Organization, Consolidation and Presentation of Financial Statements [Abstract] Description of Business Business Description and Basis of Presentation [Text Block] Document And Entity Information No definition available 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 Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity Current Reporting Status Entity Current Reporting Status Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Voluntary Filers Entity Public Float Entity Public Float Accounting Policies [Abstract] Fully executed IOs, term (less than) Revenue Recognition, Insertion Order, Term Revenue Recognition, Insertion Order, Term Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Number of Options Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Outstanding balance at beginning of period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures Exercised (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Cancelled (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period Outstanding balance at end of period (in shares) Exercisable at end of period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Vested and expected to vest at end of period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number Weighted- Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Outstanding balance at beginning of period (in usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Granted (in usd per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Exercised (in usd per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Cancelled (in usd per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price Outstanding balance at end of period (in usd per share) Exercisable at end of period (in usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Vested and expected to vest at end of period (in usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price Weighted- Average Remaining Contractual Term Share Based Compensation Arrangement By Share Based Payment Award Options Weighted Average Remaining Contractual Term [Abstract] No definition available. Outstanding balance at end of period (in years) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Exercisable at end of period (in years) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Vested and expected to vest at end of period (in years) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term Aggregate Intrinsic Value Share Based Compensation Arrangement By Share Based Payment Award Options Intrinsic Value [Abstract] No defintion available. Outstanding balance at end of period Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Exercisable at end of period Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Vested and expected to vest at end of period Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value Advertising and marketing costs Marketing and Advertising Expense Income Tax Disclosure [Abstract] Deferred Tax Assets Deferred Tax Assets, Net [Abstract] Current: Deferred Tax Assets, Net of Valuation Allowance, Current Classification [Abstract] Accrued expenses Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Accrued Liabilities Valuation allowance Deferred Tax Assets, Valuation Allowance, Current Total current deferred tax asset Deferred Tax Assets, Net of Valuation Allowance, Current Long-term: Deferred Tax Assets, Net of Valuation Allowance, Noncurrent Classification [Abstract] Stock-based compensation Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost Future benefit of carry forward losses Deferred Tax Assets, Operating Loss Carryforwards Other accruals Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Other Valuation allowance Deferred Tax Assets, Valuation Allowance, Noncurrent Total long-term deferred tax asset Deferred Tax Assets, Net of Valuation Allowance Deferred Tax Liabilities Deferred Tax Liabilities, Gross [Abstract] Current: Deferred Tax Liabilities, Net, Current Classification [Abstract] Deferred Tax Liabilities, Net, Current Classification [Abstract] Other accruals Deferred Tax Liabilities, Deferred Expense, Reserves and Accruals, Current Amount of deferred tax liability attributable to taxable temporary differences from reserves and accruals expected to be realized or consumed within one year or operating cycle, if longer. Total current deferred tax liability Deferred Tax Liabilities, Gross, Current Long-term: Deferred Tax Liabilities, Net, Noncurrent Classification [Abstract] Deferred Tax Liabilities, Net, Noncurrent Classification [Abstract] Amortization Deferred Tax Liabilities, Deferred Expense, Capitalized Software Depreciation Deferred Tax Liabilities, Property, Plant and Equipment Other accruals Deferred Tax Liabilities, Deferred Expense, Reserves and Accruals, Noncurrent Amount of deferred tax liability attributable to taxable temporary differences from reserves and accruals expected to be realized or consumed after one year (or the normal operating cycle, if longer). Total long-term deferred tax liability Deferred Tax Liabilities, Gross, Noncurrent Net deferred tax assets (liabilities) Deferred Tax Assets, Net Deferred offering costs Deferred Offering Costs Income Taxes Income Tax Disclosure [Text Block] Fair Value Disclosures [Abstract] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Liability Class [Axis] Liability Class [Axis] Fair Value by Liability Class [Domain] Fair Value by Liability Class [Domain] Lender Warrants Lender Warrants [Member] Information pertaining to lender warrants. Stock Option Liability Awards Stock Option Liability Awards [Member] Information pertaining to stock option liability awards. Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Balance as of January 1 Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value Issuance of liabilities Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Issuances Change in fair value Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings Reclassification of liabilities to equity Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Reclassification To Equity The amount of liabilities reclassified to equity classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. Balance as of December 31 Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] 2015 Employee Stock Purchase Plan Employee Stock [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Option Indexed to Issuer's Equity [Axis] Option Indexed to Issuer's Equity [Axis] Option Indexed to Issuer's Equity, Type [Domain] Option Indexed to Issuer's Equity, Type [Domain] Call Option Call Option [Member] Put Option Put Option [Member] Stock-Based compensation Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Maximum percentage of eligible compensation per employee to purchase shares of common stock Share-based Compensation Arrangement by Share-based Payment Award, Maximum Employee Subscription Rate Maximum number of shares per offering period per employee Share-based Compensation Arrangement by Share-based Payment Award, Maximum Number of Shares Per Employee Maximum share value per calendar year per employee Share-based Compensation Arrangement by Share-based Payment Award, Maximum Employee Subscription Value The maximum share value an eligible employee can purchase under the plan per calendar year. Employee purchase price, percentage of fair market value of common stock Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent Number of offering periods under terms of plan Share-based Compensation Arrangement by Share-based Payment Award, Award Number of Offering Period Represents the number of annual offering periods under general terms of plan. Fair market value of common stock (in usd per share) Share Price Offering periods beginning on May 1 and November 1 Share-based Compensation Arrangement by Share-based Payment Award, Award Offering Period Represents the duration of offering period(s). Issuance of common stock under employee stock purchase plan (in shares) Stock Issued During Period, Shares, Employee Stock Purchase Plans Accumulated employee withholdings Share Based Compensation Arrangement by Share Based Payment Award Accumulated Employee Withholdings Represents the accumulated employee withholdings under the plan. Number of employment hours requirement per week during requisite service period Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Minimum Service Hours Minimum employment hours per week required during the requisite service period of the award. Requisite service period for award eligibility per year Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period Offering period, maximum Share-based Compensation Arrangement by Share-based Payment Award, Award Maximum Offering Period Represents the maximum amount of time of offering period under terms of plan. Total shares reserved Common Stock, Capital Shares Reserved for Future Issuance Number of shares option, minimum annual increase in number of shares reserved for issuance Common Stock, Capital Shares Reserved for Future Issuance, Minimum Annual Increase, Number of Shares Option The minimum annual increase in aggregate number of common shares reserved for future issuance under the number of shares option per terms of plan. Percentage of common stock outstanding option, minimum annual increase in number of shares reserved for issuance (as a percent) Common Stock, Capital Shares Reserved for Future Issuance, Minimum Annual Increase, Percentage of Common Stock Outstanding Option The minimum annual increase in aggregate number of common shares reserved for future issuance under the percentage of common stock outstanding option per terms of plan. Expressed as a percentage of shares of common stock outstanding on the last business day of the prior fiscal year. Discount on purchase of stock (as a percent) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Discount on Purchase of Stock, Percentage Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Discount on Purchase of Stock, Percentage Fair value of option (as a percent) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Fair Value of Option, Percentage Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Fair Value of Option, Percentage Intrinsic value of shares of stock purchased under ESPP Share-based Compensation Arrangement by Share-based Payment Award, Employee Stock Purchase Plan, Stock Purchased in Period, Aggregate Intrinsic Value Amount of accumulated difference between fair market value per share on date of purchase and purchase price of shares purchased during the period, pursuant to an employee stock purchase plan. Unrecognized compensation cost related to nonvested share-based compensation arrangements Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options Expected weighted-average period for recognition of unrecognized stock-based compensation costs (in years) Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Related Party Transactions [Abstract] Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Kevin Dulsky Director [Member] Channel Partner Investor [Member] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] General and administrative General and Administrative Expense [Member] Related party transactions Related Party Transaction [Line Items] Termination of agreement, notice period Related Party Transaction, Termination of Agreement, Notice Period Related Party Transaction, Termination of Agreement, Notice Period Expense incurred related to advisor agreement Related Party Transaction, Expenses from Transactions with Related Party Accounts payable related to advisor agreement Accounts Payable, Related Parties Number of related parties Number of Related Parties Number of related parties associated with the related party transaction. Revenue generated from channel partner Revenue from Related Parties Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Capitalized internal-use software costs Software Development [Member] Internal-Use Software Development Costs Property, Plant and Equipment [Line Items] Capitalized development costs Capitalized Computer Software, Additions Amortization expense Capitalized Computer Software, Amortization Net book value Capitalized Computer Software, Net Payables and Accruals [Abstract] Accrued Expenses and Other Current Liabilities Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block] Subsequent Events [Abstract] Subsequent Events Subsequent Events [Text Block] Temporary Equity, Other Disclosures [Abstract] Convertible Preferred Stock Convertible Preferred Stock [Text Block] The entire disclosure for terms, amounts, nature of changes, rights and privileges, dividends, and other matters related to convertible preferred stock. Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table] Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table] Exercise Price Range [Axis] Exercise Price Range [Axis] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Domain] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Domain] $0.34 - $3.00 Exercise Price Range One [Member] Exercise Price, Range One [Member] $3.01 - $5.00 Exercise Price Range Two [Member] Exercise Price, Range Two [Member] $5.01 - $7.00 Exercise Price, Range Three [Member] Exercise Price, Range Three [Member] $7.01 - $9.00 Exercise Price, Range Four [Member] Exercise Price, Range Four [Member] $9.01 - $11.00 Exercise Price, Range Five [Member] Exercise Price, Range Five [Member] $11.01 - $13.00 Exercise Price, Range Six [Member] Exercise Price, Range Six [Member] $13.01 - $15.18 Exercise Price, Range Seven [Member] Exercise Price, Range Seven [Member] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] Exercise price range, minimum Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit Exercise price range, maximum Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit Options Outstanding Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options [Abstract] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options [Abstract] Number of Options (in shares) Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options Weighted Average Exercise Price (in usd per share) Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price Weighted- Average Remaining Contractual Term (in Years) Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term Options Exercisable Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options [Abstract] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options [Abstract] Number of Options (in shares) Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Exercisable Options Weighted Average Exercise Price (in usd per share) Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price Weighted- Average Remaining Contractual Term (in Years) Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Remaining Contractual Term Subsequent Event [Table] Subsequent Event [Table] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Second Amended New Loan and Security Agreement Loan And Security Agreement [Member] Represents information pertaining to the loan and security agreement which includes a revolving line of credit. Maximum Maximum [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Revolving Line of Credit Revolving Credit Facility [Member] Variable Rate Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] Prime Rate Prime Rate [Member] Subsequent Event [Line Items] Subsequent Event [Line Items] Amount of stock repurchase program authorized (up to) Stock Repurchase Program, Authorized Amount Removal of minimum cash and availability requirement Compensating Balance, Amount Potential interest rate margin (as a percent) Debt Instrument, Basis Spread on Variable Rate Debt covenant, required minimum adjusted quick ratio Debt Instrument, Covenant Compliance, Adjusted Quick Ratio Debt Instrument, Covenant Compliance, Adjusted Quick Ratio Federal statutory income tax rate (as a percent) Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Effective Income Tax Rate Reconciliation, Amount [Abstract] Effective tax rate (as a percent) Effective Income Tax Rate Reconciliation, Percent Statutory rate of 34% Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount State taxes, net of federal benefit Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount Foreign rate differential Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount Stock-based compensation permanent differences Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Compensation Cost, Amount Meals and entertainment permanent differences Effective Income Tax Rate Reconciliation, Nondeductible Expense, Meals and Entertainment, Amount Miscellaneous permanent differences Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Amount Warrant fair market value adjustment Effective Income Tax Rate Reconciliation, Nondeductible expense Fair Market Value Adjustment Warrant Liability Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to warrant fair market value adjustment. Other adjustments Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Change in valuation allowance Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount Provision for income taxes Income Tax Expense (Benefit) Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] 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] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Stock options Employee And Non Employee Stock Options [Member] An arrangement whereby an employee or member of the Board of Directors or consultants of the company 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. Other cost of revenue Cost of Sales [Member] Sales and marketing Selling and Marketing Expense [Member] Research and development Research and Development Expense [Member] Equity Incentive Plans Equity Incentive Plans [Member] Represents activity related to all equity incentive plans of the entity. Share-based compensation expense by statement of operations line item Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] Stock-based compensation expense Allocated Share-based Compensation Expense Change in fair value included in total share based compensation Share-based Compensation, Allocation of Recognized Period Costs, Fair Value Adjustment Represents the fair value adjustment, addition (reduction) related to stock option liability awards reclassified to equity during the period. Stockholders' Equity, Number of Shares, Par Value and Other Disclosures [Abstract] Increase in common shares authorized (in shares) Increase In Common Stock Shares Authorized The amount of the increase to the number of shares authorized. Common shares authorized Common Stock, Shares Authorized Total shares authorized Common And Preferred Stock Shares Authorized The maximum number of common and preferred shares permitted to be issued by an entity's charter and bylaws. Preferred shares authorized Preferred Stock, Shares Authorized Common shares par value (in usd per share) Common Stock, Par or Stated Value Per Share Preferred stock par value (in usd per share) Preferred Stock, Par or Stated Value Per Share Number of votes per common stock share Common Stock Number Of Votes The number of votes eligible for each common stock share. Statement of Cash Flows [Abstract] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Net loss Net Income (Loss) Attributable to Parent 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] Depreciation and amortization Depreciation, Depletion and Amortization Stock-based compensation expense