Natural Gas Services (NGS) 10-K 14 Mar 14 2013 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2013	Feb. 14, 2014	Jun. 30, 2013
Entity Information [Line Items]	'	'	'
Entity Registrant Name	'NATURAL GAS SERVICES GROUP INC	'	'
Entity Central Index Key	'0001084991	'	'
Current Fiscal Year End Date	'--12-31	'	'
Entity Filer Category	'Accelerated Filer	'	'
Document Type	'10-K	'	'
Document Period End Date	31-Dec-13	'	'
Document Fiscal Year Focus	'2013	'	'
Document Fiscal Period Focus	'FY	'	'
Amendment Flag	'false	'	'
Entity Common Stock, Shares Outstanding	'	12,415,803	'
Entity Well-known Seasoned Issuer	'No	'	'
Entity Voluntary Filers	'No	'	'
Entity Current Reporting Status	'Yes	'	'
Entity Public Float	'	'	$286,806,276

Balance_Sheets

Balance Sheets (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Current Assets:	'	'
Cash and cash equivalents	$24,443	$28,086
Trade accounts receivable, net of allowance for doubtful accounts of $436 and $437, respectively	6,750	6,691
Inventory, net of allowance for obsolescence of $128 and $211, respectively	26,832	26,509
Prepaid income taxes	2,281	275
Prepaid expenses and other	339	475
Total current assets	60,645	62,036
Rental equipment, net of accumulated depreciation of $86,533 and $70,266, respectively	176,420	151,015
Property and equipment, net of accumulated depreciation of $9,692 and $8,441 respectively	7,429	7,475
Goodwill	10,039	10,039
Intangibles, net of accumulated amortization of $2,191 and $2,060, respectively	2,027	2,157
Other assets	29	29
Total assets	256,589	232,751
Current Liabilities:	'	'
Line of credit	577	0
Accounts payable	3,904	3,420
Accrued liabilities	6,487	5,817
Current income tax liability	350	522
Deferred income	873	2,027
Total current liabilities	12,191	11,786
Line of credit, non-current	0	897
Deferred income tax liability	51,464	43,741
Other long-term liabilities	197	502
Total liabilities	63,852	56,926
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; 12,366 and 12,241 shares issued and outstanding, respectively	123	122
Additional paid-in capital	91,344	88,823
Retained earnings	101,270	86,880
Total stockholders' equity	192,737	175,825
Total liabilities and stockholders' equity	$256,589	$232,751

Balance_Sheets_Parenthetical

Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, except Share data, unless otherwise specified
Current Assets:	'	'
Allowance for doubtful accounts	$436	$437
Allowance for inventory obsolescence	128	211
Assets, Noncurrent [Abstract]	'	'
Accumulated depreciation, rental equipment	86,533	70,266
Accumulated depreciation, property and equipment	9,692	8,441
Accumulated amortization, intangibles	$2,191	$2,060
Stockholders' Equity Attributable to Parent [Abstract]	'	'
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$0.01	$0.01
Common stock, shares authorized	30,000,000	30,000,000
Common stock, shares issued	12,366,000	12,241,000
Common stock, shares outstanding	12,366,000	12,241,000

Statements_of_Income

Statements of Income (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenue:	'	'	'
Rental income	$69,062	$56,477	$48,619
Sales	19,479	36,375	15,419
Service and maintenance income	707	870	1,120
Total revenue	89,248	93,722	65,158
Operating costs and expenses:	'	'	'
Cost of rentals, exclusive of depreciation stated separately below	29,017	23,737	20,742
Cost of sales, exclusive of depreciation stated separately below	11,582	25,816	9,194
Cost of service and maintenance, exclusive of depreciation stated separately below	344	354	458
Selling, general, and administrative expenses	8,141	7,893	5,910
Depreciation and amortization	18,144	15,707	13,994
Total operating costs and expenses	67,228	73,507	50,298
Operating income	22,020	20,215	14,860
Other income (expense):	'	'	'
Interest expense	-56	-18	-55
Other income	548	14	824
Total other income (expense)	492	-4	769
Income before provision for income taxes	22,512	20,211	15,629
Provision for income taxes:	'	'	'
Current	399	554	75
Deferred	7,723	6,972	5,794
Total income tax expense	8,122	7,526	5,869
Net income	$14,390	$12,685	$9,760
Earnings per share:	'	'	'
Basic (in dollars per share)	$1.17	$1.04	$0.80
Diluted (in dollars per share)	$1.15	$1.03	$0.80
Weighted average shares outstanding:	'	'	'
Basic (in shares)	12,324	12,220	12,148
Diluted (in shares)	12,550	12,320	12,250

Statements_of_Stockholders_Equ

Statements of Stockholders' Equity (USD $)	Total	Preferred Stock	Common Stock	Additional Paid-In Capital	Retained Earnings
In Thousands, except Share data, unless otherwise specified
Balance, beginning of period at Dec. 31, 2010	$150,591	$0	$122	$86,034	$64,435
Common stock, shares outstanding, beginning of period at Dec. 31, 2010	'	'	12,148,000	'	'
Preferred stock, shares outstanding, beginning of period at Dec. 31, 2010	'	0	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'
Exercise of common stock options and warrants	123	0	0	123	0
Exercise of common stock options and warrants, shares	'	0	18,000	'	'
Compensation expense on common stock options	461	0	0	461	0
Issuance of restricted stock	0	0	0	0	0
Issuance of restricted stock, shares	'	0	13,000	'	'
Compensation expense on restricted common stock	607	0	0	607	0
Net income	9,760	'	'	'	9,760
Balance, end of period at Dec. 31, 2011	161,542	0	122	87,225	74,195
Common stock, shares outstanding, end of period at Dec. 31, 2011	'	'	12,179,000	'	'
Preferred stock, shares outstanding, end of period at Dec. 31, 2011	'	0	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'
Exercise of common stock options and warrants	180	0	0	180	0
Exercise of common stock options and warrants, shares	'	0	23,000	'	'
Compensation expense on common stock options	440	0	0	440	0
Issuance of restricted stock	0	0	0	0	0
Issuance of restricted stock, shares	'	0	39,000	'	'
Compensation expense on restricted common stock	978	0	0	978	0
Net income	12,685	'	'	'	12,685
Balance, end of period at Dec. 31, 2012	175,825	0	122	88,823	86,880
Common stock, shares outstanding, end of period at Dec. 31, 2012	12,241,000	'	12,241,000	'	'
Preferred stock, shares outstanding, end of period at Dec. 31, 2012	0	0	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'
Exercise of common stock options and warrants	829	0	0	829	0
Exercise of common stock options and warrants, shares	'	0	53,000	'	'
Compensation expense on common stock options	198	0	0	198	0
Issuance of restricted stock	0	0	0	0	0
Tax benefit of equity compensation	10	'	'	10	'
Issuance of restricted stock, shares	'	0	72,000	'	'
Compensation expense on restricted common stock	1,485	0	1	1,484	0
Net income	14,390	'	'	'	14,390
Balance, end of period at Dec. 31, 2013	$192,737	$0	$123	$91,344	$101,270
Common stock, shares outstanding, end of period at Dec. 31, 2013	12,366,000	'	12,366,000	'	'
Preferred stock, shares outstanding, end of period at Dec. 31, 2013	0	0	'	'	'

Statements_of_Cash_Flows

Statements of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
CASH FLOWS FROM OPERATING ACTIVITIES:	'	'	'
Net income	$14,390	$12,685	$9,760
Adjustments to reconcile net income to net cash provided by operating activities:	'	'	'
Depreciation and amortization	18,144	15,707	13,994
Deferred taxes	7,723	6,972	5,869
Gain on extinguishment of liability	-223	0	0
Gain on disposal of assets	-48	0	-717
Stock based compensation	1,682	1,418	1,068
Changes in current assets (increase) decrease in:	'	'	'
Trade accounts receivables	-59	-1,012	-400
Inventory	-323	456	-5,476
Prepaid income taxes and prepaid expenses	-1,870	-281	1,964
Changes in current liabilities increase (decrease) in:	'	'	'
Accounts payable and accrued liabilities	1,154	1,863	1,859
Current income tax liability	-162	447	1,229
Deferred income	-1,154	-2,836	4,474
Other	0	-1	-1
Tax benefit from equity compensation	-10	0	0
NET CASH PROVIDED BY OPERATING ACTIVITIES	39,244	35,418	33,623
CASH FLOWS FROM INVESTING ACTIVITIES:	'	'	'
Purchases of property and equipment	-43,419	-23,766	-36,525
Proceeds from sale of property and equipment	95	5	1,019
NET CASH USED IN INVESTING ACTIVITIES	-43,324	-23,761	-35,506
CASH FLOWS FROM FINANCING ACTIVITIES:	'	'	'
Payments from other long-term liabilities, net	-82	-21	-4
Repayments of line of credit	-320	-120	-983
Tax benefit from equity compensation	10	0	'
Proceeds from exercise of stock options	829	180	123
NET CASH PROVIDED BY (USED IN) FINANCING ACTIVITIES	437	39	-864
NET CHANGE IN CASH AND CASH EQUIVALENTS	-3,643	11,696	-2,747
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	28,086	16,390	19,137
CASH AND CASH EQUIVALENTS AT END OF PERIOD	24,443	28,086	16,390
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:	'	'	'
Interest paid	56	18	61
Income taxes paid	2,590	267	130
NON-CASH TRANSACTIONS	'	'	'
Transfer of rental equipment to inventory	$207	$8,690	$0

