Accounting Changes And Error Corrections [Text Block] Recent Accounting Pronouncements Accounts Payable Current Accounts payable Accounts Receivable Net Current Trade accounts receivable, net of allowance for doubtful accounts of $318 and $192 at September 30, 2012 and December 31, 2011, respectively Accretion Expense Accretion of fair value of deferred and contingent purchase price consideration related to acquisition Accrued acquisition contingent consideration fair value disclosure. Accrued Acquisition Contingent Consideration Fair Value Disclosure Accrued acquisition contingent consideration The fair value as of the balance sheet date of potential payments under the contingent consideration arrangement, including cash and shares as applicable, that is not expected to be settled for more than 12 months from the balance sheet date. Accrued Acquisition Contingent Consideration Non Current Accrued acquisition contingent consideration Carrying value as of the balance sheet date of liabilities incurred and payable to commercial, institutional and industrial end-users of electricity for services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Accrued Capacity Payments Current Accrued capacity payments Accrued Liabilities Current Accrued expenses and other current liabilities Carrying value as of the balance sheet date of performance adjustments incurred and payable under contract obligations for which amounts have not yet been refunded to the customer. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Accrued Performance Adjustments Accrued performance adjustments Accrued performance adjustments related to fees received Accumulated Depreciation Depletion And Amortization Property Plant And Equipment Accumulated depreciation Accumulated Other Comprehensive Income Loss Net Of Tax Accumulated other comprehensive loss Additional Paid In Capital Common Stock Additional paid-in capital Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities [Abstract] Adjustments to reconcile net income to net cash provided by operating activities: Allocated Share Based Compensation Expense Stock-based compensation Total Stock-based compensation expense All other. All Other [Member] All other [Member] Allowance For Doubtful Accounts Receivable Current Allowance for doubtful accounts receivable Amendment Flag Amendment Flag Amortization Of Financing Costs Deferred financing costs expenses Amortization Of Intangible Assets Amortization of acquired intangible assets Amortization of Intangible Assets Amount of Company's generation equipment utilized in open market demand response programs. Amount Of Companys Generation Equipment Utilized In Open Market Demand Response Programs Amount of Company's generation equipment utilized in open market demand response programs Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount Weighted average anti-dilutive shares Antidilutive Securities Excluded From Computation Of Earnings Per Share By Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Name [Domain] Antidilutive Securities, Name [Domain] Assets Total assets Assets Current Total current assets Assets Current [Abstract] Current assets Associated assets value. Associated Assets Value Associated Assets Value A U Australia [Member] Australian Subsidiary. Australian Subsidiary [Member] Australian Subsidiary [Member] Award Type [Axis] Award Type [Axis] Borrowing under letter of credit. Borrowing Under Letter Of Credit Borrowing under letter of credit Business Acquisition Acquiree [Domain] Business Acquisition, Acquiree [Domain] Business Acquisition [Axis] Business Acquisition [Axis] Business acquisition contingent consideration shares released from escrow. Business Acquisition Contingent Consideration Shares Released From Escrow Shares held in Escrow Business Acquisition Cost Of Acquired Entity Transaction Costs Direct acquisition fees and expenses Business Acquisition Date Of Acquisition Agreement 1 Acquisition date Shares to be issued in connection with deferred consideration arrangements related to a business combination that are no subject to any contingencies or adjustments. Business Acquisition Deferred Consideration Related Shares Shares to be issued related to deferred consideration arrangement related to a business combination Business Acquisition [Line Items] Business Acquisition [Line Items] Business acquisition pro forma earnings per share. Business Acquisition Pro Forma Earnings Per Share [Abstract] Net income per common share: Business Acquisition Pro Forma Earnings Per Share Basic Basic