Natural Gas Services (NGS) 10-Q 14 May 21 2021 Q1 Quarterly report Financial data

Cover

Cover - shares	3 Months Ended
	Mar. 31, 2021	May 10, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	1-31398
Entity Registrant Name	NATURAL GAS SERVICES GROUP, INC.
Entity Incorporation, State or Country Code	CO
Entity Tax Identification Number	75-2811855
Entity Address, Address Line One	404 Veterans Airpark Ln., Ste 300
Entity Address, City or Town	Midland
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	79705
City Area Code	432
Local Phone Number	262-2700
Title of 12(b) Security	Common Stock, Par Value $0.01
Trading Symbol	NGS
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		13,610,993
Entity Central Index Key	0001084991
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current Assets:
Cash and cash equivalents	$ 30,683	$ 28,925
Trade accounts receivable, net of allowance for doubtful accounts of $1,155 and $1,161, respectively	12,724	11,884
Inventory	19,982	19,926
Federal income tax receivable	11,538	11,538
Prepaid income taxes	62	66
Prepaid expenses and other	81	379
Total current assets	75,070	72,718
Long-term inventory, net of allowance for obsolescence of $37 and $221, respectively	1,105	1,065
Rental equipment, net of accumulated depreciation of $181,385 and $175,802, respectively	206,436	207,585
Property and equipment, net of accumulated depreciation of $14,521 and $13,916, respectively	21,601	21,749
Right of use assets - operating leases, net of accumulated amortization of $410 and $356, respectively	429	483
Intangibles, net of accumulated amortization of $2,040 and $2,008, respectively	1,119	1,151
Other assets	2,158	2,050
Total assets	307,918	306,801
Current Liabilities:
Accounts payable	1,181	2,373
Accrued liabilities	10,483	6,770
Line of credit	0	417
Current operating leases	169	198
Deferred income	34	1,103
Total current liabilities	11,867	10,861
Deferred income tax liability	42,013	41,890
Long-term operating leases	260	285
Other long-term liabilities	2,378	2,221
Total liabilities	56,518	55,257
Commitments and contingencies
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; 13,358 and 13,296 shares issued, respectively	134	133
Additional paid-in capital	112,864	112,615
Retained earnings	138,892	139,286
Treasury Shares, at cost, 38 shares	(490)	(490)
Total stockholders' equity	251,400	251,544
Total liabilities and stockholders' equity	$ 307,918	$ 306,801

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parentheticals) - USD ($) shares in Thousands, $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current Assets:
Allowance for doubtful accounts	$ 1,155	$ 1,161
Allowance for obsolescence	37	221
Noncurrent Assets:
Accumulated depreciation, rental equipment	181,385	175,802
Accumulated depreciation, property and equipment	14,521	13,916
Accumulated amortization, operating lease right of use assets	410	356
Accumulated amortization, intangibles	$ 2,040	$ 2,008
Stockholders’ Equity:
Preferred stock, shares authorized (in shares)	5,000	5,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, shares authorized (in shares)	30,000	30,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares issued (in shares)	13,358	13,296
Treasury shares (in shares)	38	38

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenue:
Rental income	$ 15,341	$ 16,100
Revenues	18,397	17,890
Operating costs and expenses:
Cost of rentals, exclusive of depreciation stated separately below	7,156	7,897
Cost of sales, exclusive of depreciation stated separately below	2,616	1,739
Cost of service and maintenance, exclusive of depreciation stated separately below	48	125
Selling, general and administrative expenses	2,649	2,162
Depreciation and amortization	6,297	6,240
Total operating costs and expenses	18,766	18,163
Operating loss	(369)	(273)
Other income (expense):
Interest expense	(1)	(3)
Other income (expense), net	101	(185)
Total other income (expense), net	100	(188)
Loss before provision for income taxes	(269)	(461)
Income tax (expense) benefit	(125)	4,543
Net (loss) income	$ (394)	$ 4,082
(Loss) earnings per share:
Basic (in dollars per share)	$ (0.03)	$ 0.31
Diluted (in dollars per share)	$ (0.03)	$ 0.30
Weighted average shares outstanding:
Basic (in shares)	13,263	13,157
Diluted (in shares)	13,263	13,416
Sales
Revenue:
Revenues	$ 2,711	$ 1,450
Service and maintenance income
Revenue:
Revenues	$ 345	$ 340

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Preferred Stock	Common Stock	Additional Paid-In Capital	Retained Earnings	Treasury Stock
Beginning balance (in shares) at Dec. 31, 2019		0	13,178			(38)
Beginning balance at Dec. 31, 2019	$ 247,693	$ 0	$ 132	$ 110,573	$ 137,478	$ (490)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Compensation expense on common stock options	17			17
Issuance of restricted stock (in shares)			95
Compensation expense on restricted common stock	486		$ 1	485
Taxes paid related to net shares settlement of equity awards	(149)			(149)
Net income (loss)	4,082				4,082
Ending balance (in shares) at Mar. 31, 2020		0	13,273			(38)
Ending balance at Mar. 31, 2020	252,129	$ 0	$ 133	110,926	141,560	$ (490)
Beginning balance (in shares) at Dec. 31, 2020		0	13,296			(38)
Beginning balance at Dec. 31, 2020	251,544	$ 0	$ 133	112,615	139,286	$ (490)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted stock (in shares)			62
Compensation expense on restricted common stock	474		$ 1	473
Taxes paid related to net shares settlement of equity awards	(224)			(224)
Net income (loss)	(394)				(394)
Ending balance (in shares) at Mar. 31, 2021		0	13,358			(38)
Ending balance at Mar. 31, 2021	$ 251,400	$ 0	$ 134	$ 112,864	$ 138,892	$ (490)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net (loss) income	$ (394)	$ 4,082
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation and amortization	6,297	6,240
Deferred income taxes	123	337
Stock-based compensation	474	502
Bad debt allowance	15	21
Gain on sale of assets	0	(68)
Loss (gain) on company owned life insurance	(98)	262
Changes in operating assets and liabilities:
Trade accounts receivables	(855)	(1,434)
Inventory	(100)	1,616
Federal income tax receivable	0	(14,992)
Prepaid expenses and prepaid income taxes	301	344
Accounts payable and accrued liabilities	2,523	1,013
Deferred income	(1,069)	550
Deferred tax liability increase due to tax law change	0	10,103
Other	164	(301)
NET CASH PROVIDED BY OPERATING ACTIVITIES	7,381	8,275
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of rental equipment, property and other equipment	(4,965)	(6,679)
Purchase of company owned life insurance	(17)	(54)
Proceeds from sale of property and equipment	0	68
NET CASH USED IN INVESTING ACTIVITIES	(4,982)	(6,665)
CASH FLOWS FROM FINANCING ACTIVITIES:
Payments of other long-term liabilities, net	0	(2)
Repayments of line of credit, net	(417)	0
Taxes paid related to net share settlement of equity awards	(224)	(149)
NET CASH USED IN FINANCING ACTIVITIES	(641)	(151)
NET CHANGE IN CASH AND CASH EQUIVALENTS	1,758	1,459
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	28,925	11,592
CASH AND CASH EQUIVALENTS AT END OF PERIOD	30,683	13,051
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Interest paid	1	3
Income taxes paid	0	40
NON-CASH TRANSACTIONS
Right of use asset acquired through an operating lease	$ 0	$ 4

