Debt Disclosure [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Convertible debt Convertible Debt [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Convertible senior notes due 2020 Convertible Senior Notes Due 2020 [Member] Convertible Senior Notes Due 2020 [Member] Convertible senior notes due 2023 Convertible Senior Notes Due 2023 [Member] Convertible Senior Notes Due 2023 [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Value of debt Debt Instrument, Fair Value Disclosure Share price (in dollars per share) Share Price Debt instrument, conversion price (in dollars per share) Debt Instrument, Convertible, Conversion Price Principal amount Long-term Debt, Gross Earnings Per Share [Abstract] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Shares issuable upon conversion of preferred stock Convertible Preferred Stock, Shares Issuable [Member] Convertible Preferred Stock, Shares Issuable [Member] Restricted stock units Restricted Stock Units (RSUs) [Member] Shares issuable upon conversion of 2023 Notes Convertible Debt Securities [Member] Options to purchase common stock Employee And Non Employee Stock Options [Member] An arrangement whereby an employee and non-employee is entitled to receive in the future, subject to vesting and other restrictions, a number of shares in the entity at a specified price, as defined in the agreement. Performance awards Performance Shares [Member] Shares issuable pursuant to the ESPP Employee Stock [Member] Anti-dilutive securities Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Total common stock equivalents (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Debt Instruments Debt Disclosure [Text Block] Numerator Net Income (Loss) Attributable to Parent [Abstract] Net loss Net Income (Loss) Attributable to Parent Less: Stock dividend payable and transaction costs Redeemable Preferred Stock Dividends Net loss available to common stockholders Net Income (Loss) Available to Common Stockholders, Basic Denominator Weighted Average Number of Shares Outstanding, Diluted [Abstract] Weighted-average basic and diluted common shares Weighted Average Number of Shares Outstanding, Basic and Diluted Net loss per common share, basic and diluted (in dollars per share) Earnings Per Share, Basic and Diluted Goodwill and Intangible Assets Disclosure [Abstract] Schedule of Acquired Finite-Lived Intangible Asset by Major Class [Table] Schedule of Acquired Finite-Lived Intangible Asset by Major Class [Table] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Total finite-lived intangible assets Finite-Lived Intangible Assets, Major Class Name [Domain] Patents Patents [Member] Developed technology Developed Technology Rights [Member] Customer relationships Customer Relationships, Users [Member] Customer Relationships, Users [Member] Trade names Trade Names [Member] Acquired Finite-Lived Intangible Assets [Line Items] Acquired Finite-Lived Intangible Assets [Line Items] Finite-lived intangible assets Finite-Lived Intangible Assets, Net [Abstract] Gross Carrying Amount Finite-Lived Intangible Assets, Gross Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Net Carrying Value Finite-Lived Intangible Assets, Net Business Combinations [Abstract] Share exchange ratio Merger Agreement, Equity Interest Issued or Issuable, Stock Conversion Ratio Merger Agreement, Equity Interest Issued or Issuable, Stock Conversion Ratio Contingent Termination Fee Merger Agreement, Contingent Termination Fee Merger Agreement, Contingent Termination Fee Allocation of estimated fair values of net assets acquired Business Combination, Separately Recognized Transactions [Table Text Block] Line of Credit Facility [Table] Line of Credit Facility [Table] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Line of credit Line of Credit [Member] Letter of credit Letter of Credit [Member] Debt Instruments Line of Credit Facility [Line Items] Maximum borrowings available Line of Credit Facility, Maximum Borrowing Capacity Line of Credit Facility, Option To Increase Maximum Borrowing Capacity Line of Credit Facility, Option To Increase Maximum Borrowing Capacity Line of Credit Facility, Option To Increase Maximum Borrowing Capacity Outstanding borrowings Long-term Line of Credit Outstanding amount Letters of Credit Outstanding, Amount Available borrowing capacity Line of Credit Facility, Current Borrowing Capacity Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] RSUs Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Stock-based compensation expense Allocated Share-based Compensation Expense Document and Entity Information [Abstract] Document and Entity Information [Abstract] Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Current Reporting Status Entity Current Reporting Status Entity Filer Category Entity Filer Category Entity Emerging Growth Company Entity Emerging Growth Company Entity Small Business Entity Small Business Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus (Q1,Q2,Q3,FY) Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding (in shares) Entity Common Stock, Shares Outstanding Schedule changes in goodwill