Basis of Presentation and Summary of Significant Accounting Policies	3 Months Ended
Mar. 31, 2012
Basis of Presentation and Summary of Significant Accounting Policies [Abstract]
Basis of Presentation and Significant Accounting Policies [Text Block]	Basis of Presentation and Summary of Significant Accounting Policies These notes apply to the unaudited condensed financial statements of Natural Gas Services Group, Inc. (the "Company", “NGSG”, "Natural Gas Services Group", "we" or "our") (a Colorado corporation). We were formed on December 17, 1998 for the purposes of combining the operations of certain manufacturing, service and leasing entities. The accompanying unaudited condensed financial statements present the condensed results of our Company taken from our books and records. In our opinion, such information includes all adjustments, consisting of only normal recurring adjustments, which are necessary to make our financial position at March 31, 2012 and the results of our operations for the three months ended 2012 and 2011 not misleading. As permitted by the rules and regulations of the Securities and Exchange Commission (SEC), the accompanying condensed financial statements do not include all disclosures normally required by accounting principles generally accepted in the United States of America (GAAP). These financial statements should be read in conjunction with the financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2011 on file with the SEC. In our opinion, the condensed financial statements are a fair presentation of the financial position, results of operations and cash flows for the periods presented. The results of operations for the three months ended March 31, 2012 are not necessarily indicative of the results of operations to be expected for the full fiscal year ending December 31, 2012. Revenue recognition Revenue from the sales of custom and fabricated compressors, and flare systems is recognized upon shipment of the equipment to customers or when all conditions have been met or title is transferred to the customer. Exchange and rebuild compressor revenue is recognized when both the replacement compressor has been delivered and the rebuild assessment has been completed. Revenue from compressor 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 based upon the classification of the rental agreement. Deferred income represents payments received before a product is shipped. Revenue from the sale of rental units is included in sales revenue when equipment is shipped or title is transferred to the customer. Fair Value of Financial Instruments Our financial instruments consist principally of cash and cash equivalents, accounts receivable, accounts payable and our line of credit. Pursuant to ASC 820 (Accounting Standards Codification), the fair value of our cash equivalents is determined based on “Level 1” inputs, which consist of quoted prices in active markets for identical assets. We believe that the recorded values of all of our other financial instruments approximate their current fair values because of their nature and respective relatively short maturity dates or durations. Recently Issued Accounting Pronouncements In May 2011, the FASB issued ASU No. 2011-04, “Fair Value Measurement (Topic 820): Amendments to Achieve Common Fair Value Measurement and Disclosure Requirements in U.S. GAAP and IFRS.” This ASU establishes a global standard for measuring amounts at fair value. This ASU is effective for fiscal years, and interim periods within those years, beginning after December 15, 2011. Early adoption is not permissible, and this ASU must be applied prospectively. The adoption of ASU No. 2011-04 did not have a material effect on the Company's financial position or results of operations. In June 2011, the Financial Accounting Standards Board ("FASB") issued ASU 2011-05, Presentation of Comprehensive Income. Currently, companies have three alternatives for presenting Comprehensive Income and its components in financial statements. Comprehensive income and its components may be reported below the total of net income in a single statement that reports the results of operations, in a separate statement of comprehensive income that begins with net income, or within the statement of changes in equity. Among the changes, ASU 2011-05 eliminates the option for entities to disclose comprehensive income and its components in the statement of changes in equity and as such, requires entities to report comprehensive income and its components either in a single continuous financial statement or in two separate but consecutive statements. In the case in which a single continuous financial statement is utilized, no longer will the statement be titled “Statement of Income and Comprehensive Income” and instead the statement will solely be titled “Statement of Comprehensive Income.” The adoption of ASU No. 2011-05 did not have a material effect on the Company's financial position or results of operations. In September 2011, FASB issued ASU 2011-08, Testing Goodwill for Impairment. Under the amendments in this Update, an entity has the option to first assess qualitative factors to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If, after assessing the totality of events or circumstances, an entity determines it is not more likely than not that the fair value of a reporting unit is less than its carrying amount, then performing the two-step impairment test is unnecessary. However, if an entity concludes otherwise, then it is required to perform the first step of the two-step impairment test by calculating the fair value of the reporting unit and comparing the fair value with the carrying amount of the reporting unit. If the carrying amount of a reporting unit exceeds its fair value, then the entity is required to perform the second step of the goodwill impairment test to measure the amount of the impairment loss, if any. Under the amendments in this Update, an entity has the option to bypass the qualitative assessment for any reporting unit in any period and proceed directly to performing the first step of the two-step goodwill impairment test. An entity may resume performing the qualitative assessment in any subsequent period. The amendments are effective for annual and interim goodwill impairment tests performed for fiscal years beginning after December 15, 2011. Early adoption is permitted, for year ended December 31, 2011. The adoption of ASU No. 2011-08 did not have a material effect on the Company's financial position or results of operations.