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2013
Accounting Policies [Abstract]	'
Summary of Significant Accounting Policies	'
	Summary of Significant Accounting Policies
	Organization and Principles of Consolidation
	These notes apply to the financial statements of Natural Gas Services Group, Inc.  (the "Company", “NGSG”, "Natural Gas Services Group", "we" or "our") (a Colorado corporation).  Natural Gas Services Group, Inc. was formed on December 17, 1998 for the purposes of combining the operations of certain manufacturing, service and leasing entities.
	Nature of Operations
	Natural Gas Services Group, Inc. is a leading provider of small to medium horsepower compression equipment to the natural gas industry.  We focus primarily on the non-conventional natural gas production business in the United States (such as coal bed methane, gas shale and tight gas).  We manufacture, fabricate and rent natural gas compressors that enhance the production of natural gas wells.  NGSG provides maintenance services for its natural gas compressors.  In addition, we sell custom fabricated natural gas compressors to meet customer specifications dictated by well pressures, production characteristics and particular applications.  We also manufacture and sell flare systems for oil and natural gas plant and production facilities.
	Use of Estimates
	The preparation of our financial statements in conformity with accounting principles generally accepted in the United States of America requires our management to make estimates and assumptions that affect the amounts reported in these financial statements and accompanying notes.  Actual results could differ from those estimates.  Significant estimates include fixed asset lives, bad debt allowance and the allowance for inventory obsolescence.  It is at least reasonably possible these estimates could be revised in the near term and the revisions could be material.
	Cash Equivalents
	For purposes of reporting cash flows, we consider all short-term investments with an original maturity of three months or less to be cash equivalents.
	Accounts Receivable
	Our trade receivables consist of customer obligations for the sale of compressors and flare systems due under normal trade terms, and operating leases for the use of our natural gas compressors.  The receivables are not collateralized except as provided for under lease agreements.  However, we require deposits of as much as 50% for large custom contracts.  We extend credit based on management's assessment of the customer's financial condition, receivable aging, customer disputes and general business and economic conditions.   The allowance for doubtful accounts was $436,000 and $437,000 at December 31, 2013 and 2012, respectively. Management believes that the allowance is adequate; however, actual write-offs may exceed the recorded allowance.
	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.  Exchange and rebuilt compressor revenue is recognized when both 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.
	Major Customers and Concentration of Credit Risk
	Sales and rental income to EOG Resources, Inc. ("EOG") and Devon Energy Production, Inc. ("Devon") in 2013 amounted to 18% and 15% of revenue, respectively. Sales and rental income to EOG and Devon in 2012 amounted to 32% and 12% of revenue, respectively. Sales and rental income to EOG and Devon in 2011 amounted to 17% and 16% of revenue. No other single customer accounted for more than 10% of our revenues in 2013, 2012 or 2011. EOG and Devon amounted to 18% and 14% of our accounts receivable as of December 31, 2013. EOG amounted to 17% of our accounts receivable as of December 31, 2012. No other customers amounted to more than 10% of our accounts receivable as of December 31, 2013 and 2012.
	Inventory
	Inventory is valued at the lower of cost or market.  The cost of inventories is determined by the weighted average method.  A reserve is recorded against inventory balances for estimated obsolescence.  This reserve is based on specific identification and historical experience and totaled $128,000 and $211,000 at December 31, 2013 and 2012, respectively. There were no new completed compressor units at December 31, 2013 or at December 31, 2012 available for sale or for use in our rental fleet.  At December 31, 2013 and 2012, inventory consisted of the following (in thousands):
		2013		2012
	Raw materials	$	20,524	$	19,654
	Work in process	6,308		6,855
	Total	$	26,832	$	26,509
	Property and Equipment
	Property and equipment is recorded at cost less accumulated depreciation.  Depreciation is computed using the straight-line method over the estimated useful lives of the assets, which range from three to forty years.  Rental equipment has an estimated useful life of fifteen years.
	Gains and losses resulting from sales and dispositions of property and equipment are included in current operations.  Maintenance and repairs are charged to operations as incurred.
	Goodwill
	Goodwill represents the cost in excess of fair value of the identifiable net assets acquired. Goodwill is tested for impairment annually or whenever events indicate impairment may have occurred. The annual goodwill impairment test is performed in the fourth quarter of each year.
	Intangibles
	At December 31, 2013, NGSG had intangible assets, which relate to developed technology, acquired customer contracts, distribution agreements and non-compete agreements.  The carrying amount net of accumulated amortization at December 31, 2013 and 2012 was $2.0 million and $2.2 million respectively.  Intangible assets are amortized on a straight-line basis with useful lives ranging from 5 to 20 years, with a weighted average remaining life of approximately ten years as of December 31, 2013.  Amortization expense recognized in each of the years ending December 31, 2013, 2012, and 2011 was $130,000, $125,000 and $179,000 respectively.  NGSG has an intangible asset with a gross carrying value of $654,000 at December 31, 2013 related to the trade name of SCS which was acquired in our acquisition of Screw Compression Systems in January 2005.  This asset is not being amortized as it has been deemed to have an indefinite life.
	The following table represents estimated future amortization expense:
	Years Ending December 31,    (in thousands)
	2014	$	125
	2015	125
	2016	125
	2017	125
	2018	125
	Thereafter	748
	Total	$	1,373
	Our policy is to periodically review intangibles for impairment through an assessment of the estimated future cash flows related to such assets.  In the event that assets are found to be carried at amounts in excess of estimated undiscounted future cash flows, then the assets will be adjusted for impairment to a level commensurate with a discounted cash flow analysis of the underlying assets.  Based upon our analysis, we believe no impairment of intangible assets exists as of December 31, 2013.
	Warranty
	We accrue amounts for estimated warranty claims based upon current and historical product warranty costs and any other related information known.  The warranty reserve was $28,000 and $336,000 for December 31, 2013 and 2012, respectively, and is included in accrued liabilities on the balance sheet.
	Financial Instruments and Concentrations of Credit Risk
	We invest our cash primarily in deposits and money market funds with commercial banks.  At times, cash balances at banks and financial institutions may exceed federally insured amounts.
	Per Share Data
	Basic earnings per common share is computed using the weighted average number of common shares outstanding during the period.  Diluted earnings per common share is computed using the weighted average number of common stock and common stock equivalent shares outstanding during the period.  There were no an anti-dilutive securities in 2013, 2012, and 2011.
	The following table sets forth the computation of basic and diluted earnings per share (in thousands, except per share amounts):
		Year Ended December 31,
		2013		2012		2011
	Numerator:
	Net income	$	14,390	$	12,685	$	9,760
	Denominator for basic net income per common share:
	Weighted average common shares outstanding	12,324		12,220		12,148
	Denominator for diluted net income per share:
	Weighted average common shares outstanding	12,324		12,220		12,148
	Dilutive effect of stock options and restricted shares	226		100		102
	Diluted weighted average shares	12,550		12,320		12,250
	Earnings per common share:
	Basic	$	1.17	$	1.04	$	0.8
	Diluted	$	1.15	$	1.03	$	0.8
	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 carry-forwards.  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.
	ASC Topic 740 prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. In order to record any financial statement benefit, we are required to determine, based on technical merits of the position, whether it is more likely than not (a likelihood of more than 50 percent) that a tax position will be sustained upon examination, including resolution of any related appeals or litigation processes. If that step is satisfied, then we must measure the tax position to determine the amount of benefit to recognize in the financial statements. The tax position is measured at the largest amount of the benefit that is greater than 50 percent likely of being realized upon ultimate settlement. We have no uncertain tax positions as of December 31, 2013 or 2012.
	Fair Value Measurement
	Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date under current market conditions. Topic 820 established a fair value hierarchy, which requires an entity to maximize the use of observable inputs when measuring fair value. These inputs are categorized as follows:
Level 1- quoted prices in an active market for identical assets or liabilities;
Level 2- quoted prices in an active market for similar assets or liabilities, inputs other than quoted prices that are observable for similar assets or liabilities, inputs derived principally from or corroborated by observable market data by correlation or other means; and
Level 3- valuation methodology with unobservable inputs that are significant to the fair value measurement.
The Company categorizes $577,000 and $897,000 of debt at December 31, 2013 and 2012, respectively as Level 2 measurements. Management believes that the fair value of our cash and cash equivalents, trade receivables, accounts payable and line of credit at December 31, 2013 and 2012 approximate their carrying values due to the short-term nature of the instruments or the use of prevailing market interest rates.
Segments and Related Information
ASC 280-10-50, “Operating Segments”, define 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 indeed 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.   Therefore discrete financial information is not available by product line and our CODM does not make resource allocation decisions or assess 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.  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.

Rental_Activity

Rental Activity	12 Months Ended
	Dec. 31, 2013
Leases [Abstract]	'
Rental Activity	'
	Rental Activity
	We rent natural gas compressor packages to entities in the petroleum industry.  These rental arrangements are classified as operating leases and generally have original terms of six months to two years and continue on a month-to-month basis thereafter.  Future minimum rent payments for arrangements not on a month-to-month basis at December 31, 2013 are as follows :
	Years Ending December 31, (in thousands)
	2014	$	6,470
	2015	247
	Thereafter	32
	Total	$	6,749

Property_and_Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2013
Property, Plant and Equipment [Abstract]	'
Property and Equipment	'
	Property and Equipment
	Property and equipment consists of the following at December 31, 2013 and 2012 (in thousands):
		Useful Lives (Years)	2013			2012
	Land and building	30	$	5,636		$	5,606
	Leasehold improvements	39	770			758
	Office equipment and furniture	5	1,434			1,396
	Software	5	573			573
	Machinery and equipment	7	2,635			2,433
	Vehicles	3	6,073			5,150
	Total		17,121			15,916
	Less accumulated depreciation		(9,692		)	(8,441		)
	Total		$	7,429		$	7,475
	Depreciation expense for property and equipment and the compressors described in Note 2 was $18.0 million, $15.6 million and $13.8 million for the years ended December 31, 2013, 2012 and 2011, respectively.