Schedule of Goodwill [Table Text Block] Summary of gross carrying amounts and accumulated amortization of intangible assets - finite lived Schedule of Acquired Finite-Lived Intangible Assets by Major Class [Table Text Block] Schedule of future amortization expense related to finite-lived intangible assets Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Statement of Financial Position [Abstract] Assets Assets [Abstract] Current assets Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Short-term investments Short-term Investments Accounts receivable, net of allowance of $5,352 at December 31, 2017 and $7,855 at September 30, 2018 Receivables, Net, Current Prepaid content acquisition costs Prepaid Royalties Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Total current assets Assets, Current Convertible promissory note receivable Receivable with Imputed Interest, Net Amount Property and equipment, net Property, Plant and Equipment, Net Goodwill Goodwill Intangible assets, net Intangible Assets, Net (Excluding Goodwill) Other long-term assets Other Assets, Noncurrent Total assets Assets Liabilities, redeemable convertible preferred stock and stockholders’ equity Liabilities and Equity [Abstract] Current liabilities Liabilities, Current [Abstract] Accounts payable Accounts Payable, Current Accrued liabilities Accrued Liabilities, Current Accrued content acquisition costs Accrued Royalties, Current Accrued compensation Employee-related Liabilities, Current Deferred revenue Contract with Customer, Liability, Current Total current liabilities Liabilities, Current Long-term debt, net Long-term Debt Other long-term liabilities Other Liabilities, Noncurrent Total liabilities Liabilities Redeemable convertible preferred stock: 480,000 shares issued and outstanding at December 31, 2017 and 480,000 at September 30, 2018 Temporary Equity, Carrying Amount, Including Portion Attributable to Noncontrolling Interests Stockholders’ equity Stockholders' Equity Attributable to Parent [Abstract] Common stock: 250,867,462 shares issued and outstanding at December 31, 2017 and 269,774,079 at September 30, 2018 Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital Accumulated deficit Retained Earnings (Accumulated Deficit) Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Total stockholders’ equity Stockholders' Equity Attributable to Parent Total liabilities, redeemable convertible preferred stock and stockholders’ equity Liabilities and Equity Amortization expense of intangible assets Amortization of Intangible Assets Goodwill and Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Valuation Approach and Technique [Axis] Valuation Approach and Technique [Axis] Valuation Approach and Technique [Domain] Valuation Approach and Technique [Domain] Black Scholes Options Pricing Model Black Scholes Options Pricing Model [Member] Represents information pertaining to the Black-Scholes options pricing model, a valuation method used in the computation of fair value of stock options. Stock options ESPP Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Expected life (in years) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Risk-free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Risk-free interest rate, minimum Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum Risk-free interest rate, maximum Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Maximum Expected volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Expected volatility, minimum Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum Expected volatility, maximum Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum Expected dividend yield Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Aggregate principal amount Debt Instrument, Face Amount Interest rate Debt Instrument, Interest Rate, Stated Percentage Net proceeds from sale of debt Proceeds from Debt, Net of Issuance Costs Payments for capped call transactions Payments for Derivative Instrument, Financing Activities Carrying value Loss on extinguishment of convertible debt Gain (Loss) on Extinguishment of Debt Debt instrument, conversion ratio Debt Instrument, Convertible, Conversion Ratio Carrying amount of equity component reported in additional paid-in-capital Debt Instrument, Convertible, Carrying Amount of Equity Component Debt fees and expenses Debt Instrument, Fee Amount Cash and Cash Equivalents [Abstract] Unrealized gains Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax Income Tax Disclosure [Abstract] Valuation Allowance [Table] Valuation Allowance [Table] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] AdsWizz AdsWizz, Inc. [Member] AdsWizz, Inc. [Member] Valuation Allowance [Line Items] Valuation Allowance [Line Items] Release of valuation allowance Valuation Allowances and Reserves, Period Increase (Decrease), Acquisitions Valuation Allowances and Reserves, Period Increase (Decrease), Acquisitions Schedule of cash, cash equivalents and investments Cash, Cash Equivalents and Investments [Table Text Block] Summary of available-for-sale securities' adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category