Financial Standby Letter of Credit Financial Standby Letter of Credit [Member] Impairment of goodwill Goodwill, Impairment Loss Exercised (in shares) SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsExercisesinPeriodGross Maximum employee subscription rate Share-based Compensation Arrangement by Share-based Payment Award, Maximum Employee Subscription Rate Purchase price of common stock, percent Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent Common stock, par or stated value per share Common Stock, Par or Stated Value Per Share Other Commitments [Line Items] Other Commitments [Line Items] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Basic and Diluted EPS: Earnings Per Share, Basic [Abstract] Income Statement Location [Domain] Income Statement Location [Domain] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Accounting Policies [Abstract] Marketable securities Marketable Securities Restricted cash Restricted Cash Purchases of property and equipment Payments to Acquire Property, Plant, and Equipment Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Debt Instrument, Covenant Compliance Period [Domain] Debt Instrument, Covenant Compliance Period [Domain] Debt Instrument, Covenant Compliance Period Business Combination In The Money Options Assumed Business Combination In The Money Options Assumed Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Additional Paid-In Capital Additional Paid-in Capital [Member] Line of Credit Facility [Table] Line of Credit Facility [Table] Prepaid and other assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets Common stock, shares, outstanding Beginning Balance (in shares) Ending Balance (in shares) Common Stock, Shares, Outstanding Cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Goodwill Goodwill Exercisable, aggregate intrinsic value Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Rental expense Operating Leases, Rent Expense Property and equipment, net Property, Plant and Equipment, Net Goodwill and Intangible Assets Intangible Assets Disclosure [Text Block] Debt Instrument [Axis] Debt Instrument [Axis] Outstanding, aggregate intrinsic value Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Expenses: Costs and Expenses [Abstract] Significant Other Observable Inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Preferred stock, shares outstanding Preferred Stock, Shares Outstanding Vested (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Restructuring and Other Exit Costs Restructuring and Related Activities Disclosure [Text Block] Stock Option Employee Stock Option [Member] Compliance period, December 31, 2019 and thereafter Debt Instrument, Covenant Compliance Period Three [Member] Debt Instrument, Covenant Compliance Period Three Internal use software development costs, net InternalUseSoftwareDevelopmentCostsNet Expected term (in years) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period Available borrowing capacity Line of Credit Facility, Remaining Borrowing Capacity Statement [Table] Statement [Table] Measurement Frequency [Axis] Measurement Frequency [Axis] INVESTING ACTIVITIES: Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Changes in operating assets and liabilities, net of effect of business acquisitions: Increase (Decrease) in Operating Capital [Abstract] Unrealized gain (loss) Available-for-sale Securities, Change in Net Unrealized Holding Gain (Loss), Net of Tax Number of shares available for grant Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Accumulated deficit Retained Earnings (Accumulated Deficit) Debt Debt Disclosure [Text Block] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Intrinsic value of nonvested unit Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Nonvested Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] OPERATING ACTIVITIES: Net Cash Provided by (Used in) Operating Activities [Abstract] Developed technology Developed Technology Rights [Member] Compliance period, September 30, 2019 Debt Instrument, Covenant Compliance Period Two [Member] Debt Instrument, Covenant Compliance Period Two Business Combinations Business Combination Disclosure [Text Block] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] SUPPLEMENTAL DISCLOSURES OF OTHER CASH FLOW INFORMATION: Supplemental Cash Flow Information [Abstract] Issuance of common stock related to employee stock purchase plan Stock Issued During Period, Value, Employee Stock Purchase Plan Total Finite-Lived Intangible Assets, Net U.S. Treasury, government and agency debt securities U.S. Treasury, government and agency debt securities US Treasury and Government [Member] The 2017 Restructuring Events The2017RestructuringEventsMember Risk-free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Stock-based compensation expense Allocated Share-based