Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Share-Based Compensation Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Income Statement [Abstract] Statement [Table] Statement [Table] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Cost of revenues Cost of Sales [Member] Sales and marketing Selling and Marketing Expense [Member] Research and development Research and Development Expense [Member] General and administrative General and Administrative Expense [Member] Statement [Line Items] Statement [Line Items] Stock-based Compensation Expense Allocated Share-based Compensation Expense Equity [Abstract] Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent Event [Member] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Class B common stock Common Class B [Member] Class A common stock Common Class A [Member] Class of Stock [Line Items] Class of Stock [Line Items] Preferred Stock, Shares Authorized Preferred Stock, Shares Authorized Preferred Stock, Par Value (in usd per share) Preferred Stock, Par or Stated Value Per Share Stock Repurchase Program, Authorized Amount Stock Repurchase Program, Authorized Amount Stock Repurchased and Retired During Period, Shares Stock Repurchased and Retired During Period, Shares Stock Repurchased, Average Cost Per Share Treasury Stock Acquired, Average Cost Per Share Stock Repurchased and Retired During Period, Value Stock Repurchased and Retired During Period, Value Stock Repurchase Program, Remaining Authorized Repurchase Amount Stock Repurchase Program, Remaining Authorized Repurchase Amount Common Stock, Shares Authorized Common Stock, Shares Authorized Common Stock, Par Value (in usd per share) Common Stock, Par or Stated Value Per Share Votes per Share Entitled to Share Holder Common Stock, Voting Rights, Entitled Votes Per Share Held Number of votes associated with common stock class Stock Repurchase Program, Increase to Authorized Amount Stock Repurchase Program, Increase to Authorized Amount Stock Repurchase Program, Increase to Authorized Amount Stock Repurchased And Retired, Shares Stock Repurchased And Retired, Shares Stock Repurchased And Retired, Shares Stock Repurchased And Retired, Value Stock Repurchased And Retired, Value Stock Repurchased And Retired, Value Fair Value Disclosures [Abstract] Fair Value Measurements Fair Value Disclosures [Text Block] Revenue from Contract with Customer [Abstract] Capitalized Contract Cost [Table] Capitalized Contract Cost [Table] Capitalized Contract Cost [Axis] Capitalized Contract Cost [Axis] Capitalized Contract Cost [Domain] Capitalized Contract Cost [Domain] Contract Asset [Member] Contract Asset [Member] Contract Asset [Member] Capitalized Contract Cost [Line Items] Capitalized Contract Cost [Line Items] Balances at December 31, 2017 Contract with Customer, Asset, Net Adoption of ASC 606 Cumulative Effect of New Accounting Principle in Period of Adoption Contract assets transferred to receivables Contract with Customer, Asset, Reclassified to Receivable Additions to contract assets Contract with Customer, Asset, Increase (Decrease) for Contract Acquired in Business Combination Balances at March 31, 2018 Earnings Per Share [Abstract] Schedule of New Accounting Pronouncements and Changes in Accounting Principles Schedule of New Accounting Pronouncements and Changes in Accounting Principles [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] Commitments and Contingencies Disclosure [Abstract] Operating Lease Commitments Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] Operating Lease Commitments, Remainder of 2017 Operating Leases, Future Minimum Payments, Remainder of Fiscal Year Operating Lease Commitments, 2018 Operating Leases, Future Minimum Payments Due, Next Twelve Months Operating Lease Commitments, 2019 Operating Leases, Future Minimum Payments, Due in Two Years Operating Lease Commitments, 2020 Operating Leases, Future Minimum Payments, Due in Three Years Operating Lease Commitments, 2021 Operating Leases, Future Minimum Payments, Due in Four Years Operating Lease Commitments, Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Operating Lease Commitments, Total Operating Leases, Future Minimum Payments Due Expected Sublease Receipts Operating Leases, Future Minimum Payments Receivable [Abstract] Expected Sublease Receipts, Remainder of 2017 Operating Leases, Future Minimum Payments Receivable, Remainder of Fiscal Year Expected Sublease Receipts, 2018 Operating Leases, Future Minimum Payments Receivable, Current Expected Sublease Receipts, 2019 Operating Leases, Future Minimum Payments Receivable, in Two Years Expected Sublease Receipts, 2020 Operating Leases, Future Minimum Payments Receivable, in Three Years Expected Sublease Receipts, 2021 Operating Leases, Future Minimum Payments Receivable, in Four Years Expected Sublease Receipts, Thereafter Operating Leases, Future Minimum Payments Receivable, Thereafter Expected Sublease Receipts, Total Operating Leases, Future Minimum Payments Receivable Net Operating Leases, Rent Expense, Net [Abstract] Net, Remainder of 2017 Operating Leases, Future Minimum Payments, Net, Remainder of Fiscal Year Operating Leases, Future Minimum Payments, Net, Remainder of Fiscal Year Net, 2018 Operating