PRSUs (equity-settled) granted (in shares) RSUs granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period DW SEF Dw Sef Llc [Member] DW SEF LLC (DW SEF) is a swap execution facility regulated by the Commodities Future Trading Commission. Document Type Document Type TWL Tradeweb Llc [Member] Tradeweb LLC (TWL) is a registered broker-dealer under the Securities Exchange Act of 1934, a member of the Financial Industry Regulatory Authority, a registered independent introducing broker with the Commodities Future Trading Commission and a member of the National Futures Association. Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] PRSUs (cash-settled) granted (in shares) Options granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Deposits with clearing organizations Deposits with Clearing Organizations and Others, Securities Related Party [Axis] Related Party [Axis] Accounts payable, accrued expenses and other liabilities Increase (Decrease) in Accounts Payable and Accrued Liabilities Income Tax Disclosure [Table] Income Tax Disclosure [Table] Disclosure of information pertaining to income taxes. Noncontrolling Interest [Table] Noncontrolling Interest [Table] Wholesale Wholesale Client Sector [Member] The wholesale client sector. Significant Unobservable Inputs (Level 3) Fair Value, Inputs, Level 3 [Member] Related party expense Related Party Transaction, Expenses from Transactions with Related Party Securities sold under agreements to repurchase Increase (Decrease) in Payables under Repurchase Agreements TW SEF Tw Sef Llc [Member] TW SEF LLC (TW SEF) is a swap execution facility regulated by the Commodities Future Trading Commission. Statistical Measurement [Domain] Statistical Measurement [Domain] Liabilities and Stockholders' Equity Liabilities and Equity [Abstract] Risks and Uncertainties [Abstract] Risks and Uncertainties [Abstract] 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 [Line Items] Distributions to non-controlling interests Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Deferred tax liability Deferred Income Tax Liabilities, Net Employee compensation and benefits Labor and Related Expense Floor Debt Instrument Floor Rate The Percentage of floor rate under debt instrument. Security Exchange Name Security Exchange Name Intangible assets, net of accumulated amortization Intangible Assets, Net (Excluding Goodwill) Percentage of amount of U.S. federal, state and local income or franchise tax savings Tax Receivable Agreement, Percentage Of Amount Of Federal, State And Local Income Or Franchise Tax Savings The percentage of amount of U.S. federal, state and local income or franchise tax savings under the tax receivable agreement. Operating income Operating Income (Loss) Deposits with clearing organizations Increase (Decrease) in Deposit Assets Capital distributions Capital distributions Distribution Made to Limited Liability Company (LLC) Member, Cash Distributions Declared Non-Controlling Interests Noncontrolling Interest Disclosure [Text Block] Schedule of recognized revenue and remaining deferred revenue balance Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block] Foreign currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Noncontrolling Interest Variable Rate [Domain] Variable Rate [Domain] Variable Rate [Axis] Variable Rate [Axis] Commitments and contingencies (Note 14) Commitments and Contingencies Assets Assets [Abstract] Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Accounting Policies [Abstract] Accounting Policies [Abstract] Entity Address, State or Province Entity Address, State or Province Votes Number Of Votes Per Common Stock Number Of votes per common stock. TWEU Tradeweb Eu Bv [Member] Tradeweb EU B.V. (TWEU) is a trading venue and approved publication arrangement regulated by the Netherlands Authority for the Financial Markets. Percentage of performance modifier Percentage of Performance Modifier Represents the percentage of performance modifier. Software Development Costs Internal Use Software, Policy [Policy Text Block] Retained earnings Retained Earnings (Accumulated Deficit) Equity-settled PRSUs Performance Shares Settled With Equity [Member] Performance restricted share units settled with equity. Percentage of economic interest Percentage of Economic Interest in Limited Liability Company The percentage of economic interest in limited liability company. Right-of-use assets Operating Lease, Right-of-Use Asset Class B Common Stock Common Class B [Member] Income taxes paid Income Taxes Paid Unrecognized compensation expense Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Customer [Axis] Customer [Axis] Beginning balance ( in shares) Ending balance (in shares) Shares, Outstanding Preferred stock, $.00001 par value; 250,000,000 shares authorized; none issued or outstanding Preferred Stock, Value, Issued Income Tax Income Tax, Policy [Policy Text Block] Common Stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Deferred tax asset Deferred Income Tax Assets, Net Conversion ratio Common Stock Conversion Ratio Represents the ratio for conversion of common stock. Refinitiv Direct Owner Refinitiv Direct Owner [Member] Represents information pertaining to Refinitiv Direct Owner. Gross revenue Gross revenue Revenue from Contract with Customer, Excluding Assessed Tax Denominator: Weighted Average Number of Shares Outstanding, Basic [Abstract] Potential Dilutive Potential Dilutive Securities [Member] Potential dilutive securities. Public offering price (in dollars per share) Share Price Establishment of liabilities under tax receivable agreement Liabilities Assumed LLC units Limited Liability Company Units [Member] Represents information pertaining to LLC units. Geographical [Domain] Geographical [Domain] Commissions Commissions Revenue [Member] Commission revenue from electronic and voice brokerage services on a riskless principal basis recorded on a trade-date basis. Statement [Line Items] Statement Statement [Line Items] Shares issued to acquire TWM LLC (in shares) Stock Issued During Period, Shares, Acquisitions Schedule of cash-settled PRSUs issued Schedule Of Cash Settled Performance Based Units Activity [Table Text Block] Tabular disclosure of activity for cash-settled performance-based restricted stock units (PRSUs) issued by the reporting entity. Class of Stock [Domain] Class of Stock [Domain] Refinitiv LLC Owner Refinitiv Llc Owner [Member] Represents information pertaining to Refinitiv LLC Owner. Revolving credit facility, term Debt Instrument, Term Statement [Table] Statement [Table] Recoveries collected Accounts Receivable, Allowance for Credit Loss, Writeoff Statistical Measurement [Axis] Statistical Measurement [Axis] Number of share owned (in shares) Number of share owned Number of share owned. Number of LLC Interest held by parent (in shares) Number of LLC Interests held by Tradeweb Markets Inc. (in shares) Minority Interest Number Of Interests Held By Parent The parent entity's interest in the subsidiary. Preferred stock, shares issued (in shares) Preferred Stock, Shares Issued Entity Small Business Entity Small Business Basis of Presentation and Consolidation Consolidation, Policy [Policy Text Block] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Shares issued to underwriters (in shares) Sale of Stock, Number of Shares Issued in Transaction Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Stock-based compensation expense APIC, Share-based Payment Arrangement, Restricted Stock Unit, Increase for Cost Recognition Proceeds from issuance of Class A common stock in the IPO and follow-on offerings, net of underwriting discounts Proceeds from Issuance of Common Stock IPO net income Net Income (Loss) Attributable To Limited Liability Company The amount of net income (loss) attributable to limited liability company. Amendment Flag Amendment Flag Summary of Basic and Diluted Earnings Per Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Tax Receivable Agreement Tax Receivable Agreement Liability Disclosure [Text Block] The entire disclosure of tax receivable agreement liability. Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Number of shares authorized (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Amount outstanding Long-term Line of Credit Fair Value Measurement Fair Value Measurement, Policy [Policy Text Block] Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Deposits with Clearing Organizations Deposits With Clearing Organizations [Policy Text Block] Disclosure of accounting policy for deposits with clearing organizations. Financial Resources Futures Commission Merchant, Commodity Exchange Act, Adjusted Net Capital Entity Central Index Key Entity Central Index Key Related Party [Domain] Related Party [Domain] Conversion ratio Noncontrolling Interest, Conversion Ratio The conversion ratio of shares of non-controlling interests. Operating Income and Expenses: Interest Income, Securities, Operating, by Taxable Status [Abstract] Payable to affiliates Due to Affiliate Related Party Transactions Related Party Transaction [Line Items] Allowance for Credit Losses Receivables, Trade and Other Accounts Receivable, Allowance for Doubtful Accounts, Policy [Policy Text Block] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Employee equity compensation payable Increase Decrease In Equity Compensation Payable The increase (decrease) during the period in equity compensation payable. Intangible assets that are subject to amortization Schedule of Finite-Lived Intangible Assets [Table Text Block] Geographical [Axis] Geographical [Axis] Subsequent Events Subsequent Events [Text Block] Number of shares canceled (in shares) Common Stock, Shares, Retired Number of shares of common stock canceled during the period. Summary of the ownership interest in noncontrolling interest Schedule Of Ownership Interest In Noncontrolling Interest [Table Text Block] Tabular disclosure of ownership interest in noncontrolling interest. Tax Receivable Agreement Tax Receivable Agreement No definition available. Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Schedule of regulatory capital requirements Schedule Of Regulatory Capital Requirements [Table Text Block] Tabular disclosure of the regulatory capital requirements and regulatory capital for entities subject to regulation. Property, Plant and Equipment, Type [Axis] Long-Lived Tangible Asset [Axis] Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Stock-based compensation expense under the Option Plan APIC, Share-based Payment Arrangement, Option, Increase for Cost Recognition State, local and foreign State and Local Jurisdiction [Member] Intangible assets with indefinite useful lives Indefinite-lived Intangible Assets [Line Items] Cash flows from financing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Stockholders' Equity Note [Abstract] Stockholders' Equity Note [Abstract] Amortization expense Amortization of Intangible Assets Business Segment and Geographic Information Segment Reporting Disclosure [Text Block] Issuance of common stock from equity incentive plans Stock Issued During Period, Value, New Issues Money market funds Cash and Cash Equivalents, Fair Value Disclosure Number of LLC Interest (in shares) Number of LLC Interests held by non-controlling interests (in shares) Minority interest Number Of Interests Held By Noncontrolling Owners The equity interest of noncontrolling shareholders. Concentration Risk [Table] Concentration Risk [Table] Total assets Assets Related Party Transactions