Commitments and Contingencies Disclosure [Abstract] Schedule of Future Minimum Lease Payments for Operating Leases Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Schedule of Future Minimum Lease Receipts for Operating Lease Schedule of Property Subject to or Available for Operating Lease [Table Text Block] Property, Plant and Equipment [Abstract] 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] Furniture and fixtures Furniture and Fixtures [Member] Computer and office equipment Computer and Office Equipment [Member] Computer and Office Equipment [Member] Telecommunications equipment Telecommunications Equipment [Member] Telecommunications Equipment [Member] Leasehold improvements Leasehold Improvements [Member] Software development costs Software 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Assets, Major Class Name [Domain] Indefinite-lived Intangible Assets, Major Class Name [Domain] Licenses Licensing Agreements [Member] Indefinite-lived Intangible Assets [Line Items] Indefinite-lived Intangible Assets [Line Items] Licenses, indefinite lived Indefinite-Lived Intangible Assets (Excluding Goodwill) Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Customer relationships Customer Relationships [Member] Domain name and related trademarks Domain Name and Related Trademarks [Domain] Domain Name and Related Trademarks [Domain] Non-compete agreements Noncompete Agreements [Member] Developed technology Developed Technology Rights [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum 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Equivalents, and Restricted Cash Schedule of Cash and Cash Equivalents [Table Text Block] Reconciliation of Cash, Cash Equivalents, and Restricted Cash Restrictions on Cash and Cash Equivalents [Table Text Block] Summary of Property and Equipment, Net Property, Plant and Equipment [Table Text Block] Summary of Depreciation Expense Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Stock Based Compensation Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Debt Debt Disclosure [Text Block] 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] Affiliated Entity Affiliated Entity [Member] Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] Republic Republic [Member] Republic [Member] Related Party Transaction [Axis] Related Party Transaction [Axis] Related Party Transaction [Domain] Related Party Transaction [Domain] Transition Services Agreement Transition Services Agreement [Member] Transition Services Agreement [Member] Facilities Sharing Agreement Facilities Sharing Agreement [Member] Facilities Sharing Agreement [Member] Tax Sharing Agreement Tax Sharing Agreement [Member] Tax Sharing Agreement [Member] Master Services Agreement Master Services Agreement [Member] Master Services Agreement [Member] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Revenue from related parties Revenue from Related Parties Accounts receivable, related parties Accounts Receivable, Related Parties, Current Due from related parties Due from Related Parties Rental payments received Operating Leases, Income Statement, Sublease Revenue Amount collected on behalf Proceeds from Collection of Advance to Affiliate Due to related parties Due to Related Parties 2018 (remaining) Capital Leases, Future Minimum Payments, Remainder of Fiscal Year Less amount representing interest Capital Leases, Future Minimum Payments, Interest Included in Payments Current portion of long-term capital lease obligation Capital Lease Obligations Less current maturities Capital Lease Obligations, Current Long-term capital lease obligation Capital Lease Obligations, Noncurrent Document and Entity Information [Abstract] Document and Entity Information [Abstract] Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Common Class A Common Class A [Member] Common Class B Common Class B [Member] Class of Stock [Line Items] Class of Stock [Line Items] 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 Equity [Abstract] Schedule of Reserved Shares of Common Stock for Issuance Schedule of Stock by Class [Table Text Block] Intangible Assets Intangible Assets Disclosure [Text Block] Schedule of Intangible Assets Schedule of Indefinite-Lived Intangible Assets [Table Text Block] Schedule of Future Estimated Amortization Expense Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Fair Value Disclosures [Abstract] Fair Value of Financial Instruments Fair Value Disclosures [Text Block] 2018 (remaining) 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 Preferred A stock, shares authorized (in shares) Preferred Stock, Shares Authorized Preferred A stock, par value (in usd per share) Preferred Stock, Par or Stated Value Per Share Preferred A stock, shares issued (in shares) Preferred Stock, Shares Issued Preferred A stock, shares outstanding (in shares) Preferred Stock, Shares Outstanding Common stock, shares authorized (in shares) Common Stock, Shares Authorized Common stock voting rights, votes per share (in vote) Common Stock, Voting Rights, Votes Per Share Common Stock, Voting Rights, Votes Per Share Common stock, par value (in usd per share) Common Stock, Par or Stated Value Per Share Common stock, shares issued (in shares) Common Stock, Shares, Issued Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Schedule of Fair Value of Options Granted Using the Black-Scholes Pricing Model Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Summary of Stock Option Activity Share-based Compensation, Stock Options, Activity [Table Text