Schedule of Available-for-sale Securities Reconciliation [Table Text Block] Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Developed technology Developed Technology [Member] Developed Technology [Member] Customer relationships Customer Relationships [Member] Trade name Trade Name [Member] Trade Name [Member] Business Acquisition [Line Items] Business Acquisition [Line Items] Finite-lived intangible assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles Tangible assets acquired, net Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets Deferred tax liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Noncurrent Net assets acquired Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Total fair value consideration Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net Estimated useful life in years Acquired Finite-lived Intangible Assets, Weighted Average Useful Life Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Temporary Equity Disclosure [Abstract] Temporary Equity, by Class of Stock [Table] Temporary Equity, by Class of Stock [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Series A convertible preferred stock Series A Preferred Stock [Member] Sale of Stock [Axis] Sale of Stock [Axis] Sale of Stock [Domain] Sale of Stock [Domain] Initial closing Initial Closing [Member] Initial Closing [Member] Second closing Closing Upon Certain Regulatory Approvals [Member] Closing Upon Certain Regulatory Approvals [Member] Temporary Equity [Line Items] Temporary Equity [Line Items] Agreement to sell shares (in shares) Temporary Equity, Share Subscriptions Share price (in dollars per share) Shares Issued, Price Per Share Agreement to sell shares Temporary Equity, Shares Subscribed but Unissued, Subscriptions Receivable Payments of issuance costs Payments of Stock Issuance Costs Proceeds from issuance of redeemable convertible preferred stock Proceeds from Issuance of Convertible Preferred Stock Discontinued Operations and Disposal Groups [Abstract] Dispositions Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Net Loss Per Common Share Earnings Per Share [Text Block] Series A redeemable convertible preferred stock Temporary Equity, Stock Issued During Period, Value, New Issues Issuance costs Accretion of issuance costs Accretion Expense Stock dividend payable to preferred stockholders Dividends Payable Redeemable convertible preferred stock Temporary Equity, Carrying Amount, Attributable to Parent Effective interest rate Debt Instrument, Interest Rate, Effective Percentage Contractually stated interest expense Interest Expense, Debt, Excluding Amortization Amortization of discount Amortization of Debt Discount (Premium) Schedule of assumptions used for determining the per-share fair value of shares granted under the ESPP Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions [Table Text Block] Schedule of stock-based compensation expenses related to all employee and non-employee stock-based awards Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block] Percentage of eligible compensation to purchase common stock through payroll deductions (as a percent) Share-based Compensation Arrangement by Share-based Payment Award, Maximum Employee Subscription Rate Offering period Share-Based Compensation Arrangement By Share-Based Payment Award, Offering Period Represents the offering period for award under the share based compensation. Contributions from employees withheld Share Based Compensation Arrangement by Share Based Payment Award Contribution from Employees Withheld Represents the amount of contributions from employees withheld. Common stock issued (in shares) Stock Issued During Period, Shares, Employee Stock Purchase Plans Restructuring and Related Activities [Abstract] Schedule of Restructuring and Related Costs [Table] Schedule of Restructuring and Related Costs [Table] Restructuring Plan [Axis] Restructuring Plan [Axis] Restructuring Plan [Domain] Restructuring Plan [Domain] 2018 Reduction in Force 2018 Reduction in Force [Member] 2018 Reduction in Force [Member] 2017 Reduction in Force 2017 Reduction in Force [Member] 2017 Reduction in Force [Member] Restructuring Type [Axis] Restructuring Type [Axis] Type of Restructuring [Domain] Type of Restructuring [Domain] Employee severance and benefits costs Employee Severance [Member] Restructuring Cost and Reserve [Line Items] Restructuring Cost and Reserve [Line Items] Reduction in force Restructuring and Related Cost, Number of Positions Eliminated, Period Percent Expected cash expenditures Restructuring and Related Cost, Incurred Cost Total reduction in force expenses Restructuring and Related Cost, Cost Incurred to Date Income Taxes Income Tax Disclosure [Text Block] Accounting Policies [Abstract] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Consolidation Consolidation, Policy [Policy Text Block] Reclassification Reclassification, Policy [Policy Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Business Combinations, Goodwill and Intangible Assets, net Business Combinations Policy [Policy Text Block] Concentration of Credit Risk Concentration Risk, Credit