Description of Business

Description of Business	3 Months Ended
	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of BusinessNatural Gas Services Group, Inc. (the "Company", “NGS”, "Natural Gas Services Group", "we" or "our") (a Colorado corporation), is a leading provider of natural gas compression equipment and services to the energy industry. The Company manufactures, fabricates, rents, sells and maintains natural gas compressors and flare systems for oil and natural gas production and plant facilities. NGS is headquartered in Midland, Texas, with fabrication facilities located in Tulsa, Oklahoma and Midland, Texas, and service facilities located in major oil and natural gas producing basins in the U.S.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Principles of Consolidation and Basis of Presentation The accompanying unaudited condensed consolidated financial statements include the accounts of the Company, its subsidiary, NGSG Properties, LLC and the rabbi trust associated with the Company's deferred compensation plan. All significant intercompany accounts and transactions for the periods presented have been eliminated in consolidation. These financial statements include all adjustments, consisting of only normal recurring adjustments, which are necessary to make our financial position at March 31, 2021 and the results of our operations for the three months ended March 31, 2021 and 2020 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 consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2020 on file with the SEC. In our opinion, the condensed consolidated financial statements are a fair presentation of the financial position, results of operations, changes in stockholders' equity and cash flows for the periods presented. The results of operations for the three months ended March 31, 2021 are not necessarily indicative of the results of operations to be expected for the full fiscal year ending December 31, 2021. Revenue Recognition Policy The Company recognizes revenue in accordance with ASC 606, Revenue from Contracts with Customers ("ASC 606"). Under ASC 606, revenue is measured based on a consideration specified in a customer’s contract, excluding any sale incentives and taxes collected on behalf of third parties (i.e. sales and property taxes). Revenue is recognized when a customer obtains control of promised goods or services in an amount that reflects the consideration that we expect to receive for those goods or services. To recognize revenue, we (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when, or as, we satisfy the performance obligation(s). Shipping and handling costs incurred are accounted for as fulfillment costs and are included in cost of revenues in our condensed consolidated statements of operations. Nature of Goods and Services The following is a description of principal activities from which the Company generates its revenue: Rental Revenue. The Company generates revenue from renting compressors and flare systems to our customers. These contracts, which all qualify as operating leases under ASC Topic 842, Leases (ASC 842), may also include a fee for servicing the compressor or flare during the rental contract period. Our rental contracts typically range from six Sales Revenue. The Company generates revenue by the sale of custom/fabricated compressors, flare systems and parts, as well as, exchange/rebuilding customer owned compressors and sale of used rental equipment. Custom/fabricated compressors and flare systems - The Company designs and fabricates compressors and flares based on the customer’s specifications outlined in their contract. Though the equipment being built is customized by the customer, control under these contracts does not pass to the customer until the compressor or flare package is complete and shipped, or in accordance with a bill and hold arrangement, the customer accepts title and assumes the risk and rewards of ownership. We request some of our customers to make progressive payments as the product is being built; these payments are recorded as a contract liability on the Deferred Income line on the condensed consolidated balance sheet until control has been transferred. These contracts also may include an assurance warranty clause to guarantee the product is free from defects in material and workmanship for a set duration of time; this is a standard industry practice and is not considered a performance obligation. From time to time, upon the customer’s written request, we recognize revenue when manufacturing is complete and the equipment is ready for shipment. At the customer’s request, we will bill the customer upon completing all performance obligations, but before shipment. The customer will formally request that we ship the equipment per their direction from our manufacturing facility at a later specified date and that we segregate the equipment from our finished goods, such that they are not available to fill other orders. Per the customer’s agreement change of control is passed to the customer once the equipment is complete and ready for shipment. We have operated using bill and hold agreements with certain customers for many years, with consistent and satisfactory results for both the customer and us. The credit terms on these agreements are consistent with the credit terms on all other sales. All control is maintained by the customer and there are no exceptions to the customer’s commitment to accept and pay for the manufactured equipment. There was no revenue recognized for bill and hold arrangements for the three months ended March 31, 2021. Revenue recognized related to bill and hold arrangements for the three months ended March 31, 2020 was approximately $0.9 million. Parts - Revenue is recognized after the customer obtains control of the parts. Control is passed either by the customer taking physical possession or the parts being shipped. The amount of revenue recognized is not adjusted for expected returns, as our historical part returns have been de minimis. Exchange or rebuilding customer owned compressors - Based on the contract, the Company will either exchange a new/rebuilt compressor for the customer’s malfunctioning compressor or rebuild the customer’s compressor. Revenue is recognized after control of the replacement compressor has transferred to the customer based on the terms of the contract, i.e., by physical delivery, delivery and installment, or shipment of the compressor. Used compressors or flares - From time to time, a customer may request to purchase a used compressor or flare out of our rental fleet. Revenue from the sale of rental equipment is recognized when the control has passed to the customer based on the terms of the contract, i.e., when the customer has taken physical possession or the equipment has been shipped. Service and Maintenance Revenue . The Company provides routine or call-out services on customer owned equipment. Revenue is recognized after services in the contract are rendered. Payment terms for sales revenue and service and maintenance revenue discussed above are generally 30 to 60 days, although terms for specific customers can vary. Also, transaction prices are not subject to variable consideration constraints. Disaggregation of Revenue The following table shows the Company's revenue disaggregated by product or service type for the three months ended March 31, 2021 and 2020: Three months ended March 30, 2021 2020 (in thousands) Compressors - sales $ 1,891 $ 852 Flares - sales 46 80 Other (parts/rebuilds) - sales 774 518 Service and maintenance 345 340 Total revenue from contracts with customers 3,056 1,790 Add: ASC 842 rental revenue 15,341 16,100 Total revenue $ 18,397 $ 17,890 Contract Balances As of March 31, 2021 and December 31, 2020, we had the following receivables and deferred income from contracts with customers: March 31, 2021 December 31, 2020 (in thousands) Accounts Receivable Accounts receivable - contracts with customers $ 2,937 $ 3,243 Accounts receivable - ASC 842 10,942 9,802 Total Accounts Receivable $ 13,879 $ 13,045 Less: Allowance for doubtful accounts (1,155) (1,161) Total Accounts Receivable, net $ 12,724 $ 11,884 Deferred income $ 34 $ 1,103 The Company recognized sales and rental revenues of $1.1 million and $2,000, respectively, for the three months ended March 31, 2021 that was included in deferred income at the beginning of 2021. For the year ended December 31, 2020, the Company recognized sales and rental revenues of $0.5 million and $73,000, respectively, that was included in deferred income at the beginning of 2020. The increases (decreases) of accounts receivable and deferred income were primarily due to normal timing differences between our performance and the customers’ payments. Remaining Performance Obligations As of March 31, 2021, the Company did not have revenue related to unsatisfied performance obligations. Contract Costs The Company recognizes the incremental costs of obtaining contracts as an expense when incurred if the amortization period of the assets that the Company otherwise would have recognized is one year or less. These costs are included in selling, general and administrative expenses on our condensed consolidated statements of operations. Income Taxes Deferred tax assets and liabilities are recognized for the future tax consequences attributable to temporary differences between the financial statement carrying amounts of assets and liabilities and their respective tax bases, and operating losses and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. Valuation allowances are established to reduce deferred tax assets when it is more likely than not that some portion or all of the deferred tax assets will not be realized. To the extent we establish a valuation allowance or increase this allowance in a period, we include an expense in the tax provision in our condensed consolidated statements of operations. We account for uncertain tax positions in accordance with guidance in ASC 740, which prescribes the minimum recognition threshold a tax position taken or expected to be taken in a tax return is required to meet before being recognized in the condensed consolidated financial statements. Tax benefits are recognized only for tax positions that are more likely than not to be sustained upon examination by tax authorities. The amount recognized is measured as the largest amount of benefit that is greater than 50% likely to be realized upon settlement. A liability for unrecognized tax benefits is recorded for any tax benefits claimed in our tax returns that do not meet these recognition and measurement standards. We have no liabilities for uncertain tax positions as of March 31, 2021. Our policy regarding income tax interest and penalties is to expense those items as interest expense and other expense, respectively. On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act ("CARES Act") was enacted in response to the economic impact caused by the COVID-19 pandemic. The CARES Act, among other things, permits federal income tax net operating loss ("NOL") carryovers and carrybacks to offset 100% of taxable income for taxable years beginning before 2021. In addition, the CARES Act allows NOLs incurred in 2018, 2019, and 2020 to be carried back to each of the five preceding taxable years to generate a refund of previously paid federal income taxes. Please see Note 4, Federal Income Tax Receivable for a discussion about the impact on our condensed consolidated financial statements. Recently Issued Accounting Pronouncements In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (ASC Topic 326): Measurement of Credit Losses on Financial Instruments. The amendments to ASC Topic 326 require immediate recognition of estimated credit losses expected to occur over the remaining life of many financial assets, including trade receivables. For companies that qualify as smaller reporting companies, the amendments in this update are effective for interim and annual periods beginning after January 1, 2023. We are currently evaluating the impact of ASU 2016-13 on our consolidated financial statements and note disclosures.