Block] Summary of Restricted Stock Unit Activity Nonvested Restricted Stock Shares Activity [Table Text Block] Schedule of Stock-Based Compensation Expense in Continuing Operations Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block] Financial Statement Components Additional Financial Information Disclosure [Text Block] Amortization expense Amortization of Intangible Assets Stockholders' Equity Stockholders' Equity Note Disclosure [Text Block] 2018 (remaining) Operating Leases, Future Minimum Payments Receivable, Current 2019 Operating Leases, Future Minimum Payments Receivable, in Two Years 2020 Operating Leases, Future Minimum Payments Receivable, in Three Years 2021 Operating Leases, Future Minimum Payments Receivable, in Four Years 2022 Operating Leases, Future Minimum Payments Receivable, in Five Years Future minimum lease receipts, total Operating Leases, Future Minimum Payments Receivable Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Schedule of Assets Measured at Fair Value on a Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Schedule of Contractual Maturities of Marketable Securities Marketable Securities [Table Text Block] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Revolving Credit Facility Revolving Credit Facility [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Line of credit Long-term Line of Credit Available borrowing capacity Line of Credit Facility, Remaining Borrowing Capacity Outstanding unamortized loan fees Debt Issuance Costs, Line of Credit Arrangements, Net Cost of assets under capital leases Capital Leased Assets, Gross Accumulated depreciation of assets under capital leases Capital Leases, Lessee Balance Sheet, Assets by Major Class, Accumulated Depreciation Segment and Geographic Information Segment Reporting Disclosure [Text Block] Schedule of Revenues from External Customers and Long-Lived Assets [Table] Schedule of Revenues from External Customers and Long-Lived Assets [Table] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] United States UNITED STATES International Non-US [Member] Revenues from External Customers and Long-Lived Assets [Line Items] Revenues from External Customers and Long-Lived Assets [Line Items] Revenue Revenues 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] Nonvested restricted stock units issued and outstanding Restricted Stock Units (RSUs) [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares [Roll Forward] Number of nonvested RSUs outstanding, beginning balance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Number of nonvested RSUs, granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Number of nonvested RSUs, vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Number of nonvested RSUs, forfeited or cancelled (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Number of nonvested RSUs outstanding, ending balance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Weighted-average grant date fair value, beginning balance (in usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Weighted average grant-date fair value of nonvested RSUS, granted (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 Weighted-average grant date fair value of nonvested RSUs, vested (in usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Weighted-average grant date fair value of nonvested restricted RSUs, forfeited or cancelled (in usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Weighted-average grant date fair value, ending balance (in usd per share) Employee Stock Option Employee Stock Option [Member] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Number of options outstanding, beginning balance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Number of options, granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Number of options exercised (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Number of options, forfeited or cancelled (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period Number of options outstanding, ending balance (in shares) Number of options outstanding, options vested and exercisable (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Weighted-average exercise price, beginning balance (in usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price 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 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 Weighted-average exercise price, forfeited or cancelled (in usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price Weighted-average exercise price, ending balance (in usd per share) Weighted-average exercise price, options vested and exercisable (in usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Exercise Price Weighted-average remaining contract life, options outstanding (in years) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Weighted-average remaining contract life, options vested and exercisable (in years) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Aggregate intrinsic value, options outstanding Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Aggregate intrinsic value, options exercised Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value Aggregate intrinsic value, options vested and exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Principles of Consolidation Consolidation, 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] Concentration of Credit Risk Concentration Risk, Credit Risk, Policy [Policy Text Block] Recent Accounting Standards New Accounting Pronouncements, Policy [Policy Text Block] Expected dividend yield Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Expected stock price volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Average risk-free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Average risk-free interest rate, minimum Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum Average risk-free interest rate, maximum Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Maximum Expected life (in years) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Fair value of common stock (in usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Exercise Price Lessee, Lease, Description [Table] Lessee, Lease, Description [Table] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] General and administrative General and Administrative Expense [Member] Lessee, Lease, Description [Line Items] Lessee, Lease, Description [Line Items] Office space (in square foot) Area of Real Estate Property Term of lease (in months) Lessee, Operating Lease, Term of Contract Rent expense Operating Leases, Rent Expense Reduction of rent expense Annual minimum commitments Other Commitments, Future Minimum Annual Payments Other Commitments, Future Minimum Annual Payments Term of agreement (in years) Other Commitment, Term of Agreement Other Commitment, Term of Agreement Non-cancellable purchase obligation Unrecorded Unconditional Purchase Obligation Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] CPaaS CPaaS [Member] CPaaS [Member] Other Other Segments [Member] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Number of reportable segments Number of Reportable Segments Cost of revenue Cost of Revenue Gross profit Gross Profit Statement of Financial Position [Abstract] Assets Assets [Abstract] Current assets: Assets, Current [Abstract] Marketable securities Marketable Securities, Current Accounts receivable, net of allowance for doubtful accounts Accounts Receivable, Net, Current Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Total current assets Assets, Current Property and equipment, net Intangible assets, net Deferred costs, non-current Deferred Costs, Noncurrent Other long-term assets Other Assets, Noncurrent Goodwill Goodwill Deferred tax asset Deferred Income Tax Assets, Net Total assets Assets Liabilities and stockholders’ equity Liabilities and Equity [Abstract] Current liabilities: Liabilities, Current [Abstract] Accounts payable Accounts Payable, Current Accrued expenses and other current liabilities Accrued Liabilities, Current Current portion of deferred revenue and advanced billings Deferred Revenue, Current Total current liabilities Liabilities, Current Other liabilities Other Liabilities, Noncurrent Deferred revenue, net of current portion Deferred Revenue, Noncurrent Total liabilities Liabilities Stockholders’ equity: Stockholders' Equity Attributable to Parent [Abstract] Class A and Class B common stock 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 and stockholders’ equity Liabilities and Equity Income Tax Disclosure [Abstract] Effective tax rate Effective Income Tax Rate Reconciliation, Percent Trade accounts receivable Accounts Receivable, Gross, Current Unbilled accounts receivable Unbilled Receivables, Current Allowance for doubtful accounts Allowance for Doubtful Accounts Receivable, Current Other accounts receivable Other Receivables, Net, Current Total accounts receivable, net Stock options issued and outstanding Stock Options Issued and Outstanding [Member] Stock Options Issued and Outstanding [Member] Stock purchase warrants issued and outstanding Stock Purchase Warrants Issued and Outstanding [Member] Stock Purchase Warrants Issued and Outstanding [Member] Stock-based awards available for grant under the 2017 Plan Stock Compensation Plan [Member] Common stock reserved for future issuance (in shares) Common Stock, Capital Shares Reserved for Future Issuance Employee Benefit Plan Pension and Other Postretirement Benefits Disclosure [Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization and Description of Business Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Depreciation Expense [Table] Depreciation Expense [Table] Depreciation Expense [Table] Cost of revenue Cost of Sales [Member] Research and development Research and Development Expense [Member] Sales and marketing Selling and Marketing Expense [Member] Depreciation Expense [Line Items] Depreciation Expense [Line Items] [Line Items] for Depreciation Expense [Table] Depreciation Depreciation Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] 2017 Equity Compensation Plan 2017 Equity Compensation Plan [Member] 2017 Equity Compensation Plan [Member] 2010 Equity Compensation Plan 2010 Equity Compensation Plan [Member] 2010 Equity Compensation Plan [Member] Common stock reserved for future issuance (in shares) Common stock reserved for future issuance, percent increase Common Stock, Capital Shares Reserved for Future Issuance, Percent Increase Common Stock, Capital Shares Reserved for Future Issuance, Percent Increase Increase in shares available for grant (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized Vesting period (in years) Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Contractual life (in years) Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period Vesting percentage Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Weighted average grant-date fair value of stock options granted (in usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Estimated