Related Party Transactions Disclosure [Text Block] Class P (A) Common Class Pa Shares [Member] Class P(A) shares. Package of practical expedients Lease, Practical Expedients, Package [true false] Title of 12(b) Security Title of 12(b) Security Follow On Offering Follow On Offering [Member] Follow On Offering Contract with Customer, Basis of Pricing [Axis] Contract with Customer, Basis of Pricing [Axis] Net Carrying Amount Finite-Lived Intangible Assets, Net Long-lived assets Long-Lived Assets Weighted-average grant-date fair value, cash settled (in dollars per share) Weighted-average grant-date fair value (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Subsequent Event Type [Axis] Subsequent Event Type [Axis] Shared Services Fees: Shared Services Fees [Abstract] n/a. Adjustments to non-controlling interests Minority Interest Increase Decrease From Adjustments Amount of increase (decrease) in noncontrolling interest from adjustments. Number of LLC Interests held by Tradeweb Markets Inc. Ownership percentage, Continuing LLC Owners Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners Product and Service [Axis] Product and Service [Axis] Voting power threshold percentage to require conversion of shares Voting Power Threshold Percentage To Require Conversion of Shares The voting power threshold percentage to require conversion of shares. Total liabilities Liabilities Payroll taxes paid for stock-based compensation exercises Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net Transaction fees Transaction Fee Revenue [Member] Transaction fee revenues, both variable and fixed, recorded at a point in time when the trade occurs. Threshold percentage of economic interest for conversion Threshold Percentage of Economic Interest for Conversion Threshold percentage of economic interest for conversion. Excess Regulatory Capital Excess Regulatory Capital Amount by which the entity's regulatory capital (as defined) exceeds the requirement. Expected weighted-average period Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Subscription Fees including Refinitiv market data fees Subscription Fee And Market Data Revenue [Member] Subscription fee revenue from granting access to institutional investors to the entity's electronic marketplaces and fees from the sale of market data to Refinitiv. International Non-US [Member] Purchase of LLC Interests Payments for Repurchase of Redeemable Noncontrolling Interest Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Schedule of class of common stock par value, votes and economic rights Schedule of Stock by Class [Table Text Block] Revenue recognized Contract with Customer, Liability, Revenue Recognized Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Adjusted For Refinitiv Transaction Adjusted For Refinitiv Transaction [Member] Reflects a new basis of accounting resulting from the Refinitiv transaction. Quoted Prices in active Markets for Identical Assets (Level 1) Fair Value, Inputs, Level 1 [Member] Deferred costs Deferred Offering Costs Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Remaining percentage of tax benefits Tax Receivable Agreement Remaining Percentage of Amount of Federal State and Local Income or Franchise Tax Savings The remaining percentage of amount of U.S. federal, state and local income or franchise tax savings under the tax receivable agreement. Consulting service fee for follow on offering Consulting Service Fee for Follow on Offering The amount of consulting service incurred for follow on offering. Additional Paid-In Capital Additional Paid-in Capital [Member] Net interest income (expense) Interest income Interest Income (Expense), Net Other assets Other Assets Nonrecurring Adjustment [Domain] Nonrecurring Adjustment [Domain] Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract] Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Class of Stock [Line Items] Class of Stock [Line Items] Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] One-month LIBOR One Month London Inter Bank Offered Rate [Member] One Month London Inter Bank Offered Rate. Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Revolving credit facility Revolving Credit Facility [Member] Change In Contract with Customer, Liability [Roll Forward] Change In Contract with Customer, Liability Income before taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Adjustments to reconcile net income to net cash provided by operating activities: Adjustments, Noncash Items, to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Initial Public Offering IPO [Member] Subsequent Event Subsequent Event [Member] Common Stock, shares authorized (in shares) Common Stock, Shares Authorized Schedule of RSUs issued Share-based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block] Dilutive effect (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Proceeds from stock-based compensation exercises Proceeds from Stock Options Exercised Net Income Per Share Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items] Schedule of information regarding revenue by client sector Schedule of Segment Reporting Information, by Segment [Table Text Block] Furniture, Equipment, Purchased Software and Leasehold Improvements Furniture Equipment And Purchased Software [Member] Furniture, equipment and purchased software. Common units exchanged (in shares) Common Unit Exchanged Number The number of common units exchanged. Goodwill Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block] Receivable from and Payable to Broker and Dealers and Clearing Organizations Industry Specific Policies, Broker Dealer [Policy Text Block] Accrued compensation Increase (Decrease) in Employee Related Liabilities Income Statement [Abstract] Income Statement [Abstract] Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Total LLC Interests outstanding Minority Interest Total Ownership Percentage The total ownership interest on noncontrolling interest expressed as a percentage. Adjustment to Class C Shares and Class P(C) shares in mezzanine capital Adjustments to Additional Paid in Capital, Increase in Carrying Amount of Redeemable Preferred Stock Underwriter Over-Allotment Option [Member] Occupancy Occupancy, Net Cash and cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations [Abstract] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Use of Estimates Use of Estimates, Policy [Policy Text Block] Income Tax Authority [Domain] Income Tax Authority [Domain] Dividends ($0.08 per share) Dividends Members' Capital Member Units [Member] Consolidated Entities [Axis] Consolidated Entities [Axis] Comprehensive income attributable to Tradeweb Markets Inc. Comprehensive Income (Loss), Net of Tax, Attributable to Parent Schedule of financial resources and liquid financial resources Futures Commission Merchant, Minimum Financial Requirement [Table Text Block] Preferred stock, par value (in dollars per share) Preferred Stock, Par or Stated Value Per Share Accounts receivable, net of allowance for credit losses of $120 and $195 at September 30, 2020 and December 31, 2019, respectively Account receivable excluding receivable from brokers and dealers and clearing organizations, net of allowance Account receivable excluding receivable from brokers and dealers and clearing organizations, net of allowance. Licenses License [Member] Schedule of equity-settled PRSUs issued Schedule of Nonvested Performance-based Units Activity [Table Text Block] Capitalized software development costs Payments for Software Purchase of furniture, equipment, software and leasehold improvements Payments to Acquire Property, Plant, and Equipment Legal Entity [Axis] Legal Entity [Axis] City Area Code City Area Code Income Tax Authority [Axis] Income Tax Authority [Axis] Receivable from brokers and dealers and clearing organizations Receivables from Brokers-Dealers and Clearing Organizations Document Period End Date Document Period End Date Goodwill and Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Effect of the reorganization transactions Effect Of Reorganization Transactions Effect Of Reorganization Transactions Cancellation ratio Common Stock Cancellation Ratio Represents the ratio for cancellation of common stock. Leasehold interest Leasehold Interest The amount of leasehold interests in the entity. Liquid Financial Assets Liquid Financial Assets Liquid financial assets calculated under the Commodity Exchange Act. Net income Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Breakdown of revenues between fixed and variable revenues Disaggregation of Revenue [Table Text Block] Accrued compensation Employee-related Liabilities Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Allocation of equity to non-controlling interests Minority Interest Increase From Allocation Of Equity Minority Interest Increase From Allocation Of Equity Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Class P-1 (A) Common Class P1a Shares [Member] Class P-1(A) shares. Stock-based compensation expense Share-based Payment Arrangement, Noncash Expense Entity [Domain] Entity [Domain] Payroll taxes paid for stock-based compensation exercises Payment, Tax Withholding, Share-based Payment Arrangement Cover [Abstract] Base rate Base Rate [Member] Stock surrendered (in shares) Stock Repurchased and Retired During Period, Shares Adjustment to additional paid in capital due to consulting service fee Adjustment to Additional Paid in Capital due to Consulting Service Fee The amount of adjustment to additional paid in capital for consulting service fee. Useful life Property, Plant and Equipment, Useful Life Cash and Cash Equivalents [Domain] Cash and Cash Equivalents [Domain] Affiliated Entity Affiliated Entity [Member] Shares contributed by Refinitiv Owner (in shares) Stock Contributed During Period Acquiree Majority Owner The number of shares contributed by the majority owner of the acquiree in the exchange transaction. Lessee, Lease, Description [Line Items] Lessee, Lease, Description [Line Items] TWD Tradeweb Direct Llc [Member] Tradeweb Direct LLC (TWD) is a registered broker-dealer under the Securities Exchange Act of 1934, and a member of the Financial Industry Regulatory Authority. Required Liquid Financial Assets Required Liquid Financial Assets Amount of liquid financial assets required to be maintained under the Commodity Exchange Act. Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Restricted Cash Restricted Assets Disclosure [Text Block] Class C Common Stock Common Class C [Member] Deferred revenue Increase (Decrease) in Deferred Revenue Customer relationships Customer Relationships [Member] Schedule of Earnings Per Share, Basic, by Common Class, Including Two Class Method [Table] Schedule of Earnings Per Share, Basic, by Common Class, Including Two Class Method [Table] Total expenses Operating expenses Costs and Expenses Equity Components [Axis] Equity Components [Axis] Deferred IPO and Follow-On Offering Costs Deferred Charges, Policy [Policy Text Block] Share-based Payment Arrangement [Abstract] Share-based Payment Arrangement [Abstract] Credit Risk Allowance for Credit Losses [Text Block] Minimum Minimum [Member] Pre-IPO capital distributions Payments of Capital Distribution Balance Sheet Location [Domain] Balance Sheet Location [Domain] Accounts Receivable, Allowance for Credit Loss Accounts Receivable, Allowance for Credit Loss [Table Text Block] Tradeweb Markets Inc Tradeweb Markets Inc [Member] Tradeweb Markets Inc., the reporting entity. Consolidated Entities [Domain] Consolidated