Compensation Expense Business Acquisition, Equity Interest Issued or Issuable, Number of Shares Business Acquisition, Equity Interest Issued or Issuable, Number of Shares 2019 Finite-Lived Intangible Assets, Amortization Expense, Year Two Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] ASSETS Assets [Abstract] Weighted remaining contractual maturity AvailableforsaleSecuritiesWeightedaverageRemainingContractualMaturity Business Combination Net Operating Loss Acquired Business Combination Net Operating Loss Acquired Borrowing capacity reserve Line Of Credit Facility, Borrowing Capacity, Reserves Line Of Credit Facility, Borrowing Capacity, Reserves Accretion of available for sale securities AccretionOfAvailableForSaleSecurities Preferred stock, shares authorized Preferred Stock, Shares Authorized Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Estimated Useful Life Acquired Finite-lived Intangible Assets, Weighted Average Useful Life Intent Marketing Solution IntentMarketingSolutionMember ESPP EmployeeStockPurchasePlanMember Business Acquisition [Axis] Business Acquisition [Axis] Accounts payable—trade Accounts Payable, Trade, Current Document Fiscal Year Focus Document Fiscal Year Focus Market Approach Valuation Technique Market Approach Valuation Technique [Member] Revenue from Contract with Customer [Abstract] STOCKHOLDERS' EQUITY Stockholders' Equity Attributable to Parent [Abstract] Other Commitments [Table] Other Commitments [Table] Fair value of options vested in period Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value Cash paid for interest Interest Paid, Net Fair Value Measurements Fair Value Disclosures [Text Block] Accounts payable and accrued expenses Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable Unrealized foreign currency gains, net Foreign Currency Transaction Gain (Loss), Unrealized Other assets, non-current Other Assets, Noncurrent Business Combination, Consideration Transferred Business Combination, Consideration Transferred Preferred stock, shares issued Preferred Stock, Shares Issued Available-for-sale Securities Available-for-sale Securities Accumulated Deficit Retained Earnings [Member] Net cash provided by (used in) investing activities Net Cash Provided by (Used in) Investing Activities Debt Covenant Terms [Axis] Debt Covenant Terms [Axis] Debt covenant terms Accounts payable—seller AccountsPayableSellerCurrent Schedule of Accounts Payable and Accrued Liabilities Schedule of Accounts Payable and Accrued Liabilities [Table Text Block] Restructuring Plan [Domain] Restructuring Plan [Domain] Business Acquisition [Line Items] Business Acquisition [Line Items] Unused capacity fee, percentage Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Schedule of Restructuring and Related Costs [Table] Schedule of Restructuring and Related Costs [Table] Total shares excluded from net income (loss) per share (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Statement of Financial Position [Abstract] Unrecognized employee stock-based compensation Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options Business Combinations [Abstract] Contract with Customer, Sales Channel [Domain] Contract with Customer, Sales Channel [Domain] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Issuance of common stock related to RSU vesting Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures Sales of available-for-sale securities Proceeds from Sale of Available-for-sale Securities Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Restructuring and other exit costs Restructuring Charges Schedule of Share-based Compensation, Stock Options, Activity Share-based Compensation, Stock Options, Activity [Table Text Block] Debt Disclosure [Abstract] Sales and marketing Selling and Marketing Expense [Member] Schedule of Nonvested Restricted Stock Units Activity Schedule of Nonvested Restricted Stock Units Activity [Table Text Block] Valuation Technique [Axis] Valuation Technique [Axis] Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Two Year RSUs TwoYearRSUsMember Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table] Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table] Vested Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Vesting [Domain] Vesting [Domain] 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] FINANCING ACTIVITIES: Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Variable interest rate Debt Instrument, Basis Spread on Variable Rate Taxes paid related to net share settlement Payments Related to Tax Withholding for Share-based Compensation Options to purchase common stock Equity Option [Member] Available-for-sale—short-term Short-term Investments [Member] Covenant Terms, Scenario One Covenant Terms, Scenario One [Member] Covenant Terms, Scenario One Restructuring Reserve [Roll