Entity Central Index Key Restricted cash fair value disclosure. Income tax reconciliation convertible debt and acquisition. Tax cuts and jobs act of 2017 change in tax rate income tax expense benefit. Income tax rate reconciliation transition tax. Document and entity information. Document And Entity Information [Abstract] 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 Trading Symbol Trading Symbol Entity Registrant Name Entity Registrant Name Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Well-known Seasoned Issuer Entity Well Known Seasoned Issuer Entity Current Reporting Status Entity Current Reporting Status Entity Voluntary Filers Entity Voluntary Filers Entity Filer Category Entity Filer Category Entity Common Stock, Shares Outstanding Entity Common Stock Shares Outstanding Entity Public Float Entity Public Float Amount of assets related to consideration paid in advance for costs related to third-party hosting agreement. These costs will provide economic benefits within a future period of one year or the normal operating cycle, if longer. Statement Of Financial Position [Abstract] Assets Assets [Abstract] Current assets: Assets Current [Abstract] Cash and cash equivalents Cash And Cash Equivalents At Carrying Value Short-term investments Available For Sale Securities Debt Securities Current Accounts receivable—net of allowance for doubtful accounts of $638 and $617 at December 31, 2017 and 2016, respectively Accounts Receivable Net Current Deferred commission expense Deferred Sales Commission Restricted cash Restricted Cash Current Prepaid hosting costs Prepaid Hosting Costs Prepaid expenses and other current assets Prepaid Expense And Other Assets Current Total current assets Assets Current Long-term investments Available For Sale Securities Debt Securities Noncurrent Property and equipment, net Property Plant And Equipment Net Capitalized software development costs, net Capitalized Computer Software Net Restricted cash Restricted Cash Noncurrent Other assets Other Assets Noncurrent Intangible assets, net Finite Lived Intangible Assets Net Goodwill Goodwill Total assets Assets Liabilities and stockholders’ equity Liabilities And Stockholders Equity [Abstract] Current liabilities: Liabilities Current [Abstract] Accounts payable Accounts Payable Current Accrued compensation costs Employee Related Liabilities Current Other accrued expenses Other Accrued Liabilities Current Deferred revenue Deferred Revenue Current Total current liabilities Liabilities Current Deferred rent, net of current portion Deferred Rent Credit Noncurrent Deferred revenue, net of current portion Deferred Revenue Noncurrent Other long-term liabilities Other Liabilities Noncurrent Convertible senior notes Convertible Long Term Notes Payable Total liabilities Liabilities Commitments and contingencies (Note 9) Commitments And Contingencies Stockholders’ equity: Stockholders Equity [Abstract] Common stock, $0.001 par value—authorized, 500,000 shares; issued and outstanding, 37,503 and 35,784 at December 31, 2017 and 2016, respectively Common Stock Value 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’ equity Stockholders Equity Total liabilities and stockholders’ equity Liabilities And Stockholders Equity Accounts receivable, net of allowance for doubtful accounts Allowance For Doubtful Accounts Receivable Current Common stock, par value Common Stock Par Or Stated Value Per Share Common stock, shares authorized Common Stock Shares Authorized Common stock, shares issued Common Stock Shares Issued Common stock, shares outstanding Common Stock Shares Outstanding Revenue derived from professional services performed and other miscellaneous sources. Income Statement [Abstract] Revenue: Revenues [Abstract] Subscription Subscription Revenue Professional services and other Professional Services And Other Revenue Total revenue Revenues Cost of Revenue: Cost Of Revenue [Abstract] Subscription Cost Of Goods Sold Subscription Professional services and other Cost Of Services Total cost of revenue Cost Of Revenue Gross profit Gross Profit 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 Loss from operations Operating Income Loss Other (expense) income: Nonoperating Income Expense [Abstract] Interest income Investment Income Interest Interest expense Interest Expense Other (expense) income Other Nonoperating Income Expense Total other (expense) income Nonoperating Income Expense Loss before income tax benefit (expense) Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest Income tax benefit (expense) Income Tax Expense Benefit Net loss Net Income Loss Net loss per common share, basic and diluted Earnings Per Share Basic And Diluted Weighted average common shares used in computing basic and diluted net loss per common share: Weighted Average Number Of Share Outstanding Basic And Diluted Statement Of Income And Comprehensive Income [Abstract] Net loss Other comprehensive loss: Other Comprehensive Income Loss Net Of Tax Period Increase Decrease [Abstract] Foreign currency translation adjustments Other Comprehensive Income Foreign Currency Transaction And Translation Adjustment Net Of Tax Portion Attributable To Parent Changes in unrealized (loss) gain on investments, net of income taxes of $0 in 2017, $71 in 2016, and $0 in 2015. Other Comprehensive Income Availableforsale Securities Adjustment Net Of Tax Portion Attributable To Parent Comprehensive loss Comprehensive Income Net Of Tax Changes in unrealized (loss) gain on investments, income taxes Other Comprehensive Income Availableforsale Securities Tax Portion Attributable To Parent Cumulative adjustment from adoption of stock compensation standard. Statement Of Stockholders Equity [Abstract] Statement [Table] Statement [Table] Equity Components Statement Equity Components [Axis] Equity Component Equity Component [Domain] Common Stock [Member] Common Stock [Member] Additional Paid-In Capital [Member] Additional Paid In Capital [Member] Accumulated Other Comprehensive Loss [Member] Accumulated Other Comprehensive Income [Member] Accumulated Deficit [Member] Retained Earnings [Member] Sale of Stock Subsidiary Sale Of Stock [Axis] Sale of Stock Sale Of Stock Name Of Transaction [Domain] Secondary public offering. Secondary Public Offering [Member] Secondary Public Offering [Member] Statement [Line Items] Statement [Line Items] Beginning Balance, Amount Beginning Balance, Shares Shares Outstanding Issuance of common stock under stock plans, net of shares withheld for employee taxes Stock Issued During Period Value Employee Stock Purchase Plan Issuance of common stock under stock plans, net of shares withheld for employee taxes, Shares Stock Issued During Period Shares Employee Stock Purchase Plans Stock-based compensation Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value Proceeds from secondary public offering, net of deferred offering costs Stock Issued During Period Value New Issues Proceeds from secondary public offering, net of deferred offering costs, Shares Stock Issued During Period Shares New Issues Unrealized gain (loss) on investments, net of income taxes Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax Cumulative adjustment from adoption of stock compensation standard Cumulative Adjustment From Adoption Of Stock Compensation Standard Cumulative translation adjustment Other Comprehensive Income Foreign Currency Transaction And Translation Gain Loss Arising During Period Net Of Tax Equity component of 2022 Notes (Note 7) Adjustments To Additional Paid In Capital Equity Component Of Convertible Debt Ending Balance, Amount Ending Balance, Shares Unrealized gain (loss) on investments, tax Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax Non-cash income tax benefit (expense). (Accretion) amortization of debt discount premium. Amount of noncash expense included in rent expense. The Cash outflow associated with the investments in private companies. Statement Of Cash Flows [Abstract] Operating Activities: Net Cash Provided By Used In Operating Activities Continuing Operations [Abstract] Adjustments to reconcile net loss to net cash and cash equivalents provided by (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 Share Based Compensation Deferred income tax benefit Non Cash Income Tax Benefit Expense Amortization of debt discount and issuance costs Amortization Of Financing Costs And Discounts (Accretion) amortization of bond discount premium Accretion Amortization Of Debt Discount Premium Non-cash rent expense Noncash Rent Expense Unrealized currency translation Foreign Currency Transaction Gain Loss Unrealized Changes in 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 Deferred Expense And Other Assets Deferred commission expense Increase Decrease In Deferred Compensation Accounts payable Increase Decrease In Accounts Payable Accrued expenses Increase Decrease In Accrued Liabilities Deferred rent Increase Decrease In Deferred Charges Deferred revenue Increase Decrease In Deferred Revenue Net cash and cash equivalents provided by (used