Risk, Policy [Policy Text Block] Recently Issued Accounting Standards New Accounting Pronouncements, Policy [Policy Text Block] Commitments and Contingencies Commitments and Contingencies, Policy [Policy Text Block] Accounts receivable, allowance Allowance for Doubtful Accounts Receivable Redeemable convertible preferred stock, shares issued (in shares) Temporary Equity, Shares Issued Redeemable convertible preferred stock, shares outstanding (in shares) Temporary Equity, Shares Outstanding Common stock, shares issued (in shares) Common Stock, Shares, Issued Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Revenue from Contract with Customer [Abstract] Revenues Revenue from Contract with Customer [Text Block] Investment Holdings [Table] Investment Holdings [Table] Investment Type [Axis] Investment Type [Axis] Investments [Domain] Investments [Domain] Cash Cash [Member] Money market funds Money Market Funds [Member] Commercial paper Commercial Paper [Member] Certificates of deposit Certificates of Deposit [Member] U.S. government and government agency debt securities US Government Corporations and Agencies Securities [Member] Commercial paper Commercial Paper, Not Included with Cash and Cash Equivalents [Member] Corporate debt securities Corporate Debt Securities [Member] Cash, Cash Equivalents and Investments Investment Holdings [Line Items] Cash and cash equivalents Short-term investments Cash, cash equivalents and investments Cash, Cash Equivalents, and Short-term Investments Schedule of Acquired Indefinite-lived Intangible Assets by Major Class [Table] Schedule of Acquired Indefinite-lived Intangible Assets by Major Class [Table] Acquired Indefinite-lived Intangible Assets [Line Items] Acquired Indefinite-lived Intangible Assets [Line Items] Redeemable Convertible Preferred Stock Stockholders' Equity Note Disclosure [Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Description of Business and Basis of Presentation Business Description and Basis of Presentation [Text Block] Receivables [Abstract] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Disposal Group Name [Axis] Disposal Group Name [Axis] Disposal Group Name [Domain] Disposal Group Name [Domain] Ticketfly Ticketfly, Inc. [Member] Ticketfly, Inc. [Member] Disposal Group Classification [Axis] Disposal Group Classification [Axis] Disposal Group Classification [Domain] Disposal Group Classification [Domain] Sold Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] Receivable Type [Axis] Receivable Type [Axis] Receivable [Domain] Receivable [Domain] Convertible promissory note Notes Receivable [Member] Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Aggregate unadjusted purchase price Disposal Group, Including Discontinued Operation, Consideration Cash portion of purchase price Disposal Group, Including Discontinued Operation, Consideration, Cash Disposal Group, Including Discontinued Operation, Consideration, Cash Convertible subordinated promissory note Disposal Group, Including Discontinued Operation, Consideration, Notes Receivable Disposal Group, Including Discontinued Operation, Consideration, Notes Receivable Cancellation fee Notes Receivable Cancellation Fee Notes Receivable Cancellation Fee Note term Notes Issued, Term Notes Issued, Term Stated interest rate Receivable, Interest Rate, Stated Percentage Receivable, Interest Rate, Stated Percentage Unamortized discount Receivable with Imputed Interest, Discount Purchase price adjustments Receivable with Imputed Interest, Purchase Price Adjustments Receivable with Imputed Interest, Purchase Price Adjustments Interest receivable Interest Receivable Amortization of discount Receivables with Imputed Interest, Amortization Amount Fair Value Disclosures [Abstract] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Level 3 Fair Value, Inputs, Level 3 [Member] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Recurring measurement Fair Value, Measurements, Recurring [Member] 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] Total assets measured at fair value Assets, Fair Value Disclosure Liabilities measured at fair value Financial and Nonfinancial Liabilities, Fair Value Disclosure Restructuring Charges Restructuring and Related Activities Disclosure [Text Block] Statement of Cash Flows [Abstract] Operating activities Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] 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] Goodwill impairment Goodwill, Impairment Loss Loss on dispositions Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal Loss on extinguishment of convertible debt Depreciation and amortization Depreciation, Depletion and Amortization Stock-based compensation Share-based Compensation Amortization (accretion) of premium on investments Amortization Of Premium On Investments, Net Amortization Of Premium On Investments, Net Accretion of discount on convertible promissory note receivable Accretion Of Discount On Convertible Promissory Note Receivable Accretion Of Discount On Convertible Promissory Note Receivable Other operating activities Other Operating Activities, Cash Flow Statement