Forward] Restructuring Reserve [Roll Forward] Granted (usd per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price CASH, CASH EQUIVALENTS AND RESTRICTED CASH — Beginning of period CASH, CASH EQUIVALENTS AND RESTRICTED CASH — End of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Valuation Technique [Domain] Valuation Technique [Domain] Foreign currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent Thereafter Finite-Lived Intangible Assets, Amortization Expense, after Year Five Weighted average grant date fair value Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Loss before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Outstanding Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Other comprehensive income (loss) Other comprehensive loss Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Stock-based compensation Share-based Compensation Restricted awards RestrictedawardsMember Other comprehensive income (loss): Other Comprehensive Income (Loss), Net of Tax [Abstract] Contract with Customer, Sales Channel [Axis] Contract with Customer, Sales Channel [Axis] Geographical [Axis] Geographical [Axis] Total intangible assets acquired Finite-lived Intangible Assets Acquired Weighted-Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Accounts receivable Increase (Decrease) in Accounts Receivable Significant Unobservable Inputs (Level 3) Fair Value, Inputs, Level 3 [Member] Desktop DesktopMember Unrealized gain on investments Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax Cash paid for restructuring and other exit costs Payments for Restructuring Entity Filer Category Entity Filer Category Maturities of available-for-sale securities Proceeds from Maturities, Prepayments and Calls of Available-for-sale Securities Expected future operating lease commitments Operating Leases, Future Minimum Payments Due Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Trademarks Trademarks [Member] Income Tax Disclosure [Abstract] Nonvested Restricted Stock Shares Activity Nonvested Restricted Stock Shares Activity [Table Text Block] Comprehensive loss Comprehensive Income (Loss), Net of Tax, Attributable to Parent Statement [Line Items] Statement [Line Items] Schedule of Recognized Identified Assets Acquired and Liabilities Assumed Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block] Entity Registrant Name Entity Registrant Name Adjusted EBITDA maximum Debt Instrument, Covenant Compliance, Adjusted Earnings Before Interest Taxes Depreciation And Amortization Maximum Adjusted Earnings Before Interest Taxes Depreciation And Amortization Maximum Forfeited (usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Weighted Average Grant Date Fair Value LIABILITIES Liabilities [Abstract] Issuance of common stock related to employee stock purchase plan (in shares) Stock Issued During Period, Shares, Employee Stock Purchase Plans Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Amendment Flag Amendment Flag Business Combination Restricted Stock Assumed Business Combination Restricted Stock Assumed Expired (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Expirations in Period Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Axis] Deferred tax liability, net Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Noncurrent Vesting [Axis] Vesting [Axis] Accounts receivable Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables Entity Central Index Key Entity Central Index Key Provisional GILTI inclusion for ASC Topic 740 GlobalIntangibleLowTaxedIncomeGILTIProvisionalInclusion Office Lease OfficeLeaseMember Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Schedule of Finite-Lived Intangible Assets Schedule of Finite-Lived Intangible Assets [Table Text Block] Weighted-average common shares outstanding Weighted Average Number of Shares Outstanding, Basic and Diluted Deferred income taxes Deferred Income Taxes and Tax Credits Loss on disposal of property and equipment Gain (Loss) on Disposition of Property Plant Equipment Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Common stock, shares authorized Common Stock, Shares Authorized Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] Products and Services [Domain] Products and Services [Domain] Fair Value Disclosures [Abstract] Shares withheld related to net share settlement Adjustments Related to Tax Withholding for Share-based Compensation Variable Rate [Domain] Variable Rate [Domain] Business Combination, Acquisition Related Costs Business Combination, Acquisition Related Costs Loan Agreement Loan Agreement [Member] Loan Agreement TOTAL STOCKHOLDERS' EQUITY Beginning Balance Ending Balance Stockholders' Equity Attributable to Parent Amortizable intangible assets, gross Finite-Lived Intangible Assets, Gross Costs related to non-cash stock-based compensation