Business Acquisition Pro Forma Earnings Per Share Diluted Diluted Business Acquisition Pro Forma Information Nonrecurring Adjustment [Line Items] Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] Business Acquisition Pro Forma Information Nonrecurring Adjustments [Table] Business Acquisition, Pro Forma Information, Nonrecurring Adjustments [Table] Business Acquisition Pro Forma Information [Text Block] Unaudited Pro Forma Information Business Acquisitions Pro Forma Net Income Loss Net income Business Acquisitions Pro Forma Revenue Net revenue Business Acquisition [Table] Business Acquisition [Table] Business Acquisition [Table] Capitalized Computer Software Accumulated Amortization Accumulated amortization of capitalized internal use software Capitalized Computer Software Additions Capitalized software development costs Capitalized Computer Software Amortization Amortization of capitalized internal use software Cash And Cash Equivalents At Carrying Value Cash and cash equivalents at end of period Cash and cash equivalents at beginning of period Cash and cash equivalents Cash And Cash Equivalents Period Increase Decrease Net change in cash and cash equivalents Cash Flow Noncash Investing And Financing Activities Disclosure [Abstract] Non-cash financing and investing activities Commitments And Contingencies Commitments and contingencies (Notes 7 and 8) Commitments And Contingencies Disclosure [Text Block] Commitments and Contingencies Commitments [Member] Commitments [Member] Common Stock Par Or Stated Value Per Share Common stock, par value Common Stock Shares Authorized Common stock, shares authorized Common Stock Shares Issued Common stock, shares issued Common Stock Shares Outstanding Common stock, shares outstanding Common Stock Value Common stock, $0.001 par value; 50,000,000 shares authorized, 28,919,110 and 27,306,548 shares issued and outstanding at September 30, 2012 and December 31, 2011, respectively Comprehensive Income Net Of Tax Comprehensive income Computer Software Intangible Asset [Member] Software [Member] Concentration Risk Disclosure [Text Block] Concentrations of Credit Risk Concentration Risk [Line Items] Concentration Risk [Line Items] Concentration Risk [Table] Concentration Risk [Table] Consolidation Policy [Text Block] Basis of Consolidation Contingencies And Commitments [Line Items] Contingencies And Commitments [Line Items] Contingencies And Commitments [Line Items] Contingencies And Commitments [Table] Contingencies And Commitments [Table] Contingencies And Commitments [Table] Contingent liability under outstanding letters of credit. Contingent Liability Outstanding Letters Of Credit Contingent liability under outstanding letters of credit Cost Of Services Cost of revenues Costs Associated With Exit Or Disposal Activities Or Restructurings Policy [Text Block] Exit or Disposal Cost Obligations Credit Facility 2012. Credit Facility Two Zero One Two [Member] Credit Facility 2012 [Member] Current Fiscal Year End Date Current Fiscal Year End Date Customer Advances And Deposits Deposits held by customers Customer Contracts [Member] Customer contracts [Member] Customer Relationships [Member] Customer relationships [Member] Debt Disclosure [Text Block] Financing Arrangements Debt instrument interest rate description. Debt Instrument Interest Rate Description Interest rate description on term loan Deferred acquisition consideration fair value disclosure. Deferred Acquisition Consideration Fair Value Disclosure Deferred acquisition consideration Noncurrent portion of the fair value of payments under the deferred purchase price consideration arrangement, including cash and shares as applicable. Deferred Acquisition Consideration Noncurrent Deferred acquisition consideration Deferred Compensation Arrangement With Individual Excluding Share Based Payments And Postretirement Benefits By Title Of Individual [Axis] Deferred Bonus and Profit Sharing Plan by Title of Individual [Axis] Deferred Compensation Arrangement With Individual Shares Issued Common stock issued to executives Contractual fees that have been received that have been deferred due to the potential right of refund. Deferred Fees Deferred fees Deferred Income Tax Expense Benefit Deferred taxes Deferred Rent Credit Deferred rent liability Deferred Revenue Current Deferred revenue Deferred Revenue Noncurrent Deferred revenue Deferred Tax Liabilities Noncurrent Deferred tax liability Deposits Assets Current Deposits Deposits held by customers as collateral for the Company's contractual performance