Gross Unrealized Losses Amount of accumulated unrealized loss before deducting unrealized gain on investments which are intended to be sold in the short-term (usually less than one year or the normal operating cycle, whichever is longer) including trading securities, available-for-sale securities, held-to-maturity securities, and other short-term investments not otherwise listed in the existing taxonomy. Short Term Investments Gross Unrealized Loss Accumulated in Investments Volumetric Excise Tax Credit, CNG Federal fuel tax credit - CNG (in dollars per gasoline gallon equivalent) Represents the volumetric excise tax credit per gasoline gallon equivalent of compressed natural gas (CNG). Volumetric Excise Tax Credit, LNG Federal fuel tax credit - LNG (in dollars per liquid gallon) Represents the volumetric excise tax credit per liquid gallon of liquefied natural gas (LNG). CERF Plan [Member] CERF Plan Represents information related to the entity's wholly owned subsidiary Clean Energy Renewable Fuels, LLC 2013 Unit Option Plan (the "CERF Plan"). Deferred Tax Assets Sales Type Leases Sales-type leases Amount before allocation of valuation allowances of deferred tax asset attributable to sales-type leases. Deferred Tax Liabilities Domestic Depreciation and Amortization Depreciation and amortization-domestic Amount of deferred tax liability attributable to taxable temporary differences from domestic depreciation and amortization. Depreciation and amortization-foreign Amount of deferred tax liability attributable to taxable temporary differences from foreign depreciation and amortization. Deferred Tax Liabilities Foreign Depreciation and Amortization Amount of deferred tax liability attributable to taxable temporary differences from partnership income. Deferred Tax Liabilities Partnership Income Partnership income Amount retained Business Acquisition Amount Retained for Final Purchase Price Adjustment Represents the amount retained for purposes to be applied on final purchase price adjustments under the acquisition by the entity. Cash Transferred with Sale of Subsidiary Cash transferred with sale of subsidiary The amount of cash outflow for cash transferred with sale of subsidiary. Amendment Description Take or Pay LNG Supply Contracts [Member] Take-or-pay LNG Supply Contracts Represents the take-or-pay arrangements under which the entity has purchase obligations to buy goods at predetermined prices. Amendment Flag Represents information pertaining to Mavrix, LLC , a subsidiary of the entity. Mavrix Mavrix LLC [Member] Stock Purchase Agreement [Member] Stock purchase agreement Represents information pertaining to the stock purchase agreement. Marketing Agreement [Member] Marketing Agreement Represents information pertaining to the marketing agreement. Registration rights agreement Registration Rights Agreement [Member] Represents information pertaining to the registration rights agreement. LNG Sales Agreement [Member] LNG sales agreement Represents information pertaining to a liquid natural gas sales agreement to purchase on a take-or-pay basis over the term of the agreement. Westport Parties Represents information pertaining to Westport Innovations Inc. and Westport Innovations (U.S.) Holdings Inc. Westport Innovations Inc and Westport Innovations US Holdings Inc [Member] Westport Power Inc and Westport Fuel Systems Inc [Member] Westport Affiliates Represents information pertaining to Westport Power Inc. and Westport Fuel Systems Inc. Represents the term of contract. Unrecorded Unconditional Purchase Obligation Term of Contract Term of contract Share Based Compensation Arrangement by Share Based Payment Award, Number of Nonconcurrent Offering Periods Number of non-concurrent offering periods Represents the number of consecutive non-concurrent offering period during which the eligible employees may purchase the common stock of the entity. Restricted Cash Volumetric Excise Tax Credit (VETC) Excise Tax Credit Disclosure [Text Block] Volumetric Excise Tax Credit (VETC) This element represents the entire description and presentation of excise tax credits for alternative fuels. Document and Entity Information Capitalized Lease Obligation and Receivables Represents the entire disclosure of leases under which the entity may be the lessee or the lessor. Leases of Lessee Lessor Disclosure [Text Block] Stock Issued During Period, Shares, Exercise of Warrants Issuance of common stock upon exercise of Series I warrants (in shares) Represents the number of shares of stock issued due to warrants exercised during the period. Income (Loss) from Continuing Operations Domestic and Foreign Tax Effect Taxes due on the entity's U.S. and foreign operations Represents the tax provision (benefit) attributable to the gain (loss) arising from earnings or loss from continuing operations attributable to domestic and foreign operations. Current Fiscal Year End Date Award Type [Axis] Stock Issued During Period, Value, Exercise of Warrants Issuance of common stock upon exercise of Series I warrants Represents the value of stock issued due to warrants exercised during the period. Stock Issued During Period, Value, Director Warrants Exercised Issuance of common stock upon exercise of Boone Pickens warrants Represents the value of stock issued due to the warrants exercised by Directors and subsequent holders of the warrants during the period. Represents, under a purchase agreement, the amount of acquiree's working capital that, if exceeded, triggers payment of additional consideration. Business Acquisition, Contingent Consideration, Working Capital Working capital amount for additional consideration Stock Issued During Period, Shares, Director Warrants Exercised Issuance of common stock upon exercise of Boone Pickens warrants (in shares) Represents the number of shares of stock issued due to the warrants exercised by Directors and subsequent holders of the warrants during the period. Equity Method Investment Realized Gain (Loss) on Disposal Tax Effect Represents the tax provision (benefit) attributable to the gain (loss) arising from the disposal of an equity method investment. Discrete income tax provision related to sale of the Company's interest in Peru JV A debt security issued by a state, municipality or county to finance its capital expenditures. Municipal bonds are exempt from federal taxes and from most state and local taxes, especially if you live in the state in which the bond is issued. Municipal notes are appealing to investors because they mature in one year or less, offer fixed income and are often exempt from income tax at the local, state and/or federal levels. Municipal bonds and notes Municipal Bonds and Notes [Member] Municipal bonds & notes Boone Pickens and Green Energy Investment Holdings LLC [Member] Buyers Represents information pertaining to Boone Pickens and Green Energy Investment Holdings, LLC. Northstar [Member] Northstar Represents the information pertaining to the acquisition of Northstar. Wyoming Northstar Represents the information pertaining to IMW, a company acquired by the entity. IMW [Member] IMW Weaver [Member] Weaver Represents the information pertaining to Weaver, a company acquired by the entity. ServoTech Represents the information pertaining to ServoTech Engineering, Inc., the investee for which the investments are accounted under the equity method of accounting. Servo Tech Engineering Inc [Member] Document Period End Date Vehicle Production Group LLC [Member] VPG Represents the information pertaining to Vehicle Production Group LLC, the investee for which the investments are accounted under the cost method of accounting. Canada CANADA Represents information pertaining to a debt security that does not pay interest (a coupon) but is traded at a deep discount, rendering profit at maturity when the bond is redeemed for its full face value. Zero Coupon Bonds [Member] Zero coupon bonds Tabular disclosure of the carrying amounts of other receivables. Schedule of other receivables Schedule of Other Receivables [Table Text Block] LNG Liquefaction Plant [Member] LNG liquefaction plants Long-lived, depreciable assets used for the purpose of processing liquefied natural gas. RNG Plant [Member] RNG plants Long-lived, depreciable assets used for the purpose of processing renewable natural gas. Amount of required periodic payments applied to principal to be made by the entity under debt obligation. Such payment may be made either by cash or by issuing shares to the holder of debt instrument. Cash and/or common stock required to be paid or issued on debt instrument Debt Instrument, Periodic Payment Principal by Cash and or Shares Number of annual payments Represents the number of annual payments required to be made by entity towards purchase consideration in connection with acquisition. Debt Instrument Annual Payment Number Business Acquisition Purchase Consideration Annual Retention Bonus Installments Number Number of annual retention bonus installments required to be paid to key employees, as a part of purchase consideration Represents the number of annual retention bonus payments required to be made to key employees by entity towards purchase consideration in connection with acquisition. Represents the information pertaining to contingent consideration obligations. Contingent consideration obligation Contingent Consideration Obligations [Member] Liabilities: Contingent consideration Entity [Domain] Represents the estimated remaining life of warrants. Estimated remaining life of Series I warrants Warrants Estimated Residual Life Remaining term of the warrant Represents the period before shares will be received under the holdback provision of the agreement. Agreement Holdback Period Period of holdback for shares to be received Period of time contractual agreement is in effect. Agreement Term Term of agreement Arrangements and Non-arrangement Transactions [Domain] Accrued gas and equipment purchases Carrying value as of the balance sheet date of obligations incurred through that date and payable for purchases of natural gas and equipment. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Accrued Gas and Equipment Purchase Current Carrying value as of the balance sheet date of obligations incurred through that date and payable for potential payments under the contingent consideration arrangement. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Contingent Consideration Obligations Current Contingent consideration obligations VETC credits recognized as revenue Volumetric Excise Tax Credit revenue recognized. Volumetric Excise Tax Credit Series I warrants Warrants Fair Value Disclosure Fair value, as of the balance sheet date, of warrants. A warrant is a security that gives the holder the right to purchase shares of common stock in accordance with the terms of the instrument, usually upon payment of a specified amount. Claims disallowed under Volumetric Excise Tax Credit program by IRS Income Tax Examination Claims Disallowed The amount of claims disallowed under the income tax examination. Miscellaneous Other Receivables [Member] Represents the information pertaining to miscellaneous other receivables. Other Represents information pertaining to the 7.5 percent convertible Chesapeake Notes issued to Chesapeake NG Ventures Corporation (Chesapeake), an indirect wholly-owned subsidiary of Chesapeake Energy Corporation. 7.5% Notes CHK Notes / 7.5% Notes Chesapeake Notes [Member] Baytree Investments Mauritius Pte Ltd [Member] Baytree Investments (Mauritius) Pte Ltd Represents the information pertaining to Baytree Investments (Mauritius) Pte Ltd. Green Energy Investment Holdings LLC [Member] Green Energy Investment Holdings, LLC Represents information pertaining to Green Energy Investment Holdings, LLC, an affiliate of Leonard Green and Partners, L.P. Debt Instrument, Principal Amount Transferred Principal amount transferred Represents the principal amount of notes transferred. Represents the information pertaining to notes issued in connection with acquisition of entity's membership interests in Dallas Clean Energy, LLC ("DCE"). DCE Notes [Member] DCEMB notes Schedule of assumptions used in estimating fair value of each RSU on the date of grant Tabular disclosure of the significant assumptions used during the year to estimate the fair value of restricted stock units. Schedule of Share Based Payment Award Restricted Stock Units Award Valuation Assumptions [Table Text Block] Represents the number of shares of common stock the holder is entitled to receive for each award unit held. Share Based Compensation Arrangement by Share Based Payment Award, Number of Shares of Common Stock Entitled Per Unit of Award Held Number of shares of common stock to be received for each performance unit Share Based Compensation Arrangement by Share Based Payment Award, Period from Date of Grant in which Closing Common Stock Price Must Equal or Exceed Closing Price on Award Grant Date Period from the date of grant in which the closing price of the entity's common stock must exceed the closing price in order for a holder to receive one share of common stock for each award Represents the period from the date of grant in which the closing price of the entity's common stock must exceed the closing price on the grant date in order for a holder to receive one share of common stock for each award. Period from the date of grant after which awards will be automatically forfeited if the Stock Price Condition is not satisfied Represents the period from the date of grant after which awards will be automatically forfeited if the closing price of the entity's common stock does not exceed the closing price on the grant date during specified period. Share Based Compensation Arrangement by Share Based Payment Award, Period from Date of Grant after which Award will be Automatically Forfeited Number of consecutive trading days during which the closing price of the entity's common stock must exceed the closing price on the grant date in order for a holder to receive one share of common stock for each award Represents the number of consecutive trading days during which the closing price of the entity's common stock must exceed the closing price on the grant date in order for a holder to receive one share of common stock for each award. Share Based Compensation Arrangement by Share Based Payment Award, Number of Consecutive Trading Days when Closing Common Stock Price Must Equal or Exceed Closing Price on Award Grant Date Share Based Compensation Arrangement by Share Based Payment Award Common Stock Closing Price as Percentage of Closing Price on Award Grant Date Percentage of the closing price of the entity's common stock that the closing price must equal or exceed in order for an award holder to receive one share of common stock for each award Represents the percentage of the closing price of the entity's common stock for twenty consecutive trading days that the closing sales price of the entity's common stock must equal or exceed in order for the holder to receive one share of common stock for each award. Total short-term investments at amortized cost The aggregate amortized cost of investments which are intended to be sold in the short-term (usually less than one year or the normal operating cycle, whichever is longer) including trading securities, available-for-sale securities, held-to-maturity securities, and other short-term investments not otherwise listed in the existing taxonomy. Short Term Investments at Amortized Cost Schedule of inputs used in the fair value measurement of assets and liabilities. This disclosure may include, but is not limited to, the fair value of the asset and liability, valuation technique used to measure fair value, the inputs used to measure fair value, the ranges of the inputs, and the weighted averages of the inputs. Fair Value Inputs Assets and Liabilities Quantitative Information [Table] Discounted cash flow (DCF) valuation technique used to measure fair value. Discounted Cash Flow Valuation Technique [Member] Discounted Cash Flow Model Black-Scholes Model valuation technique used to measure fair value. Black Scholes Model [Member] Black-Scholes Model Represents the simple average of a range of values. Simple average Simple Average [Member] Valuation processes for Level 3 Fair Value Measurements Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Fair Value Inputs Assets and Liabilities Quantitative Information [Line Items] Represents the gross profit projection, used as an input to measure fair value. Fair Value Inputs Gross Profit Projection Gross profit projection Probability of reaching target gross profit (as a percent) Represents the percentage of likelihood of reaching target gross profit, used as an input to measure fair value. Fair Value Inputs Probability of Reaching Target Gross Profit Represents the volatility of the gross profit rate of a peer group, used as an input to measure the fair value. Fair Value Inputs Volatility of Gross Profit Rate Volatility of gross profit (peer group) (as a percent) Dallas Clean Energy McCommas Bluff, LLC Represents the information pertaining to Dallas Clean Energy McCommas Bluff, LLC, a Delaware limited liability company (DCEMB), a subsidiary owned by the entity. Dallas Clean Energy Mc Commas Bluff LLC [Member] Represents the information pertaining to loan taken to finance the acquisition of entity's membership interests in Dallas Clean Energy, LLC (DCE). Facility A Loan [Member] Facility A Loan Plains Capital Bank loan Represents the information pertaining to loan taken to finance capital improvements of processing facility and to pay certain costs and expenses related to the acquisition of membership interests in Dallas Clean Energy, LLC (DCE). Facility B Loan [Member] A Line of Credit Represents the information pertaining to A line of credit facility entered in connection with acquisition of acquisition of membership interests in Dallas Clean Energy, LLC (DCE). A Line of Credit [Member] DCEMB Revenue Bonds Represents the information pertaining to revenue bonds issued by the Dallas Clean Energy McCommas Bluff, LLC, a Delaware limited liability company (DCEMB). DCEMB Revenue Bonds [Member] DCEMB bonds DCEMB Revenue Bonds (non-recourse