Credit_Facility

Credit Facility	12 Months Ended
	Dec. 31, 2013
Debt Disclosure [Abstract]	'
Credit Facility	'
	Credit Facility
	On December 31, 2011, we established a $20 million senior secured revolving credit agreement (subject to a right, on an uncommitted basis, to increase the commitments thereunder to up to $40 million) with JP Morgan Chase Bank, N.A. On December 31, 2012, we amended and renewed the Credit Agreement, which was set to expire on December 31, 2012 (the "Amended Credit Agreement"). The Amended Credit Agreement increased our aggregate commitment amount from $20 million 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 $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.  JPMorgan Chase Bank (the “Lender”) may adjust the borrowing base components if material deviations in the collateral are discovered in future audits of the collateral. We had $29.3 million borrowing base availability at December 31, 2013 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 1.25%.
	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, 2014, 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.
	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 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 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 December 31, 2013, 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 December 31, 2013 our balance on the line of credit was $577,000. Our interest rate for 2013 was 1.42%.

Other_Longterm_Liabilities

Other Long-term Liabilities	12 Months Ended
	Dec. 31, 2013
Other Liabilities Disclosure [Abstract]	'
Other Long-term Liabilities	'
	Other Long-term Liabilities
	At December 31, 2012, we had a long-term liability of $275,000 to Midland Development Corporation. The liability was fully satisfied during the quarter ended March 31, 2013. As a result of our performance under the agreement, a payment to Midland Development Corporation of $52,000 was made to settle the liability, resulting in a gain of $223,000, which is included in the other income line, in our statement of income.
	In addition, we entered into a purchase agreement with a vendor on July 30, 2008 pursuant to which we agreed to purchase up to $4.8 million of our paint and coating requirements exclusively from the vendor.  In connection with the execution of the agreement, the vendor paid us a $300,000 fee which is considered to be a discount toward future purchases from the vendor.  The $300,000 payment we received is recorded as a long-term liability and will decrease as the purchase commitment is fulfilled.  The long-term liability remaining for the purchase commitment was  $197,000 and $227,000 as of December 31, 2013 and 2012, respectively.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2013
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	Income Taxes
	The provision for income taxes for the years ended December 31, 2013, 2012 and 2011, consists of the following (in thousands):
		2013				2012				2011
	Current provision:
	Federal	$	69			$	332			$	—
	State	330				222				75
	Total current provision	399				554				75
	Deferred provision:
	Federal	7,723				6,972				5,166
	State	—				—				628
	Total deferred provision	7,723				6,972				5,794
	Total provision	$	8,122			$	7,526			$	5,869
	The income tax effects of temporary differences that give rise to significant portions of deferred income tax assets and (liabilities) as of December 31, 2013 and 2012, are as follows (in thousands):
		2013				2012
	Deferred income tax assets:
	Net operating loss carryover	$	—			$	1,117
	Other	961				1,459
	Total deferred income tax assets	$	961			$	2,576
	Deferred income tax liabilities:
	Property and equipment	(51,377		)		(45,242		)
	Goodwill and other intangible assets	(1,048		)		(1,075		)
	Total deferred income tax liabilities	(52,425		)		(46,317		)
	Net deferred income tax liabilities	$	(51,464	)		$	(43,741	)
	The effective tax rate for the years ended December 31, 2013, 2012 and 2011, differs from the statutory rate as follows:
		2013			2012			2011
	Statutory rate	34	%		34	%		34	%
	State and local taxes	1.7	%		0.7	%		3	%
	Other	0.4	%		2.5	%		0.6	%
	Effective rate	36.1	%		37.2	%		37.6	%
	Our policy regarding income tax interest and penalties is to expense those items as general and administrative expense. During the years ended December 31, 2013, 2012 and 2011, there were no significant income tax interest or penalty items in the statement of income.
	We had a federal net operating loss carry forward of $3.2 million as of December 31, 2012, which was utilized in the year ended December 31, 2013. We file income tax returns in the U.S. federal jurisdiction and various state jurisdictions.  With few exceptions, we are no longer subject to U.S. federal or state income tax examination by tax authorities for years before 2008.

Stockholders_Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2013
Stockholders' Equity Attributable to Parent [Abstract]	'
Stockholders' Equity	'
	Stockholders' Equity
	Preferred Stock
	We have a total of 5.0 million authorized preferred shares with rights and preferences as designated by the Board of Directors.  As of December 31, 2013 and 2012, there were no issued or outstanding preferred shares.

StockBased_Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Stock-Based Compensation	'
	Stock-Based Compensation
	Restricted Stock
	On June 16, 2009, at our annual meeting of shareholders, our shareholders adopted the 2009 Restricted Stock/Unit Plan.  A total of 300,000 shares of Company common stock are reserved for issuance under the restricted stock plan.  On March 21, 2013, the Compensation Committee awarded 20,000 shares of restricted common stock to two of our three named executive officers. The restricted shares issued to Messrs. Hazlett and Lawrence vest one year from the grant date. We also awarded and issued a total of 10,000 shares of restricted stock (2,500 each) to our Board of Directors as partial payment for 2013 Directors' fees. The restricted stock vests in quarterly installments beginning March 31, 2014. In accordance with Mr. Taylor's employment agreement, 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 2012 performance, Mr. Taylor, our Chief Executive Officer, was awarded 56,950 restricted shares on April 30, 2013, which vest one year from the date of grant. Compensation expense related to the restricted shares was approximately $1,484,000, $978,000 and $607,000 for the years ended December 31, 2013, 2012, and 2011, respectively. As of December 31, 2013, there was a total of approximately $720,000 of unrecognized compensation expense related to the nonvested portion of these restricted shares.  This expense is expected to be recognized within one year.
	A summary of all restricted stock activity as of December 31, 2013 and changes during the year then ended is presented below.
		Number		Weighted Average				Weighted		Aggregate
		of		Grant Date Fair Value				Average		Intrinsic
		Shares						Remaining		Value
								Contractual Life (years)		(in thousands)
	Outstanding, December 31, 2012	89,166		$	14.71			9.05		$	1,464
	Granted	86,950		19.69						1,712
	Vested	(72,498	)	14.65						1,385
	Canceled/Forfeited	—		—						—
	Outstanding, December 31, 2013	103,618		$	18.94			9.07		$	2,857
	Stock Option Plan
	Our 1998 Stock Option Plan (the "Plan"), which is stockholder approved, permits the grant of stock options to its employees for up to 550,000 shares of common stock.  On June 16, 2009, at our annual meeting of shareholders, our shareholders approved a proposed amendment to the Plan to add additional 200,000 shares of common stock to the Plan, thereby authorizing the issuance of up to 750,000 shares of common stock under the Plan.  We believe that such awards better align the interests of our employees with our stockholders.  Option awards are generally granted with an exercise price equal to the market price of our stock at the date of grant; those option awards generally vest based on three years of continuous service and have ten-year contractual terms.  Certain option and share awards provide for accelerated vesting if there is a change in control of the Company (as defined in the Plan).  The last date that grants can be made under the Plan is March 1, 2016.  As of December 31, 2013, 243,336 shares were still available for issue under the Plan.
	The fair value of each option award is estimated on the date of grant using the Black-Scholes option valuation model that uses the assumptions noted in the following table.  The risk-free rate for periods within the contractual life of the option is based on the U.S. Treasury yield curve in effect at the time of grant.  The expected life of options granted is based on the vesting period and historical exercise and post-vesting employment termination behavior for similar grants.  We use historical data to estimate option exercise and employee termination within the valuation model; separate groups of employees that have similar historical exercise behavior are considered separately for valuation purposes.
	Weighted average Black -Scholes fair value assumption during the years ended December 31, are as follows:	2013			2012				2011
	Risk free rate	1.02	%		0.98	%			2.09	%
	Expected life	6 years			5 years				2 years
	Expected volatility	60.39	%		62.37	%			64.89	%
	Expected dividend yield	—			—				—
	A summary of all option activity as of December 31, 2013 and changes during the year then ended is presented below.
		Number		Weighted Average				Weighted		Aggregate
		of		Exercise				Average		Intrinsic
		Stock Options		Price				Remaining		Value
								Contractual Life (years)		(in thousands)
	Outstanding, December 31, 2012	394,322		$	15.3			5.79		$	910
	Granted	47,000		18.75
	Exercised	(52,637	)	15.75						458
	Canceled/Forfeited	(9,833	)	17.68
	Expired	—		—
	Outstanding, December 31, 2013	378,852		$	15.61			5.23		$	4,533
	Exercisable, December 31, 2013	315,770		$	15.15			4.54		$	3,921
	We granted an option to purchase 47,000 shares to non-executive employees on March 21, 2013 at an exercise price of $18.75 with a three year vesting period.
	The weighted average grant date fair value of options granted during the years 2013, 2012, and 2011 was $10.30, $8.22, and $10.00 respectively.  The total intrinsic value, or the difference between the exercise price and the market price on the date of exercise, of options exercised during the years ended December 31, 2013, 2012,and 2011 was approximately $458,000, $151,000, and $127,000 respectively.  Cash received from stock options exercised during the years ended December 31, 2013, 2012, and 2011 was $829,000, $180,000, and $123,000, respectively.
	The following table summarizes information about our stock options outstanding at December 31, 2013:
			Options Outstanding								Options Exercisable
	Range of Exercise Prices		Shares		Weighted		Weighted				Shares	Weighted
					Average		Average					Average
					Remaining		Exercise					Exercise
					Contractual		Price					Price
					Life (years)
	$0.01-9.43		71,352		2.96		$	8.72			71,352	$	8.72
	$9.44-15.60		70,500		5.08		12.53				58,834	12.06
	$15.61-20.48		237,000		5.96		18.59				185,584	18.61
			378,852		5.23		15.61				315,770	15.15
	The summary of the status of our unvested stock options as of December 31, 2013 and changes during the year then ended is presented below.
		Shares		Weighted Average
				Grant Date Fair Value
	Unvested stock options:
	Unvested at December 31, 2012	49,334		$	9.01
	Granted	47,000		$	10.3
	Vested	(26,335	)	$	9.05
	Cancelled/Forfeited	(6,917	)	$	9.79
	Unvested at December 31, 2013	63,082		$	9.87
	We recognized stock compensation expense from stock options vesting of $198,000, $440,000, and $461,000 for the years ended December 31, 2013, 2012 and 2011, respectively. As of December 31, 2013, there was approximately $337,000 of total unamortized compensation cost related to unvested stock options.  We expect to recognize such cost over a weighted-average period of 2.0 years.
	The total income tax benefit recognized in the income statement for stock based compensation was $57,000, $264,000 and $148,000, for the years ended December 31, 2013, 2012 and 2011, respectively. There was no income tax benefit realized for the tax deductions from stock options exercised for the years ended 2012 and 2011 due to utilization of net operating loss carryforwards.

