Basic and

Earnings per Share - Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Numerator:
Net income	$ 375	$ 1,259	$ 627	$ 3,800
Denominator for basic net income per common share:
Weighted average common shares outstanding (in shares)	12,831,000	12,709,000	12,818,000	12,678,000
Denominator for diluted net income per share:
Weighted average common shares outstanding (in shares)	12,831,000	12,709,000	12,818,000	12,678,000
Dilutive effect of stock options and restricted stock (in shares)	299,000	227,000	275,000	209,000
Diluted weighted average shares (in shares)	13,130,000	12,936,000	13,093,000	12,887,000
Earnings per common share:
Basic (in USD per share)	$ 0.03	$ 0.10	$ 0.05	$ 0.30
Diluted (in USD per share)	$ 0.03	$ 0.10	$ 0.05	$ 0.29
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of shares not included in the computation of dilutive income per share (in shares)	83,917	107,500	83,917	107,500
Antidilutive Effect
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Exercise price of shares not included in the computation of dilutive income per share, lower limit (in USD per share)	$ 28.15	$ 22.90	$ 28.15	$ 22.90
Exercise price of shares not included in the computation of dilutive income per share, upper limit (in USD per share)	$ 33.36	$ 33.36	$ 33.36	$ 33.36

Segment Information (Details)

Segment Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017USD ($)	Jun. 30, 2016USD ($)	Jun. 30, 2017USD ($)segment	Jun. 30, 2016USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment			1
Revenue	$ 16,218	$ 17,194	$ 35,120	$ 38,770
Operating costs and corporate expenses	15,804	15,321	34,363	33,130
Total other income (expense), net	1	(9)	2	8
Income before provision for income taxes	415	1,864	759	5,648
Corporate
Segment Reporting Information [Line Items]
Revenue	0	0	0	0
Operating costs and corporate expenses	7,700	7,589	16,074	15,661
Total other income (expense), net	1	(9)	2	8
Income before provision for income taxes	(7,699)	(7,598)	(16,072)	(15,653)
Rental
Segment Reporting Information [Line Items]
Revenue	11,420	14,655	23,342	31,063
Operating costs and corporate expenses	4,255	5,411	8,923	11,105
Total other income (expense), net	0	0	0	0
Income before provision for income taxes	7,165	9,244	14,419	19,958
Sales
Segment Reporting Information [Line Items]
Revenue	4,407	2,300	11,044	7,210
Operating costs and corporate expenses	3,745	2,236	9,168	6,168
Total other income (expense), net	0	0	0	0
Income before provision for income taxes	662	64	1,876	1,042
Service & Maintenance
Segment Reporting Information [Line Items]
Revenue	391	239	734	497
Operating costs and corporate expenses	104	85	198	196
Total other income (expense), net			0	0
Income before provision for income taxes	$ 287	$ 154	$ 536	$ 301