Vesting of restricted stock units, net of shares withheld for taxes (in shares) Restricted Stock Units, Shares Issued Net Of Shares For Tax Withholdings Restricted Stock Units, Shares Issued Net Of Shares For Tax Withholdings Share repurchase program, authorized amount Stock Repurchase Program, Authorized Amount Liability for reported claims and claims incurred but not reported Liability for Claims and Claims Adjustment Expense, Property Casualty Liability Goodwill divested Disposal Group, Including Discontinued Operation, Goodwill Net (Loss) Income per Common Share Earnings Per Share, Policy [Policy Text Block] Vested (in shares) Share-based compensation options vested in period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Trademarks and trade names Trademarks and Trade Names [Member] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Net (loss) income Net (loss) income Net income Net Income (Loss) Attributable to Parent Entity Emerging Growth Company Entity Emerging Growth Company Operating lease right-of-use assets Operating lease right-of-use assets Operating Lease, Right-of-Use Asset Investment securities—current Debt Securities, Available-for-sale, Current Preferred stock, shares outstanding (in shares) Preferred Stock, Shares Outstanding Accrued employee expenses—current Total accrued employee expenses—current Employee-related Liabilities, Current Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Statistical Measurement [Domain] Statistical Measurement [Domain] Entity Address, Address Line One Entity Address, Address Line One Consideration for disposal of subsidiary Disposal Group, Including Discontinued Operation, Consideration Forfeited (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Cash divested Cash Divested from Deconsolidation 2022 Capitalized Computer Software, Amortization Expense, Year One Capitalized Computer Software, Amortization Expense, Year One Payment of contingent consideration Payment for Contingent Consideration Liability, Financing Activities Entity Filer Category Entity Filer Category Other long-term assets Other Assets, Noncurrent Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] 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 Stock-based compensation APIC, Share-based Payment Arrangement, Increase for Cost Recognition Income tax payable Increase (Decrease) in Income Taxes Payable Deposits held with a third party related to insurance services collateral Property, Liability And Casualty Insurance, Deposits Held With Third Party As Collateral For Services Property, Liability And Casualty Insurance, Deposits Held With Third Party As Collateral For Services Options cancelled/forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period Document Fiscal Year Focus Document Fiscal Year Focus Accrued bonuses Accrued Bonuses, Current Lessee, Lease, Description [Line Items] Lessee, Lease, Description [Line Items] Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Amortization expense Amortization of Intangible Assets Other current assets Other Current Assets [Member] Variable lease cost Variable Lease, Cost Net deferred tax assets Deferred Tax Assets, Net Shares excluded from net loss per share computation (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Revenue recognized from deferred revenue Contract with Customer, Liability, Revenue Recognized Adjustment to the employee retention bonus pool Noncash or Part Noncash Divestiture, Adjustment to Consideration Noncash or Part Noncash Divestiture, Adjustment to Consideration Granted (in dollars 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 Title of Individual [Domain] Title of Individual [Domain] Proceeds from maturities of available-for-sale investments Gross Proceeds from Maturities Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-sale Changes in unrealized (losses) gains on investment securities OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax Disposal Group Name [Axis] Disposal Group Name [Axis] Award Type [Domain] Award Type [Domain] Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract] Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract] Assets Assets [Abstract] Schedule of Available-for-sale Securities Schedule of Available-for-sale Securities Reconciliation [Table Text Block] Available-for-sale Investments, by Remaining Contract Maturity Investments Classified by Contractual Maturity Date [Table Text Block] Granted (in shares) Shares granted in period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Schedule of Sales, Calls, and Maturities Schedule of Realized Gain (Loss) [Table Text Block] Capitalization of software development costs included in accrued expenses and accrued employee expenses Capitalized Computer Software Additions, Incurred But Not Yet Paid Capitalized Computer Software Additions, Incurred But Not Yet Paid Intangible Assets, net Goodwill and Intangible Assets Disclosure [Text Block] Preferred stock, $0.0001 par value, 25,000 shares authorized and no shares issued and outstanding as of September 30, 2021 