to the Company) Purchase Notes [Member] Purchase Note Represents the information pertaining to notes issued in connection with an acquisition. IMW Notes Dallas Clean Energy LLC [Member] DCE Dallas Clean Energy, LLC Represents the information pertaining to Dallas Clean Energy, LLC, (DCE), a subsidiary owned by the entity. Represents information pertaining to Mansfield Gas Equipment Systems Corporation (MGES), an acquiree of the entity. Mansfield Gas Equipment Systems Corporation [Member] MGES Represents information pertaining to an operating line of credit facility for IMW. Operating Line of Credit [Member] IMW assumed operating line of credit Total available-for-sale securities Available-for-sale Securities [Member] Bank Guarantee Line of Credit [Member] IMW bank guarantee line Represents information pertaining to line of credit facility which allows IMW to provide guarantees and/or standby letters of credit. Forward Exchange Contract Line of Credit [Member] IMW forward exchange contract line Represents information pertaining to a forward exchange contract line for IMW. IMW Renminbi line of credit Represents information pertaining to Renminbi line of credit facility. Renminbi Line of Credit [Member] Renminbi Operating Line of Credit [Member] IMW Renminbi operating line of credit Represents information pertaining to Renminbi operating line of credit facility. Represents information pertaining to Renminbi sub-limit line of credit facility entered by IMW. Renminbi Sub Limit Line of Credit [Member] IMW Renminbi sub-limit line of credit Represents information pertaining to Bengali Taka operating line of credit facility entered by IMW. Bengali Taka Operating Line of Credit [Member] IMW Bengali Taka operating line of credit Entity Well-known Seasoned Issuer Bangladeshi Taka Operating Line of Credit [Member] IMW Bangladeshi Taka operating line of credit Represents information pertaining to Bangladeshi Taka operating line of credit facility. Entity Voluntary Filers IMW Colombian Peso operating line of credit Colombian Peso Operating Line of Credit [Member] Represents information pertaining to Colombian Peso operating line of credit facility. Entity Current Reporting Status Represents 7.5% convertible notes due 2016. SLG Notes [Member] SLG Notes Entity Filer Category IMW Lines of Credit [Member] IMW Lines of Credit Represents information pertaining to lines of credit assumed in connection with the acquisition of IMW. IMW assumed debt Entity Public Float Mavrix Note Represents information pertaining to the secured multi-draw promissory notes issued. Secured Multi Draw Promissory Note [Member] Mavrix Note (non-recourse to the Company) Entity Registrant Name Option to extend the maturity date from August 14, 2011 The period of time for which the reporting entity has the option to extend the maturity date of a debt agreement. Debt Instrument Maturity Date Length of Extension Period Entity Central Index Key Line of Credit Facility Periodic Payment Principal Percentage Percentage of principal required to be paid as per debt repayment schedule Percentage of the required periodic payment applied to principal. Prior annual payment of principal delayed Represents the annual payment for the prior year which was delayed. Line of Credit Facility Prior Year Annual Principal Payment Delayed Represents the number of calendar quarters used to measure the debt service coverage ratio. Debt Instrument Covenant Debt Service Coverage Ratio Number of Quarters Measured Debt Service Coverage Ratio, number of calendar quarters measured Required debt service coverage ratio for the most recent four calendar quarters Represents the debt service coverage ratio required to be maintained for the most recent four calendar quarters. Debt Instrument Covenant Debt Service Historic Coverage Ratio Entity Common Stock, Shares Outstanding Projected debt service coverage ratio for the next four calendar quarters Represents the debt service coverage ratio projected to be maintained for the next four calendar quarters. Debt Instrument Covenant Projected Debt Service Coverage Ratio Debt covenant period considered for cash on hand Represents the period considered for cash on hand required to be maintained under the terms of the financial covenant. Debt Instrument Covenant Period for Cash on Hand Debt covenant value, cash on hand Represents the cash on hand required to be maintained under the terms of the financial covenant. Debt Instrument Covenant Cash on Hand Debt Instrument Covenant Debt to Tangible Net Worth Ratio Debt covenant, debt to tangible net worth ratio Represents the debt to tangible net worth ratio required under the financial covenants. Debt covenant, tangible net worth Represents the tangible net worth required to be maintained under the financial covenants. Debt Instrument Covenant Tangible Net Worth Debt Instrument Covenant Current Ratio Debt covenant, current assets to current liabilities ratio Represents the current assets to current liabilities ratio required to be maintained under the terms of the Assumption Agreement's covenants. Debt Instrument Number Number of convertible promissory notes to be issued Represents the number of convertible promissory notes to be issued by the entity. Represents the number of wholly owned subsidiaries through which the entity entered into a financing arrangement. Number of Wholly Owned Subsidiaries Through which Entity Entered into Financing Arrangement Number of wholly owned subsidiaries through which the entity entered into a financing arrangement Number of LNG Production Facilities being Financed Number of LNG production facilities being financed Represents the number of LNG production facilities, the development, construction and operation of which is being financed. LNG Facility Expected Production Capacity LNG production facilities expected production capacity (in gallons per day) Represents expected LNG production capacity for project. Principal amount of each debt instrument to be issued The stated principal amount of each debt instrument at time of issuance. Debt Instrument Face Amount Per Instrument Project completion period after the funding of the initial loans Represents the project completion period after the funding of the initial loans. Project Completion Period after Initial Funding of Loans Amortization Period Term Loan Amortization period following conversion into term loan Represents the amortization period of the debt following its conversion into a term loan. Debt Instrument Registration Statement Number Number of registration statements required to be filed under Registration Rights Agreement Represents the number of registration statements required to be filed by entity relating to the resale of the entity's common stock issuable upon conversion of the debt instrument with Securities and Exchange Commission under the terms of Registration Rights Agreement. Debt Instrument Participation in Underwritten Offerings Number Number of underwritten offerings in which the entity would be required to participate under Registration Rights Agreement Represents the number of underwritten offerings of the entity's common stock issuable upon conversion of debt instrument in which the entity would be required to participate on the request of Chesapeake under the terms of Registration Rights Agreement. Monthly liquidated damages expressed as a percentage of principal amount of debt instrument under Registration Rights Agreement Represents the liquidated damages expressed as a percentage of principal amount of debt instrument which the entity would be required to be paid monthly if the entity does not meet certain of its obligations under the Registration Rights Agreement. Debt Instrument Monthly Liquidated Damages Percentage Debt Instrument Annual Liquidated Damages Percentage Limit Annual liquidated damages as a percentage of aggregate principal amount of debt Represents the maximum annual liquidated damages expressed as a percentage of aggregate principal amount of debt instrument which the entity would be required to be paid if the entity does not meet certain of its obligations under the agreement. Document Fiscal Year Focus Financing commitment received Financing Commitment Maximum Amount Represents the maximum amount of financing to be received under the agreement. Document Fiscal Period Focus Amount of required periodic payments applied to principal to be made by the entity under debt obligation. Such payment will be by cash to the holder of debt instrument. Annual cash required to be paid on debt instrument Annual payment required Debt Instrument, Periodic Payment, Principal by Cash Additional amount of advances under the obligation assumed Represents the additional amount of advances to be made to the entity under the obligation that is assumed by the acquirer of the original debt instrument. Debt Instrument Obligation to Advance Additional Amount Assumed Represents the remaining percentage of common stock of the acquiree for which the entity has an option to purchase. Business Acquisition Option to Purchase Remaining Interest Percentage Remaining interest for