Entities [Domain] Deferred revenue Contract with Customer, Liability, Related Parties Amount of obligation to transfer good or service to related parties for which consideration has been received or is receivable. Percentage of combined voting power Percentage of Combined Voting Power of Common Stock The percentage of combined voting power of common stock. Less: Net income attributable to non-controlling interests Comprehensive income, net income Net Income (Loss) Attributable to Noncontrolling Interest Tax liability Accrued Income Taxes Entity Interactive Data Current Entity Interactive Data Current U.S. UNITED STATES Revenues Revenue: Revenues [Abstract] Fair Value of Financial Instruments Fair Value Disclosures [Text Block] Bank Stockholders Bank Stockholders [Member] Information relating to the Bank Stockholders. Cash flows from operating activities Net Cash Provided by (Used in) Operating Activities [Abstract] Stockholders’ Equity Stockholders' Equity Note Disclosure [Text Block] Schedule of options issued Share-based Payment Arrangement, Option, Activity [Table Text Block] Commitment fee, percentage Line of Credit Facility, Commitment Fee Percentage Stock-Based Compensation Share-based Payment Arrangement [Policy Text Block] Customer [Domain] Customer [Domain] Tax receivable agreement liability and deferred taxes arising from LLC Interest ownership exchanges Adjustments to Additional Paid in Capital Tax Receivable Agreement Liability and Deferred Taxes Reorganization Transaction and IPO Amount of decrease to additional paid in capital (APIC) resulting from tax receivable agreement liability and deferred taxes arising from the reorganization transactions and IPO. Change from net income attributable to Tradeweb Markets Inc. and transfers (to) from non-controlling interests Net Income Attributable To Parent And Transfers (To) From Noncontrolling Interest The amount of net income (loss) attributable to parent and transfers (to) from noncontrolling interests. Cash Settled PSRUs Performance Shares Settled With Cash [Member] Performance restricted share units settled with cash. Intangible Assets Goodwill and Intangible Assets, Intangible Assets, Policy [Policy Text Block] Entity Registrant Name Entity Registrant Name Subsequent Event Type [Domain] Subsequent Event Type [Domain] Credit Risk Concentration Risk [Line Items] TEL Tradeweb Europe Limited [Member] Tradeweb Europe Limited (TEL) is a Multilateral Trading Facility regulated by the Financial Conduct Authority in the UK, which maintains branches in Asia which are regulated by certain Asian securities regulators. Accounts Receivable, Allowance for Credit Loss [Roll Forward] Accounts Receivable, Allowance for Credit Loss [Roll Forward] Regulatory Capital Requirements Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] Stockholders' Equity Members' Equity [Abstract] Activities related to exchanges of LLC Interests, net of offering costs and cancellations Stock Issued During Period, Value, Conversion of Convertible Securities Receivable from/payable to affiliates, net Increase (Decrease) Due from Affiliates Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Ownership interest Number of LLC Interests held by Tradeweb Markets Inc. Noncontrolling Interest, Ownership Percentage by Parent Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Noncontrolling Interest [Abstract] Noncontrolling Interest [Abstract] Refinitiv Refinitiv [Member] Refinitiv, formerly the Thomson Reuters Financial & Risk Business. Adjustments for New Accounting Pronouncements [Axis] Accounting Standards Update [Axis] Subscription fees Subscription Fee Revenue [Member] Subscription fee revenue from granting access to institutional investors to the entity's electronic marketplaces. Restricted Cash Equivalents [Abstract] Restricted Cash Equivalents [Abstract] Translation of Foreign Currency Foreign Currency Transactions and Translations Policy [Policy Text Block] ASU 2016-02 Accounting Standards Update 2016-02 [Member] Sale of Stock [Axis] Sale of Stock [Axis] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Foreign currency translation adjustments attributable to Tradeweb Markets Inc. Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent Technology and communications Communications and Information Technology Goodwill Goodwill Document Transition Report Document Transition Report Title of Individual [Axis] Title of Individual [Axis] Numerator: Net Income (Loss) Attributable to Parent [Abstract] Dividends (in dollars per share) Cash dividend declared (in dollars per share) Common Stock, Dividends, Per Share, Declared Significant Observable Inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Tradeweb Markets LLC TradeWeb Markets Llc [Member] Tradeweb Markets LLC. Document Quarterly Report Document Quarterly Report Total assets measured at fair value Assets, Fair Value Disclosure Accounts receivable Accounts Receivable, Related Parties Equity [Abstract] Variable Variable Pricing [Member] Contract with customer in which amount of consideration is based on variable components such as transaction based fees. Subsequent Event [Line Items] Subsequent Event [Line Items] Diluted (in shares) Weighted average shares of Class A and Class B common stock outstanding - Diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Schedule of fair value measurements Fair Value Measurements, Recurring and Nonrecurring [Table Text Block] Basic (in dollars per share) Earnings per share - Basic (in dollars per share) Earnings Per Share, Basic Schedule of Indefinite-Lived Intangible Assets [Table] Schedule of Indefinite-Lived Intangible Assets [Table] Entity File Number Entity File Number Other Financial Service, Other [Member] Current-period provision for