and December 31, 2020 Preferred Stock, Value, Issued Options outstanding, beginning balance (in shares) Options outstanding, ending balance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Entity Address, City or Town Entity Address, City or Town Retained Earnings/(Accumulated Deficit) Retained Earnings [Member] Prepaid expenses and other current assets Increase (Decrease) in Prepaid Expense and Other Assets Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Accounts receivable Increase (Decrease) in Accounts Receivable Discrete tax expense Discontinued Operation, Tax Effect of Discontinued Operation Purchases of property and equipment included in accounts payable and accrued expenses Capital Expenditures Incurred but Not yet Paid Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] 2021 Capitalized Computer Software, Amortization Expense, Remainder of Fiscal Year Capitalized Computer Software, Amortization Expense, Remainder of Fiscal Year Stock-based compensation capitalized for software development Share-based Payment Arrangement, Amount Capitalized Capitalized Software Development Costs, net Research, Development, and Computer Software Disclosure [Text Block] Entity Interactive Data Current Entity Interactive Data Current Gain on sale of business Gain (Loss) on Disposition of Business Basic (in dollars per share) Earnings Per Share, Basic 2024 Lessee, Operating Lease, Liability, to be Paid, Year Three Retention period Disposal Group, Including Discontinued Operation, Retention Period Disposal Group, Including Discontinued Operation, Retention Period Revenue and Other Information Revenue from Contract with Customer [Text Block] Unvested, beginning balance (in shares) Unvested, ending balance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Document Type Document Type Due after one year through three years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year One Through Five Schedule of Product Information by Revenue Categories Disaggregation of Revenue [Table Text Block] Accrued employee expenses—noncurrent Employee-related Liabilities, Noncurrent Employee-related Liabilities, Noncurrent Amortized Cost Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract] Number of Shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Entity Current Reporting Status Entity Current Reporting Status Schedule of Restricted Stock Awards Activity Nonvested Restricted Stock Shares Activity [Table Text Block] Accrued employee expenses—noncurrent Increase (Decrease) In Employee-related Liabilities, Noncurrent Increase (Decrease) In Employee-related Liabilities, Noncurrent Weighted Average Grant Date Fair Value per Share Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Other Other Noncash Income (Expense) Restricted cash included in other assets Restricted Cash and Cash Equivalents 2023 Capitalized Computer Software, Amortization Expense, Year Two Capitalized Computer Software, Amortization Expense, Year Two Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Proceeds from issuance of debt Proceeds from Issuance of Secured Debt Tax associated with gain on sale Discontinued Operation, Tax Effect of Gain (Loss) from Disposal of Discontinued Operation Plan Name [Axis] Plan Name [Axis] PSUs Granted in 2020 Performance Stock Units Granted in 2020 [Member] Performance Stock Units Granted in 2020 Total Assets, Fair Value Disclosure Capitalized software divested Disposal Group, Including Discontinued Operation, Capitalized Software Disposal Group, Including Discontinued Operation, Capitalized Software Level 1 Fair Value, Inputs, Level 1 [Member] Cash from investing activities Net Cash Provided by (Used in) Investing Activities [Abstract] Document Transition Report Document Transition Report Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Years ending December 31, Lessee, Operating Lease, Liability, Payment, Due [Abstract] Conversion of Class B stock to Class A stock (in shares) Conversion of Stock, Shares Converted Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Total liabilities and stockholders’ equity Liabilities and Equity Vesting Tranche One Share-based Payment Arrangement, Tranche One [Member] Deferred revenue Contract with Customer, Liability, Current Options exercised, weighted average exercise price (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Non-compete agreements Noncompete Agreements [Member] Additional paid-in capital Additional Paid in Capital Lessee, Lease, Description [Table] Lessee, Lease, Description [Table] Liabilities and Stockholders’ Equity Liabilities and Equity [Abstract] Accounts payable Increase (Decrease) in Accounts Payable Schedule of Capitalized Computer Software Future Amortization Expense Schedule Of Capitalized Computer Software, Future Amortization Expense [Table Text Block] Schedule of Capitalized Computer Software, Future Amortization Expense [Table Text Block] Performance Stock Units Granted in 2019 and 2018 Performance Stock Units Granted in 2019 and 2018 [Member] Performance Stock Units Granted in 2019 and 2018 [Member] Assets divested Disposal Group, Including Discontinued Operation, Assets Repurchase of common stock Reduction to stockholders' equity Treasury Stock, Value, Acquired, Cost Method 2025 Finite-Lived Intangible Asset, Expected Amortization, Year Four Cash and Cash Equivalents [Domain] Cash and Cash Equivalents [Domain] Exercise of stock options Stock Issued During Period, Value, Stock Options Exercised Minimum Minimum [Member] Gross Realized Gains Debt Securities, Available-for-sale, Realized Gain 2023 Lessee, Operating Lease, Liability, to be Paid, Year Two Balance Sheet Location [Domain] Balance Sheet Location [Domain] Options cancelled/forfeited, weighted average exercise price (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price Other comprehensive (loss) income: Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Preferred stock, shares authorized (in shares) Preferred Stock, Shares Authorized Prepaid expenses and other current assets Operating Lease, Prepaid Expenses And Other Current Assets Operating Lease, Prepaid Expenses And Other Current Assets Gross Unrealized Gains Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax Number of directors to authorize repurchases Stock Repurchase Program, Number Of Directors To Authorize Repurchases Stock Repurchase Program, Number Of Directors To Authorize Repurchases Trading Symbol Trading Symbol Deferred income taxes—noncurrent Deferred Income Tax Assets, Net Current liabilities Liabilities, Current [Abstract] Capitalization of software development costs Payments to Develop Software General and administrative General and Administrative Expense Beginning balance (in shares) Ending balance (in shares) Shares, Outstanding Stock-Based Compensation Share-based Payment Arrangement [Text Block] Level 3 Fair Value, Inputs, Level 3 [Member] Accounting Policies [Abstract] Accounting Policies [Abstract] Employee retention bonus pool Noncash or Part Noncash Divestiture, Amount of Consideration Received Weighted Average Remaining Contractual Life in Years Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Total lease liabilities Operating Lease, Liability Domain names Internet Domain Names [Member] Common stock Common Stock, Value, Issued Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Stock-based compensation expense, weighted average recognition period Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Unvested, beginning balance (in dollars per share) Unvested, ending balance (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Basis of Presentation and Significant Accounting Policies Basis of Accounting, Policy [Policy Text Block] PSUs Performance Shares [Member] Commitments and contingencies (Note 9) Commitments and Contingencies Leases Lessee, Operating Leases [Text Block] Proceeds from sale of business, net of cash divested Proceeds from Divestiture of Businesses, Net of Cash Divested Accumulated other comprehensive (loss) income Accumulated Other Comprehensive Income (Loss), Net of Tax 2021 Lessee, Operating Lease, Liability, to be Paid, Remainder of Fiscal Year Divestitures Business Combination Disclosure [Text Block] Restricted Stock Awards Restricted Stock [Member] Cash, cash equivalents and restricted cash Cash and Cash Equivalents, at Carrying Value [Abstract] Disposal Group Classification [Axis] Disposal Group Classification [Axis] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Document Period End Date Document Period End Date Plus: Weighted average options, restricted stock units and restricted shares used to compute diluted net income per common share (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Total costs and operating expenses Costs and Expenses Class of Stock [Axis] Class of Stock [Axis] Entity Registrant Name Entity Registrant Name Treasury stock (in shares) Treasury Stock, Shares Interest income (expense), net Interest Income (Expense), Net Less: imputed interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Financial Instrument [Axis] Financial Instrument [Axis] Accrued expenses Accrued Liabilities, Current Revenue Revenue from Contract with Customer, Excluding Assessed Tax Total Lessee, Operating Lease, Liability, Net Of Current Portion Lessee, Operating Lease, Liability, Net Of Current Portion Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Accrued vacation Accrued Vacation, Current Capitalized software development costs Capitalized Computer Software, Additions 2024 Capitalized Computer Software, Amortization Expense, Year Three Capitalized Computer Software, Amortization Expense, Year Three Equity [Abstract] Equity [Abstract] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Interest income, net of amortization and accretion of premium and discount Investment Income, Interest Common Stock Common Stock [Member] (Loss) income from operations Operating Income (Loss) Other current liabilities Operating lease, current Operating Lease, Liability, Current Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-sale [Line Items] Due after one year through three