Amortization of debt discount Amortization of Debt Issuance Costs and Discounts Interest income Interest Income, Operating Provision for bad debt Provision for Doubtful Accounts Changes in operating assets and liabilities Increase (Decrease) in Operating Capital [Abstract] Accounts receivable Increase (Decrease) in Accounts Receivable Prepaid content acquisition costs Increase (Decrease) in Prepaid Royalties Prepaid expenses and other assets Increase (Decrease) in Prepaid Expense and Other Assets Accounts payable, accrued and other current liabilities Increase (Decrease) in Accounts Payable and Accrued Liabilities Accrued content acquisition costs Increase (Decrease) in Royalties Payable Accrued compensation Increase (Decrease) in Employee Related Liabilities Other long-term liabilities Increase (Decrease) in Other Noncurrent Liabilities Deferred revenue Increase (Decrease) in Contract with Customer, Liability Reimbursement of cost of leasehold improvements Payments for (Proceeds from) Tenant Allowance Net cash used in operating activities Net Cash Provided by (Used in) Operating Activities Investing activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Purchases of property and equipment Payments to Acquire Property, Plant, and Equipment Internal-use software costs Payments to Develop Software Payments related to acquisition, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Purchases of investments Payments to Acquire Investments Proceeds from maturities of investments Proceeds from Sale, Maturity and Collection of Investments Proceeds from cancellation of convertible promissory note receivable Proceeds from Collection of Notes Receivable Proceeds from sales of subsidiaries, net of cash Proceeds from Divestiture of Businesses, Net of Cash Divested Net cash provided by (used in) investing activities Net Cash Provided by (Used in) Investing Activities Financing activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Proceeds from issuance of redeemable convertible preferred stock Proceeds from Issuance of Redeemable Convertible Preferred Stock Payments of issuance costs Payments of Debt Issuance Costs Repayment of debt arrangements Repayments of Debt Proceeds from employee stock purchase plan Proceeds from Stock Plans Proceeds from exercise of stock options Proceeds from Issuance of Common Stock Tax withholdings related to net share settlements of restricted stock units Payments Related to Tax Withholding for Share-based Compensation Net cash provided by (used in) financing activities Net Cash Provided by (Used in) Financing Activities Effect of exchange rate changes on cash, cash equivalents and restricted cash Effect of Exchange Rate on Cash and Cash Equivalents Net increase (decrease) in cash, cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Cash, cash equivalents and restricted cash at beginning of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash, cash equivalents and restricted cash at end of period Supplemental disclosures of cash flow information Supplemental Cash Flow Information [Abstract] Purchases of property and equipment recorded in accounts payable and accrued liabilities Capital Expenditures Incurred but Not yet Paid Cash paid during the period for interest Interest Paid, Excluding Capitalized Interest, Operating Activities Accretion of preferred stock issuance costs Stock dividend payable to preferred stockholders Dividends, Preferred Stock Contingent consideration related to acquisition Business Combination, Contingent Consideration, Liability Fair value of shares issued related to acquisition Business Acquisition, Equity Interest Issued or Issuable, Value Assigned Fair value of convertible promissory note received as partial consideration for sale of subsidiary Noncash or Part Noncash Divestiture, Amount of Consideration Received Employee stock purchase plan (ESPP) purchases Noncash Equity Stock Purchase Plan Purchases Increase (Decrease) in Noncash Equity Liability Contract duration Contract Duration Contract Duration Maximum payment term Maximum Payment Term Maximum Payment Term Revenue from External Customers by Products and Services [Table] Revenue from External Customers by Products and Services [Table] Revenue from External Customer [Line Items] Revenue from External Customer [Line Items] Subscription payment term Subscription Payment Term Subscription Payment Term Revenues recognized, previously included deferred revenue Contract with Customer, Liability, Revenue Recognized Schedule of long-term debt Schedule of Long-term Debt Instruments [Table Text Block] Summary of the effective interest rate, contractually stated interest expense and costs related to amortization of discount for the Notes Convertible Debt [Table Text Block] Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Convertible Promissory Note Receivable Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Stock-based Compensation Plans and Awards Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Schedule of fair value of financial assets and liabilities inputs Fair Value Measurements, Recurring and Nonrecurring [Table Text Block] Cash, Cash