Leases, Future Minimum Payments Due, Net, Next Twelve Months Operating Leases, Future Minimum Payments Due, Net, Next Twelve Months Net, 2019 Operating Leases, Future Minimum Payments, Net, Due in Two Years Operating Leases, Future Minimum Payments, Net, Due in Two Years Net, 2020 Operating Leases, Future Minimum Payments, Net, Due in Three Years Operating Leases, Future Minimum Payments, Net, Due in Three Years Net, 2021 Operating Leases, Future Minimum Payments, Net, Due in Four Years Operating Leases, Future Minimum Payments, Net, Due in Four Years Net, Thereafter Operating Leases, Future Minimum Payments, Net, Due Thereafter Operating Leases, Future Minimum Payments, Net, Due Thereafter Net, Total Operating Leases, Future Minimum Payments Due, Net Operating Leases, Future Minimum Payments Due, Net Statement of Financial Position [Abstract] Liabilities and stockholders' equity Liabilities and Equity [Abstract] Current liabilities Liabilities, Current [Abstract] Accounts payable Accounts Payable, Current Accrued compensation and employee-related benefits Employee-related Liabilities, Current Other accrued liabilities Accrued Liabilities and Other Liabilities Income taxes payable Accrued Income Taxes, Current Deferred revenue Deferred Revenue, Current Total current liabilities Liabilities, Current Deferred revenue Deferred Revenue, Noncurrent Other long-term liabilities Other Liabilities, Noncurrent Total liabilities Liabilities Commitments and contingencies (Note 9) Commitments and Contingencies Stockholders' equity Stockholders' Equity Attributable to Parent [Abstract] Preferred stock, $0.0001 par value, 10,000,000 shares authorized; none issued Preferred Stock, Value, Issued Additional paid-in capital Additional Paid in Capital Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated deficit Retained Earnings (Accumulated Deficit) Total stockholders' equity Stockholders' Equity Attributable to Parent Total liabilities and stockholders' equity Liabilities and Equity Assets Assets [Abstract] Current assets Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Short-term investments Short-term Investments Accounts receivable, net of allowance for doubtful accounts of $972 and $1,003 Accounts Receivable, Net, Current Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Income taxes receivable Income Taxes Receivable, Current Total current assets Assets, Current Long-term investments Long-term Investments Property and equipment, net Property, Plant and Equipment, Net Goodwill Goodwill Deferred income taxes Deferred Tax Assets, Net Other long-term assets Deposits Assets and Other Assets, Noncurrent Amount of asset related to long term deposits and other assets. Total assets Assets Common stock Common Stock, Value, Issued Revenue, Initial Application Period Cumulative Effect Transition [Table] Revenue, Initial Application Period Cumulative Effect Transition [Table] Initial Application Period Cumulative Effect Transition [Axis] Initial Application Period Cumulative Effect Transition [Axis] Initial Application Period Cumulative Effect Transition [Domain] Initial Application Period Cumulative Effect Transition [Domain] Impacts from Adoption Difference between Revenue Guidance in Effect before and after Topic 606 [Member] Without Adoption (ASC 605) Calculated under Revenue Guidance in Effect before Topic 606 [Member] Revenue, Initial Application Period Cumulative Effect Transition [Line Items] Revenue, Initial Application Period Cumulative Effect Transition [Line Items] Net loss per share - basic and diluted Earnings Per Share, Basic and Diluted [Abstract] Net loss Net Income (Loss) Attributable to Parent Weighted average shares outstanding used to compute basic and diluted net loss per share Weighted Average Number of Shares Outstanding, Basic and Diluted Net loss per share - basic and diluted (in usd per share) Earnings Per Share, Basic and Diluted Antidilutive shares excluded from computation of diluted net loss Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Investments, Debt and Equity Securities [Abstract] Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Domain] Major Types of Debt and Equity Securities [Domain] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Schedule of Available-for-sale Securities Schedule of Available-for-sale Securities [Line Items] Short-term and Long-term Investments Disclosure Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Investment Type [Axis] Investment Type [Axis] Investment Type Categorization [Domain] Investments [Domain] Short-term investments Short-term Investments [Member] Long-term investments Long-term Investments [Member] Long-term Investments [Member] Commercial Paper, Not Included with Cash and Cash Equivalents [Member] Commercial Paper, Not Included with Cash and Cash Equivalents [Member] U.S. treasury securities US Treasury Securities [Member] U.S. agency securities US Government Agencies Debt Securities [Member] Corporate bonds Corporate Debt Securities [Member] Amortized Cost Available-for-sale Debt Securities, Amortized Cost Basis Unrealized Gains Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax Unrealized Losses Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax Fair Value Available-for-sale