Inventory

Inventory	3 Months Ended
	Mar. 31, 2021
Inventory Disclosure [Abstract]
Inventory	Inventory Our inventory, net of allowance for obsolescence of $37,000 at March 31, 2021 and $221,000 at December 31, 2020, consisted of the following amounts: March 31, 2021 December 31, 2020 (in thousands) Raw materials - current $ 18,619 $ 18,026 Work-in-process 1,363 1,900 Inventory - current 19,982 19,926 Raw materials - long term (net of allowances of $37 and $221, respectively) 1,105 1,065 Inventory - total $ 21,087 $ 20,991 Our long-term inventory consists of raw materials that remain viable but that the Company does not expect to sell or use within the year. Inventory Allowance Due to the slow moving nature or obsolescence of a portion of its long-term inventory and inventory related to the periodic retirement of rental equipment, the Company routinely reviews its inventory allowance balance for costs that may not be recoverable in the future. A summary of our inventory allowance is as follows: March 31, 2021 December 31, 2020 (in thousands) Beginning balance $ (221) $ (24) Accruals — (251) Write-offs 184 54 Ending balance $ (37) $ (221)

Federal Income Tax Receivable

Federal Income Tax Receivable	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Federal Income Tax Receivable	Federal Income Tax ReceivableAs discussed in Note 2, the CARES Act allows NOLs incurred in 2018, 2019, and 2020 to be carried back to each of the five preceding taxable years to generate a refund of previously paid federal income taxes. The Company generated significant NOLs during 2018 and 2019, and has filed amended returns to carryback these losses for five years. Accordingly, during 2020, the Company recorded a federal income tax receivable of $15.0 million and an increase to its deferred income tax liability of $10.1 million on its condensed consolidated balance sheet. During the third quarter of 2020, the Company received refunds totaling $3.9 million related to its 2018 NOLs, which reduced its federal income tax receivable to $11.5 million on its condensed consolidated balance sheet as of March 31, 2021.

Rental Equipment

Rental Equipment	3 Months Ended
	Mar. 31, 2021
Property, Plant and Equipment [Abstract]
Rental Equipment	Rental Equipment Our rental equipment and associated accumulated depreciation as of March 31, 2021 and December 31, 2020, respectively, consisted of the following: March 31, 2021 December 31, 2020 (in thousands) Compressor units $ 385,067 $ 379,623 Work-in-process 2,754 3,764 Rental equipment 387,821 383,387 Accumulated depreciation (181,385) (175,802) Rental equipment, net of accumulated depreciation $ 206,436 $ 207,585

Credit Facility

Credit Facility	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Credit Facility	Credit Facility Previous Credit Agreement We had a senior secured revolving credit agreement the ("Previous Credit Agreement") with JP Morgan Chase Bank, N.A (the "Lender") that matured on March 31, 2021. The Previous Credit Agreement had an aggregate commitment of $30 million, subject to collateral availability. Subsequent to March 31, 2021, we entered into a new credit facility. See footnote 10.