which the entity has an option to purchase (as a percent) Represents the amount to be paid to acquire remaining interest in the acquiree. Business Acquisition Amount to be Paid to Purchase Remaining Interest Exercise price Represents the period over which the entity may purchase remaining interest in the acquiree. Business Acquisition Period over which Remaining Interest May be Acquired Period during which remaining interest may be acquired Clean Energy Del Peru [Member] Peru JV Represents information pertaining to Clean Energy del Peru, joint venture in Lima, Peru that operates CNG stations. Demand revolving line of credit Represents information pertaining to a demand revolving line of credit facility. Demand Revolving Line of Credit [Member] Demand Revolving Bank Guarantee and Standby Letter of Credit [Member] Demand revolving bank guarantee and standby letter of credit line Represents information pertaining to a demand revolving bank guarantee and standby letter of credit line. Represents the maximum amount of annual retention bonus payments required to be made by entity to key employees towards purchase consideration in connection with acquisition. Business Acquisition, Purchase Consideration, Maximum Aggregate Retention Bonus, Payment Maximum aggregate retention bonus required to be paid to key employees, as a part of purchase consideration Business Acquisition, Contingent Consideration, Cash Payment Contingent consideration payment Contingent consideration paid relating to business acquisitions Amount of cash payments that resulted from a contingent consideration arrangement. Traded Options Term Term of traded options Represents the term of the traded options. Legal Entity [Axis] Volumetric Excise Tax Credits [Policy Text Block] Volumetric Excise Tax Credits (VETC) Describes the entity's accounting policy related to Volumetric Excise Tax Credits (VETC). Document Type LNG Transportation Costs Describes the entity's accounting policy related to LNG transportation costs. LNG Transportation Costs [Policy Text Block] Acquired Contracts [Member] Acquired contracts Represents details pertaining to the contracts acquired by the entity. Volumetric Excise Tax Credit [Abstract] Volumetric Excise Tax Credits (VETC) Represents the maximum percentage of foreign trade receivables covered by the accounts receivable insurance. Maximum Percentage of Foreign Trade Receivables Covered by Accounts Receivable Insurance Maximum percentage of foreign trade receivables covered by accounts receivable insurance Income before Income Taxes Excluding Portion Attributable to Noncontrolling Interests Income (loss) before income taxes, total Represents income or loss from continuing operations before income taxes, excluding the portion attributable to noncontrolling interest. Refund of alternative minimum taxes Represents the portion of the difference between total income tax expense or benefit as reported in the income statement and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to income that is exempt from income tax because of refund of alternative minimum taxes the entity has received in the period. Income Tax Reconciliation Refund of Alternative Minimum Taxes Represents information pertaining to Williams Gas Processing Company. Williams Gas Processing Company [Member] Williams Gas Processing Company Represents information pertaining to Shell Energy. Shell Energy [Member] Shell Energy Represents information pertaining to SoCal Gas Company and San Diego Gas and Electric. So Cal Gas Company and San Diego Gas and Electric [Member] SoCal Gas Company and San Diego Gas and Electric Tabular disclosure of future minimum lease payments receivables as of the date of the latest balance sheet presented, in aggregate and for each of the five years succeeding fiscal years, with separate deductions from the total for the amount representing executor costs, including any profit thereon, included in the minimum lease payments receivables and for the amount of the imputed interest necessary to reduce the net minimum lease payments receivables to present value. Schedule of Future Minimum Lease Payments Receivable for Capital Leases [Table Text Block] Schedule of future receipts under the leases Capital Leases Weighted Average Interest Rate Weighted average interest rate (as a percent) Represents the calculation as of the balance sheet date of the average interest rate weighted of the amount of leased equipments under capital leases. Capital Leases Sales Type Leases Interest Rate Sales-type leases interest rate (as a percent) Represents the interest rate applicable on the amount of equipment leased under the sales-type leases. Less amount representing interest Amount necessary to reduce net minimum lease payment receivables to present value for capital leases. Capital Leases Future Minimum Payments Receivable Interest Included in Receipts Capital Leases Future Minimum Payments Receivable Present Value of Net Minimum Receipts Present value of future minimum lease receipts Represents the present value of minimum lease payment receivables for capital leases. Other disclosures Fair Value Liabilities Other Disclosures [Abstract] Receivable Type [Axis] Debt Instrument Annual Payments Made Number Number of annual payments made Represents the number of payment terms of the debt instrument. Represents the information pertaining to the disposal of BAF Technologies, Inc. ("BAF"), a subsidiary of the entity, under a stock purchase agreement. BAF BAF Technologies Inc [Member] Accrued Liabilities Accounts Payable and Accrued Liabilities Disclosure [Text Block] Business Acquisition Purchase Price Allocation Customer Owned Inventory Recorded as Liability Represents the amount of acquisition cost of a business combination allocated to customer-owned inventory recorded as liability. BusinessAcquisitionPurchasePriceAllocationCustomerOwnedInventoryRecordedAsLiability Customer-owned inventory recorded as an liability Basic and diluted (in dollars per share) Business Acquisitions Pro Forma Earning Per Share Basic and Diluted Represents the pro forma basic and diluted net income per share for a period as if the business combination or combinations had been completed at the beginning of a period. Business Combination Contingent Consideration Arrangements Basis Acquiree Gross Profits Percentage For contingent consideration arrangements recognized in connection with a business combination, this element represents the percentage of aquiree's future gross profit as basis for determining the amount payable. Percentage of acquiree's gross profits as basis for additional contingent consideration Business Combination Contingent Consideration Arrangements Basis for Amount Acquiree Gross Profit Maximum For contingent consideration arrangements recognized in connection with a business combination, this element represents the amount of aquiree's future gross profit as basis for determining the maximum amount payable. Acquiree's future gross profits as basis for maximum aggregate contingent consideration Business Combination Contingent Consideration Arrangements Basis for Amount Period For contingent consideration arrangements recognized in connection with a business combination, this element represents the period of the basis for determining the amount of the payment recorded. Period of acquiree's future gross profits as basis for additional contingent consideration Represents the information pertaining to the acquisition of IMW Compressors (Shanghai) Co. Ltd. IMW Compressors (Shanghai) Co. Ltd IMW Compressors Shanghai Co Ltd [Member] Represents the number of classes of capital stock authorized by the entity's certificate of incorporation. Capital Stock Number of Authorized Classes Authorized number of classes of capital stock The maximum number of shares permitted to be issued by an entity's charter and bylaws. Shares Authorized Authorized shares Number of votes per share held by holders of common stock Represents the number of voting rights per common share held. Common Stock Voting Rights Per Share Key Executive [Member] Key executives Represents key executives of the entity. Series I Warrant [Member] Series I Warrant Represents information pertaining to Series I warrant. GE Credit Agreement [Member] GE Credit Agreement Represents the financing arrangement entered by entity with General Electric. Tranche A Loan [Member] Tranche A Loans Represents information pertaining to Tranche A Loans under the GE credit agreement. Tranche B Loan [Member] Tranche B Loans Represents information pertaining to Tranche B Loans under the GE credit agreement. Represents information pertaining to the warrant issued to General Electric. GE Warrant [Member] GE Warrant Series II Warrant Represents information pertaining to Series II warrant. Series II Warrant [Member] Series I Warrant Amended [Member] Amended Series I Warrant Represents information pertaining to amended Series I warrant. Accounts receivable, net of allowance for doubtful accounts of $832 and $987 as of December 31, 2013 and March 31, 2014, respectively Accounts Receivable, Net, Current Number of Shares