years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five Gross Unrealized Losses Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax 2023 Finite-Lived Intangible Asset, Expected Amortization, Year Two Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Stock-based compensation Share-based Payment Arrangement, Noncash Expense Additional Paid-in Capital Additional Paid-in Capital [Member] Cash and cash equivalents Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Reversal of deferred tax liabilities Increase (Decrease) in Deferred Income Taxes Treasury Stock Treasury Stock [Member] Purchases of available-for-sale investments Payments to Acquire Debt Securities, Available-for-sale Quota share of tenant liability insurance provided, percent Reinsurance Retention Policy, Reinsured Risk, Percentage Deferred revenue divested Disposal Group, Including Discontinued Operation, Deferred Revenue Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] Other (loss) income, net Other Nonoperating Income (Expense) Other liabilities Increase (Decrease) in Other Operating Liabilities Purchases of property, equipment and intangible assets Payments to Acquire Property, Plant, and Equipment Other current liabilities Other Liabilities, Current Maximum Maximum [Member] Share-based Payment Arrangement [Abstract] Share-based Payment Arrangement [Abstract] Total liabilities Liabilities Award Type [Axis] Award Type [Axis] 2022 Finite-Lived Intangible Asset, Expected Amortization, Year One Options granted, weighted average exercise price (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Cash from financing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Schedule of Minimum Lease Payments Under Leases Lessee, Operating Lease, Liability, Maturity [Table Text Block] Total stockholders’ equity Beginning balance Ending balance Stockholders' Equity Attributable to Parent Common stock, shares issued (in shares) Common Stock, Shares, Issued Preferred stock, shares issued (in shares) Preferred Stock, Shares Issued Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Disclosure [Abstract] Gross Realized Losses Debt Securities, Available-for-sale, Realized Loss Accrued expenses Increase (Decrease) in Other Accrued Liabilities Purchase of treasury stock Payments for Repurchase of Common Stock Estimated Fair Value Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value [Abstract] Stockholders’ equity: Stockholders' Equity Attributable to Parent [Abstract] Noncash investing and financing activities Noncash Investing and Financing Items [Abstract] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Operating lease liabilities Operating lease liabilities Operating Lease, Liability, Noncurrent Measurement Frequency [Domain] Measurement Frequency [Domain] PSUs Granted in 2021 Performance Stock Units Granted in 2021 [Member] Performance Stock Units Granted in 2021 Accrued employee expenses—current Increase (Decrease) in Employee Related Liabilities Discontinued Operations and Disposal Groups [Abstract] Operating lease liabilities Increase (Decrease) In Operating Leases Increase (Decrease) In Operating Leases City Area Code City Area Code Retained earnings Retained Earnings (Accumulated Deficit) Accrued Employee Expenses Compensation Related Costs, General [Text Block] Lease term Lessee, Operating Lease, Term of Contract Restricted Stock Units (RSUs) Restricted Stock Units (RSUs) [Member] Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Business Acquisition [Line Items] Business Acquisition [Line Items] Vesting Tranche Two Share-based Payment Arrangement, Tranche Two [Member] Treasury securities Treasury securities US Treasury Securities [Member] Income Statement [Abstract] Income Statement [Abstract] Amendment Flag Amendment Flag Proceeds from stock option exercises Proceeds from Stock Options Exercised Capitalized software development costs, net Capitalized software development costs, net Capitalized Computer Software, Net Summary of Significant Accounting Policies Basis of Presentation and Significant Accounting Policies [Text Block] Issuance of restricted stock awards (in shares) Stock Issued During Period, Shares, Restricted Stock Award, Gross Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] (Benefit from) provision for income taxes Income Tax Expense (Benefit) Accounts receivable, net Accounts Receivable, after Allowance for Credit Loss, Current Equity Components [Axis] Equity Components [Axis] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Total current assets Assets, Current Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Total future minimum lease payments Lessee, Operating Lease, Liability, to be Paid Forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period RSUs and PSUs Restricted Stock Units And Performance Stock Units [Member] Restricted Stock Units And Performance Stock Units [Member] Entity File Number Entity File Number Accrued employee expenses—noncurrent Employee-related Liabilities 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] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Product