Stock-Based and Other Long-Term

Stock-Based and Other Long-Term Incentive Compensation	3 Months Ended
	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
Stock-Based and Other Long-Term Incentive Compensation	Stock-Based and Other Long-Term Incentive Compensation Stock Options A summary of all option activity as of December 31, 2020, and changes during the three months ended March 31, 2021 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, 2020 161,334 $ 24.48 3.48 $ — Granted — — — — Cancelled / Forfeited — — — — Expired (16,000) 17.81 — — Outstanding, March 31, 2021 145,334 $ 25.21 3.61 $ — Exercisable, March 31, 2021 145,334 $ 25.21 3.61 $ — The following table summarizes information about our stock options outstanding at March 31, 2021: Range of Exercise Prices Options Outstanding Options Exercisable Shares Weighted Average Remaining Contractual Life (years) Weighted Average Exercise Price Shares Weighted Average Exercise Price $0.01-18.00 8,500 0.82 $ 14.89 8,500 $ 14.89 $18.01-22.00 20,500 1.97 18.75 20,500 18.75 $22.01-26.00 42,167 4.04 22.90 42,167 22.90 $26.01-30.00 30,000 5.88 28.15 30,000 28.15 $30.01-34.00 44,167 2.97 30.41 44,167 30.41 145,334 3.61 $ 25.21 145,334 $ 25.21 As of March 31, 2021 and December 31, 2020, there were no unvested stock options. As of March 31, 2021, there was no unrecognized compensation cost related to unvested options. For the three months ended March 31, 2020, total compensation expense for stock options was $17,000. For the three months ended March 31, 2021 there was no compensation expense for stock options. Restricted Shares/Units In accordance with the Company's employment agreement with Stephen Taylor, the Company's Chief Executive Officer, the Compensation Committee of the Company's Board of Directors reviewed his performance in determining the issuance of restricted common stock. Based on this review, which included consideration of the Company's 2020 performance, Mr. Taylor was awarded 109,212 restricted shares/units on March 18, 2021, which vest over three years, in equal annual installments, beginning March 18, 2022. On March 18, 2021, the Compensation Committee awarded 20,000 restricted shares/units to our Vice President of Technical Services, James Hazlett. The restricted shares to Mr. Hazlett vest over three years, in equal annual installments, beginning March 18, 2022. On March 18, 2021, we also awarded and issued 5,612 shares of restricted common stock to each of our three independent members of our Board of Directors as partial payment for their services in 2021. These awards of restricted stock vest one year from the date of grant. Total compensation expense related to these and previously granted restricted stock awards was $474,000 and $485,000 for the three months ended March 31, 2021 and 2020, respectively. As of March 31, 2021, there was a total of $2.6 million of unrecognized compensation expense related to these shares/units which is expected to be recognized over the next 2.0 years. A summary of all restricted stock/units activity as of December 31, 2020 and changes during the three months ended March 31, 2021 is presented below: Number Weighted Average Weighted Aggregate Intrinsic Value (in thousands) Outstanding, December 31, 2020 258,101 $ 12.87 8.61 $ 2,447 Granted 146,048 8.91 — 1,301 Vested (85,457) 20.25 — 804 Canceled/Forfeited (3,333) 12.26 — 31 Outstanding, March 31, 2021 315,359 $ 9.04 9.26 $ 2,977 Other Long-Term Incentive Compensation On April 28, 2020, based on its review of Mr. Taylor's 2019 performance, the Compensation Committee issued a long-term incentive award of $1,061,820 to Mr. Taylor that vests in equal, annual tranches over 3 years beginning on the anniversary of the grant date. At the time of vesting, each tranche will be payable in cash or common stock at the discretion of the Compensation Committee. On March 18, 2021, based on its review of Mr. Taylor's 2020 performance, the Compensation Committee issued a long-term incentive award of $973,080 to Mr. Taylor that vests in equal, annual tranches over 3 years beginning on the anniversary of the grant date. In addition, on April 28, 2020, we issued a $50,000 award to three of our independent members of our Board of Directors as partial payment for their services in 2020. These awards vest one year from the date of grant and are payable in cash upon vesting. On March 18, 2021, we issued a $50,000 award to three of our independent members of our Board of Directors as partial payment for their services in 2021. These awards vest one year from the date of grant and are payable in cash upon vesting. The Company accounts for these other long-term incentive awards to Mr. Taylor and our independent Board members as liabilities under accrued liabilities on our condensed consolidated balance sheet. The vesting of these awards awards is subject to acceleration upon certain events, such as (i) death or disability of the recipient, (ii) certain circumstances in connection with a change of control of the Company, (iii) for executive officers, termination without cause (as defined in the agreement), and (iv) for executive officers, resignation for good reason (as defined). Total compensation expense related to these other long-term incentive awards was approximately $166,000 for the three months ended March 31, 2021. As of March 31, 2021, there was a total of $1.8 million of unrecognized compensation expense related to these other long-term incentive awards which is expected to be recognized over the next 2.4 years.

(Loss) Earnings per Share

(Loss) Earnings per Share	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
(Loss) Earnings per Share	(Loss) Earnings per Share The following table reconciles the numerators and denominators of the basic and diluted (loss) earnings per share computation: Three months ended March 31, 2021 2020 (in thousands, except per share data) Numerator: Net (loss) income $ (394) $ 4,082 Denominator for (loss) earnings per basic common share: Weighted average common shares outstanding 13,263 13,157 Denominator for (loss) earnings per diluted common share: Weighted average common shares outstanding 13,263 13,157 Dilutive effect of stock options and restricted shares — 259 Diluted weighted average shares 13,263 13,416 (Loss) earnings per common share: Basic $ (0.03) $ 0.31 Diluted $ (0.03) $ 0.30 For the three months ended March 31, 2021, 315,359 restricted stock/units and 145,334 stock options were not included in the computation of diluted loss per share due to their antidilutive effect. For the three months ended March 31, 2020, options to purchase 182,839 weighted average shares of common stock were not included in the computation of diluted earnings per share due to their antidilutive effect.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and ContingenciesFrom 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.