Share-based Compensation Change in fair value of warrants Fair Value Adjustment of Warrants Bad debt expense Provision for Doubtful Accounts Amortization and write-off of debt discount Amortization of Debt Discount (Premium) Amortization and write-off of deferred financing costs Amortization of Financing Costs Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Accounts receivable Increase (Decrease) in Accounts Receivable Prepaid expenses and other current assets Increase (Decrease) in Prepaid Expense and Other Assets Security deposits Increase (Decrease) in Deposit Assets Accounts payable Increase (Decrease) in Accounts Payable Accrued expenses and other current liabilities Increase (Decrease) in Accrued Liabilities Other long-term liabilities Increase (Decrease) in Other Noncurrent Liabilities Net cash used in operating activities Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Purchases of property, equipment and software Payments to Acquire Productive Assets Capitalized internal-use software costs Payments to Develop Software Changes to restricted cash Increase (Decrease) in Restricted Cash Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Proceeds from the issuance of common stock in initial public offering, net of underwriting discounts and commissions Proceeds from Issuance Initial Public Offering Payments of costs related to initial public offering Payments of Stock Issuance Costs Proceeds from debt Proceeds from Issuance of Debt Repayment of debt Repayments of Debt Proceeds from stock option exercises Proceeds from Stock Options Exercised Proceeds from issuance of common stock under employee stock purchase plan Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Excluding Stock Options Payments of issuance costs related to debt Payments of Debt Issuance Costs Proceeds from unvested stock option exercises Proceeds from Nonvested Stock Options Exercised The cash inflow associated with the amount received from holders early exercising their stock options. Net cash provided by financing activities Net Cash Provided by (Used in) Financing Activities Effect of exchange rate changes on cash and cash equivalents Effect of Exchange Rate on Cash and Cash Equivalents Net (decrease) increase in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents at beginning of period Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents at end of period Supplemental disclosures of other cash flow information: Supplemental Cash Flow Information [Abstract] Cash paid for interest Interest Paid Supplemental disclosures of non-cash investing and financing activities: Noncash Investing and Financing Items [Abstract] Purchases of property, equipment and software included in accounts payable and accruals Capital Expenditures Incurred but Not yet Paid Vesting of restricted stock subject to repurchase Vesting Of Restricted Stock Subject To Repurchase Vesting of stock options that were previously subject to the Company's right of repurchase as a result of being early exercised. Issuance of lender warrants allocated to debt discount Adjustments to Additional Paid in Capital, Warrant Issued Conversion of convertible preferred stock to common stock Stock Issued During Period, Value, Conversion of Convertible Securities Warrant derivative liability reclassified to additional paid-in capital Adjustments to Additional Paid In Capital, Fair Value of Warrant Liabilities Transferred to Equity Amount of increase (decrease) to additional paid in capital (APIC) resulting from changes in fair value of common stock warrants initially classified as liabilities transferred during the period from liabilities to equity upon qualifying as an equity instrument. Liability-based option awards reclassified to additional paid-in capital Adjustments to Additional Paid in Capital, Fair Value of Liabilities Transferred to Equity Amount of increase (decrease) to additional paid in capital (APIC) resulting from changes in fair value of share-based awards initially classified as liabilities transferred during the period from liabilities to equity upon qualifying as equity-based awards. Deferred offering costs included in accounts payable and accruals Deferred Offering Costs Incurred But Not Yet Paid Deferred offering costs, incurred but not yet paid, that are included in accounts payable and accrued expenses. Deferred offering costs reclassified to additional paid-in capital Deferred Offering Costs Reclassified To Additional Paid In Capital Deferred offering costs reclassified to additional paid in capital. Stock-based compensation capitalized in internal-use software costs Stock Based Compensation Capitalized in Internally Developed Software Cost Represents the amount of stock-based compensation capitalized in internally developed software during the period. Stock Options Non-Employee Stock Options Non Employee Stock Option [Member] An arrangement whereby a member of the Board of Directors or consultants of the company 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. Weighted-average grant date fair value (in usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Unrecognized compensation cost related to nonvested share-based compensation arrangements Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options Intrinsic value of options exercised Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value Options granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Options granted that were accounted for as liability based awards (in shares) Stock Option Grants That Exceeded Authorized Shares Total options granted that exceeded authorized common stock amounts that were accounted for as liability based awards. Options outstanding that were accounted for as liability based awards (in shares) Stock Options Outstanding That Exceeded Authorized Shares Options outstanding that exceeded authorized common stock amounts that were accounted for as liability based awards. Accrued share-based compensation Deferred Compensation Share-based Arrangements, Liability, Current and Noncurrent Number of liability-based awards exercisable (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Exercisable Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Exercisable Reclassification from other long-term liabilities to equity Debt Disclosure [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Amended New Loan and Security Agreement Amended Mezzanine Loan and Security Agreement Mezzanine Loan And Security Agreement [Member] Represents information pertaining to the mezzanine loan and security agreement which includes a term loan. Prime Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Amended Term Loan - First Tranche Term Loan Tranche One [Member] Represents information pertaining to the first tranche of the term loan under the mezzanine loan and security agreement. Amended Term Loan - Second Tranche Term Loan Tranche Two [Member] Represents information pertaining to the second tranche of the term loan under the mezzanine loan and security agreement. Amended Term Loan - 2015 Term Loan Amended Term Loan2015 Term Loan [Member] Represents information pertaining to the 2015 amended term loan of the Mezzanine Loan and Security Agreement. Debt Debt Instrument [Line Items] Number of debt arrangements Number Of Debt Arrangements Represents the number of debt arrangements entered into by the company. Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Percentage of accounts receivable used in calculation of amount available under the borrowing base Line Of Credit Facility Percent Of Accounts Receivable Used In Calculation Of Amount Available Under Borrowing Base Represents the percentage of eligible accounts receivable used in the calculation of the amount available under the borrowing base. Minimum amount required to be maintained by the company at all times Debt instrument maximum borrowing capacity Debt Instrument Maximum Borrowing Capacity Amount Maximum borrowing capacity under the long-term financing arrangement without consideration of current restrictions on the amount that could be borrowed. Number of tranches Number Of Tranches Represents the number of tranches. Total face amount of debt Debt Instrument, Face Amount Interest rate on outstanding amounts (as a percent) Debt Instrument, Interest Rate, Stated Percentage Number of shares of common stock that may be purchased based on lender warrants issued Class of Warrant or Right, Number of Securities Called by Warrants or Rights Exercise price of warrants (in usd per share) Class of Warrant or Right, Exercise Price of Warrants or Rights Minimum percentage of the Company’s total cash and cash equivalents balance required to be maintained with lender Debt Instrument Percentage Of Total Cash And Cash Equivalents Required To Be Maintained With Lender Minimum Represents the minimum percentage of the Company’s total cash and cash equivalents balance required to be maintained with lender. Increase to borrowing capacity Line of Credit Facility, Increase to Maximum Borrowing Capacity The amount of the increase to the maximum borrowing capacity under the credit facility. Available borrowing capacity Line of Credit Facility, Current Borrowing Capacity Effective interest rate Debt Instrument, Interest Rate, Effective Percentage Repayment of debt Employee Stock Options Employee Stock Option [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] 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 Risk-free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Expected term (years) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term 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 volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Dividend yield Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Compensation and Retirement Disclosure [Abstract] Plan eligibility, minimum age Defined Contribution Plan, Participant Eligibility, Minimum Age Defined Contribution Plan, Participant Eligibility, Minimum Age Company contributions to Retirement Plan Defined Contribution Plan, Employer Discretionary Contribution Amount Property, Plant and Equipment [Abstract] Furniture and office equipment Computer Equipment [Member] Furniture and office equipment Furniture and Fixtures [Member] Leasehold improvements Leasehold Improvements [Member] Property, Plant and Equipment [Line Items] Total Property, Plant and Equipment, Gross Less: accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Property, equipment and software, net Property, Plant and Equipment, Net Depreciation and amortization expense Domestic Income (Loss) from Continuing Operations before Income Taxes, Domestic International Income (Loss) from Continuing Operations before Income Taxes, Foreign Loss before income taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest Operating Loss Carryforwards [Table] Operating Loss Carryforwards [Table] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] Federal Domestic Tax Authority [Member] State State and Local Jurisdiction [Member] Foreign Foreign Tax Authority [Member] Operating loss carryforwards Operating Loss Carryforwards [Line Items] Operating loss carry forwards Operating Loss Carryforwards Undistributed earnings of non-U.S. subsidiary Undistributed Earnings of Foreign Subsidiaries Fair Value Measurements Fair Value Disclosures [Text Block] Property, Equipment and Software, Net Property, Plant and Equipment Disclosure [Text Block] Schedule of debt Schedule of Long-term Debt Instruments [Table Text Block] Schedule of future principal payments of long-term debt Schedule of Maturities of Long-term Debt [Table Text Block] Year Ending December 31, Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] 2016 Operating Leases, Future Minimum Payments Due, Next Twelve Months 2017 Operating Leases, Future Minimum Payments, Due in Two Years 2018 Operating Leases, Future Minimum Payments, Due in Three Years 2019 Operating Leases, Future Minimum Payments, Due in Four Years 2020 Operating Leases, Future Minimum Payments, Due in Five Years Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Total minimum lease payments Operating Leases, Future Minimum Payments Due Accrued commissions Accrued Sales Commission, Current Accrued bonuses Accrued Bonuses, Current Accrued salaries, wages, benefits and related costs Accrued Salaries, Wages, Benefits and Related Costs, Current Carrying value as of the balance sheet date of the obligations incurred through that date and payable for salaries, wages and related employee benefits. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Accrued deferred offering costs Accrued Deferred Offering Costs, Current Carrying value as of the balance sheet date of obligations incurred through that date and payable arising from deferred offering costs. Used to reflect the current portion of the amount in accrued expenses (due within one year or within the normal operating cycle if longer). Accrued credit card purchases Accrued Credit Card Purchases, Current Carrying value as of the balance sheet date of obligations incurred through that date and payable for accrued credit card purchases. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Other accrued expenses and current liabilities Other Accrued Liabilities, Current Accrued expenses and other current liabilities Accrued Liabilities and Other Liabilities Earnings Per Share [Abstract] Earnings Per Share Earnings Per Share [Text Block] Schedule of property, equipment and software, net Property, Plant and Equipment [Table Text Block] Schedule of future minimum lease payments Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Principles of Consolidation Consolidation, Policy [Policy Text Block] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Restricted Cash Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Concentration of Credit Risk Concentration Risk, Credit Risk, Policy [Policy Text Block] Allowance for Doubtful Accounts Receivables, Policy [Policy Text Block] Internal-Use Software Development Costs Internal Use Software, Policy [Policy Text Block] Property, Equipment and Software, Net Property, Plant and Equipment, Policy [Policy Text Block] Impairment of Long-lived Assets Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block] Deferred Offering Costs Deferred Charges, Policy [Policy Text Block] Common Stock Warrants Fair Value Measurement, Policy [Policy Text Block] Fair Value of Financial Instruments Fair Value of Financial Instruments, Policy [Policy Text Block] Foreign Currency Translation and Transactions Foreign Currency Transactions and Translations Policy [Policy Text Block] Revenue Recognition Revenue Recognition, Policy [Policy Text Block] Cost of Revenue Cost of Sales, Policy [Policy Text Block] Research and Development Research and Development Expense, Policy [Policy Text Block] Advertising and Marketing Advertising Costs, Policy [Policy Text Block] Stock-Based Compensation Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] Income Taxes Income Tax, Policy [Policy Text Block] Basic and Diluted Loss per Common Share Earnings Per Share, Policy [Policy Text Block] Recently Adopted Accounting Pronouncements and Recent Accounting Pronouncements Not Yet Adopted New Accounting Pronouncements, Policy [Policy Text Block] Employee Retirement Savings Plan Compensation and Employee Benefit Plans, Other than Share-based Compensation [Text Block] Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] United Kingdom UNITED KINGDOM Sale of Stock [Axis] Sale of Stock [Axis] Sale of Stock [Domain] Sale of Stock [Domain] IPO IPO [Member] Description of Business and Basis of Presentation Class of Stock [Line Items] Number of offices Number Of Offices Represents the number of offices. Stock split conversion ratio Stockholders' Equity Note, Stock Split, Conversion Ratio Shares issued during period Stock Issued During Period, Shares, New Issues Shares issued price per share (in usd per share) Shares Issued, Price Per Share Shares issued upon conversion Convertible Preferred Stock, Shares Issued upon Conversion ESPP stock-based compensation expense by statement of operations line item Schedule of stock-based compensation expense Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block] Summary of the assumptions used for estimating the fair value of stock options granted Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Summary of stock option activity Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block] Summary of options outstanding and vested by exercise price range Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block] Summary of the assumptions used for estimating the fair value of shares to be granted under the 2015 ESPP Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions [Table Text Block] Debt Instrument [Line Items] Amended Mezzanine Loan and Security Agreement Loans Payable to Bank, Noncurrent Discount on Amended Mezzanine Loan and Security Agreement Debt Instrument, Unamortized Discount Amended New Revolving Line of Credit Long-term Line of Credit Total debt Long-term Debt Less: short-term debt Long-term Debt, Current Maturities Long-term debt, net Long-term Debt, Excluding Current Maturities Year Ending December 31, Long-term Debt, Fiscal Year Maturity [Abstract] 2016 Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months Thereafter Long-term Debt, Maturities, Repayments of Principal After Year One Long-term Debt, Maturities, Repayments of Principal After Year One Short-term debt Schedule of changes in the allowance for doubtful accounts Allowance for Credit Losses on Financing Receivables [Table Text Block] Related Parties Related Party Transactions Disclosure [Text Block] Schedule of fair value of financial instruments measured on recurring basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Schedule of changes in instruments measured at fair value on recurring basis Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Schedule of assumptions used Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Table Text Block] 2015 Equity Incentive Plan Equity Incentive Plan2015 [Member] Information pertaining to the 2015 Equity Incentive Plan. 2010 Equity Incentive Plan Equity Incentive Plan2010 [Member] Information pertaining to the 2010 Equity Incentive Plan. Vesting [Axis] Vesting [Axis] Vesting [Domain] Vesting [Domain] One Year Cliff Share-based Compensation Award, Tranche One [Member] Second Offering Period Share-based Compensation Award, Tranche Two [Member] Stock Options Subject to Right of Repurchase Stock Options Subject To Right Of Repurchase [Member] Reporesents activity related to stock options issued that are subject to right of repurchase by entity if vesting terms are not met. Initial shares available for grant from equity incentive plan Initial Shares Available For Grant From Equity Incentive Plan The initial maximum number of shares authorized for issuance under the equity incentive plan, prior to the transfer of the maximum number of shares authorized for issuance under the previous equity incentive plan. Maximum shares available for grant transferred between equity incentive plans. Maximum Shares Available For Grant Transferred From Equity Incentive Plan The maximum number of shares authorized for issuance under the equity incentive plan transferred to a subsequent equity incentive plan. Shares available for future