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2013
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	Commitments and Contingencies
	401(k) Plan
	We offer a 401(k) Plan to all employees that have reached the age of eighteen and have completed six months of service.  The participants may contribute up to 100% of their salary subject to IRS limitations.  Employer contributions are subject to Board discretion and are subject to a vesting schedule of 20% each year after the first year and 100% after six years.  We contributed $294,000, $283,000, and $410,000 to the 401(k) Plan in 2013, 2012 and 2011, respectively.
	Rented Facilities, Vehicles and Equipment
	We lease certain of our facilities, vehicles and equipment under operating leases with terms generally ranging from month-to-month to five years.  Most leases contain renewal options.  Remaining future minimum rental payments due under these leases are as follows:
	Years Ending December 31, (in thousands)
	2014	$	341
	2015	267
	2016	234
	2017	207
	Thereafter	78
	Total	$	1,127
	Rent expense under such leases was $358,000, $453,000, and $450,000 for the years ended December 31, 2013, 2012 and 2011, respectively.
	Legal Proceedings
	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 effect on our financial position, results of operations or cash flow.  We are not currently a party to any bankruptcy, receivership, reorganization, adjustment or similar proceeding, and we are not aware of any other threatened litigation.

Segment_Information

Segment Information	12 Months Ended
	Dec. 31, 2013
Segment Reporting [Abstract]	'
Segment Information	'
	Segment Information
	Our management does not capture full financial information or utilize operating segments to make decisions about the business. As discussed in Note 1, management believes that it operates in one business segment. However, our management does rely on the before tax components in the tables below as major categories useful in managing the business.  All sales and assets are currently located in continental United Sates.
	For the Year Ended December 31, 2013
		Rental		Sales		Service & Maintenance		Corporate			Total
		(in thousands of dollars)
	Revenue	$	69,062	$	19,479	$	707	$	—		$	89,248
	Operating costs and expenses	29,017		11,582		344		26,285			67,228
	Other income	—		—		—		492			492
	Income (loss) before provision for income taxes	$	40,045	$	7,897	$	363	$	(25,793	)	$	22,512
	For the Year Ended December 31, 2012
		Rental		Sales		Service & Maintenance		Corporate			Total
		(in thousands of dollars)
	Revenue	$	56,477	$	36,375	$	870	$	—		$	93,722
	Operating costs and expenses	23,737		25,816		354		23,600			73,507
	Other expense	—		—		—		(4		)	(4		)
	Income (loss) before provision for income taxes	$	32,740	$	10,559	$	516	$	(23,604	)	$	20,211
	For the Year Ended December 31, 2011
		Rental		Sales		Service & Maintenance		Corporate			Total
		(in thousands of dollars)
	Revenue	$	48,619	$	15,419	$	1,120	$	—		$	65,158
	Operating costs and expenses	20,742		9,194		458		19,904			50,298
	Other income	—		—		—		769			769
	Income (loss) before provision for income taxes	$	27,877	$	6,225	$	662	$	(19,135	)	$	15,629

Quarterly_Financial_Data_Unaud

Quarterly Financial Data – Unaudited	12 Months Ended
	Dec. 31, 2013
Quarterly Financial Data [Abstract]	'
Quarterly Financial Data – Unaudited	'
	Quarterly Financial Data (in thousands, except per share data) – Unaudited
	2013	Q1		Q2		Q3		Q4		Total
	Total revenue	$	23,983	$	20,258	$	21,865	$	23,142	$	89,248
	Operating income	6,138		5,844		5,088		4,950		22,020
	Net income	3,994		3,844		3,394		3,158		14,390
	Net income per share - Basic	0.33		0.31		0.28		0.25		1.17
	Net income per share - Diluted	0.32		0.31		0.27		0.25		1.15
	2012	Q1		Q2		Q3		Q4		Total
	Total revenue	$	26,376	$	24,508	$	19,290	$	23,548	$	93,722
	Operating income	5,622		4,829		4,241		5,523		20,215
	Net income	3,508		3,000		2,606		3,571		12,685
	Net income per share - Basic	0.29		0.25		0.21		0.29		1.04
	Net income per share - Diluted	0.29		0.24		0.21		0.29		1.03

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2013
Accounting Policies [Abstract]	'
Organization and Principles of Consolidation	'
	Organization and Principles of Consolidation
	These notes apply to the financial statements of Natural Gas Services Group, Inc.  (the "Company", “NGSG”, "Natural Gas Services Group", "we" or "our") (a Colorado corporation).  Natural Gas Services Group, Inc. was formed on December 17, 1998 for the purposes of combining the operations of certain manufacturing, service and leasing entities.
Nature of Operations	'
	Nature of Operations
	Natural Gas Services Group, Inc. is a leading provider of small to medium horsepower compression equipment to the natural gas industry.  We focus primarily on the non-conventional natural gas production business in the United States (such as coal bed methane, gas shale and tight gas).  We manufacture, fabricate and rent natural gas compressors that enhance the production of natural gas wells.  NGSG provides maintenance services for its natural gas compressors.  In addition, we sell custom fabricated natural gas compressors to meet customer specifications dictated by well pressures, production characteristics and particular applications.  We also manufacture and sell flare systems for oil and natural gas plant and production facilities.
Use of Estimates	'
	Use of Estimates
	The preparation of our financial statements in conformity with accounting principles generally accepted in the United States of America requires our management to make estimates and assumptions that affect the amounts reported in these financial statements and accompanying notes.  Actual results could differ from those estimates.  Significant estimates include fixed asset lives, bad debt allowance and the allowance for inventory obsolescence.  It is at least reasonably possible these estimates could be revised in the near term and the revisions could be material.
Cash Equivalents	'
	Cash Equivalents
	For purposes of reporting cash flows, we consider all short-term investments with an original maturity of three months or less to be cash equivalents.
Accounts Receivable	'
	Accounts Receivable
	Our trade receivables consist of customer obligations for the sale of compressors and flare systems due under normal trade terms, and operating leases for the use of our natural gas compressors.  The receivables are not collateralized except as provided for under lease agreements.  However, we require deposits of as much as 50% for large custom contracts.  We extend credit based on management's assessment of the customer's financial condition, receivable aging, customer disputes and general business and economic conditions.   The allowance for doubtful accounts was $436,000 and $437,000 at December 31, 2013 and 2012, respectively. Management believes that the allowance is adequate; however, actual write-offs may exceed the recorded allowance.
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.  Exchange and rebuilt compressor revenue is recognized when both 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.
Major Customers and Concentration of Credit Risk	'
	Major Customers and Concentration of Credit Risk
	Sales and rental income to EOG Resources, Inc. ("EOG") and Devon Energy Production, Inc. ("Devon") in 2013 amounted to 18% and 15% of revenue, respectively. Sales and rental income to EOG and Devon in 2012 amounted to 32% and 12% of revenue, respectively. Sales and rental income to EOG and Devon in 2011 amounted to 17% and 16% of revenue. No other single customer accounted for more than 10% of our revenues in 2013, 2012 or 2011. EOG and Devon amounted to 18% and 14% of our accounts receivable as of December 31, 2013. EOG amounted to 17% of our accounts receivable as of December 31, 2012. No other customers amounted to more than 10% of our accounts receivable as of December 31, 2013 and 2012.
Inventory	'
	Inventory
	Inventory is valued at the lower of cost or market.  The cost of inventories is determined by the weighted average method.  A reserve is recorded against inventory balances for estimated obsolescence.  This reserve is based on specific identification and historical experience and totaled $128,000 and $211,000 at December 31, 2013 and 2012, respectively. There were no new completed compressor units at December 31, 2013 or at December 31, 2012 available for sale or for use in our rental fleet.  At December 31, 2013 and 2012, inventory consisted of the following (in thousands):
		2013		2012
	Raw materials	$	20,524	$	19,654
	Work in process	6,308		6,855
	Total	$	26,832	$	26,509
Property and Equipment	'
	Property and Equipment
	Property and equipment is recorded at cost less accumulated depreciation.  Depreciation is computed using the straight-line method over the estimated useful lives of the assets, which range from three to forty years.  Rental equipment has an estimated useful life of fifteen years.
	Gains and losses resulting from sales and dispositions of property and equipment are included in current operations.  Maintenance and repairs are charged to operations as incurred.
Goodwill	'
	Goodwill
	Goodwill represents the cost in excess of fair value of the identifiable net assets acquired. Goodwill is tested for impairment annually or whenever events indicate impairment may have occurred. The annual goodwill impairment test is performed in the fourth quarter of each year.
Intangibles	'
	Intangibles
	At December 31, 2013, NGSG had intangible assets, which relate to developed technology, acquired customer contracts, distribution agreements and non-compete agreements.  The carrying amount net of accumulated amortization at December 31, 2013 and 2012 was $2.0 million and $2.2 million respectively.  Intangible assets are amortized on a straight-line basis with useful lives ranging from 5 to 20 years, with a weighted average remaining life of approximately ten years as of December 31, 2013.  Amortization expense recognized in each of the years ending December 31, 2013, 2012, and 2011 was $130,000, $125,000 and $179,000 respectively.  NGSG has an intangible asset with a gross carrying value of $654,000 at December 31, 2013 related to the trade name of SCS which was acquired in our acquisition of Screw Compression Systems in January 2005.  This asset is not being amortized as it has been deemed to have an indefinite life.
	The following table represents estimated future amortization expense:
	Years Ending December 31,    (in thousands)
	2014	$	125
	2015	125
	2016	125
	2017	125
	2018	125
	Thereafter	748
	Total	$	1,373
	Our policy is to periodically review intangibles for impairment through an assessment of the estimated future cash flows related to such assets.  In the event that assets are found to be carried at amounts in excess of estimated undiscounted future cash flows, then the assets will be adjusted for impairment to a level commensurate with a discounted cash flow analysis of the underlying assets.  Based upon our analysis, we believe no impairment of intangible assets exists as of December 31, 2013.
Warranty	'
	Warranty
	We accrue amounts for estimated warranty claims based upon current and historical product warranty costs and any other related information known.
Financial Instruments and Concentrations of Credit Risk	'
	Financial Instruments and Concentrations of Credit Risk
	We invest our cash primarily in deposits and money market funds with commercial banks.  At times, cash balances at banks and financial institutions may exceed federally insured amounts.
Per Share Data	'
	Per Share Data
	Basic earnings per common share is computed using the weighted average number of common shares outstanding during the period.  Diluted earnings per common share is computed using the weighted average number of common stock and common stock equivalent shares outstanding during the period.
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 carry-forwards.  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.
	ASC Topic 740 prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. In order to record any financial statement benefit, we are required to determine, based on technical merits of the position, whether it is more likely than not (a likelihood of more than 50 percent) that a tax position will be sustained upon examination, including resolution of any related appeals or litigation processes. If that step is satisfied, then we must measure the tax position to determine the amount of benefit to recognize in the financial statements. The tax position is measured at the largest amount of the benefit that is greater than 50 percent likely of being realized upon ultimate settlement. We have no uncertain tax positions as of December 31, 2013 or 2012.
Fair Value Measurement	'
	Fair Value Measurement
	Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date under current market conditions. Topic 820 established a fair value hierarchy, which requires an entity to maximize the use of observable inputs when measuring fair value. These inputs are categorized as follows:
	Level 1- quoted prices in an active market for identical assets or liabilities;
	Level 2- quoted prices in an active market for similar assets or liabilities, inputs other than quoted prices that are observable for similar assets or liabilities, inputs derived principally from or corroborated by observable market data by correlation or other means; and
	Level 3- valuation methodology with unobservable inputs that are significant to the fair value measurement.
	The Company categorizes $577,000 and $897,000 of debt at December 31, 2013 and 2012, respectively as Level 2 measurements. Management believes that the fair value of our cash and cash equivalents, trade receivables, accounts payable and line of credit at December 31, 2013 and 2012 approximate their carrying values due to the short-term nature of the instruments or the use of prevailing market interest rates.
Segments and Related Information	'
	Segments and Related Information
	ASC 280-10-50, “Operating Segments”, define 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 indeed 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.   Therefore discrete financial information is not available by product line and our CODM does not make resource allocation decisions or assess 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.  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.