Securities, Debt Securities, Current Fair Value Available-for-sale Securities, Debt Securities, Noncurrent Fair Value Available-for-sale Securities, Debt Securities Short-term and Long-term Investments Investment [Table Text Block] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2014-09 [Member] Accounting Standards Update 2014-09 [Member] Net loss Adjustments to reconcile net loss 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 expense Depreciation Accretion (Amortization) of Discounts and Premiums, Investments Accretion (Amortization) of Discounts and Premiums, Investments Stock-based compensation expense Share-based Compensation Deferred income taxes Deferred Income Taxes and Tax Credits Changes in operating assets and liabilities Increase (Decrease) in Operating Capital [Abstract] Increase (Decrease) in Accounts Receivable Increase (Decrease) in Accounts Receivable Increase (Decrease) in Prepaid Expense and Other Assets Increase (Decrease) in Prepaid Expense and Other Assets Increase (Decrease) in Income Taxes Receivable Increase (Decrease) in Income Taxes Receivable Deferred revenue Increase (Decrease) in Deferred Revenue Accounts payable and accrued liabilities Increase (Decrease) in Accounts Payable and Accrued Liabilities Income taxes payable Increase (Decrease) in Income Taxes Payable Net Cash Provided by (Used in) Operating Activities, Continuing Operations Net Cash Provided by (Used in) Operating Activities, Continuing Operations Investing activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Payments to Acquire Property, Plant, and Equipment Payments to Acquire Property, Plant, and Equipment Payments to Acquire Available-for-sale Securities Payments to Acquire Available-for-sale Securities Maturities of investments Proceeds from Maturity of Marketable Securities The cash inflow associated with the aggregate amount received by the entity through mautiry of marketable securities (held-to-maturity or available-for-sale) during the period. Sales of investments Proceeds from Sale of Marketable Securities The cash inflow associated with the aggregate amount received by the entity through sale of marketable securities (held-to-maturity or available-for-sale) during the period. Net Cash Provided by (Used in) Investing Activities, Continuing Operations Net Cash Provided by (Used in) Investing Activities, Continuing Operations Financing activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Proceeds from issuance of common stock Proceeds from Stock Options Exercised Payments for Repurchase of Common Stock Payments for Repurchase of Common Stock Net Cash Provided by (Used in) Financing Activities, Continuing Operations Net Cash Provided by (Used in) Financing Activities, Continuing Operations Effect of exchange rate changes on cash and cash equivalents Effect of Exchange Rate on Cash and Cash Equivalents Cash, Period Increase (Decrease) Cash, Period Increase (Decrease) Cash and cash equivalents Cash and Cash Equivalents [Abstract] Beginning of period End of period Accounting Policies [Abstract] Revenue Recognition Revenue Recognition, Policy [Policy Text Block] Deferred Commissions Deferred Charges, Policy [Policy Text Block] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Risk And Uncertainties Risk And Uncertainties Policy [Policy Text Block] Disclosure of accounting policy related to risks and uncertainties inherent in our business Segments Segment Reporting, Policy [Policy Text Block] Concentrations of Credit Risk Concentration Risk, Credit Risk, Policy [Policy Text Block] Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Number of key products Number of Products Number of Products offered by company Contract with Customer, Asset and Liability Contract with Customer, Asset and Liability [Table Text Block] 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] 2013 Plan 2013 Plan [Member] 2013 Plan [Member] 2013 ESPP ESPP [Member] ESPP [Member] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] 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, Equity Awards, Outstanding [Roll Forward] Share Based Compensation Arrangement by Share Based Payment Award, Number of Shares Available for Grant [Roll Forward] -- None. No documentation exists for this element. -- Equity Based Awards, Beginning of Period, Shares Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Authorized, Shares Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized Granted, Shares Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Granted, Shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Forfeited, Shares Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Number of Shares Forfeited, Shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Equity Based Awards, End of Period, Shares Future Minimum Rental Payments for Operating Leases, Net of Expected Sublease Receipts Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Segment Reporting [Abstract] Segments and Information about Revenues by Geographic Area Segment Reporting Disclosure [Text Block] Statement of Comprehensive Income [Abstract] Other comprehensive income (loss), net of tax: Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Foreign currency translation Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax Net unrealized loss on available-for-sale securities Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax Comprehensive loss Comprehensive Income (Loss), Net of Tax, Attributable to Parent Description of Business Nature of Operations [Text Block] Revenues Revenues [Abstract] License Licenses Revenue Maintenance and services Maintenance Revenue Total revenues Revenues Cost of revenues Cost of Revenue [Abstract] License License Costs Maintenance and services Maintenance Costs Total cost of revenues Cost of Revenue 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 Operating loss Operating Income (Loss) Other income, net Nonoperating Income (Expense) Loss before income tax expense (benefit) Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income tax expense (benefit) Income Tax Expense (Benefit) Net loss Net loss per share: Basic Earnings Per Share, Basic Diluted Earnings Per Share, Diluted Weighted average shares used to compute net loss per share: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Basic (shares) Weighted Average Number of Shares Outstanding, Basic Diluted (shares) Weighted Average Number of Shares Outstanding, Diluted Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Fair Value of Financial Assets Fair Value, Assets Measured on Recurring Basis [Table Text Block] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Revenue Revenue from Contract with Customer [Text Block] Deferred Commissions [Member] Deferred Commissions [Member] Deferred Commissions [Member] Adoption of ASC 606 Capitalized Contract Cost, Gross Capitalized Contract Cost, Gross Amortization of deferred contract costs Capitalized Contract Cost, Amortization Amortization period, deferred commissions Amortization period, deferred commissions Amortization period, deferred commissions Deferred Costs, Current Deferred Costs, Current Number of Operating Segments Number of Operating Segments Terms of Payment due Revenue Recognition, Terms of Payment Typical terms of payment after delivery. New Accounting Pronouncements or Change in Accounting Principle [Table] New Accounting Pronouncements or Change in Accounting Principle [Table] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Stockholders' Equity Retained Earnings [Member] Liability Class [Axis] Deferred Revenue Arrangement Type [Axis] Deferred Revenue [Domain] Deferred Revenue [Domain] Deferred Revenue [Member] Deferred Revenue [Member] Deferred Revenue [Member] New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] Adoption of ASC 606 Reconciliation of Revenue from Segments to Consolidated Revenue from External Customers by Geographic Areas [Table Text Block] Prepaid Expense and Other Assets, Current Assets, Current Assets Liabilities, Current Liabilities Stockholders' Equity Attributable to Parent Liabilities and Equity Allowance for doubtful accounts Allowance for Doubtful Accounts Receivable Preferred Stock, Shares Issued Preferred Stock, Shares Issued Common Stock, Shares Issued Common Stock, Shares, Issued Common Stock, Shares Outstanding Common Stock, Shares, Outstanding Stockholders' Equity Stockholders' Equity Note Disclosure [Text Block] Revenues Cost of Revenue Gross Profit Operating Expenses Operating Income (Loss) Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Summary of Option Activity Share-based Compensation, Stock Options, Activity [Table Text Block] Summary of RSU Activity Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block] Summary of Shares Available for Grant Schedule of Share-based Compensation, Options and Restricted Stock Units Available for Grant [Table Text Block] Disclosure of the number of options and restricted stock units that are available for grant Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] United States and Canada United States and Canada [Member] Member for United States and Canada International International [Member] Member for International Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Statement of Cash Flows [Abstract] Operating activities Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Amortization of premiums on investments, net Accounts receivable, net Prepaid expenses and other assets Income taxes receivable Net cash provided by operating activities Purchases of property and equipment Purchases of investments Net cash used in investing activities Repurchases of common stock Net cash used in financing activities Net increase (decrease) in cash and cash equivalents Non-cash activities Supplemental Cash Flow Information [Abstract] Accrued purchases of property and equipment Capital Expenditures Incurred but Not yet Paid Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Cash and cash equivalents Money Market Funds [Member] Commercial Paper [Member] Commercial Paper [Member] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value, Measurements, 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] 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] Investments Fair Value Investments, Fair Value Disclosure Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Period performance obligation is expected to be recognized [Axis] Period performance obligation is expected to be recognized [Axis] Period performance obligation is expected to be