grant date fair value of options vested Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value Unrecognized cost for stock based compensation Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options Unrecognized cost for stock based compensation, period for recognition (in years) Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Unrecognized compensation cost related to non-vested RSUs Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options Income Statement [Abstract] Operating expenses: Operating Expenses [Abstract] Research and development Research and Development Expense Sales and marketing Selling and Marketing Expense General and administrative General and Administrative Expense Total operating expenses Operating Expenses Operating income Operating Income (Loss) Other (expense) income, net Other Nonoperating Income (Expense) Income before taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income tax (provision) benefit Income Tax Expense (Benefit) Net income Net Income (Loss) Attributable to Parent Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Unrealized gain (loss) on marketable securities, net of income tax benefit Other Comprehensive Income (Loss), Net of Tax Total comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Net income Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent Less: net income allocated to participating securities Undistributed Continuing Operation Earnings (Loss), Allocation to Participating Securities, Basic Net income attributable to common stockholders Net Income (Loss) from Continuing Operations Available to Common Shareholders, Basic Net income per share: Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract] Basic (in usd per share) Income (Loss) from Continuing Operations, Per Basic Share Diluted (in usd per share) Income (Loss) from Continuing Operations, Per Diluted Share Weighted average number of common shares outstanding: Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Basic (in shares) Weighted Average Number of Shares Outstanding, Basic Diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted 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] Series A redeemable convertible preferred stock outstanding Redeemable Convertible Preferred Stock [Member] Stock options issued and outstanding Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive securities excluded from calculation of weighted-average common shares outstanding Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Statement of Cash Flows [Abstract] Operating activities Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Net income Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation and Amortization, Net of Amortization of Debt Issuance Costs Depreciation and Amortization, Net of Amortization of Debt Issuance Costs Accretion of bond discount Accretion (Amortization) of Discounts and Premiums, Investments Amortization of debt issuance costs Amortization of Debt Issuance Costs Stock-based compensation Share-based Compensation Change in fair value of shareholders’ anti-dilutive arrangement Liabilities, Fair Value Adjustment Deferred taxes Deferred Income Tax Expense (Benefit) Loss on disposal of property and equipment Gain (Loss) on Disposition of Property Plant Equipment Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Accounts receivable Increase (Decrease) in Accounts Receivable Prepaid expenses and other assets Increase (Decrease) in Prepaid Expense and Other Assets Deferred costs Increase (Decrease) in Deferred Charges Accounts payable Increase (Decrease) in Accounts Payable Accrued expenses and other liabilities Increase (Decrease) in Accrued Liabilities Deferred revenue and advanced billings Increase (Decrease) in Deferred Revenue Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Investing activities Net Cash Provided by (Used in) Investing Activities [Abstract] Purchase of property and equipment Payments to Acquire Property, Plant, and Equipment Capitalized software development costs Payments to Develop Software Proceeds from sale of property and equipment Proceeds from Sale of Property, Plant, and Equipment Purchase of marketable securities Payments to Acquire Marketable Securities Maturities of marketable securities Proceeds from Sale and Maturity of Marketable Securities Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Financing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Borrowings on line of credit Proceeds from Lines of Credit Repayments on line of credit Repayments of Lines of Credit Payments on capital leases Repayments of Long-term Capital Lease Obligations Repayments on term loan Repayments of Secured Debt Payment of costs related to the initial public offering Payments of Stock Issuance Costs Proceeds from issuances of common stock Proceeds from Issuance of Common Stock Net cash (used in) provided by financing activities Net Cash Provided by (Used in) Financing Activities Net (decrease) increase 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, beginning of period Cash, cash equivalents, and restricted cash, end of period Supplemental disclosure of cash flow information Supplemental Cash Flow Information [Abstract] Cash paid during the year for interest Interest Paid Cash paid for taxes Income Taxes Paid, Net Supplemental disclosure of noncash investing and financing activities Noncash Investing and Financing Items [Abstract] Purchase of property and equipment, accrued but not paid Capital Expenditures Incurred but Not yet Paid Property