expected credit losses Accounts Receivable, Allowance for Credit Loss, Recovery Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities 2019 Omnibus Equity Incentive Plan Omnibus2019 Equity Incentive Plan [Member] Represents the information pertaining to omnibus 2019 equity incentive plan. Business Segment and Geographic Information Revenues from External Customers and Long-Lived Assets [Line Items] PRSUs compensation expense Compensation expense Share-based Payment Arrangement, Expense Balance Sheet Location [Axis] Balance Sheet Location [Axis] Common stock Common Stock, Value, Issued April 2020 Follow-On Offering April Two Thousand and Twenty Follow-On Offering [Member] April Two Thousand and Twenty Follow-On Offering Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Disclosure [Abstract] Intangible Assets Intangible assets that are subject to amortization Finite-Lived Intangible Assets [Line Items] Document Fiscal Year Focus Document Fiscal Year Focus Deferred rent Deferred Rent Credit Dividends Payments of Ordinary Dividends Cash and Cash Equivalents [Axis] Cash and Cash Equivalents [Axis] Capital distributions to non-controlling interests Payments Of Capital Distribution To Noncontrolling Interest Amount of cash outflow in the form of capital distribution to noncontrolling interests. Entity Current Reporting Status Entity Current Reporting Status Professional fees Professional Fees Related Party Transaction [Axis] Related Party Transaction [Axis] Subsequent Event [Table] Subsequent Event [Table] DW Dealerweb [Member] Dealerweb Inc. (DW) is a registered broker-dealer under the Securities Exchange Act of 1934, a member of the Financial Industry Regulatory Authority, a registered independent introducing broker with the Commodities Future Trading Commission and a member of the National Futures Association. Earnings Per Share Earnings Per Share, Policy [Policy Text Block] Exercise period following a change in control Share Based Compensation Arrangements By Share Based Payment Award Exercise Period Following Change In Control Share Based Compensation Arrangements By Share Based Payment Award Exercise Period Following Change In Control Non-controlling interests Stockholders' Equity Attributable to Noncontrolling Interest Weighted-average grant-date fair value, equity settled (in dollars per share) Weighted-average grant-date fair value (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 Cash flows from investing activities Net Cash Provided by (Used in) Investing Activities [Abstract] Common stock, shares issued (in shares) Number of shares owned Common Stock, Shares, Issued Cash and cash equivalents Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Lease liability Operating Lease, Liability Subsidiary or Equity Method Investee, Sale of Stock by Subsidiary or Equity Investee [Table] Subsidiary or Equity Method Investee, Sale of Stock by Subsidiary or Equity Investee [Table] Software development costs, net of accumulated amortization Capitalized Computer Software, Net Segment Reporting [Abstract] Segment Reporting [Abstract] Contract with Customer, Basis of Pricing [Domain] Contract with Customer, Basis of Pricing [Domain] Accounts receivable Increase (Decrease) in Accounts Receivable New billings Contract With Customer Liability, New Billings Amount of deferred revenue recognized for new billing arising during the current reporting period. Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Total stockholders' equity attributable to Tradeweb Markets Inc. Total stockholder's equity Stockholders' Equity Attributable to Parent Offering costs from issuance of Class A common stock in the IPO and follow-on offerings Payments of Stock Issuance Costs Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table] Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table] Excess net capital Banking Regulation, Total Risk-Based Capital, Excess, Actual Total liabilities and stockholders' equity Liabilities and Equity Commitments and Contingencies Loss Contingencies [Line Items] Accumulated other comprehensive income Accumulated Other Comprehensive Income (Loss), Net of Tax Income Taxes Income Tax Disclosure [Text Block] Entity Address, City or Town Entity Address, City or Town Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] RSU Restricted Stock Units (RSUs) [Member] Fixed Fixed-price Contract [Member] Content and data Media Content [Member] Type of Adoption [Domain] Accounting Standards Update [Domain] Nonrecurring Adjustment [Axis] Nonrecurring Adjustment [Axis] Excess Liquid Financial Assets Excess Liquid Financial Assets The amount by which actual liquid financial assets exceeds (does not exceed) required liquid financial assets under the Commodity Exchange Act Weighted-average shares (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Entity Ex Transition Period Entity Ex Transition Period Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets [Axis] Useful life of intangible assets Amortization Period Finite-Lived Intangible Asset, Useful Life Equity Component [Domain] Equity Component [Domain] Total LLC Interests outstanding (in shares) Minority Interest Total Number Of Interests The total number of shares of the subsidiary. Liabilities Liabilities [Abstract] Furniture, equipment, purchased software and leasehold improvements, net of accumulated depreciation and amortization Property, Plant and Equipment, Net Class D Common Stock Common Class D [Member] Classification of common stock that has different rights than provided to other classes of common stock, representing interest in a corporation. Increase (decrease) in operating liabilities: Increase (Decrease) in Operating Liabilities [Abstract] Entity Tax Identification Number Entity Tax Identification