obligations. Deposits Held By Customers Deposits held by certain customers Depreciation Depreciation Description of business. Description Of Business Policy [Text Block] Description of Business Description Of Lessee Leasing Arrangements Operating Leases Terms for future minimum lease payments Developed Technology Rights [Member] Developed technology [Member] Disclosure - Additional Information About Restricted Stock [Abstract] Disclosure Additional Information About Restricted Stock [Abstract] Disclosure - Additional Information About Restricted Stock [Abstract] Disclosure - Additional Information about Restricted Stock Units [Abstract] Disclosure Additional Information About Restricted Stock Units [Abstract] Disclosure - Additional Information about Restricted Stock Units [Abstract] Disclosure Assets And Liabilities Measured At Fair Value On Recurring Basis [Abstract] Disclosure Assets And Liabilities Measured At Fair Value On Recurring Basis [Abstract] Disclosure Assets And Liabilities Measured At Fair Value On Recurring Basis [Abstract] Disclosure - Changes in Carrying Amount of Goodwill [Abstract] Disclosure Changes In Carrying Amount Of Goodwill [Abstract] Disclosure - Changes in Carrying Amount of Goodwill [Abstract] Disclosure Commitments And Contingencies Additional Information [Abstract] Disclosure Commitments And Contingencies Additional Information [Abstract] Disclosure Commitments And Contingencies Additional Information [Abstract] Disclosure - Components of Stock-Based Compensation Expense [Abstract] Disclosure Components Of Stock Based Compensation Expense [Abstract] Disclosure - Components of Stock-Based Compensation Expense [Abstract] Disclosure - Concentrations of Credit Risk - Additional Information [Abstract] Disclosure Concentrations Of Credit Risk Additional Information [Abstract] Disclosure - Concentrations of Credit Risk - Additional Information [Abstract] Disclosure - Concentrations of Credit Risk of Significant Customers [Abstract] Disclosure Concentrations Of Credit Risk Of Significant Customers [Abstract] Disclosure - Concentrations of Credit Risk of Significant Customers [Abstract] Disclosure - Description of Business and Basis of Presentation [Abstract] Disclosure Description Of Business And Basis Of Presentation [Abstract] Disclosure - Description of Business and Basis of Presentation [Abstract] Disclosure - Description of Business and Basis of Presentation - Additional Information [Abstract] Disclosure Description Of Business And Basis Of Presentation Additional Information [Abstract] Disclosure - Description of Business and Basis of Presentation - Additional Information [Abstract] Disclosure - Disclosure of Fair Value of Financial Instruments [Abstract] Disclosure Disclosure Of Fair Value Of Financial Instruments [Abstract] Disclosure - Disclosure of Fair Value of Financial Instruments [Abstract] Disclosure - Financing Arrangements - Additional Information [Abstract] Disclosure Financing Arrangements Additional Information [Abstract] Disclosure - Financing Arrangements - Additional Information [Abstract] Disclosure - Future Minimum Lease Payments for Operating Leases [Abstract] Disclosure Future Minimum Lease Payments For Operating Leases [Abstract] Disclosure - Future Minimum Lease Payments for Operating Leases [Abstract] Disclosure - Gross Carrying Amount and Related Accumulated Amortization of Intangible Assets [Abstract] Disclosure Gross Carrying Amount And Related Accumulated Amortization Of Intangible Assets [Abstract] Disclosure - Gross Carrying Amount and Related Accumulated Amortization of Intangible Assets [Abstract] Disclosure Income Taxes Additional Information [Abstract] Disclosure Income Taxes Additional Information [Abstract] Disclosure Income Taxes Additional Information [Abstract] Disclosure - Intangible Assets and Goodwill - Additional Information [Abstract] Disclosure Intangible Assets And Goodwill Additional Information [Abstract] Disclosure - Intangible Assets and Goodwill - Additional Information [Abstract] Disclosure - Net Income Per Share - Additional Information [Abstract] Disclosure Net Income Per Share Additional Information [Abstract] Disclosure - Net Income Per Share - Additional Information [Abstract] Disclosure Of Compensation Related Costs Share Based Payments [Text Block] Stock-Based Compensation Disclosure of fair value of financial instruments. Disclosure Of Fair Value Of Financial Instruments Disclosure [Text Block] Disclosure of Fair Value of Financial Instruments Disclosure - Reconciliation of Basic