and Service [Axis] Product and Service [Axis] Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Schedule of Weighted Average Number of Shares Schedule of Weighted Average Number of Shares [Table Text Block] Entity Small Business Entity Small Business Preferred stock, par value (in dollars per share) Preferred Stock, Par or Stated Value Per Share Remaining stock-based compensation expense for unvested shares, not yet recognized Share-based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount Equity Component [Domain] Equity Component [Domain] Other Other Services [Member] Other Services [Member] Sales and marketing Selling and Marketing Expense 2022 Lessee, Operating Lease, Liability, to be Paid, Year One Discontinued Operations, Disposed of by Sale Discontinued Operations, Disposed of by Sale [Member] Disposal Group Name [Domain] Disposal Group Name [Domain] Thereafter Finite-Lived Intangible Asset, Expected Amortization, after Year Four Finite-Lived Intangible Asset, Expected Amortization, after Year Four Lease renewal term Lessor, Operating Lease, Renewal Term Statement [Line Items] Statement [Line Items] Deferred revenue Increase (Decrease) in Contract with Customer, Liability Schedule of Accrued Employee Expenses Schedule of Accrued Employee Expenses [Table Text Block] Schedule of Accrued Employee Expenses Weighted Average Exercise Price per Share Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Investment securities—noncurrent Debt Securities, Available-for-sale, Noncurrent Available-for-sale Securities, Debt Maturities [Abstract] Available-for-sale Securities, Debt Maturities [Abstract] Estimated Fair Value Total available-for-sale investment securities Available-for-sale investment securities Debt Securities, Available-for-sale 2025 Lessee, Operating Lease, Liability, to be Paid, Year Four Weighted Average Useful Life in Years Weighted Average [Member] Entity Address, State or Province Entity Address, State or Province (Loss) income before (benefit from) provision for income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Level 2 Fair Value, Inputs, Level 2 [Member] Document Information [Table] Document Information [Table] Segment Reporting [Abstract] Segment Reporting [Abstract] Total available-for-sale investment securities Debt Securities, Available-for-sale, Amortized Cost Weighted Average Useful Life in Years Finite-Lived Intangible Asset, Useful Life Use of Estimates Use of Estimates, Policy [Policy Text Block] Options granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Entity Shell Company Entity Shell Company Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Agency securities Agency securities Agency securities Agency Securities [Member] Local Phone Number Local Phone Number Vesting [Axis] Vesting [Axis] Total assets Assets Less: Weighted average unvested restricted shares subject to repurchase (in shares) Weighted Average Number of Shares, Restricted Stock Deferred income taxes Deferred Income Taxes and Tax Credits Tenant improvement allowance, remainder of fiscal year Lessee, Operating Lease, Tenant Allowance, Remainder Of Fiscal Year Lessee, Operating Lease, Tenant Allowance, Remainder Of Fiscal Year Plan Name [Domain] Plan Name [Domain] Common stock, shares authorized (in shares) Common Stock, Shares Authorized Weighted average common shares outstanding (in shares) Weighted Average Number of Shares Issued, Basic Principal payments on debt Repayments of Secured Debt Title of Individual [Axis] Title of Individual [Axis] Product and Service [Domain] Product and Service [Domain] Schedule of Restricted Stock Units Activity Schedule of Nonvested Restricted Stock Units Activity [Table Text Block] Research and product development Research and Development Expense 2021 Three Year Plan 2021 Three Year Plan [Member] 2021 Three Year Plan Percent of achievement of award target performance metric Share-based Compensation Arrangements by Share-based Payment Award, Percent Of Achievement Of Award Target Performance Metric Share-based Compensation Arrangements by Share-based Payment Award, Percent Of Achievement Of Award Target Performance Metric Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] MyCase MyCase [Member] MyCase Measurement Frequency [Axis] Measurement Frequency [Axis] Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Maximum contractual maturity period Available-For-Sale Securities, Maximum Contractual Maturity Available-For-Sale Securities, Maximum Contractual Maturity Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Schedule of Components of Lease Expense Lease, Cost [Table Text Block] Entity Tax Identification Number Entity Tax Identification Number Corporate bonds Corporate bonds Corporate bonds Corporate Bond Securities [Member] Core solutions Core Solutions [Member] Core Solutions [Member] Value+ services Value Plus Services [Member] Value Plus Services [Member] Basic (in shares) Weighted average common shares outstanding; basic (in shares) Weighted Average Number of Shares