Non-cash stock-based compensation for restructuring and other exit costs Restructuring Reserve, Settled without Cash Plan Name [Axis] Plan Name [Axis] Revenues Revenue from Contract with Customer [Text Block] Document and Entity Information [Abstract] Document and Entity Information [Abstract] Investments [Domain] Investments [Domain] Equity Component [Domain] Equity Component [Domain] Exercisable (usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Common Stock Common Stock [Member] Fixed assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment Realized gain (loss) Available-for-sale Securities, Gross Realized Gain (Loss) Lease Arrangement, Type [Axis] Lease Arrangement, Type [Axis] Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Geographical [Domain] Geographical [Domain] Accrued restructuring costs Accrued restructuring and other exit costs at December 31, 2017 Accrued restructuring and other exit costs at September 30, 2018 Restructuring Reserve Streamline Period [Domain] Debt Instrument, Covenant Compliance, Streamline Period [Domain] Debt Instrument, Covenant Compliance, Streamline Period Exercisable (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Capitalized debt issuance costs Debt Issuance Costs, Net Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Current Fiscal Year End Date Current Fiscal Year End Date 2014 Employee Stock Purchase Plan A2014EmployeeStockPurchasePlanMember Intrinsic values of options exercised Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value Unvested restricted stock awards Restricted Stock Awards Restricted Stock [Member] Equity Award [Domain] Equity Award [Domain] Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract] Intangible assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill Granted (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Provision for doubtful accounts Provision for Doubtful Accounts Prime Rate Prime Rate [Member] Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Quoted Prices in Active Markets for Identical Assets (Level 1) Fair Value, Inputs, Level 1 [Member] Amortized Cost Available-for-sale Debt Securities, Amortized Cost Basis Proceeds from issuance of common stock under employee stock purchase plan Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options Stock-Based Compensation Disclosure of Compensation Related Costs, Share-based Payments [Text Block] General and administrative General and Administrative Expense [Member] Income Statement Location [Axis] Income Statement Location [Axis] Available-for-sale — long-term Other Long-term Investments [Member] Canceled Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities Net cash provided by (used in) operating activities Net Cash Provided by (Used in) Operating Activities Beginning balance (in shares) Ending balance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Prepaid expenses and other assets Increase (Decrease) in Prepaid Expense and Other Assets Interest income, net Interest Income (Expense), Net Investment Type [Axis] Investment Type [Axis] Sales and marketing Selling and Marketing Expense Recurring Fair Value, Measurements, Recurring [Member] Restructuring and Related Activities [Abstract] Remaining 2018 Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year Loss from operations Operating Income (Loss) Total liabilities assumed Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities Commitments and Contingencies Disclosure [Abstract] Foreign exchange (gain) loss, net Foreign Currency Transaction Gain (Loss), before Tax Unrecognized employee stock-based compensation, period for recognition Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Basic and Diluted (usd per share) Basic and diluted net loss per share Earnings Per Share, Basic and Diluted Compliance period, September 30, 2018 through June 30, 2019 Debt Instrument, Covenant Compliance Period One [Member] Debt Instrument, Covenant Compliance Period One Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Beginning balance Ending balance Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Loss Contingency Nature [Axis] Loss Contingency Nature [Axis] Accrued employee-related payables Employee-related Liabilities, Current Expected volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Business Acquisition, Pro Forma Revenue Business Acquisition, Pro Forma Revenue Control premium Fair Value Inputs, Control Premium 2022 Finite-Lived Intangible Assets, Amortization Expense, Year Five Commitments and contingencies (Note 10) Commitments and Contingencies London Interbank Offered Rate (LIBOR) London Interbank Offered Rate (LIBOR) [Member] Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Statement of Stockholders' Equity [Abstract] Technology and development Research and Development Expense TOTAL LIABILITIES