Number Lessee, Lease, Description [Table] Lessee, Lease, Description [Table] Stock-Based Compensation Plans Share-based Payment Arrangement [Text Block] Limited Liability Company (LLC) Members' Equity [Abstract] Limited Liability Company (LLC) Members' Equity [Abstract] Net income attributable to Tradeweb Markets Inc. Net income attributable to Tradeweb Markets Inc. Net income attributable to Tradeweb Markets Inc. Net Income (Loss) Attributable to Parent Accounts payable, accrued expenses and other liabilities Accounts Payable Accrued Expenses And Other Liabilities [Member] Represents the information pertaining to accounts payable, accrued expenses and other liabilities. TWJ Tradeweb Japan Kk [Member] Tradeweb Japan K.K. (TWJ) is a security house regulated by the Japanese Financial Services Agency and the Japan Securities Dealers Association. Accounts payable, accrued expenses and other liabilities Accounts Payable, Accrued Expenses and Other Liabilities Related Parties Accounts Payable, Accrued Expenses and Other Liabilities Related Parties (Increase) decrease in operating assets: Increase (Decrease) in Operating Assets [Abstract] LIBOR London Interbank Offered Rate (LIBOR) [Member] Tradename Trade Names [Member] October 2019 Follow-On Offering October Two Thousand Nineteen Follow On Offering [Member] October 2019 Follow On Offering. Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Current Fiscal Year End Date Current Fiscal Year End Date Expenses Operating Expenses [Abstract] Comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest EPS calculations for post-IPO and pre-IPO periods Earnings Per Share [Abstract] Earnings Per Share [Abstract] Class P (C) Common Class Pc Shares [Member] Class P(C) shares. Operating Expense Reimbursement Operating Expense Reimbursement [Member] Operating expense reimbursement arrangement in which the reporting entity reimburses affiliates of the counterparty for various services including salaries and bonuses, marketing, professional fees, communications, data costs and certain other administrative services. Refinitiv market data fees Market Data Revenue [Member] Market data revenue earned from the sale of market data to Refinitiv, which redistributes the data. Includes real-time market data fees and historical data sets. Voting power percentage Voting power percentage Voting power percentage. Receivable from/payable to brokers and dealers and clearing organizations, net Increase (Decrease) in Receivables from Brokers-Dealers and Clearing Organizations PRSU Equity Settled Performance Based Restricted Stock Units [Member] Equity Settled Performance Based Restricted Stock Units [Member] LLC Interests Llc Interests [Member] Information pertaining to LLC Interests. Tax receivable agreement liability Tax Receivable Agreement Liability The carrying amount as on the balance sheet date of tax receivable agreement liability. Document Fiscal Period Focus Document Fiscal Period Focus Subsidiary, Sale of Stock [Line Items] Subsidiary, Sale of Stock [Line Items] Software Development Costs Software Development [Member] Regulatory Capital Regulatory Capital Regulatory capital as calculated for each entity under applicable regulations. Change in non-controlling interests as a result of ownership changes Noncontrolling Interest, Period Increase (Decrease) Supplemental disclosure of cash flow information Supplemental Cash Flow Information [Abstract] Consulting service fee for IPO Consulting Service Fee for IPO The amount of consulting service incurred for IPO. Entity Filer Category Entity Filer Category Common Stock Common Stock [Member] Furniture, Equipment, Purchased Software and Leasehold Improvements Property, Plant and Equipment [Line Items] Product and Service [Domain] Product and Service [Domain] Property, Plant and Equipment, Type [Domain] Long-Lived Tangible Asset [Domain] Regulatory Capital Requirements Regulatory Capital Requirements [Text Block] The entire disclosure of capital requirements and required financial resources under applicable regulations. Issuance of common stock from equity incentive plans (in shares) Shares issued (in shares) Stock Issued During Period, Shares, New Issues Revenue Recognition Disaggregation of Revenue [Abstract] Cost Finite-Lived Intangible Assets, Gross Activities related to exchanges of LLC Interests, net of offering costs and cancellations (in shares) Stock Issued During Period, Shares, Conversion of Convertible Securities Write-offs charged against the allowance Accounts Receivable, Credit Loss Expense (Reversal) Money market funds Money Market Funds [Member] Class A Common Stock Common Class A [Member] Excess Financial Resources Futures Commission Merchant, Commodity Exchange Act, Excess Net Capital Schedule of balances from transactions with affiliates included in the consolidated statements Schedule of Related Party Transactions [Table Text Block] Non-cash financing activities - Items arising from LLC Interest ownership changes Noncash Investing and Financing Items [Abstract] Reconciliation of cash, cash equivalents and restricted cash as shown on the statements of financial condition: Additional Cash Flow Elements and Supplemental Cash Flow Information [Abstract] Related Party Transactions [Abstract] Related Party Transactions [Abstract] Net increase (decrease) in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Summary of the impact on equity due to changes in the Company’s ownership interest in noncontrolling interest Schedule Of Impact On Equity Due To Changes In The Company’S Ownership Interest In Noncontrolling Interest [Table Text Block] Tabular disclosure of impact on equity due to changes in the Company’s ownership interest in noncontrolling interest. Options Share-based Payment