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2013
Accounting Policies [Abstract]	'
Schedule of Inventory	'
	At December 31, 2013 and 2012, inventory consisted of the following (in thousands):
		2013		2012
	Raw materials	$	20,524	$	19,654
	Work in process	6,308		6,855
	Total	$	26,832	$	26,509
Schedule of Estimated Future Amortization Expense	'
	The following table represents estimated future amortization expense:
	Years Ending December 31,    (in thousands)
	2014	$	125
	2015	125
	2016	125
	2017	125
	2018	125
	Thereafter	748
	Total	$	1,373
Computation of Basic and Diluted Earnings Per Share	'
	The following table sets forth the computation of basic and diluted earnings per share (in thousands, except per share amounts):
		Year Ended December 31,
		2013		2012		2011
	Numerator:
	Net income	$	14,390	$	12,685	$	9,760
	Denominator for basic net income per common share:
	Weighted average common shares outstanding	12,324		12,220		12,148
	Denominator for diluted net income per share:
	Weighted average common shares outstanding	12,324		12,220		12,148
	Dilutive effect of stock options and restricted shares	226		100		102
	Diluted weighted average shares	12,550		12,320		12,250
	Earnings per common share:
	Basic	$	1.17	$	1.04	$	0.8
	Diluted	$	1.15	$	1.03	$	0.8

Rental_Activity_Tables

Rental Activity (Tables)	12 Months Ended
	Dec. 31, 2013
Leases [Abstract]	'
Future Minimum Rent Payments for Operating Leases	'
	Future minimum rent payments for arrangements not on a month-to-month basis at December 31, 2013 are as follows :
	Years Ending December 31, (in thousands)
	2014	$	6,470
	2015	247
	Thereafter	32
	Total	$	6,749
	Remaining future minimum rental payments due under these leases are as follows:
	Years Ending December 31, (in thousands)
	2014	$	341
	2015	267
	2016	234
	2017	207
	Thereafter	78
	Total	$	1,127

Property_and_Equipment_Tables

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2013
Property, Plant and Equipment [Abstract]	'
Property and Equipment	'
	Property and equipment consists of the following at December 31, 2013 and 2012 (in thousands):
		Useful Lives (Years)	2013			2012
	Land and building	30	$	5,636		$	5,606
	Leasehold improvements	39	770			758
	Office equipment and furniture	5	1,434			1,396
	Software	5	573			573
	Machinery and equipment	7	2,635			2,433
	Vehicles	3	6,073			5,150
	Total		17,121			15,916
	Less accumulated depreciation		(9,692		)	(8,441		)
	Total		$	7,429		$	7,475

Income_Taxes_Income_Taxes_Tabl

Income Taxes Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2013
Income Tax Disclosure [Abstract]	'
Provision for Income Taxes	'
	The provision for income taxes for the years ended December 31, 2013, 2012 and 2011, consists of the following (in thousands):
		2013				2012				2011
	Current provision:
	Federal	$	69			$	332			$	—
	State	330				222				75
	Total current provision	399				554				75
	Deferred provision:
	Federal	7,723				6,972				5,166
	State	—				—				628
	Total deferred provision	7,723				6,972				5,794
	Total provision	$	8,122			$	7,526			$	5,869
Deferred Tax Assets and Liabilities	'
	The income tax effects of temporary differences that give rise to significant portions of deferred income tax assets and (liabilities) as of December 31, 2013 and 2012, are as follows (in thousands):
		2013				2012
	Deferred income tax assets:
	Net operating loss carryover	$	—			$	1,117
	Other	961				1,459
	Total deferred income tax assets	$	961			$	2,576
	Deferred income tax liabilities:
	Property and equipment	(51,377		)		(45,242		)
	Goodwill and other intangible assets	(1,048		)		(1,075		)
	Total deferred income tax liabilities	(52,425		)		(46,317		)
	Net deferred income tax liabilities	$	(51,464	)		$	(43,741	)
Effective Income Tax Rate Reconciliation	'
	The effective tax rate for the years ended December 31, 2013, 2012 and 2011, differs from the statutory rate as follows:
		2013			2012			2011
	Statutory rate	34	%		34	%		34	%
	State and local taxes	1.7	%		0.7	%		3	%
	Other	0.4	%		2.5	%		0.6	%
	Effective rate	36.1	%		37.2	%		37.6	%

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Schedule of Share-based Compensation, Restricted Stock Activity	'
	A summary of all restricted stock activity as of December 31, 2013 and changes during the year then ended is presented below.
		Number		Weighted Average				Weighted		Aggregate
		of		Grant Date Fair Value				Average		Intrinsic
		Shares						Remaining		Value
								Contractual Life (years)		(in thousands)
	Outstanding, December 31, 2012	89,166		$	14.71			9.05		$	1,464
	Granted	86,950		19.69						1,712
	Vested	(72,498	)	14.65						1,385
	Canceled/Forfeited	—		—						—
	Outstanding, December 31, 2013	103,618		$	18.94			9.07		$	2,857
Stock Options, Valuation Assumptions	'
	Weighted average Black -Scholes fair value assumption during the years ended December 31, are as follows:	2013			2012				2011
	Risk free rate	1.02	%		0.98	%			2.09	%
	Expected life	6 years			5 years				2 years
	Expected volatility	60.39	%		62.37	%			64.89	%
	Expected dividend yield	—			—				—
Schedule of Share-based Compensation, Stock Options, Activity	'
	A summary of all option activity as of December 31, 2013 and changes during the year then ended is presented below.
		Number		Weighted Average				Weighted		Aggregate
		of		Exercise				Average		Intrinsic
		Stock Options		Price				Remaining		Value
								Contractual Life (years)		(in thousands)
	Outstanding, December 31, 2012	394,322		$	15.3			5.79		$	910
	Granted	47,000		18.75
	Exercised	(52,637	)	15.75						458
	Canceled/Forfeited	(9,833	)	17.68
	Expired	—		—
	Outstanding, December 31, 2013	378,852		$	15.61			5.23		$	4,533
	Exercisable, December 31, 2013	315,770		$	15.15			4.54		$	3,921
Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range	'
	The following table summarizes information about our stock options outstanding at December 31, 2013:
			Options Outstanding								Options Exercisable
	Range of Exercise Prices		Shares		Weighted		Weighted				Shares	Weighted
					Average		Average					Average
					Remaining		Exercise					Exercise
					Contractual		Price					Price
					Life (years)
	$0.01-9.43		71,352		2.96		$	8.72			71,352	$	8.72
	$9.44-15.60		70,500		5.08		12.53				58,834	12.06
	$15.61-20.48		237,000		5.96		18.59				185,584	18.61
			378,852		5.23		15.61				315,770	15.15
Schedule of Stock Options Roll Forward	'
	The summary of the status of our unvested stock options as of December 31, 2013 and changes during the year then ended is presented below.
		Shares		Weighted Average
				Grant Date Fair Value
	Unvested stock options:
	Unvested at December 31, 2012	49,334		$	9.01
	Granted	47,000		$	10.3
	Vested	(26,335	)	$	9.05
	Cancelled/Forfeited	(6,917	)	$	9.79
	Unvested at December 31, 2013	63,082		$	9.87