grants Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Plan terms Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract] Plan term (in years) Share-based Compensation Arrangement by Share-based Payment Award, Plan Expiration Period Period from plan inception date that an equity-based plan expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Award terms Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract] Vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Term of grant (in years) Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period Number of shares early exercised, subject to repurchase Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Subject to Repurchase Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Subject to Repurchase Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Table] Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Table] Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items] Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items] Risk-free interest rate Fair Value Assumptions, Risk Free Interest Rate Expected term Fair Value Assumptions, Expected Term Expected volatility Fair Value Assumptions, Expected Volatility Rate Dividend yield Fair Value Assumptions, Expected Dividend Rate Schedule of common stock reserved for issuance Schedule Of Common Stock Reserved For Issuance [Table Text Block] Tabular disclosure of shares of common stock reserved for issuance. Debt Debt Disclosure [Text Block] Statement of Financial Position [Abstract] Statement [Table] Statement [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Convertible Series A Preferred Stock Series A Preferred Stock [Member] Convertible Series B Preferred Stock Series B Preferred Stock [Member] Convertible Series C Preferred Stock Series C Preferred Stock [Member] Convertible Series D Preferred Stock Series D Preferred Stock [Member] Statement [Line Items] Statement [Line Items] Assets Assets [Abstract] Current assets: Assets, Current [Abstract] Cash and cash equivalents Accounts receivable, net Accounts Receivable, Net, Current Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Restricted cash, short-term Restricted Cash and Cash Equivalents, Current Total current assets Assets, Current Property, equipment and software, net Restricted cash, long-term Restricted Cash and Cash Equivalents, Noncurrent Other long-term assets Other Assets, Noncurrent Total assets Assets Liabilities, Convertible preferred stock and Stockholders’ (deficit) equity Liabilities and Equity [Abstract] Current liabilities: Liabilities, Current [Abstract] Accounts payable Accounts Payable, Current Accrued expenses and other current liabilities Short-term debt Total current liabilities Liabilities, Current Other long-term liabilities Other Liabilities, Noncurrent Total liabilities Liabilities Commitments and contingencies Commitments and Contingencies Convertible preferred stock: Temporary Equity [Abstract] Total convertible preferred stock Temporary Equity, Carrying Amount, Attributable to Parent Stockholders’ (deficit) equity: Stockholders' Equity Attributable to Parent [Abstract] Common stock, $0.00005 par value; 22,000,000 shares authorized, 4,217,419 shares issued and outstanding as of December 31, 2014; 500,000,000 shares authorized, 26,243,950 shares issued and outstanding as of December 31, 2015 Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital, Common Stock Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated deficit Retained Earnings (Accumulated Deficit) Total stockholders’ (deficit) equity Stockholders' Equity Attributable to Parent Total liabilities, convertible preferred stock and stockholders’ (deficit) equity Liabilities and Equity Components of loss before income taxes Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block] Reconciliation of differences between statutory U.S. federal and effective income tax rate Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Components of current and long-term deferred tax assets (liabilities) Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Forecast Scenario, Forecast [Member] Expected term Fair value per share (in usd 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 Schedule of Compensating Balances [Table] Schedule of Compensating Balances [Table] Compensating Balances [Line Items] Compensating Balances [Line Items] Allowance for doubtful accounts: Allowance for Doubtful Accounts Receivable [Roll Forward] Balance, beginning of period Allowance for Doubtful Accounts Receivable, Current Add: adjustment for bad debts Less: write-offs, net of recoveries Allowance for Doubtful Accounts Receivable, Write-offs Balance, end of period Par value (in usd per share) Temporary Equity, Par or Stated Value Per Share Convertible preferred stock shares authorized Temporary Equity, Shares Authorized Convertible preferred stock shares issued Temporary Equity, Shares Issued Convertible preferred stock shares outstanding Temporary Equity, Shares Outstanding Liquidation preference Temporary Equity, Liquidation Preference Common stock Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract] Common shares issued Common Stock, Shares, Issued Common shares outstanding Common Stock, Shares, Outstanding Deferred rent Deferred Rent Credit Outstanding letters of credit Letters of Credit Outstanding, Amount Rent expense Operating Leases, Rent Expense Total contractual commitments Unrecorded Unconditional Purchase Obligation Commitments due within next year Unrecorded Unconditional Purchase Obligation, Due in Next Rolling Twelve Months Commitments due within one to two years Unrecorded Unconditional Purchase Obligation, Due in Rolling Year Two Commitments due within two to three years Unrecorded Unconditional Purchase Obligation, Due in Rolling Year Three Estimated useful life of property, equipment and software Property, Plant and Equipment, Useful Life 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] Common Stock Subject to Repurchase Common Stock Subject To Repurchase [Member] Common stock subject to repurchase Lender and Additional Lender Warrants to Purchase Common Stock Warrant [Member] 2015 ESPP Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Anti-dilutive securities excluded from the calculation of weighted average common shares outstanding Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Statement of Stockholders' Equity [Abstract] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Stock Common Stock [Member] Additional