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2021
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On May 11, 2021, we entered into a five year senior secured revolving credit agreement ("Credit Agreement") with Texas Capital Bank, National Association (the "Lender") with an initial commitment of $20 million and an accordion feature that would increase the maximum commitment to $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 $30 million on the aggregate commitment; provided, however, the aggregate commitment amount is not permitted to exceed $50 million. The maturity date of the Credit Agreement is May 11, 2026. The obligations under the Credit Agreement are secured by a first priority lien on all of our assets, including inventory and accounts receivable along with a first priority lien on a variable number of our leased compressor equipment. Borrowing Base. At any time before the maturity of the 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) 90% of eligible accounts receivable owed to the Company by investment grade debtors, plus (b) 85% of the eligible accounts receivable owing by non-investment grade debtors, plus (c) 50% of the eligible inventory, valued at the lower of cost or market value at such time, subject to a cap of this component not to exceed $2,000,000, plus (d) the lesser of (i) 95% of the net book value of the compressors that the Lender has determined are eligible for the extension of credit, valued at the lower of cost or market value with depreciation not to exceed 25 years, at such time and (ii) 80% of the net liquidation value percentage of the net book value of the eligible compressors that the Lender has determined are eligible for the extension of credit, valued at the lower of cost or market value with depreciation not to exceed 25 years, at such time, plus (e) 80% of the value at cost (excluding any costs for capitalized interest or other non-cash capitalized costs) of the eligible new compressor fleet, minus (f) any required availability reserves determined by the Lender in its sole discretion. The Lender may adjust the borrowing base components if material deviations in the collateral are discovered in future audits of the collateral. Interest and Fees. Under the terms of the Credit Agreement, we have the option of selecting the applicable variable rate for each revolving loan, or portion thereof, of either (a) the Base Rate (as defined below) plus the Applicable Margin, or (b) in the case of a Eurodollar Rate Loan, the Adjusted Eurodollar Rate plus the Applicable Margin. "Base Rate" means, for any day, a rate of interest per annum equal to the highest of (a) the prime rate for such day; (b) the sum of the federal funds rate fro such day plus 0.50%; and (c) the Adjusted Eurodollar Rate for such day plus 1.00%. The Applicable Margin is determined based upon the leverage ratio as set forth in the most recent compliance certificate received by the Lender for each fiscal quarter from time to time pursuant to the Credit Agreement. Depending on the leverage ratio, the Applicable Margin can be 0.25% to 0.75% for Base Rate Loans (as defined in the Credit Agreement) and 1.25% to 1.75% for Eurodollar Rate Loans and for requested letters of credit. Accrued interest is payable monthly on outstanding principal amounts, provided that accrued interest on Eurodollar Rate Loans is payable at the end of each interest period, but in no event less frequently than quarterly. Covenants. The Credit Agreement contains customary representations and warranties, as well as covenants which, among other things, condition or 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 are applicable during certain trigger periods specified in the Credit Agreement and require us during such trigger periods to maintain a leverage ratio less than or equal to 3.00 to 1.00 as of the last day of each fiscal quarter and a fixed charge coverage ratio greater than or equal to 1.00 to 1.00 as of the last day of each fiscal quarter. Events of Default and Acceleration. The 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 Credit Agreement and the other transaction 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 $1,000,000; certain bankruptcy or insolvency events; the rendering of certain judgments in excess of $1,000,000; certain ERISA events; certain change in control events and the defectiveness of any liens under the secured revolving credit agreement. Obligations outstanding under the Credit Agreement may be accelerated upon the occurrence of an event of default. On May 11,2021, we had no amounts outstanding under the Credit Agreement.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Basis of Accounting	The accompanying unaudited condensed consolidated financial statements include the accounts of the Company, its subsidiary, NGSG Properties, LLC and the rabbi trust associated with the Company's deferred compensation plan. All significant intercompany accounts and transactions for the periods presented have been eliminated in consolidation. These financial statements include all adjustments, consisting of only normal recurring adjustments, which are necessary to make our financial position at March 31, 2021 and the results of our operations for the three months ended March 31, 2021 and 2020 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 consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2020 on file with the SEC. In our opinion, the condensed consolidated financial statements are a fair presentation of the financial position, results of operations, changes in stockholders' equity and cash flows for the periods presented. The results of operations for the three months ended March 31, 2021 are not necessarily indicative of the results of operations to be expected for the full fiscal year ending December 31, 2021.
Revenue Recognition Policy	Revenue Recognition Policy The Company recognizes revenue in accordance with ASC 606, Revenue from Contracts with Customers ("ASC 606"). Under ASC 606, revenue is measured based on a consideration specified in a customer’s contract, excluding any sale incentives and taxes collected on behalf of third parties (i.e. sales and property taxes). Revenue is recognized when a customer obtains control of promised goods or services in an amount that reflects the consideration that we expect to receive for those goods or services. To recognize revenue, we (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when, or as, we satisfy the performance obligation(s). Shipping and handling costs incurred are accounted for as fulfillment costs and are included in cost of revenues in our condensed consolidated statements of operations. Nature of Goods and Services The following is a description of principal activities from which the Company generates its revenue: Rental Revenue. The Company generates revenue from renting compressors and flare systems to our customers. These contracts, which all qualify as operating leases under ASC Topic 842, Leases (ASC 842), may also include a fee for servicing the compressor or flare during the rental contract period. Our rental contracts typically range from six Sales Revenue. The Company generates revenue by the sale of custom/fabricated compressors, flare systems and parts, as well as, exchange/rebuilding customer owned compressors and sale of used rental equipment. Custom/fabricated compressors and flare systems - The Company designs and fabricates compressors and flares based on the customer’s specifications outlined in their contract. Though the equipment being built is customized by the customer, control under these contracts does not pass to the customer until the compressor or flare package is complete and shipped, or in accordance with a bill and hold arrangement, the customer accepts title and assumes the risk and rewards of ownership. We request some of our customers to make progressive payments as the product is being built; these payments are recorded as a contract liability on the Deferred Income line on the condensed consolidated balance sheet until control has been transferred. These contracts also may include an assurance warranty clause to guarantee the product is free from defects in material and workmanship for a set duration of time; this is a standard industry practice and is not considered a performance obligation. From time to time, upon the customer’s written request, we recognize revenue when manufacturing is complete and the equipment is ready for shipment. At the customer’s request, we will bill the customer upon completing all performance obligations, but before shipment. The customer will formally request that we ship the equipment per their direction from our manufacturing facility at a later specified date and that we segregate the equipment from our finished goods, such that they are not available to fill other orders. Per the customer’s agreement change of control is passed to the customer once the equipment is complete and ready for shipment. We have operated using bill and hold agreements with certain customers for many years, with consistent and satisfactory results for both the customer and us. The credit terms on these agreements are consistent with the credit terms on all other sales. All control is maintained by the customer and there are no exceptions to the customer’s commitment to accept and pay for the manufactured equipment. There was no revenue recognized for bill and hold arrangements for the three months ended March 31, 2021. Revenue recognized related to bill and hold arrangements for the three months ended March 31, 2020 was approximately $0.9 million. Parts - Revenue is recognized after the customer obtains control of the parts. Control is passed either by the customer taking physical possession or the parts being shipped. The amount of revenue recognized is not adjusted for expected returns, as our historical part returns have been de minimis. Exchange or rebuilding customer owned compressors - Based on the contract, the Company will either exchange a new/rebuilt compressor for the customer’s malfunctioning compressor or rebuild the customer’s compressor. Revenue is recognized after control of the replacement compressor has transferred to the customer based on the terms of the contract, i.e., by physical delivery, delivery and installment, or shipment of the compressor. Used compressors or flares - From time to time, a customer may request to purchase a used compressor or flare out of our rental fleet. Revenue from the sale of rental equipment is recognized when the control has passed to the customer based on the terms of the contract, i.e., when the customer has taken physical possession or the equipment has been shipped. Service and Maintenance Revenue . The Company provides routine or call-out services on customer owned equipment. Revenue is recognized after services in the contract are rendered. Payment terms for sales revenue and service and maintenance revenue discussed above are generally 30 to 60 days, although terms for specific customers can vary. Also, transaction prices are not subject to variable consideration constraints. Contract Costs The Company recognizes the incremental costs of obtaining contracts as an expense when incurred if the amortization period of the assets that the Company otherwise would have recognized is one year or less. These costs are included in selling, general and administrative expenses on our condensed consolidated statements of operations.
Income Taxes	Income Taxes Deferred tax assets and liabilities are recognized for the future tax consequences attributable to temporary differences between the financial statement carrying amounts of assets and liabilities and their respective tax bases, and operating losses and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. Valuation allowances are established to reduce deferred tax assets when it is more likely than not that some portion or all of the deferred tax assets will not be realized. To the extent we establish a valuation allowance or increase this allowance in a period, we include an expense in the tax provision in our condensed consolidated statements of operations. We account for uncertain tax positions in accordance with guidance in ASC 740, which prescribes the minimum recognition threshold a tax position taken or expected to be taken in a tax return is required to meet before being recognized in the condensed consolidated financial statements. Tax benefits are recognized only for tax positions that are more likely than not to be sustained upon examination by tax authorities. The amount recognized is measured as the largest amount of benefit that is greater than 50% likely to be realized upon settlement. A liability for unrecognized tax benefits is recorded for any tax benefits claimed in our tax returns that do not meet these recognition and measurement standards. We have no liabilities for uncertain tax positions as of March 31, 2021. Our policy regarding income tax interest and penalties is to expense those items as interest expense and other expense, respectively. On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act ("CARES Act") was enacted in response to the economic impact caused by the COVID-19 pandemic. The CARES Act, among other things, permits federal income tax
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (ASC Topic 326): Measurement of Credit Losses on Financial Instruments. The amendments to ASC Topic 326 require immediate recognition of estimated credit losses expected to occur over the remaining life of many financial assets, including trade receivables. For companies that qualify as smaller reporting companies, the amendments in this update are effective for interim and annual periods beginning after January 1, 2023. We are currently evaluating the impact of ASU 2016-13 on our consolidated financial statements and note disclosures.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Disaggregation of Revenue	The following table shows the Company's revenue disaggregated by product or service type for the three months ended March 31, 2021 and 2020: Three months ended March 30, 2021 2020 (in thousands) Compressors - sales $ 1,891 $ 852 Flares - sales 46 80 Other (parts/rebuilds) - sales 774 518 Service and maintenance 345 340 Total revenue from contracts with customers 3,056 1,790 Add: ASC 842 rental revenue 15,341 16,100 Total revenue $ 18,397 $ 17,890
Schedule of Contract with Customer, Asset and Liability	As of March 31, 2021 and December 31, 2020, we had the following receivables and deferred income from contracts with customers: March 31, 2021 December 31, 2020 (in thousands) Accounts Receivable Accounts receivable - contracts with customers $ 2,937 $ 3,243 Accounts receivable - ASC 842 10,942 9,802 Total Accounts Receivable $ 13,879 $ 13,045 Less: Allowance for doubtful accounts (1,155) (1,161) Total Accounts Receivable, net $ 12,724 $ 11,884 Deferred income $ 34 $ 1,103