Equivalents and Investments Cash, Cash Equivalents, and Marketable Securities [Text Block] 1.75% convertible senior notes due 2020 Effective interest rate Receivable with Imputed Interest, Effective Yield (Interest Rate) Contractually stated interest income Interest Income, Contractual Amount Interest Income, Contractual Amount Schedule of redeemable convertible preferred stock Schedule of Stock by Class [Table Text Block] 1.75% convertible senior notes due 2023 1.75% convertible senior notes Unamortized discount and deferred issuance costs Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net Long-term debt, net Purchase price Business Combination, Consideration Transferred Payments related to acquisition, net of cash acquired Payments to Acquire Businesses, Gross Stock issued for acquisition (in shares) Stock Issued During Period, Shares, Acquisitions Content acquisition costs Payments for Royalties Total future minimum guarantee payments Royalty Guarantees, Commitments, Amount Future minimum guarantee commitments to be paid this year Royalty Guarantees, Commitments, Future Minimum Payments Due, Remainder of Fiscal Year Royalty Guarantees, Commitments, Future Minimum Payments Due, Remainder of Fiscal Year Fair Value Fair Value Disclosures [Text Block] Quoted Prices in Active Markets for Identical Instruments (Level 1) Fair Value, Inputs, Level 1 [Member] Significant Other Observable Inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Commercial paper Assets Assets, Fair Value Disclosure [Abstract] Money market funds Cash and Cash Equivalents, Fair Value Disclosure Assets measured at fair value Debt Securities, Available-for-sale Total assets measured at fair value Schedule of the computation of historical basic and diluted net loss per share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Schedule of potential common shares outstanding excluded 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Debt Conversion, Converted Instrument, Shares Debt instrument, threshold note trading days Debt Instrument, Convertible, Threshold Note Trading Days Debt Instrument, Convertible, Threshold Note Trading Days Debt instrument, threshold consecutive note trading days Debt Instrument, Convertible Note, Threshold Consecutive Trading Days Debt Instrument, Convertible Note, Threshold Consecutive Trading Days Debt instrument, threshold principle amount of note trigger Debt Instrument, Convertible, Threshold Principle Amount of Note Trigger Debt Instrument, Convertible, Threshold Principle Amount of Note Trigger Debt instrument, threshold percentage of note price trigger Debt Instrument, Convertible, Threshold Percentage Of Note Price Trigger Debt Instrument, Convertible, Threshold Percentage Of Note Price Trigger Remainder of 2018 Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year 2019 Finite-Lived Intangible Assets, Amortization Expense, Year Two 2020 Finite-Lived Intangible Assets, Amortization Expense, Year Three 2021 Finite-Lived Intangible Assets, Amortization Expense, Year Four 2022 Finite-Lived Intangible Assets, Amortization Expense, Year Five Thereafter Finite-Lived Intangible Assets, Amortization Expense, after Year Five Schedule of interest rates and amortization discount Schedule Of Interest Rates And Amortization Discount [Table Text Block] Schedule Of Interest Rates And Amortization Discount [Table Text Block] Income Statement [Abstract] Statement [Table] Statement [Table] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Advertising Advertising [Member] Subscription and other License and Service [Member] Ticketing service Admission [Member] Cost of revenue—Content acquisition costs Royalty [Member] Cost of revenue—Other Service, Other [Member] Statement [Line Items] Statement [Line Items] Revenue Revenues [Abstract] Revenue Revenue from Contract with Customer, Excluding Assessed Tax Cost of revenue Cost of Revenue [Abstract] Cost of revenue Cost of Goods and Services Sold Gross profit Gross Profit Operating expenses Operating Expenses [Abstract] Product development Research and Development Expense (Excluding Acquired in Process Cost) Sales and marketing Selling and Marketing Expense General and administrative General and Administrative Expense Contract termination (benefit) fees Gain (Loss) on Contract Termination Total operating expenses Operating Expenses Loss from operations Operating Income (Loss) Interest expense Interest Expense Other income, net Other Nonoperating Income Total other expense, net Other Nonoperating Income (Expense) Loss before (provision for) benefit from income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest (Provision for) benefit from income taxes Income Tax Expense (Benefit) Net loss Net loss available to common stockholders Basic and diluted net loss per common share (in dollars per share) Goodwill [Roll Forward] Goodwill [Roll Forward] Balance as of December 31, 2017 Goodwill related to acquisition of AdsWizz Goodwill, Acquired During Period Balance as of September 30, 2018 Sirius XM Holdings Inc. Merger Agreement Mergers, Acquisitions and Dispositions Disclosures [Text Block]