and Diluted Share Amounts [Abstract] Disclosure Reconciliation Of Basic And Diluted Share Amounts [Abstract] Disclosure - Reconciliation of Basic and Diluted Share Amounts [Abstract] Disclosure - Schedule of Unaudited Pro Forma Financial Information [Abstract] Disclosure Schedule Of Unaudited Pro Forma Financial Information [Abstract] Disclosure - Schedule of Unaudited Pro Forma Financial Information [Abstract] Disclosure Stock Based Compensation [Abstract] Disclosure Stock Based Compensation [Abstract] Disclosure Stock Based Compensation [Abstract] Disclosure Stock Based Compensation Additional Information [Abstract] Disclosure Stock Based Compensation Additional Information [Abstract] Disclosure Stock Based Compensation Additional Information [Abstract] Disclosure - Stock Option Activity Additional Information [Abstract] Disclosure Stock Option Activity Additional Information [Abstract] Disclosure - Stock Option Activity Additional Information [Abstract] Disclosure - Summarizes Company's Restricted Stock Unit Activity [Abstract] Disclosure Summarizes Companys Restricted Stock Unit Activity [Abstract] Disclosure - Summarizes Company's Restricted Stock Unit Activity [Abstract] Disclosure - Summary of Company's Restricted Stock Activity [Abstract] Disclosure Summary Of Companys Restricted Stock Activity [Abstract] Disclosure - Summary of Company's Restricted Stock Activity [Abstract] Disclosure - Summary of Company's Stock Option Activity [Abstract] Disclosure Summary Of Companys Stock Option Activity [Abstract] Disclosure - Summary of Company's Stock Option Activity [Abstract] Disclosure - Unaudited Pro Forma Information - Additional Information [Abstract] Disclosure Unaudited Pro Forma Information Additional Information [Abstract] Disclosure - Unaudited Pro Forma Information - Additional Information [Abstract] Disclosure - Weighted Average Assumptions Used to Estimate Fair Value of Options [Abstract] Disclosure Weighted Average Assumptions Used To Estimate Fair Value Of Options [Abstract] Disclosure - Weighted Average Assumptions Used to Estimate Fair Value of Options [Abstract] Dividends Common Stock Dividends paid to common stock Document Documentand Entity Information [Abstract] Document Documentand Entity Information [Abstract] Document Documentand Entity Information [Abstract] Document Fiscal Period Focus Document Fiscal Period Focus Document Fiscal Year Focus Document Fiscal Year Focus Document Information [Table] Document Information [Table] Document Period End Date Document Period End Date Document Type Document Type Earnings Per Share [Abstract] Net income per common share Earnings Per Share Basic Basic Earnings Per Share Diluted Diluted Earnings Per Share [Text Block] Net Income Per Share Effective Income Tax Rate Continuing Operations Effective tax rate Effect Of Exchange Rate On Cash And Cash Equivalents Effects of exchange rate changes on cash and cash equivalents Electric Power Division [Member] Electric Power Division [Member] Electric Power Grid [Member] Employee Related Liabilities Current Accrued payroll and related expenses Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount Material compensation cost capitalized Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] Employee Service Share Based Compensation Allocation Of Recognized Period Costs Report Line [Domain] Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Report Line [Domain] Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Nonvested stock-based compensation expense related to employees Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition 1 Weighted average period of stock options Employee Service Share Based Compensation Tax Benefit From Compensation Expense Material income tax benefit from share-based compensation Employee Stock Option [Member] Stock Option [Member] Employment agreements and non-compete agreements. Employment Agreements And Noncompete Agreements [Member] Employment agreements and non-compete agreements [Member] Energy response. Energy Response [Member] Energy Response [Member] Entity Central Index Key Entity Central Index Key Entity Common Stock Shares Outstanding Entity Common Stock, Shares Outstanding Entity [Domain] Entity [Domain] Entity Filer Category Entity Filer Category Entity Information [Line Items] Entity Information [Line Items] Entity Registrant Name Entity Registrant Name Entity wide accounts receivable major customer percentage. Entity Wide Accounts Receivable Major Customer Percentage Percentage of Accounts Receivables Entity wide accounts receivable