in) operating activities Net Cash Provided By Used In Operating Activities Continuing Operations Investing Activities: Net Cash Provided By Used In Investing Activities Continuing Operations [Abstract] Purchases of investments Payments To Acquire Available For Sale Securities Debt Maturities and sales of investments Proceeds From Sale Maturity And Collections Of Investments Purchases of property and equipment Payments To Acquire Property Plant And Equipment Capitalization of software development costs Payments To Develop Software Acquisition of a business and purchase of technology Payments To Acquire Businesses Gross Purchase of strategic investments Payment For Purchase Of Strategic Investments Restricted cash Increase Decrease In Restricted Cash Net cash and cash equivalents used in investing activities 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 common stock offerings, net of offering costs paid of $583 Proceeds From Issuance Of Common Stock Employee taxes paid related to the net share settlement of stock-based awards Payments Related To Tax Withholding For Share Based Compensation Proceeds related to the issuance of common stock under stock plans Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans Including Stock Options Proceeds from issuance of convertible notes, net of issuance costs paid of $10,767 Proceeds From Issuance Of Long Term Debt Purchase of note hedge related to convertible notes Payments For Hedge Financing Activities Proceeds from the issuance of warrants related to convertible notes, net of issuance costs paid of $200 Proceeds From Issuance Of Warrants Repayment of capital lease obligations Repayments Of Long Term Capital Lease Obligations Net cash and cash equivalents provided by financing activities Net Cash Provided By Used In Financing Activities Continuing Operations Effect on exchange rate changes on cash and cash equivalents Effect Of Exchange Rate On Cash And Cash Equivalents Net increase (decrease) in cash and cash equivalents Cash And Cash Equivalents Period Increase Decrease Cash and cash equivalents, beginning of year Cash and cash equivalents, end of year Supplemental cash flow disclosure: Supplemental Cash Flow Information [Abstract] Cash paid for interest Interest Paid Cash paid for income taxes Income Taxes Paid Non-cash investing and financing activities: Cash Flow Noncash Investing And Financing Activities Disclosure [Abstract] Property and equipment acquired under capital lease Capital Lease Obligations Incurred Capital expenditures incurred but not yet paid Capital Expenditures Incurred But Not Yet Paid Asset retirement obligations Settlement Of Asset Retirement Obligations Through Noncash Payments Amount Warrant [Member] Warrant [Member] Offering and issuance costs paid Payments Of Stock Issuance Costs Convertible notes, issuance costs Payments Of Debt Issuance Costs Accounting Policies [Abstract] Organization and Operations Organization Consolidation And Presentation Of Financial Statements Disclosure [Text Block] Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Fair Value Disclosures [Abstract] Fair Value of Financial Instruments Fair Value Disclosures [Text Block] Property Plant And Equipment [Abstract] Property and Equipment Property Plant And Equipment Disclosure [Text Block] Business Combinations [Abstract] Business Acquisition and Purchase of Technology Business Combination Disclosure [Text Block] Goodwill And Intangible Assets Disclosure [Abstract] Intangible Assets Intangible Assets Disclosure [Text Block] Debt Disclosure [Abstract] 0.25% Convertible Senior Notes, Convertible Note Hedge and Warrant Long Term Debt [Text Block] Segment Reporting [Abstract] Geographic Data Segment Reporting Disclosure [Text Block] Commitments And Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments And Contingencies Disclosure [Text Block] Equity [Abstract] Changes in Accumulated Other Comprehensive Loss Comprehensive Income Note [Text Block] Stockholders equity and stock based compensation. Stockholders Equity And Stock Based Compensation [Abstract] Stockholders' Equity and Stock-Based Compensation Shareholders Equity And Share Based Payments [Text Block] Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] Employee Stock Purchase Plan Disclosure Of Compensation Related Costs Share Based Payments [Text Block] Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] Compensation And Retirement Disclosure [Abstract] Employee Benefit Plan Pension And Other Postretirement Benefits Disclosure [Text Block]