Outstanding, Basic Diluted (in dollars per share) Earnings Per Share, Diluted Vesting [Domain] Vesting [Domain] Accrued payroll taxes and other Accrued Payroll Taxes, Current Comprehensive (loss) income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Intangible assets, net Intangible Assets, Net (Excluding Goodwill) Partner relationships Partner Relationships [Member] Partner Relationships [Member] Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities Treasury stock, at cost, 419 shares of Class A common stock as of September 30, 2021 and December 31, 2020 Treasury Stock, Value Weighted average common shares outstanding: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Deferred income taxes—noncurrent Deferred Income Tax Liabilities, Net Vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Accounts payable Accounts Payable, Current Depreciation and amortization Depreciation, Depletion and Amortization Accrued payroll Accrued Salaries, Current 2024 Finite-Lived Intangible Asset, Expected Amortization, Year Three Fair Value, Assets Measured on Recurring Basis Fair Value, Assets Measured on Recurring Basis [Table Text Block] Less: Accumulated amortization Capitalized Computer Software, Accumulated Amortization Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] 2021 Finite-Lived Intangible Asset, Expected Amortization, Remainder of Fiscal Year Years Ending December 31, Capitalized Computer Software, Net [Abstract] Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Financial Instruments [Domain] Financial Instruments [Domain] Tenant improvement allowance, 2022 Lessee, Operating Lease, Tenant Allowance, Year One Lessee, Operating Lease, Tenant Allowance, Year One Cost of revenue (exclusive of depreciation and amortization) Cost of Goods and Services Sold Class B common stock Common Class B [Member] Research and Development [Abstract] Research and Development [Abstract] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Per incident policy limit Property, Liability And Casualty Insurance, Per Incident And Per Residence Coverage Limit Property, Liability And Casualty Insurance, Per Incident And Per Residence Coverage Limit Vesting of restricted stock units, net of shares withheld for taxes Restricted Stock Units, Value, Shares Issued Net Of Tax Withholdings Restricted Stock Units, Value, Shares Issued Net Of Tax Withholdings Number of Shares Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Proceeds from divestiture of subsidiary Proceeds from Divestiture of Interest in Consolidated Subsidiaries Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Total lease cost Lease, Cost Tenant improvement allowance, 2024 Lessee, Operating Lease, Tenant Allowance, Year Three Lessee, Operating Lease, Tenant Allowance, Year Three Schedule of Capitalized Computer Software Schedule Of Capitalized Computer Software [Table Text Block] Schedule Of Capitalized Computer Software [Table Text Block] Customer relationships Customer Relationships [Member] Due in one year or less Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, Year One Amortization of operating lease right-of-use assets Amortization Of Operating Lease, Right-Of-Use Assets Amortization Of Operating Lease, Right-Of-Use Assets Compensation Related Costs [Abstract] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Property and equipment, net Property, Plant and Equipment, Net Tenant improvement allowance, 2023 Lessee, Operating Lease, Tenant Allowance, Year Two Lessee, Operating Lease, Tenant Allowance, Year Two Technology Technology [Member] Technology [Member] Capitalized software development costs, gross Capitalized Computer Software, Gross Schedule of Finite-Lived Intangible Assets, Future Amortization Expense Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Repurchase of common stock (in shares) Repurchased shares (in shares) Treasury Stock, Shares, Acquired Net (loss) income per common share: Earnings Per Share [Abstract] Document Quarterly Report Document Quarterly Report Other assets Increase (Decrease) in Other Operating Assets Other current liabilities Other Current Liabilities [Member] Gain on sale of subsidiary Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax Proceeds from sales of available-for-sale investments Gross Proceeds from Sales Proceeds from Sale of Debt Securities, Available-for-sale Options outstanding, weighted average exercise price, beginning balance (in dollars per share) Options outstanding, weighted average exercise price, ending balance (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Costs and operating expenses: Costs and Expenses [Abstract] Patents Patents [Member] Stock-based compensation expense Share-based Payment Arrangement, Expense Weighted Average Grant Date Fair Value per Share Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Document Fiscal Period Focus Document Fiscal Period Focus Investment Securities and Fair Value Measurements Investment Securities And Fair Value Measurements, Disclosure [Text Block] Investment Securities And Fair Value