major customer threshold percentage. Entity Wide Accounts Receivable Major Customer Threshold Percentage Customers who comprised on accounts receivables Entity Wide Disclosure On Geographic Areas Revenue From External Customers Attributed To Foreign Countries Revenues based upon customer location Entity wide revenue geographical region percentage. Entity Wide Revenue Geographical Region Percentage Entity wide revenue geographical region percentage Entity Wide Revenue Major Customer Amount Revenues Entity Wide Revenue Major Customer Percentage % of Total Revenues Entity wide revenue major customer threshold percentage. Entity Wide Revenue Major Customer Threshold Percentage Entity Wide Revenue Major Customer Threshold Percentage Expected Tax Provision Expected Tax Provision Expected provision for income taxes for the tax deductible goodwill and foreign taxes resulting from guaranteed profits Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value By Fair Value Hierarchy Level [Axis] Fair Value, Hierarchy [Axis] Fair Value By Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value Disclosures [Text Block] Fair Value Measurements Fair Value Inputs Level 1 [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] Fair Value Inputs Level 3 [Member] Unobservable Inputs (Level 3) [Member] Fair Value Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value Measurement Inputs Disclosure [Text Block] Assets and Liabilities Measured at Fair Value on a Recurring Basis Fair Value Measurements Fair Value Hierarchy [Domain] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Measurements Recurring [Member] Fair value, measurements, recurring [Member] Fair Value Of Financial Instruments Policy Fair Value Measurements and Disclosures Fair value of lease termination obligation. Fair Value Of Lease Termination Obligation Fair value of lease termination payment Financial Instruments Financial Assets Balance Sheet Groupings [Abstract] Assets Financial Instruments Financial Liabilities Balance Sheet Groupings [Abstract] Liabilities Net carrying amount after accumulated amortization as of the balance sheet date to an asset acquired in a business combination representing a favorable existing relationship with customers having a finite beneficial life. Finite Lived Customer Relationships Net Customer relationship intangible assets, net Finite Lived Intangible Assets Accumulated Amortization Accumulated Amortization Finite Lived Intangible Assets Amortization Expense After Year Five Estimated amortization, Thereafter Finite Lived Intangible Assets Amortization Expense Next Twelve Months Estimated amortization, 2012 Finite Lived Intangible Assets Amortization Expense Year Five Estimated amortization, 2016 Finite Lived Intangible Assets Amortization Expense Year Four Estimated amortization, 2015 Finite Lived Intangible Assets Amortization Expense Year Three Estimated amortization, 2014 Finite Lived Intangible Assets Amortization Expense Year Two Estimated amortization, 2013 Finite Lived Intangible Assets By Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite Lived Intangible Assets Gross Gross Carrying Amount Finite Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Finite Lived Intangible Assets Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite Lived Intangible Asset Useful Life Intangible asset Estimated useful lives Weighted Average Amortization Period (in years) Foreign Currency Transaction Gain Loss Realized Gain (loss) arising from transactions denominated in foreign currencies Foreign Currency Transaction Gain Loss Unrealized Unrealized foreign exchange transaction (gain) loss Foreign Currency Transactions And Translations Policy [Text Block] Foreign Currency Translation Future Minimum Payments Under Non Cancelable Operating Leases With Initial Terms Of One Year Or More [Line Items] Future Minimum Payments Under Non Cancelable Operating Leases With Initial Terms Of One Year Or More [Line Items] Future Minimum Payments Under Non Cancelable Operating Leases With Initial Terms Of One Year Or More [Line Items] Future Minimum Payments Under Non Cancelable Operating Leases With Initial Terms Of One Year Or More [Table] Future Minimum Payments Under Non Cancelable Operating Leases With Initial Terms Of One Year Or More [Table] Future Minimum Payments Under Non Cancelable Operating Leases With Initial Terms Of One Year Or More [Table] General And Administrative Expense General and administrative General And Administrative Expense [Member] General and administrative expense [Member]