and Equipment Property, Plant and Equipment Disclosure [Text Block] Net income Less: net income allocated to participating securities Net income per share: Earnings Per Share, Basic and Diluted [Abstract] Weighted Average Number of Common Shares Outstanding Earnings Per Share, Basic, Other Disclosures [Abstract] Dilutive effect of stock options, restricted stock units, and warrants (in shares) Incremental Common Shares Attributable to Dilutive Effect of Call Options and Warrants Diluted (in shares) 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] Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] Stock-based compensation expense Allocated Share-based Compensation Expense Number of operating segments Number of Operating Segments Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Receivable Type [Axis] Receivable Type [Axis] Receivable [Domain] Receivable [Domain] Carrier Access Billing (CAB) Carrier Access Billing [Member] Carrier Access Billing [Member] Products and Services [Axis] Products and Services [Axis] Products and Services [Domain] Products and Services [Domain] Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Settlement agreement lump sum payment Proceeds from Legal Settlements Write-off of previously outstanding and fully reserved billings related to settlement Allowance for Doubtful Accounts Receivable, Write-offs Related to Settlements Allowance for Doubtful Accounts Receivable, Write-offs Related to Settlements Revenue recognized as a result of settlement agreement Litigation Settlement, Amount Awarded from Other Party Concentration Risk [Table] Concentration Risk [Table] Customer [Axis] Customer [Axis] Customer [Domain] Customer [Domain] Customer One Customer One [Member] Customer One [Member] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Accounts Receivable Accounts Receivable [Member] Concentration Risk [Line Items] Concentration Risk [Line Items] Concentration risk percentage Concentration Risk, Percentage Accounts Receivable, Excluding Carrier Access Billing (CAB) Accounts Receivable, Excluding Carrier Access Billing (CAB) [Member] Accounts Receivable, Excluding Carrier Access Billing (CAB) [Member] Allowance for Doubtful Accounts Receivable [Roll Forward] Allowance for Doubtful Accounts Receivable [Roll Forward] Balance, beginning of period Allowance for Doubtful Accounts Receivable Write-off of previously outstanding and fully reserved billings related to settlement Billings deemed not probable of collection Provision for Doubtful Accounts Revenue recognized as a result of settlement agreement Deductions Allowance for Doubtful Accounts Receivable, Write-offs Balance, end of period Billed Gross Billings Income Taxes Income Tax Disclosure [Text Block] Schedule of Accounts Receivable, CABS Revenue and Allowance for Doubtful Accounts Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Schedule of Accrued Expenses and Other Current Liabilities Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block] Schedule of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] 2018 (remaining) Operating Leases, Future Minimum Payments, Remainder of Fiscal Year 2019 Operating Leases, Future Minimum Payments, Due in Two Years 2020 Operating Leases, Future Minimum Payments, Due in Three Years 2021 Operating Leases, Future Minimum Payments, Due in Four Years 2022 Operating Leases, Future Minimum Payments, Due in Five Years Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Future minimum payments due, total Operating Leases, Future Minimum Payments Due Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] U.S. treasury securities US Treasury Securities [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] Amortized cost Available-for-sale Securities, Debt Maturities, Next Twelve Months, Amortized Cost Basis Aggregate fair value Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value Interest earned on marketable securities Interest and Dividend Income, Securities, Operating, Available-for-sale 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] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value, Measurements, Recurring Fair Value, Measurements, Recurring [Member] Money market account Money Market Funds [Member] U.S. Reverse repurchase agreements US Reverse Repurchase Agreements [Member] US Reverse Repurchase Agreement [Member] Financial assets Financial Assets [Member] Financial Assets [Member] Cash and cash equivalents, amortized cost or carrying value Cash and cash equivalents, unrealized gains Cash and Cash Equivalents, Gross Unrealized Gain Cash and Cash Equivalents, Gross Unrealized Gain Cash and cash equivalents, unrealized loss Cash and Cash Equivalents, Gross Unrealized Loss Cash and Cash Equivalents, Gross Unrealized Loss Cash and cash equivalents, fair value Cash and Cash Equivalents, Fair Value Disclosure Marketable securities, amortized cost or carrying value Available-for-sale Debt Securities, Amortized Cost Basis Marketable securities, unrealized gain Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax Marketable securities, net unrealized losses Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax Marketable securities, fair value Available-for-sale Securities, Debt Securities Total financial assets, fair value Assets, Fair Value Disclosure Financial assets, unrealized gain Financial Assets, Gross Unrealized Gain Financial Assets, Gross Unrealized Gain Financial assets, unrealized loss Financial Assets, Gross Unrealized Loss Financial Assets, Gross Unrealized Loss