recognized [Axis] Recognized Over Next 24 Months [Domain] Recognized Over Next 24 Months [Domain] Recognized Over Next 24 Months [Domain] Total to be recognized [Domain] Total to be recognized [Domain] Total to be recognized [Domain] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation Revenue, Remaining Performance Obligation Option expiration period (in years) Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period Vesting period (in years) Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Payroll Deduction, Percent Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Payroll Deduction, Percent Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Payroll Deduction, Percent Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Purchase Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Purchase Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Purchase Period Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent Unrecognized compensation expense Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Recognition period (in years) Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Document Information [Abstract] Document Information [Abstract] Document Information [Line Items] Document Information [Line Items] Document Type Document Type Amendment Flag Amendment Flag Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus 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 Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Comprehensive Income (Loss), Net of Tax, Attributable to Parent Net Loss Per Share Earnings Per Share [Text Block] Balances at December 31, 2017 Contract with Customer, Liability Deferred revenue recognized Contract with Customer, Liability, Revenue Recognized Additional amounts deferred Contract With Customer Liability, Amounts Deferred Contract With Customer Liability, Amounts Deferred Balances at March 31, 2018 Shares Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Options Outstanding, Shares, Beginning of Period Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Options Outstanding, Shares, Options Exercised Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Options Outstanding, Shares, End of Period Options Outstanding, Shares, Vested and Expected to Vest Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number Options Outstanding, Shares, Exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Weighted Average Exercise Price Per Share Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Options Outstanding, Weighted Average Exercise Price, Beginning of Period, USD per Share Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Options Outstanding, Weighted Average Exercise Price, Options Exercised, USD per Share Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Options Outstanding, Weighted Average Exercise Price, End of Period, USD per Share Options Outstanding, Weighted Average Exercise Price Per Share, Vested and Expected to Vest, USD per Share Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price Options Outstanding, Weighted Average Exercise Price Per Share, Exercisable, USD per Share Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract] Options Outstanding, Weighted Average Remaining Contractual Term, End of Period (in years) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Options Outstanding, Weighted Average Remaining Contractual Term, Vested and Expected to Vest (in years) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term Options Outstanding, Weighted Average Remaining Contractual Term, Exercisable (in years) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Options Outstanding, Aggregate Intrinsic Value, End of Period Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Options Outstanding, Aggregate Intrinsic Value, Vested and Expected to Vest Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value Options Outstanding, Aggregate Intrinsic Value, Exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] RSUs Restricted Stock Units (RSUs) [Member] Number of Shares Underlying Outstanding RSUs Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward] RSU Shares Outstanding, Beginning of Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number RSUs granted, Shares RSUs vested, Shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period RSUs forfeited, Shares RSU Shares Outstanding, End of Period Weighted-Average Grant-Date Fair Value per RSU Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Weighted Average Exercise Price [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Weighted Average Exercise Price [Roll Forward] Weighted Average Fair Value, Beginning of Period, 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 Fair Value, RSUs Granted, 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 Fair Value, RSUs Vested, 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 Fair Value, RSUs Forfeited, 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 Fair Value, End of Period, USD per Share Income Tax Expense Benefit [Table] Income Tax Expense Benefit [Table] Income Tax Expense Benefit [Table] Income Tax Expense Benefit [Line Items] Income Tax Expense Benefit [Line Items] Income Tax Expense Benefit [Line Items] Effective tax rate Effective Income Tax Rate Reconciliation, Percent