Inventory (Tables)

Inventory (Tables)	3 Months Ended
	Mar. 31, 2021
Inventory Disclosure [Abstract]
Schedule of Inventory	Our inventory, net of allowance for obsolescence of $37,000 at March 31, 2021 and $221,000 at December 31, 2020, consisted of the following amounts: March 31, 2021 December 31, 2020 (in thousands) Raw materials - current $ 18,619 $ 18,026 Work-in-process 1,363 1,900 Inventory - current 19,982 19,926 Raw materials - long term (net of allowances of $37 and $221, respectively) 1,105 1,065 Inventory - total $ 21,087 $ 20,991 A summary of our inventory allowance is as follows: March 31, 2021 December 31, 2020 (in thousands) Beginning balance $ (221) $ (24) Accruals — (251) Write-offs 184 54 Ending balance $ (37) $ (221)

Rental Equipment (Tables)

Rental Equipment (Tables)	3 Months Ended
	Mar. 31, 2021
Property, Plant and Equipment [Abstract]
Schedule of Rental Equipment	Our rental equipment and associated accumulated depreciation as of March 31, 2021 and December 31, 2020, respectively, consisted of the following: March 31, 2021 December 31, 2020 (in thousands) Compressor units $ 385,067 $ 379,623 Work-in-process 2,754 3,764 Rental equipment 387,821 383,387 Accumulated depreciation (181,385) (175,802) Rental equipment, net of accumulated depreciation $ 206,436 $ 207,585

Stock-Based and Other Long-Te_2

Stock-Based and Other Long-Term Incentive Compensation (Tables)	3 Months Ended
	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
Summary of Option Activity	A summary of all option activity as of December 31, 2020, and changes during the three months ended March 31, 2021 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, 2020 161,334 $ 24.48 3.48 $ — Granted — — — — Cancelled / Forfeited — — — — Expired (16,000) 17.81 — — Outstanding, March 31, 2021 145,334 $ 25.21 3.61 $ — Exercisable, March 31, 2021 145,334 $ 25.21 3.61 $ —
Summary of Stock Options Outstanding	The following table summarizes information about our stock options outstanding at March 31, 2021: Range of Exercise Prices Options Outstanding Options Exercisable Shares Weighted Average Remaining Contractual Life (years) Weighted Average Exercise Price Shares Weighted Average Exercise Price $0.01-18.00 8,500 0.82 $ 14.89 8,500 $ 14.89 $18.01-22.00 20,500 1.97 18.75 20,500 18.75 $22.01-26.00 42,167 4.04 22.90 42,167 22.90 $26.01-30.00 30,000 5.88 28.15 30,000 28.15 $30.01-34.00 44,167 2.97 30.41 44,167 30.41 145,334 3.61 $ 25.21 145,334 $ 25.21
Summary of Restricted Stock Activity	A summary of all restricted stock/units activity as of December 31, 2020 and changes during the three months ended March 31, 2021 is presented below: Number Weighted Average Weighted Aggregate Intrinsic Value (in thousands) Outstanding, December 31, 2020 258,101 $ 12.87 8.61 $ 2,447 Granted 146,048 8.91 — 1,301 Vested (85,457) 20.25 — 804 Canceled/Forfeited (3,333) 12.26 — 31 Outstanding, March 31, 2021 315,359 $ 9.04 9.26 $ 2,977