Paid-in Capital Additional Paid-in Capital [Member] Accumulated Other Comprehensive Loss AOCI Attributable to Parent [Member] Accumulated Deficit Retained Earnings [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Balance - beginning of period ( in shares) Balance - beginning of period Issuance of common stock from initial public offering, net of issuance costs (in shares) Issuance of common stock from initial public offering, net of issuance costs Stock Issued During Period, Value, New Issues Conversion of convertible preferred stock to common stock (in shares) Stock Issued During Period, Shares, Conversion of Convertible Securities Exercise of stock options ( in shares) Exercise of stock options Stock Issued During Period, Value, Stock Options Exercised Issuance of common stock under employee stock purchase plan Stock Issued During Period, Value, Employee Stock Purchase Plan Stock-based compensation Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Issuance of common stock warrant Foreign currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Balance - end of period ( in shares) Balance - end of period Summary of anti-dilutive securities which are excluded from the calculation of weighted average common shares outstanding Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Schedule of issuances of convertible preferred stock Temporary Equity [Table Text Block] Summary of activity for the convertible preferred stock Schedule of Conversions of Stock [Table Text Block] Segment Reporting [Abstract] Number of operating segments Number of Operating Segments Number of reportable segments Number of Reportable Segments Schedule of Revenues from External Customers and Long-Lived Assets [Table] Schedule of Revenues from External Customers and Long-Lived Assets [Table] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Long-lived Assets Long-lived Assets [Member] Long-lived assets other than financial instruments, long-term customer relationships of a financial institution, mortgage and other servicing rights, deferred policy acquisition costs, and deferred tax assets, when it serves as a benchmark in a concentration of risk calculation. Revenue Sales Revenue, Services, Net [Member] United States UNITED STATES Revenues from External Customers and Long-Lived Assets [Line Items] Revenues from External Customers and Long-Lived Assets [Line Items] Concentration risk, percentage Concentration Risk, Percentage Statement of Comprehensive Income [Abstract] Net loss Other comprehensive loss: Other Comprehensive Income (Loss), Net of Tax [Abstract] Foreign currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent Comprehensive loss Comprehensive Income (Loss), Net of Tax, Attributable to Parent Series A convertible preferred stock Series B convertible preferred stock Series C convertible preferred stock Series D convertible preferred stock Lender Warrants and Additional Lender Warrant to purchase common stock Common Stock Reserved for Issuance Schedule of accrued expenses Schedule of Accrued Liabilities [Table Text Block] Income Statement [Abstract] Revenue, net Sales Revenue, Services, Net Traffic acquisition costs Traffic Acquisition Costs Represents media costs for advertising impressions purchased from real-time bidding exchanges, which are expensed as incurred. Other cost of revenue Other Cost of Services Gross profit Gross Profit Operating expenses: Operating Expenses [Abstract] Sales and marketing Selling and Marketing Expense Research and development Research and Development Expense General and administrative General and Administrative Expense Total operating expenses Operating Expenses Income (loss) from operations Operating Income (Loss) Other expense (income): Other Nonoperating Income (Expense) [Abstract] Interest expense Interest Expense Derivative fair value adjustment related to common stock warrants Other income Other Nonoperating Income (Expense) Total other expense Nonoperating Income (Expense) Provision for income taxes Net loss Net loss per basic and diluted share of common stock (in usd per share) Earnings Per Share, Basic and Diluted Weighted-average shares used to compute net loss per basic and diluted share of common stock Weighted Average Number of Shares Outstanding, Basic and Diluted Stock-Based Compensation Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Class of Warrant or Right [Table] Class of Warrant or Right [Table] Class of Warrant or Right [Line Items] Class of Warrant or Right [Line Items] Borrowing capacity remaining Debt Instrument, Unused Borrowing Capacity, Amount Fair value of warrants Warrants and Rights Outstanding Segment and Geographic Information Segment Reporting Disclosure [Text Block] Common and Preferred Stock Common And Preferred Stock Text Block The entire disclosure for terms, amounts, nature of changes, rights and privileges, dividends, and other matters related to common and preferred stock. Temporary Equity, by Class of Stock [Table] Temporary Equity, by Class of Stock [Table] Convertible Preferred Stock Temporary Equity [Line Items] Number of Shares Authorized Number of Shares Outstanding Original Issue and Conversion Price per Share (in usd per share) Temporary Equity, Redemption Price Per Share Increase (Decrease) in Temporary Equity [Roll Forward] Increase (Decrease) in Temporary Equity [Roll Forward] Balance of convertible preferred stock Balance, beginning of period Conversion to common stock upon IPO Conversion of Stock, Amount Converted Balance, end of period Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Recurring Fair Value, Measurements, Recurring [Member] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Level 1 Fair Value, Inputs, Level 1 [Member] Level 2 Fair Value, Inputs, Level 2 [Member] Level 3 Fair Value, Inputs, Level 3 [Member] Asset Class [Axis] Asset Class [Axis] Asset Class [Domain] Asset Class [Domain] Money Market Fund Money Market Funds [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] Liabilities: Liabilities, Fair Value Disclosure [Abstract] Other long-term liabilities Other Liabilities, Fair Value Disclosure Total liabilities measured at fair value Financial and Nonfinancial Liabilities, Fair Value Disclosure Assets: Assets, Fair Value Disclosure [Abstract] Cash and cash equivalents — Money Market Fund Cash and Cash Equivalents, Fair Value Disclosure Summary of Significant Accounting Policies Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Text Block]