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2013
Commitments and Contingencies Disclosure [Abstract]	'
Future Minimum Rent Payments for Operating Leases	'
	Future minimum rent payments for arrangements not on a month-to-month basis at December 31, 2013 are as follows :
	Years Ending December 31, (in thousands)
	2014	$	6,470
	2015	247
	Thereafter	32
	Total	$	6,749
	Remaining future minimum rental payments due under these leases are as follows:
	Years Ending December 31, (in thousands)
	2014	$	341
	2015	267
	2016	234
	2017	207
	Thereafter	78
	Total	$	1,127

Segment_Information_Tables

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2013
Segment Reporting [Abstract]	'
Segment Reporting Information	'
	All sales and assets are currently located in continental United Sates.
	For the Year Ended December 31, 2013
		Rental		Sales		Service & Maintenance		Corporate			Total
		(in thousands of dollars)
	Revenue	$	69,062	$	19,479	$	707	$	—		$	89,248
	Operating costs and expenses	29,017		11,582		344		26,285			67,228
	Other income	—		—		—		492			492
	Income (loss) before provision for income taxes	$	40,045	$	7,897	$	363	$	(25,793	)	$	22,512
	For the Year Ended December 31, 2012
		Rental		Sales		Service & Maintenance		Corporate			Total
		(in thousands of dollars)
	Revenue	$	56,477	$	36,375	$	870	$	—		$	93,722
	Operating costs and expenses	23,737		25,816		354		23,600			73,507
	Other expense	—		—		—		(4		)	(4		)
	Income (loss) before provision for income taxes	$	32,740	$	10,559	$	516	$	(23,604	)	$	20,211
	For the Year Ended December 31, 2011
		Rental		Sales		Service & Maintenance		Corporate			Total
		(in thousands of dollars)
	Revenue	$	48,619	$	15,419	$	1,120	$	—		$	65,158
	Operating costs and expenses	20,742		9,194		458		19,904			50,298
	Other income	—		—		—		769			769
	Income (loss) before provision for income taxes	$	27,877	$	6,225	$	662	$	(19,135	)	$	15,629

Quarterly_Financial_Data_Table

Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2013
Quarterly Financial Data [Abstract]	'
Quarterly Financial Data	'
	2013	Q1		Q2		Q3		Q4		Total
	Total revenue	$	23,983	$	20,258	$	21,865	$	23,142	$	89,248
	Operating income	6,138		5,844		5,088		4,950		22,020
	Net income	3,994		3,844		3,394		3,158		14,390
	Net income per share - Basic	0.33		0.31		0.28		0.25		1.17
	Net income per share - Diluted	0.32		0.31		0.27		0.25		1.15
	2012	Q1		Q2		Q3		Q4		Total
	Total revenue	$	26,376	$	24,508	$	19,290	$	23,548	$	93,722
	Operating income	5,622		4,829		4,241		5,523		20,215
	Net income	3,508		3,000		2,606		3,571		12,685
	Net income per share - Basic	0.29		0.25		0.21		0.29		1.04
	Net income per share - Diluted	0.29		0.24		0.21		0.29		1.03

Summary_of_Significant_Account3

Summary of Significant Accounting Policies (Narrative) (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
									segment
Accounting Policies [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Cash equivalents, qualification, maximum original maturity of short-term investments	'	'	'	'	'	'	'	'	'3 months	'	'
Customer deposit requirements, large custom contracts, maximum percentage	'	'	'	'	'	'	'	'	50.00%	'	'
Allowance for doubtful accounts	$436,000	'	'	'	$437,000	'	'	'	$436,000	$437,000	'
Inventory valuation reserves, deductions	'	'	'	'	'	'	'	'	128,000	211,000	'
Raw materials	20,524,000	'	'	'	19,654,000	'	'	'	20,524,000	19,654,000	'
Work in process	6,308,000	'	'	'	6,855,000	'	'	'	6,308,000	6,855,000	'
Inventory, net	26,832,000	'	'	'	26,509,000	'	'	'	26,832,000	26,509,000	'
Product warranty reserves	28,000	'	'	'	336,000	'	'	'	28,000	336,000	'
Anti-dilutive securities	'	'	'	'	'	'	'	'	0	0	0
Numerator:	'	'	'	'	'	'	'	'	'	'	'
Net income	3,158,000	3,394,000	3,844,000	3,994,000	3,571,000	2,606,000	3,000,000	3,508,000	14,390,000	12,685,000	9,760,000
Denominator for basic net income per common share:	'	'	'	'	'	'	'	'	'	'	'
Weighted average common shares outstanding (in shares)	'	'	'	'	'	'	'	'	12,324,000	12,220,000	12,148,000
Denominator for diluted net income per share:	'	'	'	'	'	'	'	'	'	'	'
Dilutive effect of stock options and restricted shares (in shares)	'	'	'	'	'	'	'	'	226,000	100,000	102,000
Diluted weighted average shares (in shares)	'	'	'	'	'	'	'	'	12,550,000	12,320,000	12,250,000
Earnings per common share:	'	'	'	'	'	'	'	'	'	'	'
Basic (in dollars per share)	$0.25	$0.28	$0.31	$0.33	$0.29	$0.21	$0.25	$0.29	$1.17	$1.04	$0.80
Diluted (in dollars per share)	$0.25	$0.27	$0.31	$0.32	$0.29	$0.21	$0.24	$0.29	$1.15	$1.03	$0.80
Uncertain tax positions	$0	'	'	'	$0	'	'	'	$0	$0	'
Number of business segments	'	'	'	'	'	'	'	'	1	'	'

Summary_of_Significant_Account4

Summary of Significant Accounting Policies (Concentration Risk) (Details)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Concentration Risk [Line Items]	'	'	'
Concentration risk, percentage	10.00%	'	'
EOG | Sales and Rental Income | Customer Concentration Risk	'	'	'
Concentration Risk [Line Items]	'	'	'
Concentration risk, percentage	18.00%	32.00%	17.00%
EOG | Accounts Receivable | Customer Concentration Risk	'	'	'
Concentration Risk [Line Items]	'	'	'
Concentration risk, percentage	18.00%	17.00%	'
Devon | Sales and Rental Income | Customer Concentration Risk	'	'	'
Concentration Risk [Line Items]	'	'	'
Concentration risk, percentage	15.00%	12.00%	16.00%
Devon | Accounts Receivable | Customer Concentration Risk	'	'	'
Concentration Risk [Line Items]	'	'	'
Concentration risk, percentage	14.00%	'	'

Summary_of_Significant_Account5

Summary of Significant Accounting Policies (Property and Equipment) (Details)	12 Months Ended
	Dec. 31, 2013
Minimum	'
Property, Plant and Equipment [Line Items]	'
Property and equipment, estimated useful life	'3 years
Maximum	'
Property, Plant and Equipment [Line Items]	'
Property and equipment, estimated useful life	'40 years
Equipment Leased to Other Party	'
Property, Plant and Equipment [Line Items]	'
Property and equipment, estimated useful life	'15 years

Summary_of_Significant_Account6

Summary of Significant Accounting Policies (Intangibles) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Intangible Assets [Line Items]	'	'	'
Intangibles, net of accumulated amortization	$2,027,000	$2,157,000	'
Estimated future amortization expense:	'	'	'
2014	125,000	'	'
2015	125,000	'	'
2016	125,000	'	'
2017	125,000	'	'
2018	125,000	'	'
Thereafter	748,000	'	'
Total future amortization	1,373,000	'	'
Impairment of intangible assets	0	'	'
Trade Names	'	'	'
Intangible Assets [Line Items]	'	'	'
Indefinite-lived intangible asset, gross carrying value	654,000	'	'
Developed Technology, Acquired Customer Contracts, Distribution Agreements and Non-compete Agreements	'	'	'
Intangible Assets [Line Items]	'	'	'
Intangibles, net of accumulated amortization	2,000,000	2,200,000	'
Intangible assets, weighted average remaining life	'10 years	'	'
Amortization expense	$130,000	$125,000	$179,000
Developed Technology, Acquired Customer Contracts, Distribution Agreements and Non-compete Agreements | Minimum	'	'	'
Intangible Assets [Line Items]	'	'	'
Intangible assets, useful lives	'5 years	'	'
Developed Technology, Acquired Customer Contracts, Distribution Agreements and Non-compete Agreements | Maximum	'	'	'
Intangible Assets [Line Items]	'	'	'
Intangible assets, useful lives	'20 years	'	'