Liabilities Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Restructuring and Other Exit Costs Restructuring and Related Costs [Table Text Block] United States UNITED STATES Capitalized assets financed by accounts payable and accrued expenses Capital Expenditures Incurred but Not yet Paid Document Period End Date Document Period End Date EFFECT OF EXCHANGE RATE CHANGES ON CASH, CASH EQUIVALENTS AND RESTRICTED CASH Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination [Table Text Block] Cash and cash equivalents Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents Weighted-average unvested restricted shares Weighted Average Number of Shares, Restricted Stock Other Balance Sheet Amounts Supplemental Balance Sheet Disclosures [Text Block] Revolving Credit Facility Revolving Credit Facility [Member] Common stock, $0.00001 par value; 500,000 shares authorized at September 30, 2018 and December 31, 2017; 50,750 and 50,239 shares issued and outstanding at September 30, 2018 and December 31, 2017, respectively Common Stock, Value, Issued Technology and development Research and Development Expense [Member] Cost of revenue Cost of Sales [Member] Dividend yield Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Investments in available-for-sale securities Payments to Acquire Available-for-sale Securities Trademark & trade name Trademarks and Trade Names [Member] Basis of Presentation and Summary of Significant Accounting Policies Basis of Accounting, Policy [Policy Text Block] Stock-based compensation Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Business Acquisition, Pro Forma Net Income (Loss) Business Acquisition, Pro Forma Net Income (Loss) TOTAL ASSETS Assets Schedule of Finite-Lived Intangible Assets, Future Amortization Expense Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Fair Value Available-for-sale Securities, Debt Securities Plan Name [Domain] Plan Name [Domain] Exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Major Types of Debt and Equity Securities [Domain] Major Types of Debt and Equity Securities [Domain] Restricted stock awards, net Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures Basic and Diluted (in shares) Weighted-average common shares outstanding used to compute net loss per share WeightedAverageNumberOfSharesOutstandingUsedToComputeEarningsPerShareBasicandDiluted Other non-current assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets Document Fiscal Period Focus Document Fiscal Period Focus Expired (usd per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Expirations in Period, Weighted Average Exercise Price Document Type Document Type Capitalized internal use software development costs Payments to Develop Software Income Statement [Abstract] Streamline Period Does Not Apply Streamline Period Not In Effect [Member] Streamline Period Not In Effect Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets Provisional Transition Tax recorded due to Tax Act TaxCutsAndJobsActOf2017IncompleteAccountingProvisionalIncomeTaxExpenseBenefit Restructuring and other exit costs Restructuring Charges [Member] Other (income) expense: Nonoperating Income (Expense) [Abstract] Amortization expense of intangible assets Amortization of Intangible Assets Total expenses Costs and Expenses Restructuring Plan [Axis] Restructuring Plan [Axis] Corporate debt securities Corporate Debt Securities [Member] Use of Estimates Use of Estimates, Policy [Policy Text Block] Provision for income taxes Income Tax Expense (Benefit) Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] TOTAL CURRENT ASSETS Assets, Current CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect 2021 Finite-Lived Intangible Assets, Amortization Expense, Year Four Payments to Acquire Businesses, Net of Cash Acquired Payments to Acquire Businesses, Net of Cash Acquired TOTAL CURRENT LIABILITIES Liabilities, Current EBITDA multiple Fair Value Inputs, Earnings before Interest, Taxes, Depreciation, and Amortization Multiple Discounted cash flow rate Fair Value Inputs, Discount Rate Total assets acquired Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets General and administrative General and Administrative Expense Balance Sheet Related Disclosures [Abstract] Unvested restricted stock units Restricted Stock Units (RSUs) Restricted Stock Units (RSUs) [Member] Other income Other Operating Income Covenant Terms, Scenario Two Covenant Terms, Scenario Two [Member] Covenant Terms, Scenario Two TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY Liabilities and Equity Investments in Marketable Securities Marketable Securities [Table Text Block] Additional paid-in capital Additional Paid in Capital Accounts receivable, net Accounts Receivable, Net, Current Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Number of