(Loss) Earnings per Share (Tabl

(Loss) Earnings per Share (Tables)	3 Months Ended
	Mar. 31, 2021
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 (loss) earnings per share computation: Three months ended March 31, 2021 2020 (in thousands, except per share data) Numerator: Net (loss) income $ (394) $ 4,082 Denominator for (loss) earnings per basic common share: Weighted average common shares outstanding 13,263 13,157 Denominator for (loss) earnings per diluted common share: Weighted average common shares outstanding 13,263 13,157 Dilutive effect of stock options and restricted shares — 259 Diluted weighted average shares 13,263 13,416 (Loss) earnings per common share: Basic $ (0.03) $ 0.31 Diluted $ (0.03) $ 0.30

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Revenue from External Customer [Line Items]
Revenues	$ 18,397	$ 17,890
Minimum
Revenue from External Customer [Line Items]
Amortization period of capitalized contract costs	1 year
Minimum | Rental Contracts, Excluding Large Horsepower Compressors
Revenue from External Customer [Line Items]
Rental contract term	6 months
Maximum | Rental Contracts, Excluding Large Horsepower Compressors
Revenue from External Customer [Line Items]
Rental contract term	24 months
Maximum | Rental Contracts, Large Horsepower Compressors
Revenue from External Customer [Line Items]
Rental contract term	60 months
Sales
Revenue from External Customer [Line Items]
Revenues	$ 2,711	1,450
Revenue recognized	1,100		$ 500
Rental income
Revenue from External Customer [Line Items]
Revenue recognized	2		$ 73
Bill and Hold Arrangement
Revenue from External Customer [Line Items]
Revenues	$ 0	$ 900

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 3,056	$ 1,790
Rental income	15,341	16,100
Total revenue	18,397	17,890
Compressors - sales
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,891	852
Flares - sales
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	46	80
Other (parts/rebuilds) - sales
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	774	518
Service and maintenance
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	345	340
Total revenue	$ 345	$ 340

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Contract Balances (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Accounts Receivable
Accounts receivable - contracts with customers	$ 2,937	$ 3,243
Accounts receivable - ASC 842	10,942	9,802
Total Accounts Receivable	13,879	13,045
Less: Allowance for doubtful accounts	(1,155)	(1,161)
Total Accounts Receivable, net	12,724	11,884
Deferred income	$ 34	$ 1,103

Inventory - Schedule of Invento

Inventory - Schedule of Inventory (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Allowance for obsolescence	$ 37	$ 221	$ 24
Raw materials - current	18,619	18,026
Work-in-process	1,363	1,900
Inventory - current	19,982	19,926
Raw materials - long term (net of allowances of $37 and $221, respectively)	1,105	1,065
Inventory - total	$ 21,087	$ 20,991

Inventory - Schedule of Inven_2

Inventory - Schedule of Inventory Allowance (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Inventory Valuation Reserves [Roll Forward]
Beginning balance	$ (221)	$ (24)
Accruals	0	(251)
Write-offs	184	54
Ending balance	$ (37)	$ (221)

Federal Income Tax Receivable -

Federal Income Tax Receivable - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Sep. 30, 2020	Mar. 31, 2020	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Federal income tax receivable	$ 11,538		$ 15,000	$ 11,538
Deferred tax liability increase due to tax law change	$ 0		$ 10,103
Income tax received refunds		$ 3,900

Rental Equipment - Schedule of

Rental Equipment - Schedule of Rental Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Accumulated depreciation	$ (14,521)	$ (13,916)
Rental Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	387,821	383,387
Accumulated depreciation	(181,385)	(175,802)
Rental equipment, net of accumulated depreciation	206,436	207,585
Rental Equipment | Compressor units
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	385,067	379,623
Rental Equipment | Work-in-process
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 2,754	$ 3,764

Credit Facility (Details)

Credit Facility (Details) $ in Millions	Mar. 31, 2021USD ($)
Revolving Credit Facility
Line of Credit Facility [Line Items]
Aggregate credit agreement commitment	$ 30

Stock-Based and Other Long-Te_3

Stock-Based and Other Long-Term Incentive Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Number  of Stock Options
Outstanding, beginning of period (in shares)	161,334
Granted (in shares)	0
Canceled/Forfeited (in shares)	0
Expired (in shares)	(16,000)
Outstanding, end of period (in shares)	145,334	161,334
Exercisable (in shares)	145,334
Weighted AverageExercise Price
Outstanding, beginning of period (in dollars per share)	$ 24.48
Granted (in dollars per share)	0
Canceled/Forfeited (in dollars per share)	0
Expired (in dollars per share)	17.81
Outstanding, end of period (in dollars per share)	25.21	$ 24.48
Exercisable (in dollars per share)	$ 25.21
WeightedAverageRemainingContractual Life (years)
Outstanding, weighted average remaining contractual life	3 years 7 months 9 days	3 years 5 months 23 days
Exercisable, weighted average remaining contractual life	3 years 7 months 9 days
AggregateIntrinsicValue(in thousands)
Outstanding, aggregate intrinsic value	$ 0	$ 0
Exercisable, aggregate intrinsic value	$ 0

Stock-Based and Other Long-Te_4

Stock-Based and Other Long-Term Incentive Compensation - Stock Options Outstanding (Details)	3 Months Ended
	Mar. 31, 2021$ / sharesshares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding, shares (in shares) | shares	145,334
Options outstanding, weighted average remaining contractual life (years)	3 years 7 months 9 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 25.21
Options exercisable, shares (in shares) | shares	145,334
Options exercisable, weighted average exercise price (in dollars per share)	$ 25.21
$0.01-18.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, lower limit (in dollars per share)	0.01
Range of exercise prices, upper limit (in dollars per share)	$ 18
Options outstanding, shares (in shares) | shares	8,500
Options outstanding, weighted average remaining contractual life (years)	9 months 25 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 14.89
Options exercisable, shares (in shares) | shares	8,500
Options exercisable, weighted average exercise price (in dollars per share)	$ 14.89
$18.01-22.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, lower limit (in dollars per share)	18.01
Range of exercise prices, upper limit (in dollars per share)	$ 22
Options outstanding, shares (in shares) | shares	20,500
Options outstanding, weighted average remaining contractual life (years)	1 year 11 months 19 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 18.75
Options exercisable, shares (in shares) | shares	20,500
Options exercisable, weighted average exercise price (in dollars per share)	$ 18.75
$22.01-26.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, lower limit (in dollars per share)	22.01
Range of exercise prices, upper limit (in dollars per share)	$ 26
Options outstanding, shares (in shares) | shares	42,167
Options outstanding, weighted average remaining contractual life (years)	4 years 14 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 22.90
Options exercisable, shares (in shares) | shares	42,167
Options exercisable, weighted average exercise price (in dollars per share)	$ 22.90
$26.01-30.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, lower limit (in dollars per share)	26.01
Range of exercise prices, upper limit (in dollars per share)	$ 30
Options outstanding, shares (in shares) | shares	30,000
Options outstanding, weighted average remaining contractual life (years)	5 years 10 months 17 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 28.15
Options exercisable, shares (in shares) | shares	30,000
Options exercisable, weighted average exercise price (in dollars per share)	$ 28.15
$30.01-34.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, lower limit (in dollars per share)	30.01
Range of exercise prices, upper limit (in dollars per share)	$ 34
Options outstanding, shares (in shares) | shares	44,167
Options outstanding, weighted average remaining contractual life (years)	2 years 11 months 19 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 30.41
Options exercisable, shares (in shares) | shares	44,167
Options exercisable, weighted average exercise price (in dollars per share)	$ 30.41