Summary_of_Significant_Account7

Summary of Significant Accounting Policies (Fair Value) (Details) (Level 2, USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Level 2	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Debt, fair value	$577	$900

Rental_Activity_Details

Rental Activity (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013
Property Subject to or Available for Operating Lease [Line Items]	'
2014	6,470
2015	247
Thereafter	32
Total	6,749
Minimum	'
Property Subject to or Available for Operating Lease [Line Items]	'
Rental arrangements, original term	'6 months
Maximum	'
Property Subject to or Available for Operating Lease [Line Items]	'
Rental arrangements, original term	'2 years

Property_and_Equipment_Details

Property and Equipment (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Property, Plant and Equipment [Line Items]	'	'	'
Property and equipment, gross	$17,121,000	$15,916,000	'
Less accumulated depreciation	-9,692,000	-8,441,000	'
Property and equipment, net	7,429,000	7,475,000	'
Depreciation	18,000,000	15,600,000	13,800,000
Land and building	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'
Property and equipment, gross	5,636,000	5,606,000	'
Useful lives	'30 years	'	'
Leasehold improvements	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'
Property and equipment, gross	770,000	758,000	'
Useful lives	'39 years	'	'
Office equipment and furniture	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'
Property and equipment, gross	1,434,000	1,396,000	'
Useful lives	'5 years	'	'
Software	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'
Property and equipment, gross	573,000	573,000	'
Useful lives	'5 years	'	'
Machinery and equipment	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'
Property and equipment, gross	2,635,000	2,433,000	'
Useful lives	'7 years	'	'
Vehicles	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'
Property and equipment, gross	$6,073,000	$5,150,000	'
Useful lives	'3 years	'	'

Credit_Facility_Details

Credit Facility (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013
			Revolving Credit Facility	Revolving Credit Facility	LIBOR-based Rate	CB Floating Rate	Maximum	Maximum	Minimum
					Revolving Credit Facility	Revolving Credit Facility	Revolving Credit Facility	LIBOR-based Rate	Revolving Credit Facility
								Revolving Credit Facility
								loan
Line of Credit Facility [Line Items]	'	'	'	'	'	'	'	'	'
Maximum borrowing capacity	'	'	$30,000,000	$20,000,000	'	'	'	'	'
Potential maximum borrowing capacity	'	'	50,000,000	40,000,000	'	'	'	'	'
Potential increase in borrowing capacity	'	'	20,000,000	'	'	'	'	'	'
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	'	'	29,300,000	'	'	'	'	'	'
Reference rate, number of allowable LIBOR-based borrowings outstanding	'	'	'	'	'	'	'	3	'
Variable rate, applicable margin	'	'	'	'	1.50%	1.25%	'	'	'
Minimum commitment coverage ratio allowed	'	'	'	'	'	'	'	'	2
Maximum leverage ratio allowed	'	'	'	'	'	'	2.5	'	'
Default trigger, certain defaults of other company indebtedness, amount	'	'	'	'	'	'	50,000	'	'
Default trigger, rendering of certain judgments, amount	'	'	'	'	'	'	150,000	'	'
Line of credit	$577,000	$0	$577,000	'	'	'	'	'	'
Weighted average interest rate	'	'	1.42%	'	'	'	'	'	'

Other_Longterm_Liabilities_Det

Other Long-term Liabilities (Details) (USD $)	3 Months Ended		0 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Jul. 30, 2008	Dec. 31, 2013	Dec. 31, 2012
			Paint and Coatings	Paint and Coatings	Paint and Coatings
Other Long-term Liabilities	'	'	'	'	'
Deferred revenue, noncurrent, related to certain staffing requirements	'	$275,000	'	'	'
Payments to settle deferred revenue liability	52,000	'	'	'	'
Gain (loss) on settlement of deferred revenue liability	223,000	'	'	'	'
Long-term purchase commitment, amount	'	'	4,800,000	'	'
Cash received from supplier as discount toward future purchases	'	'	300,000	'	'
Liability related to deferred discount	'	'	$300,000	$197,000	$227,000

Income_Taxes_Components_of_Pro

Income Taxes (Components of Provision for Income Taxes) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Current provision:	'	'	'
Federal	$69	$332	$0
State	330	222	75
Total current provision	399	554	75
Deferred provision:	'	'	'
Federal	7,723	6,972	5,166
State	0	0	628
Total deferred provision	7,723	6,972	5,794
Total income tax expense	$8,122	$7,526	$5,869

Income_Taxes_Components_of_Def

Income Taxes (Components of Deferred Tax Assets and Liabilities) (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Deferred income tax assets:	'	'
Net operating loss carryover	$0	$1,117
Other	961	1,459
Total deferred income tax assets	961	2,576
Deferred income tax liabilities:	'	'
Property and equipment	-51,377	-45,242
Goodwill and other intangible assets	-1,048	-1,075
Total deferred income tax liabilities	-52,425	-46,317
Net deferred income tax liabilities	($51,464)	($43,741)

Income_Taxes_Income_Tax_Reconc

Income Taxes (Income Tax Reconciliation) (Details)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]	'	'	'
Statutory rate	34.00%	34.00%	34.00%
State and local taxes	1.70%	0.70%	3.00%
Other	0.40%	2.50%	0.60%
Effective rate	36.10%	37.20%	37.60%

Income_Taxes_Narrative_Details

Income Taxes (Narrative) (Details) (Federal, USD $)	Dec. 31, 2013
In Millions, unless otherwise specified
Federal	'
Operating Loss Carryforwards [Line Items]	'
Net operating toss carryforward	$3.20

Stockholders_Equity_Details

Stockholders' Equity (Details)	Dec. 31, 2013	Dec. 31, 2012
Stockholders' Equity Attributable to Parent [Abstract]	'	'
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0

StockBased_Compensation_Restri

Stock-Based Compensation (Restricted Stock Narrative) (Details) (USD $)	0 Months Ended		12 Months Ended			0 Months Ended
In Thousands, except Share data, unless otherwise specified	Apr. 30, 2013	Jun. 16, 2009	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Mar. 21, 2013	Mar. 21, 2013	Mar. 21, 2013	Apr. 30, 2013
			Restricted Stock [Member]	Restricted Stock [Member]	Restricted Stock [Member]	Executive Officer [Member]	Director [Member]	Individual Director [Member]	Chief Executive Officer [Member]
						Restricted Stock [Member]	Restricted Stock [Member]	Restricted Stock [Member]
						officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'	'	'	'	'
Common shares reserved for future issuance	'	300,000	'	'	'	'	'	'	'
Granted	56,950	'	86,950	'	'	20,000	10,000	2,500	'
Number of executive officers receiving awards	'	'	'	'	'	2	'	'	'
Number of named executive officers	'	'	'	'	'	3	'	'	'
Award vesting period	'	'	'	'	'	'1 year	'	'	'1 year
Share-based compensation expense	'	'	$1,484	$978	$607	'	'	'	'
Total unrecognized compensation expense	'	'	$720	'	'	'	'	'	'
Unrecognized compensation cost related to stock options, weighted average period for recognition	'	'	'1 year	'	'	'	'	'	'

StockBased_Compensation_Restri1

Stock-Based Compensation (Restricted Stock Activity) (Details) (USD $)	0 Months Ended	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Apr. 30, 2013	Dec. 31, 2013	Dec. 31, 2012
		Restricted Stock [Member]	Restricted Stock [Member]
Number of Shares	'	'	'
Outstanding, December 31, 2012	'	89,166	'
Granted	56,950	86,950	'
Vested	'	-72,498	'
Canceled/Forfeited	'	0	'
Outstanding, December 31, 2013	'	103,618	89,166
Weighted Average Grant Date Fair Value	'	'	'
Outstanding, December 31, 2012 (in dollars per share)	'	$14.71	'
Granted (in dollars per share)	'	$19.69	'
Vested (in dollars per share)	'	$14.65	'
Canceled/Forfeited (in dollars per share)	'	$0	'
Outstanding, December 31, 2013 (in dollars per share)	'	$18.94	$14.71
Weighted Average Remaining Contractual Life (years)	'	'	'
Weighted Average Remaining Contractual Life (years)	'	'9 years 0 months 26 days	'9 years 0 months 18 days
Aggregate Intrinsic Value (in thousands)	'	'	'
Aggregate Intrinsic Value, Outstanding	'	$2,857	$1,464
Aggregate Intrinsic Value, Granted	'	1,712	'
Aggregate Intrinsic Value, Released	'	$1,385	'

StockBased_Compensation_Stock_

Stock-Based Compensation (Stock Options Narrative) (Details) (USD $)	12 Months Ended							0 Months Ended			0 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013	Jun. 16, 2009	Dec. 31, 2013	Dec. 31, 2008	Mar. 21, 2013
				Stock Options	Stock Options	Stock Options	Stock Options	Stock Options	Stock Options	Stock Options	Non-Executive Employees [Member]
							1998 Stock Option Plan	Common Stock	Common Stock	Common Stock
								1998 Stock Option Plan	1998 Stock Option Plan	1998 Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Number of shares authorized	'	'	'	'	'	'	'	750,000	'	550,000	'
Additional shares authorized	'	'	'	'	'	'	'	200,000	'	'	'
Award vesting period	'	'	'	'	'	'	'3 years	'	'	'	'3 years
Award expiration period	'	'	'	'	'	'	'10 years	'	'	'	'
Number of shares available for grant	'	'	'	'	'	'	'	'	243,336	'	'
Options granted in period (in shares)	47,000	'	'	'	'	'	'	'	'	'	47,000
Options granted in period, weighted average exercise price (in dollars per share)	$18.75	'	'	'	'	'	'	'	'	'	$18.75
Weighted average grant date fair value of options granted (in dollars per share)	$10.30	$8.22	$10	'	'	'	'	'	'	'	'
Total intrinsic value of options exercised	$458,000	$151,000	$127,000	'	'	'	'	'	'	'	'
Proceeds from exercise of stock options	829,000	180,000	123,000	'	'	'	'	'	'	'	'
Share-based compensation expense	'	'	'	198,000	440,000	461,000	'	'	'	'	'
Unrecognized compensation cost related to stock options	337,000	'	'	'	'	'	'	'	'	'	'
Unrecognized compensation cost related to stock options, weighted average period for recognition	'	'	'	'2 years	'	'	'	'	'	'	'
Total income tax benefit recognized in the income statement for stock based compensation	57,000	264,000	148,000	'	'	'	'	'	'	'	'
Tax benefit realized from exercise of stock options	'	$0	$0	'	'	'	'	'	'	'	'