of Common Stock in Unit Number of shares of the company's common stock in a unit Represents the number of shares of the company's common stock in each unit. Unit Price Unit price (in dollars per unit) Price of a single unit of a number of saleable units offered by the company. Class of Warrant or Rights Period from which Warrants or Rights Exercisable Period from which warrants are exercisable Represents the period from which warrants are exercisable. The period of time, from the date warrants became exercisable until the time at which they expire. Class of Warrant or Rights Expiration Term Expiration term Class of Warrant or Rights Number of Holders of Warrant Entering into Amendment Number of holders of warrants entering into amendment with the company Represents the number of holders of warrants entering into an amendment with the entity. Class of Warrant or Right Gain on Exercise of Warrants Gain on exercise of warrants Represents the gain on exercise of warrants. Stock Option Plan 2002 [Member] 2002 Plan Represents the 2002 Stock Option Plan (the 2002 Plan) of the entity. Equity Incentive Plan 2006[Member] 2006 Plan Represents the 2006 Equity Incentive Plan (the 2006 Plan) of the entity. Share Based Compensation Arrangements by Share Based Payment Award Options Expiration Term Expiration term The period of time, from the grant date until the time at which the share-based option award expires. Share Based Compensation Arrangement by Share Based Payment Award for Options Granted to 10 Percent Shareholder Purchase Price of Common Stock Percent Purchase price of options granted to 10% stockholders expressed as percentage of fair market value of common stock Represents the purchase price of options granted to 10 percent stockholders expressed as a percentage of the fair market value of the entity's common stock on the grant date. Percentage ownership of stock for which the option purchase price will be 110% of fair market Represents the ownership percentage of stock to whom the purchase price of an option is not less than 110 percent of the fair market value on the grant date. Share Based Compensation Arrangement by Share Based Payment Award Options Percentage of Shareholders 110 Percent FV Ownership Interest in Wholly Owned Subsidiary Ownership interest in ServoTech (as a percent) Represents the percentage of ownership interest in wholly owned subsidiaries. Complimentary gasoline provided under the agreement (in gallons) Represents the quantity of complimentary gasoline to be provided by the entity as a marketing incentive under the agreement. Complimentary Gasoline Quantity Provided Stock Issued During Period, Shares Exercise of Overallotment Option Represents the number of shares issued to underwriter upon exercise of its overallotment option. Number of shares issued to underwriter upon exercise of options Disposal Group Number of Shares Received Number of common stock shares received Represents the number of shares received as part of a business disposal. Disposal Group Number of Shares Sold Number of common stock shares sold Represents the number of shares sold which was initially received as part of a business disposal. Disposal Group Number of Shares Receivable Number of common stock shares receivable Represents the number of shares receivable as part of a business disposal. Units Authorized Represents the number of units authorized under a placement agreement. Number of units authorized under the Placement Agent Agreement Number of shares issued for units under Placement Agent Agreement Stock Issued During Period, Shares for Units Number of shares of common stock issued during the period for units under a placement agreement. Class of Warrant or Right Number of Warrants Immediately Exercisable Number of shares immediately exercisable Represents the number of shares that are immediately exercisable under the warrant. Represents the number of warrants that will become exercisable at the time that specified loan is made under the credit agreement. Class of Warrant or Right Additional Number of Warrants Become Exercisable when Specified Loan will be Made under Credit Agreement Number of shares that will become exercisable at the time the specified loan is made under the credit agreement Class of Warrant or Right Additional Number of Warrants Become Exercisable when Specified Principal Amount of Specified Loan will be Made under Credit Agreement Number of additional shares that will become exercisable at the time that specified loan of at least $15,000,000 principal amount is made under the credit agreement Represents the number of additional shares that will become exercisable at the time that specified loan in specified aggregate principal amount is made under the credit agreement. Represents the minimum specified principal amount of specified loan under the credit agreement, at which additional shares become exercisable. Class of Warrant or Right Additional Number of Warrants become Exercisable Based on Minimum Specified Principle Amount Made under Specified Loan Minimum specified principal amount for additional shares to become exercisable Represents the additional number of shares that will be exercisable under the warrant if no loans are made. Class of Warrant or Right Additional Number of Warrants Become Exercisable if No Loans are Made Additional number of shares that will be exercisable if no loans are made Represents the trigger percentage of the market price the entity's stock can be issued, below which the warrant holder is entitled to a dilution adjustment. Warrant Dilution Protection Trigger Percentage of Market Price for Sale of Stock Percentage of market price below which stock sale is a "Dilutive Issuance" Accounts Payable, Current Accounts payable Proceeds from Issuance of Units Represents the proceeds received after deducting the placement agent's fees and other offering expenses related to the sale of units. Proceeds after deducting the placement agent's fees and other offering expenses related to the sale of units Other Receivables Accounts, Notes, Loans and Financing Receivable [Line Items] Class of Warrant or Rights, Amount Paid on Modification of Term Represents the amount paid to warrant holder on modification of the term of the warrant. Amount paid to holders on modification of term Number of shares issued during the period due to warrants exercised. Total number of warrants exercised (in shares) Stock Issued During Period, Shares Warrants Exercised Stock Issued During Period, Value, Warrants Exercised Value of stock issued as a result of the exercise of warrants. Total value of warrants exercised Federal and State [Member] Federal and state Represents the tax departments of the federal and state governments entitled to levy and collect income taxes from the entity. Fuel Tax and Carbon Credits [Member] Fuel tax and carbon credits Represents information pertaining to the amount of fuel tax and carbon credits receivable by the entity. Unrecorded Unconditional Purchase Obligation Balance Years One to Four Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing from the next four fiscal years. 2013 through 2016 Antidilutive Securities Included in Computation of Earnings Per Share Amount Common stock related to the GE Warrant included in the basic and dilutive net loss per share calculation Represents the securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share or earnings per unit in the future that were included in the computation of diluted EPS or EPU for the period presented. Business Acquisition Amount Paid to Purchase Remaining Interest Percentage Percentage of amount to be paid to purchase remaining interest Represents the percentage of amount to be paid to purchase remaining interest under the business acquisition. Debt Instrument Periodic Payment Common Share Issue Common stock issued on debt instrument Represents the amount of periodic payments made by the issue of common shares applied to the principal under the debt obligation. Percentage of the budgeted costs of the Projects which the Company agreed to pay Represent the percentage of the budgeted costs of the LNG projects which the entity agreed to pay. Payment as Percentage of Budgeted Cost of Projects Volumetric Excise Tax Credit revenue related to CNG and LNG the entity sold in a prior period and was recognized in the current period. Volumetric Excise Tax Credit Prior Period VETC credits related to prior periods Paid in kind interest (as a percent) Represents the interest paid other than in cash for example by issuing additional debt securities, expressed as a percentage. Paid in Kind Interest Rate Represents the number of quarterly installments for repayment of the principal amount of debt. Debt Instrument Number of Quarterly Repayment Installments Number of quarterly installments for repayment of principal amount Percentage of purchase consideration payable in cash Represents the percentage of purchase consideration payable in cash to acquire the entity. Business Acquisition Cost of Acquired Entity Cash Payable Percentage Business Acquisition, Cost of Acquired Entity, Equity Issued, Percent