Stock-Based and Other Long-Te_5

Stock-Based and Other Long-Term Incentive Compensation - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested stock options (in shares)	0		0
Total unrecognized compensation expense	$ 0
Share-based compensation expense		$ 485
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 0	$ 17

Stock-Based and Other Long-Te_6

Stock-Based and Other Long-Term Incentive Compensation - Restricted Stock Narrative (Details) $ in Thousands	Mar. 18, 2022	Mar. 18, 2021independent_directorshares	Mar. 31, 2021USD ($)shares	Mar. 31, 2020USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense | $				$ 485
Total unrecognized compensation expense | $			$ 0
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)			146,048
Share-based compensation expense | $			$ 474
Total unrecognized compensation expense | $			$ 2,600
Recognition period			2 years
Restricted Stock | Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)		109,212
Award vesting period		3 years
Restricted Stock | Chief Financial Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)		20,000
Restricted Stock | Vice President of Technical Services
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)		20,000
Restricted Stock | Executive Officers | Forecast
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Restricted Stock | Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)		5,612
Award vesting period		1 year
Number of independent directors | independent_director		3

Stock-Based and Other Long-Te_7

Stock-Based and Other Long-Term Incentive Compensation - Restricted Stock (Details) - Restricted Stock - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Number  of Shares
Outstanding, beginning of period (in shares)	258,101
Granted (in shares)	146,048
Vested (in shares)	(85,457)
Canceled/Forfeited (in shares)	(3,333)
Outstanding, beginning of period (in shares)	315,359	258,101
Weighted Average Grant Date Fair Value
Outstanding, beginning of period (in dollars per share)	$ 12.87
Granted (in dollars per share)	8.91
Vested (in dollars per share)	20.25
Canceled/Forfeited (in dollars per share)	12.26
Outstanding, end of period (in dollars per share)	$ 9.04	$ 12.87
Weighted Average Remaining Contractual Life (years)
Weighted average remaining contractual life (years)	9 years 3 months 3 days	8 years 7 months 9 days
Aggregate Intrinsic Value
Outstanding, begging balance	$ 2,447
Granted	1,301
Vested	804
Canceled/Forfeited	31
Outstanding, ending balance	$ 2,977	$ 2,447

Stock-Based and Other Long-Te_8

Stock-Based and Other Long-Term Incentive Compensation - Other Long-Term Incentive Compensation - Narrative (Details)	Mar. 18, 2021USD ($)compressor	Apr. 28, 2020USD ($)	Mar. 31, 2021USD ($)	Mar. 31, 2020USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense				$ 485,000
Total unrecognized compensation expense			$ 0
Other Long-Term Incentive Compensation
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted	$ 973,080	$ 1,061,820
Award vesting period	3 years	3 years	1 year
Share-based compensation expense			$ 166,000
Total unrecognized compensation expense			$ 1,800,000
Recognition period			2 years 4 months 24 days
Other Long-Term Incentive Compensation | Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted	$ 50,000	$ 50,000
Award vesting period		1 year
Number of independent directors | compressor	3

(Loss) Earnings per Share (Deta

(Loss) Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Numerator:
Net (loss) income	$ (394)	$ 4,082
Denominator for (loss) earnings per basic common share:
Weighted average common shares outstanding (in shares)	13,263,000	13,157,000
Denominator for (loss) earnings per diluted common share:
Dilutive effect of stock options and restricted shares (in shares)	0	259,000
Diluted weighted average shares (in shares)	13,263,000	13,416,000
(Loss) earnings per common share:
Basic (in dollars per share)	$ (0.03)	$ 0.31
Diluted (in dollars per share)	$ (0.03)	$ 0.30
Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of shares not included in the computation of dilutive income (loss) per share (in shares)	315,359
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of shares not included in the computation of dilutive income (loss) per share (in shares)	145,334	182,839

Subsequent Events - Narrative (

Subsequent Events - Narrative (Details) - Revolving Credit Facility - USD ($)	May 11, 2021	Mar. 31, 2021
Subsequent Event [Line Items]
Aggregate credit agreement commitment		$ 30,000,000
Subsequent Event
Subsequent Event [Line Items]
Debt instrument, term	5 years
Borrowing base amount available	$ 20,000,000
Aggregate credit agreement commitment	30,000,000
Potential increase in borrowing capacity	30,000,000
Potential maximum borrowing capacity	$ 50,000,000
Borrowing base, component, percentage of eligible accounts receivable	90.00%
Percentage of eligible non investment grade decors	85.00%
Percentage of eligible inventory	50.00%
Line of credit facility, non exceeding cap of components	$ 2,000,000
Percentage of eligible compressors for extension of credit	95.00%
Term for depreciation	25 years
Percentage of net liquidation value of eligible compressors for extension of credit	80.00%
Percentage of eligible value at cost	80.00%
Maximum leverage ratio allowed	3
Fixed charge coverage ratio	1
Outstanding balance	$ 0
Subsequent Event | Maximum
Subsequent Event [Line Items]
Default trigger, certain defaults of other company indebtedness, amount	1,000,000
Default trigger, rendering of certain judgments, amount	$ 1,000,000
Subsequent Event | Federal Fund Rate
Subsequent Event [Line Items]
Variable rate, applicable margin	0.50%
Subsequent Event | Euro Dollar Rate
Subsequent Event [Line Items]
Variable rate, applicable margin	1.00%
Subsequent Event | Euro Dollar Rate | Maximum
Subsequent Event [Line Items]
Variable rate, applicable margin	1.75%
Subsequent Event | Euro Dollar Rate | Minimum
Subsequent Event [Line Items]
Variable rate, applicable margin	1.25%
Subsequent Event | Base Rate | Maximum
Subsequent Event [Line Items]
Variable rate, applicable margin	0.75%
Subsequent Event | Base Rate | Minimum
Subsequent Event [Line Items]
Variable rate, applicable margin	0.25%