StockBased_Compensation_Valuat

Stock-Based Compensation (Valuation Assumptions) (Details)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'	'	'
Risk free rate	1.02%	0.98%	2.09%
Expected life	'6 years	'5 years	'2 years
Expected volatility	60.39%	62.37%	64.89%
Expected dividend yield	0.00%	0.00%	0.00%

StockBased_Compensation_Stock_1

Stock-Based Compensation (Stock Option Activity) (Details) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Number of Stock Options	'	'	'
Outstanding, beginning of period (in shares)	394,322	'	'
Granted (in shares)	47,000	'	'
Exercised (in shares)	-52,637	'	'
Canceled/Forfeited (in shares)	-9,833	'	'
Expired (in shares)	0	'	'
Outstanding, end of period (in shares)	378,852	394,322	'
Exercisable (in shares)	315,770	'	'
Weighted Average Exercise Price	'	'	'
Outstanding, weighted average exercise price, beginning of period (in dollars per share)	$15.30	'	'
Granted, weighted average exercise price (in dollars per share)	$18.75	'	'
Exercised, weighted average exercise price (in dollars per share)	$15.75	'	'
Canceled/Forfeited, weighted average exercise price (in dollars per share)	$17.68	'	'
Expired, weighted average exercise price (in dollars per share)	$0	'	'
Outstanding, weighted average exercise price, end of period (in dollars per share)	$15.61	$15.30	'
Exercisable, weighted average exercise price (in dollars per share)	$15.15	'	'
Weighted Average Remaining Contractual Life (years)	'	'	'
Outstanding, weighted average remaining contractual life	'5 years 2 months 23 days	'5 years 9 months 15 days	'
Exercisable, weighted average remaining contractual life	'4 years 6 months 15 days	'	'
Aggregate Intrinsic Value	'	'	'
Outstanding, aggregate intrinsic value	$4,533	$910	'
Exercised, aggregate intrinsic value	458	151	127
Exercisable, aggregate intrinsic value	$3,921	'	'

StockBased_Compensation_Stock_2

Stock-Based Compensation (Stock Options by Exercise Price Range) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'
Options outstanding, shares	378,852
Options outstanding, weighted average remaining contractual life	'5 years 2 months 23 days
Options outstanding, weighted average exercise price	$15.61
Options exercisable, shares	315,770
Options exercisable, weighted average exercise price	$15.15
Range of exercise prices, lower limit	$0
Range of exercise prices, upper limit	$20.48
Range of Exercise Prices: $0.01 - 9.43	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'
Options outstanding, shares	71,352
Options outstanding, weighted average remaining contractual life	'2 years 11 months 16 days
Options outstanding, weighted average exercise price	$8.72
Options exercisable, shares	71,352
Options exercisable, weighted average exercise price	$8.72
Range of exercise prices, lower limit	$0.01
Range of exercise prices, upper limit	$9.43
Range of Exercise Prices: $9.44 - 15.60	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'
Options outstanding, shares	70,500
Options outstanding, weighted average remaining contractual life	'5 years 0 months 29 days
Options outstanding, weighted average exercise price	$12.53
Options exercisable, shares	58,834
Options exercisable, weighted average exercise price	$12.06
Range of exercise prices, lower limit	$9.44
Range of exercise prices, upper limit	$15.60
Range of Exercise Prices: $15.61 - 20.48	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'
Options outstanding, shares	237,000
Options outstanding, weighted average remaining contractual life	'5 years 11 months 16 days
Options outstanding, weighted average exercise price	$18.59
Options exercisable, shares	185,584
Options exercisable, weighted average exercise price	$18.61
Range of exercise prices, lower limit	$15.61
Range of exercise prices, upper limit	$20.48

StockBased_Compensation_Summar

Stock-Based Compensation (Summary of Unvested Stock Options) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Employee Service Share-based Compensation, Nonvested Awards, Stock Options, Outstanding [Roll Forward]	'	'	'
Unvested, beginning of period (in shares)	49,334	'	'
Granted (in shares)	47,000	'	'
Vested (in shares)	-26,335	'	'
Cancelled/Forfeited (in shares)	-6,917	'	'
Unvested, end of period (in shares)	63,082	49,334	'
Employee Service Share-based Compensation, Nonvested Awards, Stock Options, Weighted Average Grant Date Fair Value [Roll Forward]	'	'	'
Unvested, weighted average grant date fair value, beginning of period (in dollars per share)	$9.01	'	'
Granted, weighted average exercise price (in dollars per share)	$10.30	$8.22	$10
Vested, weighted average exercise price (in dollars per share)	$9.05	'	'
Cancelled/Forfeited, weighted average exercise price (in dollars per share)	$9.79	'	'
Unvested, weighted average grant date fair value, end of period (in dollars per share)	$9.87	$9.01	'

Commitments_and_Contingencies_1

Commitments and Contingencies (Narrative) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Commitments and Contingencies Disclosure [Abstract]	'	'	'
401(k) plan, minimum eligibility age	'18 years	'	'
401(k) plan, requisite service period	'6 months	'	'
401(k) plan, maximum annual contribution per employee, percent	100.00%	'	'
401(k) plan, employer's matching contribution, annual vesting percentage	20.00%	'	'
401(k) plan, employer contribution, ultimate vesting percentage	100.00%	'	'
401(k) plan, employer's matching contribution, vesting term	'6 years	'	'
401(k) plan, employer contribution amount	$294	$283	$410
Operating leases, maximum term	'5 years	'	'
Operating leases, rent expense	$358	$453	$450

Commitments_and_Contingencies_2

Commitments and Contingencies (Future Lease Payments) (Details) (USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified
Commitments and Contingencies Disclosure [Abstract]	'
2014	$341
2015	267
2016	234
2017	207
Thereafter	78
Total	$1,127

Segment_Information_Details

Segment Information (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Revenue	$23,142	$21,865	$20,258	$23,983	$23,548	$19,290	$24,508	$26,376	$89,248	$93,722	$65,158
Operating costs and expenses	'	'	'	'	'	'	'	'	67,228	73,507	50,298
Other income/(expense)	'	'	'	'	'	'	'	'	492	-4	769
Income before provision for income taxes	'	'	'	'	'	'	'	'	22,512	20,211	15,629
Operating Segments | Rental	'	'	'	'	'	'	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Revenue	'	'	'	'	'	'	'	'	69,062	56,477	48,619
Operating costs and expenses	'	'	'	'	'	'	'	'	29,017	23,737	20,742
Other income/(expense)	'	'	'	'	'	'	'	'	0	0	0
Income before provision for income taxes	'	'	'	'	'	'	'	'	40,045	32,740	27,877
Operating Segments | Sales	'	'	'	'	'	'	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Revenue	'	'	'	'	'	'	'	'	19,479	36,375	15,419
Operating costs and expenses	'	'	'	'	'	'	'	'	11,582	25,816	9,194
Other income/(expense)	'	'	'	'	'	'	'	'	0	0	0
Income before provision for income taxes	'	'	'	'	'	'	'	'	7,897	10,559	6,225
Operating Segments | Service & Maintenance	'	'	'	'	'	'	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Revenue	'	'	'	'	'	'	'	'	707	870	1,120
Operating costs and expenses	'	'	'	'	'	'	'	'	344	354	458
Other income/(expense)	'	'	'	'	'	'	'	'	0	0	0
Income before provision for income taxes	'	'	'	'	'	'	'	'	363	516	662
Corporate	'	'	'	'	'	'	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Revenue	'	'	'	'	'	'	'	'	0	0	0
Operating costs and expenses	'	'	'	'	'	'	'	'	26,285	23,600	19,904
Other income/(expense)	'	'	'	'	'	'	'	'	492	-4	769
Income before provision for income taxes	'	'	'	'	'	'	'	'	($25,793)	($23,604)	($19,135)

Quarterly_Financial_Data_Detai

Quarterly Financial Data (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Data [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Total revenue	$23,142	$21,865	$20,258	$23,983	$23,548	$19,290	$24,508	$26,376	$89,248	$93,722	$65,158
Operating income	4,950	5,088	5,844	6,138	5,523	4,241	4,829	5,622	22,020	20,215	14,860
Net income	$3,158	$3,394	$3,844	$3,994	$3,571	$2,606	$3,000	$3,508	$14,390	$12,685	$9,760
Net income per share - Basic (in dollars per share)	$0.25	$0.28	$0.31	$0.33	$0.29	$0.21	$0.25	$0.29	$1.17	$1.04	$0.80
Net income per share - Diluted (in dollars per share)	$0.25	$0.27	$0.31	$0.32	$0.29	$0.21	$0.24	$0.29	$1.15	$1.03	$0.80