Percentage of purchase consideration paid in shares Represents the percentage of purchase consideration paid in the form of equity interests of the entity in consideration for the business combination. Disposal Group Value Shares Value of common stock shares to be received Represents the fair value of shares to be received as part of a business disposal. Represents the number of shares to be received as part of a business disposal. Disposal Group Number of Shares Number of common stock shares to be received Gross Unrealized Losses Available for Sale Securities Accumulated Gross Unrealized Loss before Tax Amount of accumulated unrealized loss before deducting unrealized gain on investments in available-for-sale securities impacting investments. Available for Sale Securities Accumulated Gross Unrealized Loss before Tax Other Geographical Other [Member] Geographical areas classified as other. Amount recognized for tangible assets. Price allocated to tangible assets Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed Tangible Assets Acquired Gross Unrealized Gains Available for Sale Securities Accumulated Gross Unrealized Gain before Tax Available for Sale Securities Accumulated Gross Unrealized Gain before Tax Amount of accumulated unrealized gain before deducting unrealized loss on investments in available-for-sale securities impacting investments. Convertible Senior Notes 5.25 Percent Due 2018 [Member] 5.25% Notes Represents information pertaining to 5.25 percent Convertible Senior Notes due in 2018. Debt Instrument Redemption Price as Percentage of Principal Amount of Instruments Redeemed Redemption price as percentage of principal amount of notes to be redeemed Represents the redemption price of debt instrument as a percentage of the principal amount of instruments redeemed. Percentage of principal amount at which notes may be required to be repurchased in event of fundamental change by the entity Represents the redemption price as a percentage of the principal amount at which the debt instrument may be required to be repurchased in the event of a fundamental change by the entity. Debt Redemption Price due to Fundamental Change as Percentage of Principal Amount Percentage of Principal Amount of Debt Instrument Outstanding Allowing Holders to Accelerate All Amounts Due in Event of Default under Indenture Percentage of principal amount of notes outstanding allowing holders to accelerate all amounts due under notes in event of default under the Indenture Represents the percentage of principal amount of notes outstanding allowing holders to accelerate all amounts due under notes in the event of default under the indenture. Market Based Restricted Stock Units RSU [Member] Market-based Restricted Stock Units Represents the market-based share instrument which is convertible to stock or an equivalent amount of cash, after a specified period of time or when specified performance conditions are met. Represents the service-based share instrument which is convertible to stock or an equivalent amount of cash, after a specified period of time or when specified performance conditions are met. Service Based Restricted Stock Units RSU [Member] Service-based Restricted Stock Units Vesting Over the First Year [Member] Vesting over the first year Represents information pertaining to stock-based compensation awards vesting over first year. Represents information pertaining to stock-based compensation awards vesting over second year. Vesting Over the Second Year [Member] Vesting over the second year Vesting over the third year Represents information pertaining to stock-based compensation awards vesting over third year. Vesting Over the Third Year [Member] Debt issuance costs accrued Accrued Debt Issuance Cost, Current Carrying value as of the balance sheet date of obligations to third parties in connection with debt origination costs. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Short Term Investments Gross Unrealized Gain Accumulated in Investments Gross Unrealized Gains Amount of accumulated unrealized gain before deducting unrealized loss on investments which are intended to be sold in the short-term (usually less than one year or the normal operating cycle, whichever is longer) including trading securities, available-for-sale securities, held-to-maturity securities, and other short-term investments not otherwise listed in the existing taxonomy. Product Warranty Accrual Warranties Issued and Pre Existing Increase (Decrease) Costs accrued for new warranty contracts and changes in estimates for pre-existing warranties Represents the aggregate increase in the liability for accruals related to product warranties issued and also the aggregate increase or decrease in the liability for accruals related to pre-existing product warranties, during the reporting period. Product Warranty Accrual Sale of Subsidiary Sale of subsidiary Represents the aggregate decrease in the liability for accruals related to product warranties as a result of the sale of a subsidiary during the reporting period. Amount of long-term debt and capital lease obligation, excluding related party debt, due after one year or beyond the normal operating cycle, if longer. Long Term Debt and Capital Lease Obligations Excluding Related Parties Long-term debt and capital lease obligations, less current portion Canton Bonds ($11,400 non-recourse to the Company) Canton Bonds Canton bonds Represents information pertaining to Canton Revenue Bonds issued by Canton Renewables, LLC, a wholly owned subsidiary of the entity. Canton Revenue Bonds [Member] Fair Value Measurement with Unobservable Inputs Reconciliation Recurring Basis Liability Exercises Represents exercises of warrants that have taken place during the period in relation to liabilities measured at fair value and categorized within level 3 of the fair value hierarchy. Exercise of warrants Debt Instrument Reference Rate Minimum Percent The minimum reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate. Reference rate minimum (as a percent) Holdback Shares Value Write Down Write down in value of the Holdback Shares Represents the write down in value of the holdback shares by the entity during the period. Federal Tax Benefit on Extension of Alternative Fuel Credit for Current Period Fuel Sales Tax benefit related to exclusion of VETC associated with 2013 fuel sales Represents the amount of tax benefit related to the exclusion of the alternative fuel credit associated with current period fuel sales recorded during the period. Tax benefit related to exclusion of VETC associated with 2006 to 2012 fuel sales Represents the amount of tax benefit related to the exclusion of the alternative fuel credit associated with prior period fuel sales recorded during the period. Federal Tax Benefit on Extension of Alternative Fuel Credit for Prior Period Fuel Sales Memphis Light Gas and Water Division [Member] MLGW Represents information pertaining to Memphis Light, Gas and Water Division (MLGW). DGS Represents information pertaining to Desert Gas Services (formerly known as Spectrum Energy Services, LLC) (DGS). Desert Gas Services [Member] BP Energy [Member] BP Energy Represents information pertaining to BP Energy. Number of Equipment Purchased During Period Number of CNG-In-A-Box units purchased Represents the number of equipment purchased during the period by the entity. Kinetrex Energy [Member] Kinetrex Represents information pertaining to Kinetrex Energy. Number of Sales Agreement Entered into During Period Number of additional LNG sales agreement entered into Represents the number of sales agreements entered into by the entity during the period. Debt Instrument Periodic Payment Principal Retained Amount of annual payment retained Represents the amount of principal payments not paid and retained by the entity by exercising its right to retain the payment pending resolution of an indemnity claim. Canton Renewables LLC [Member] Canton Represents information pertaining to Canton Renewables, LLC, a wholly owned subsidiary, which is a Michigan limited liability company. Canton Renewables, LLC Warrant Valuation Series I warrant valuation This element represents the total gain/loss arising out of valuation of financial instruments like warrants etc included in the earning for the period. Key Employee [Member] Key employee Represents a key employee of the entity. United States UNITED STATES Accrued liabilities Accrued Liabilities [Member] Accrued Employee Benefits, Current Accrued employee benefits Accrued Salaries, Current Salaries and wages Accrued liabilities Total Accrued Liabilities, Current Accrued professional fees Accrued Professional Fees, Current Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Less: accumulated depreciation Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated Other Comprehensive Income (Loss) Accumulated Other Comprehensive Income (Loss) [Member] Additional paid-in capital Additional Paid in Capital, Common Stock Additional Paid-In Capital Additional Paid-in Capital [Member] Fair value of warrants issued, additional paid-in capital Adjustments to Additional