Shares Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Equity Components [Axis] Equity Components [Axis] Granted Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Variable Rate [Axis] Variable Rate [Axis] Canceled (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Cost of revenue Cost of Revenue Award Type [Axis] Award Type [Axis] Intangible assets, net Intangible Assets, Net (Excluding Goodwill) Adjusted Quick Ratio Debt Instrument, Adjusted Quick Ratio Debt Instrument, Adjusted Quick Ratio Mobile MobileMember Common stock, shares, issued Common Stock, Shares, Issued Deferred revenue Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Deferred Revenue Preferred stock, par or stated value per share (usd per share) Preferred Stock, Par or Stated Value Per Share Debt Covenant Terms [Domain] Debt Covenant Terms [Domain] Debt Covenant Terms Debt Instrument, Covenant Compliance Period [Axis] Debt Instrument, Covenant Compliance Period [Axis] Debt Instrument, Covenant Compliance Period nToggle nToggle [Member] Beginning balance (usd per share) Ending balance (usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Cash paid for income taxes Income Taxes Paid Preferred stock, $0.00001 par value, 10,000 shares authorized at September 30, 2018 and December 31, 2017; 0 shares issued and outstanding at September 30, 2018 and December 31, 2017 Preferred Stock, Value, Issued Percentage of adjusted EBITDA Debt Instrument, Covenant Compliance, Adjusted EBITDA, Variance From Projections Debt Instrument, Covenant Compliance, Adjusted EBITDA, Variance From Projections Adjusted Quick Ratio, in streamline period Debt Instrument Adjusted Quick Ratio, In Streamline Period Debt Instrument Adjusted Quick Ratio, In Streamline Period Income Approach Valuation Technique Income Approach Valuation Technique [Member] Award vesting rights, percentage Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Adjusted EBITDA minimum Debt Instrument, Covenant Compliance, Adjusted Earnings Before Interest Taxes Depreciation And Amortization Minimum Debt Instrument, Covenant Compliance, Adjusted Earnings Before Interest Taxes Depreciation And Amortization Minimum Capitalized stock-based compensation Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount Net loss Net loss Net loss Net Income (Loss) Attributable to Parent Total accumulated amortization—intangible assets Finite-Lived Intangible Assets, Accumulated Amortization Organization and Summary of Significant Accounting Policies Basis of Presentation and Significant Accounting Policies [Text Block] Adjustments to reconcile net loss to net cash provided by (used in) operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Schedule of Available-for-sale Securities [Line Items] Schedule of Available-for-sale Securities [Line Items] Business Acquisition, Pro Forma Information Business Acquisition, Pro Forma Information [Table Text Block] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Total net assets acquired Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Fair value of restricted stock Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value 2020 Finite-Lived Intangible Assets, Amortization Expense, Year Three Shares withheld related to net share settlement (in shares) Shares Paid for Tax Withholding for Share Based Compensation Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs for all Plans Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Other liabilities Increase (Decrease) in Other Operating Liabilities Vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Products and Services [Axis] Products and Services [Axis] Depreciation and amortization Depreciation, Depletion and Amortization Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Letters of credit outstanding, amount Letters of Credit Outstanding, Amount Employee Stock Employee Stock [Member] Lease Arrangement, Type [Domain] Lease Arrangement, Type [Domain] Total other (income) expense, net Nonoperating Income (Expense) Streamline Period Applies Streamline Period In Effect [Member] Streamline Period In Effect Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Current liabilities: Liabilities, Current [Abstract] Data Centers For Cloud-Based Services DataCentersForCloudBasedServicesMember Nonrecurring Fair Value, Measurements, Nonrecurring [Member] Fair Value, Assets Measured on Recurring Basis Fair Value, Assets Measured on Recurring Basis [Table Text Block] Gross Unrealized Gains Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax Exercise of common stock options (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period LIABILITIES AND STOCKHOLDERS' EQUITY Liabilities and Equity [Abstract] Beginning balance (in dollars per share) Ending balance (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted 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