Measurements, Disclosure [Text Block] PSUs Granted in 2018 Performance Stock Units Granted in 2018 [Member] Performance Stock Units Granted in 2018 [Member] Class A common stock Common Class A [Member] Beginning of period End of period Total cash, cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Allowance for credit losses for available-for-sale investment securities Debt Securities, Available-for-sale, Allowance for Credit Loss Percent of targeted performance metric Share-based Compensation Arrangements by Share-based Payment Award, Percent Of Award Target Performance Metric Share-based Compensation Arrangements by Share-based Payment Award, Percent Of Award Target Performance Metric Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Income tax payable Taxes Payable, Current Current assets Assets, Current [Abstract] Gross Carrying Value Finite-Lived Intangible Assets, Gross Leases [Abstract] Leases [Abstract] Entity Central Index Key Entity Central Index Key Schedule of Finite-Lived Intangible Assets Schedule of Finite-Lived Intangible Assets [Table Text Block] Amortization expense Capitalized Computer Software, Amortization Security Exchange Name Security Exchange Name Percent of cash bonus payments on initial targets, percent Share-Based Compensation Arrangements By Share-Based Payment Award, Percent Of Cash Bonus Payment On Initial Targets Share-Based Compensation Arrangements By Share-Based Payment Award, Percent Of Cash Bonus Payment On Initial Targets PSUs Granted in 2019 Performance Stock Units Granted in 2019 [Member] Performance Stock Units Granted in 2019 [Member] Cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Disposal Group Classification [Domain] Disposal Group Classification [Domain] Exercise of stock options (in shares) Options exercised (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period PSUs Performance Stock Units [Member] Performance Stock Units [Member] Diluted (in shares) Weighted average common shares outstanding; diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Fair value, recurring measurements Fair Value, Recurring [Member] Income received Disposal Group, Including Discontinued Operation, Other Income Income Taxes Income Tax Disclosure [Text Block] Current Fiscal Year End Date Current Fiscal Year End Date Summary of Stock Option Activity Share-based Payment Arrangement, Option, Activity [Table Text Block] Share Repurchase Program Stockholders' Equity Note Disclosure [Text Block] Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Working capital adjustment Disposal Group, Including Discontinued Operation, Working Capital Adjustment Disposal Group, Including Discontinued Operation, Working Capital Adjustment Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Net cash (used in) provided by investing activities Net Cash Provided by (Used in) Investing Activities Performance based cash bonus payment percent Share-based Compensation Arrangements by Share-based Payment Award, Performance Based Cash Bonus Payment, Percent Share-based Compensation Arrangements by Share-based Payment Award, Performance Based Cash Bonus Payment, Percent Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Cash from operating activities Net Cash Provided by (Used in) Operating Activities [Abstract] Vested (in dollars 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 Total current liabilities Liabilities, Current Tax withholding for net share settlement Payment, Tax Withholding, Share-based Payment Arrangement Class of Stock [Domain] Class of Stock [Domain] Money market funds Money Market Funds [Member] Loss Contingencies [Table] Loss Contingencies [Table] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Accrued commissions Accrued Sales Commission, Current Document Information [Line Items] Document Information [Line Items] Title of 12(b) Security Title of 12(b) Security Statement [Table] Statement [Table] Recent Accounting Pronouncements Adopted in 2020 and 2021 New Accounting Pronouncements, Policy [Policy Text Block] Prepaid Expenses and Other Current Assets Prepaid Expenses and Other Current Assets [Member] Statistical Measurement [Axis] Statistical Measurement [Axis] Cover [Abstract] Cover [Abstract] Database Database [Member] Database [Member] Net Carrying Value Finite-Lived Intangible Assets, Net Goodwill Goodwill Thereafter Lessee, Operating Lease, Liability, to be Paid, after Year Four Lessee, Operating Lease, Liability, to be Paid, after Year Four Nature of Business Nature of Operations [Text Block] 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] Due in one year or less Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Operating lease cost Operating Lease, Cost Cash and Cash Equivalents [Axis] Cash and Cash Equivalents [Axis] Depreciation and amortization Depreciation, Depletion and Amortization, Excluding Amortization of Financing Costs Depreciation, Depletion and Amortization, Excluding Amortization of Financing Costs Executive Executive Officer [Member] Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table]