Paid in Capital, Warrant Issued Issuance of warrants in connection with the GE Credit Agreement Adjustments to reconcile net loss to net cash used in operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Stock-based compensation Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Advertising expense Advertising Expense Advertising Costs Advertising Costs, Policy [Policy Text Block] Stock-based compensation expense, net of tax Allocated Share-based Compensation Expense, Net of Tax Stock-based compensation expense Allocated Share-based Compensation Expense Accounts receivable, allowance for doubtful accounts (in dollars) Allowance for Doubtful Accounts Receivable, Current Allowance for Doubtful Notes Receivables Allowance for Notes Receivable [Member] Allowances for Doubtful Trade Receivables Allowance for Trade Receivables [Member] Amortization of debt issuance cost Amortization of Financing Costs Amortization expense Amortization of Intangible Assets Accretion of notes payable Amortization of Debt Discount (Premium) Proceeds from grants Amount of Regulatory Assistance Received Antidilutive Securities [Axis] Earnings Per Share Net Loss Per Share Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities, Name [Domain] Anti-dilutive securities (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Accretion expense Asset Retirement Obligation, Accretion Expense Asset Retirement Obligations Asset Retirement Obligation [Abstract] Asset retirement obligation, included in other long-term liabilities Asset Retirement Obligations, Noncurrent Asset Retirement Obligations Asset Retirement Obligations, Policy [Policy Text Block] Asset impairments Asset Impairment Charges Beginning balance Ending balance Asset Retirement Obligation Activity of the asset retirement obligation Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] Liabilities settled Asset Retirement Obligation, Liabilities Settled Liabilities incurred Asset Retirement Obligation, Liabilities Incurred Assets: Assets, Fair Value Disclosure [Abstract] Total assets Assets Current assets: Assets, Current [Abstract] Assets Assets [Abstract] Total current assets Assets, Current Loans to customers to finance vehicle purchases Automobile Loan [Member] Available-for-sale securities Available-for-sale Securities Estimated Fair Value Available-for-sale Securities, Current Amortized Cost Available-for-sale Securities, Amortized Cost Basis HSBC's U.S. base rate Base Rate [Member] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Current liabilities assumed Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities Current assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets Business Acquisition [Axis] Pro forma results of operations Business Acquisition, Pro Forma Information [Abstract] Total assets acquired Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets Cash acquired Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents Schedule of Company's unaudited pro forma results of operations as if the acquisition had occurred at on January 1, 2010 Business Acquisition, Pro Forma Information [Table Text Block] Contingent consideration obligation Business Combination, Contingent Consideration, Liability Fair value of contingent consideration Debt acquired Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt Identifiable intangible assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill Liabilities assumed Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities Acquisitions Natural Gas Fueling Compressors Business Acquisition [Line Items] Gain on contingent consideration for acquisition Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability Interest acquired (as a percent) Business Acquisition, Percentage of Voting Interests Acquired Ownership interest acquired (as a percent) Revenue Business Acquisition, Pro Forma Revenue Business Acquisition, Acquiree [Domain] Net (loss) Business Acquisition, Pro Forma Net Income (Loss) Acquisitions and Divestitures Amount paid for acquisition Total purchase consideration Business Combination, Consideration Transferred Number of common stock shares issued Business Acquisition, Equity Interest Issued or Issuable, Number of Shares Customer-owned inventory recorded as an asset Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory Acquisitions and Deconsolidation Business Combination Disclosure [Text Block] Aggregate contingent consideration payment Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High Contingent liability Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Contingent Liability Allocation of aggregate purchase price Estimate of fair values of assets acquired and liabilities assumed Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract] Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment Property, plant and equipment Acquisitions Business Combination, Description [Abstract] Contingent consideration Business Combination, Contingent Consideration Arrangements [Abstract] Gain resulting from re-measurement at fair value of previously held equity interest in the acquiree Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain (Loss), Net Net loss Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual Revenue Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual Total purchase price Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net Counterparty Name [Axis] Impairment charge Cost-method Investments, Other than Temporary Impairment Impairment of cost method investment Impairment charge related to an investment 2015 Capital Leases, Future Minimum Payments Due in Two Years Total minimum lease payments Capital Leases, Future Minimum Payments Due 2018 Capital Leases, Future Minimum Payments Due in Five Years Less amount representing interest Capital Leases, Future Minimum Payments, Interest Included in Payments Less current portion Capital Lease Obligations, Current 2014 Capital Leases, Future Minimum Payments Receivable, Next Twelve Months Value of the equipment under capital lease Capital Leased Assets, Gross Capital lease obligations, less current portion Capital Lease Obligations, Noncurrent Capital lease obligations Capital Lease Obligations [Member] Future receipts under the leases Capital Leases, Future Minimum Payments Receivable, Fiscal Year Maturity [Abstract] 2018 Capital Leases, Future Minimum Payments, Receivable in Five Years 2017 Capital Leases, Future Minimum Payments, Receivable in Four Years 2015 Capital Leases, Future Minimum Payments, Receivable in Two Years Amount included in accounts payable balances Capital Expenditures Incurred but Not yet Paid 2016 Capital Leases, Future Minimum Payments Due in Three Years 2016 Capital Leases, Future Minimum Payments, Receivable in Three Years 2017 Capital Leases, Future Minimum Payments Due in Four Years Future payments under these capital leases Capital Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] Accumulated amortization Capital Leases, Lessee Balance Sheet, Assets by Major Class, Accumulated Depreciation Present value of future minimum lease payments Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments Thereafter Capital Leases, Future Minimum Payments Due Thereafter Total Capital Leases, Future Minimum Payments Receivable Capital Capital Loss Carryforward [Member] 2014 Capital Leases, Future Minimum Payments Due, Next Twelve Months Amortization expense related to the capitalized software costs Capitalized Computer Software, Amortization Capitalized software costs, net Capitalized Computer Software, Net Capitalized Computer Software, Accumulated Amortization Accumulated amortization on the capitalized software costs Cash and Cash Equivalents Cash and Cash Equivalents Disclosure [Text Block] Cash and cash equivalents Cash, beginning of period Cash, end of period Cash and Cash Equivalents, at Carrying Value Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Cash and Cash Equivalents Certificate of deposits Certificates of Deposit [Member] Shares of common stock related to the GE Warrant included in the basic and dilutive net loss per share calculation Class of Warrant or Right, Outstanding Stockholders' equity Class of Stock [Line Items] Class of Warrant or Right [Axis] Class of Warrant or Right [Domain] Number of shares that can be purchased upon exercise of warrants Class of Warrant or Right, Number of Securities Called by Warrants or Rights Exercise price of the warrant (in dollars per share) Exercise price (in dollars per share) Class of Warrant or Right, Exercise Price of Warrants or Rights Number of shares that can be purchased upon exercise of warrant Class of Warrant or Right, Number of Securities Called by Each Warrant or Right Number of shares that can be purchased upon exercise of each warrant Class of Stock [Domain] Environmental Matters, Litigation, Claims, Commitments and Contingencies Commitments Contingencies and Guarantees [Text Block] Environmental Matters, Litigation, Claims, Commitments and Contingencies Commitments and contingencies Commitments and Contingencies. Common stock, par value (in dollars per share) Common stock, Par value (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock Common Stock [Member] Common stock, $0.0001 par value. Authorized 149,000,000 shares; issued and outstanding 89,364,397 shares and 89,858,816 shares at December 31, 2013 and March 31, 2014, respectively Common Stock, Value, Issued Common stock, issued shares Balance (in shares) Balance (in shares) Common Stock, Shares, Issued Common stock, Authorized shares Common Stock, Shares Authorized Number of shares reserved Common Stock, Capital Shares Reserved for Future Issuance Common stock, outstanding shares Common Stock, Shares, Outstanding 401(k) Plan Components of Deferred Tax Assets [Abstract] Deferred tax assets: Deferred tax liabilities: Components of Deferred Tax Liabilities [Abstract] Comprehensive Income (Loss) Comprehensive Income, Policy [Policy Text Block] Comprehensive loss Comprehensive income (loss) Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Concentration Risk Type [Domain] Concentration of Credit Risk Supplier Concentrations Concentration Risk [Line Items] Concentration Risk Benchmark [Domain] Concentration of Credit Risk Concentration Risk, Credit Risk, Policy [Policy Text Block] Concentration Risk Type [Axis] Concentration Risk [Table] Supplier Concentrations Concentration Risk Disclosure [Text Block] Concentration Risk Benchmark [Axis] Concentration risk (as a percent) Concentration Risk, Percentage Basis of Presentation Consolidation, Policy [Policy Text Block] Construction in progress Construction in Progress [Member] Convertible Notes Convertible Notes Payable [Member] Corporate bonds Corporate Debt Securities [Member] Investments in Other Entities Cost and Equity Method Investments Disclosure [Text Block] Product cost of sales (includes $_ and $_ accumulated other comprehensive (income) loss reclassifications for net (gains) losses on cash flow hedges for the three months ended March 31, 2012 and 2013, respectively) Product cost of sales Cost of Goods Sold Investments in other entities Cost Method Investments Natural gas expense Cost of Goods, Product Line [Member] Service cost of sales Cost of Services Cost of sales (exclusive of depreciation and amortization shown separately below): Cost of Goods and Services Sold [Abstract] Operating expenses: Costs and Expenses [Abstract] Total operating expenses Costs and Expenses Credit Facility [Axis] Credit Facility [Domain] State Current State and Local Tax Expense (Benefit) Current: Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Foreign Current Foreign Tax Expense (Benefit) Federal Current Federal Tax Expense (Benefit) Total current Current Income Tax Expense (Benefit) Customer relationships Customer Relationships [Member] Debt, variable interest rate basis Debt Instrument, Description of Variable Rate Basis Long-term debt Debt Instrument [Line Items] Schedule of Long-term Debt Instruments [Table] Number of shares of common stock into which Notes are convertible Debt Instrument, Convertible, Number of Equity Instruments Amount of principal and accrued interest under debt conversion Amount of principal converted into stock Debt Conversion, Original Debt, Amount Common stock issued upon conversion of debt (in shares) Debt Conversion, Converted Instrument, Shares Issued Debt issuance amount Principal amount Debt Instrument, Face Amount Long-term Debt Debt and Capital Leases Disclosures [Text Block] Total debt and capital lease obligations Debt and Capital Lease Obligations Percentage of margin added to reference rate to determine interest rate on debt Debt Instrument, Basis Spread on Variable Rate Long-term Debt Percentage of the trade price of common stock that the conversion price must be at premium for the Company to force conversion Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger Number of consecutive trading days used to determine the conversion obligation on the notes for the Company to force conversion Debt Instrument, Convertible, Threshold Consecutive Trading Days Number of days within 30 consecutive trading days in which the trade price of the entity's common stock must be at premium of the conversion price for the Company to force conversion Debt Instrument, Convertible, Threshold Trading Days Long-term Debt, Gross Aggregate principal amount Period during which the debt instrument principal balance is required to be paid following its issuance Maturity period from the Closing Date Debt Instrument, Term Debt Instrument [Axis] Debt, Weighted Average Interest Rate Coupon interest rate (as a percent) Average coupon interest rate (as a percent) Debt Instrument, Convertible, Conversion Price Conversion price of shares (in dollars per share) Annual payment required Debt Instrument, Annual Principal Payment Debt Instrument, Name [Domain] Interest rate (as a percent) Base interest rate (as a percent) Debt Instrument, Interest Rate, Stated Percentage Annual payment required Debt Instrument, Periodic Payment, Principal Total deferred tax liabilities Deferred Tax Liabilities, Gross Federal Deferred Federal Income Tax Expense (Benefit) Deferred: Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Foreign Deferred Foreign Income Tax Expense (Benefit) Total deferred Deferred Income Tax Expense (Benefit) State Deferred State and Local Income Tax Expense (Benefit) Derivative loss Deferred Tax Assets, Derivative Instruments Deferred revenue Deferred Revenue, Current Total deferred tax assets Deferred Tax Assets, Gross Stock option expense Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost Other Deferred Tax Assets, Other Net deferred tax assets Deferred Tax Assets, Net of Valuation Allowance Accrued expenses Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Accrued Liabilities Loss carryforwards Deferred Tax Assets, Operating Loss Carryforwards Alternative minimum tax and general business credits Deferred Tax Assets, Tax Credit Carryforwards Less valuation allowance Valuation allowance Deferred Tax Assets, Valuation Allowance Net deferred tax liabilities Deferred Tax Liabilities, Net Maximum percentage of base pay that can be contributed by employees through salary deferrals Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent Contribution by the company Defined Contribution Plan, Cost Recognized Depreciation and amortization Depreciation, Depletion and Amortization Natural gas futures contracts Derivative liability Derivative Liability Derivative Transactions Derivative [Line Items] Derivative Financial Instruments Derivative Instrument Detail [Abstract] Derivative [Table] Derivative Transactions Derivative Instruments and Hedging Activities Disclosure [Text Block] Derivative Transactions Derivative asset Derivative Asset Derivative liability Short-term liability related to derivative instruments included in accrued liabilities Derivative Liability, Current Derivative, by Nature [Axis] Derivative (gain) loss Series I warrant valuation Derivative gain Derivative, Gain (Loss) on Derivative, Net Derivative (gains) losses: Derivative, Gain (Loss) on Derivative, Net [Abstract] Number of natural gas futures contracts outstanding Derivative, Number of Instruments Held Derivative, Name [Domain] Derivative Financial Instruments Derivatives, Policy [Policy Text Block] Boone Pickens Mr. Pickens Director [Member] Stock-Based Compensation Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Stock-Based Compensation Disposal Groups, Including Discontinued Operations, Name [Domain] Earnings Per Share, Basic and Diluted Basic and diluted (in dollars per share) Earnings Per Share Earnings Per Share [Text Block] Net Loss Per Share Earnings Per Share, Policy [Policy Text Block] Basic (in dollars per share) Earnings Per Share, Basic Diluted (in dollars per share) Earnings Per Share, Diluted Loss per share attributable to Clean Energy Fuels Corp.: Earnings Per Share Effect of exchange rates on cash and cash equivalents Effect of Exchange Rate on Cash and Cash Equivalents, Continuing Operations Reconciliation of the income tax provision Effective Income Tax Rate Reconciliation, Percent [Abstract] Federal income tax rate (as a percent) Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Options Stock options Employee Stock Option [Member] Employee Stock Purchase Plan Employee Stock [Member] Total unrecognized compensation cost related to non-vested units Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options Total unrecognized compensation cost related to non-vested shares Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Weighted average period over which the total unrecognized compensation cost related to non-vested units is expected to be recognized Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Summary of stock-based compensation expense Employee Service Share-based Compensation, Aggregate Disclosures [Abstract] Total unrecognized compensation cost related to non-vested shares Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options Equity Method Investment, Ownership Percentage Ownership interest (as a percent) Gain on sale recognized Gain from sale of equity method investment Gain on sale of equity method investment Equity Method Investment, Realized Gain (Loss) on Disposal