Basis of Presentation and Summary of Significant Accounting Policies

These notes apply to the unaudited condensed financial statements of Natural Gas Services Group, Inc. (the "Company", “NGSG”, "Natural Gas Services Group", "we" or "our") (a Colorado corporation). We were formed on December 17, 1998 for the purposes of combining the operations of certain manufacturing, service and leasing entities.

The accompanying unaudited condensed financial statements present the condensed results of our Company taken from our books and records. In our opinion, such information includes all adjustments, consisting of only normal recurring adjustments, which are necessary to make our financial position at March 31, 2012 and the results of our operations for the three months ended 2012 and 2011 not misleading. As permitted by the rules and regulations of the Securities and Exchange Commission (SEC), the accompanying condensed financial statements do not include all disclosures normally required by accounting principles generally accepted in the United States of America (GAAP). These financial statements should be read in conjunction with the financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2011 on file with the SEC. In our opinion, the condensed financial statements are a fair presentation of the financial position, results of operations and cash flows for the periods presented.

The results of operations for the three months ended March 31, 2012 are not necessarily indicative of the results of operations to be expected for the full fiscal year ending December 31, 2012.

Revenue recognition

Revenue from the sales of custom and fabricated compressors, and flare systems is recognized upon shipment of the equipment to customers or when all conditions have been met or title is transferred to the customer. Exchange and rebuild compressor revenue is recognized when both the replacement compressor has been delivered and the rebuild assessment has been completed. Revenue from compressor 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 based upon the classification of the rental agreement. Deferred income represents payments received before a product is shipped. Revenue from the sale of rental units is included in sales revenue when equipment is shipped or title is transferred to the customer.

Fair Value of Financial Instruments

Our financial instruments consist principally of cash and cash equivalents, accounts receivable, accounts payable and our line of credit. Pursuant to ASC 820 (Accounting Standards Codification), the fair value of our cash equivalents is determined based on “Level 1” inputs, which consist of quoted prices in active markets for identical assets. We believe that the recorded values of all of our other financial instruments approximate their current fair values because of their nature and respective relatively short maturity dates or durations.

Recently Issued Accounting Pronouncements

In May 2011, the FASB issued ASU No. 2011-04, “Fair Value Measurement (Topic 820): Amendments to Achieve Common Fair Value Measurement and Disclosure Requirements in U.S. GAAP and IFRS.” This ASU establishes a global standard for measuring amounts at fair value. This ASU is effective for fiscal years, and interim periods within those years, beginning after December 15, 2011. Early adoption is not permissible, and this ASU must be applied prospectively. The adoption of ASU No. 2011-04 did not have a material effect on the Company's financial position or results of operations.

In June 2011, the Financial Accounting Standards Board ("FASB") issued ASU 2011-05, Presentation of Comprehensive Income. Currently, companies have three alternatives for presenting Comprehensive Income and its components in financial statements. Comprehensive income and its components may be reported below the total of net income in a single statement that reports the results of operations, in a separate statement of comprehensive income that begins with net income, or within the statement of changes in equity. Among the changes, ASU 2011-05 eliminates the option for entities to disclose comprehensive income and its components in the statement of changes in equity and as such, requires entities to report comprehensive income and its components either in a single continuous financial statement or in two separate but consecutive statements. In the case in which a single continuous financial statement is utilized, no longer will the statement be titled “Statement of Income and Comprehensive Income” and instead the statement will solely be titled “Statement of Comprehensive Income.” The adoption of ASU No. 2011-05 did not have a material effect on the Company's financial position or results of operations.

In September 2011, FASB issued ASU 2011-08, Testing Goodwill for Impairment. Under the amendments in this Update, an entity has the option to first assess qualitative factors to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If, after assessing the totality of events or circumstances, an entity determines it is not more likely than not that the fair value of a reporting unit is less than its carrying amount, then performing the two-step impairment test is unnecessary. However, if an entity concludes otherwise, then it is required to perform the first step of the two-step impairment test by calculating the fair value of the reporting unit and comparing the fair value with the carrying amount of the reporting unit. If the carrying amount of a reporting unit exceeds its fair value, then the entity is required to perform the second step of the goodwill impairment test to measure the amount of the impairment loss, if any. Under the amendments in this Update, an entity has the option to bypass the qualitative assessment for any reporting unit in any period and proceed directly to performing the first step of the two-step goodwill impairment test. An entity may resume performing the qualitative assessment in any subsequent period. The amendments are effective for annual and interim goodwill impairment tests performed for fiscal years beginning after December 15, 2011. Early adoption is permitted, for year ended December 31, 2011. The adoption of ASU No. 2011-08 did not have a material effect on the Company's financial position or results of operations.