Arrangement, Option [Member] Basis of Accounting Basis of Accounting, Policy [Policy Text Block] Basic (in shares) Weighted average shares of Class A and Class B common stock outstanding - Basic (in shares) Weighted Average Number of Shares Outstanding, Basic Spread Debt Instrument, Basis Spread on Variable Rate Subsequent Events [Abstract] Subsequent Events [Abstract] Ownership [Axis] Ownership [Axis] Foreign currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Sale of Stock [Domain] Sale of Stock [Domain] Regulatory Capital Requirement Regulatory Capital Requirement Amount of regulatory capital required to be maintained for each entity under applicable regulations. Loss Contingencies [Table] Loss Contingencies [Table] Ownership [Domain] Ownership [Domain] Revenue Revenue from Contract with Customer [Text Block] Total equity Beginning balance Ending balance Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Organization Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Net proceeds Proceeds from Issuance Initial Public Offering Additional paid-in capital Additional Paid in Capital Revenue Total revenue Revenues Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Class of Stock [Axis] Class of Stock [Axis] Provision for income taxes Income Tax Expense (Benefit) Beginning of period End of period Cash, cash equivalents and restricted cash shown in the statement of cash flows Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Schedule of affiliates were included in the consolidated statements of income Schedule Of Related Party Transactions Affiliates [Table Text Block] Schedule Of Related Party Transactions Affiliates. Furniture, Equipment, Purchased Software and Leasehold Improvements Property, Plant and Equipment, Policy [Policy Text Block] Effect of exchange rate changes on cash and cash equivalents Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations Title of Individual [Domain] Title of Individual [Domain] Indefinite-lived Intangible Assets, Major Class Name [Domain] Indefinite-lived Intangible Assets, Major Class Name [Domain] Diluted (in dollars per share) Earnings per share - Diluted (in dollars per share) Earnings Per Share, Diluted Schedule of revenue and long-lived assets by geographic location Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Table Text Block] Local Phone Number Local Phone Number Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Non-Controlling Interests Noncontrolling Interest [Line Items] Summary of intangible assets which have an indefinite useful life Schedule of Indefinite-Lived Intangible Assets [Table Text Block] Entity Address, Address Line One Entity Address, Address Line One Pushdown Accounting Pushdown Accounting [Policy Text Block] Deferred revenue Deferred revenue balance - beginning of period Deferred revenue balance - end of period Contract with Customer, Liability Related Party Transaction [Domain] Related Party Transaction [Domain] Other assets Increase (Decrease) in Other Operating Assets Entity Emerging Growth Company Entity Emerging Growth Company Intangible assets which have an indefinite useful life Indefinite-lived Intangible Assets (Excluding Goodwill) Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Deferred taxes Deferred tax asset Deferred Income Tax Expense (Benefit) Market Data Market Data Client Sector [Member] The market data client sector. Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Award Type [Axis] Award Type [Axis] Receivable from affiliates Due from Affiliates Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Maximum Maximum [Member] Fed Funds Effective Rate Fed Funds Effective Rate Overnight Index Swap Rate [Member] Preferred stock, shares authorized (in shares) Preferred Stock, Shares Authorized Non- Controlling Interests Noncontrolling Interest [Member] Restricted cash Restricted cash Restricted Cash Accounts payable, accrued expenses and other liabilities Accounts Payable and Accrued Liabilities Retained Earnings Retained Earnings [Member] Preferred stock, shares outstanding (in shares) Preferred Stock, Shares Outstanding Net transfers (to) from non-controlling interests Transfers From (To) Noncontrolling Interests Amount of net transfers from (to) non controlling interest. Fair Value of Financial Instruments Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Effective tax rate Effective Income Tax Rate Reconciliation, Percent Significant Accounting Policies Significant Accounting Policies [Text Block] Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities General and administrative Other General and Administrative Expense Payable to brokers and dealers and clearing organizations Broker-Dealer, Payable to Other Broker-Dealer and Clearing Organization Institutional Institutional Client Sector [Member] The institutional client sector. Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Accounts receivable, allowance for credit losses Allowance for doubtful accounts Beginning balance, prior to adoption of ASC 326 - December 31, 2019 Ending balance - September 30, 2020 Accounts Receivable, Allowance for Credit Loss Award Type [Domain] Award Type [Domain] Trading Symbol Trading Symbol Income Tax Disclosure [Line Items] Income Tax Disclosure [Line Items] Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Weighted average shares outstanding Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Retail Retail Client Sector [Member] The retail client sector. Public Investors Public Investors [Member] This member stands for public investors, collectively. Schedule of Revenues from External Customers and Long-Lived Assets [Table] Schedule of Revenues from External Customers and Long-Lived Assets [Table] Amortization of pushdown accounting allocation Amortization Period Pushdown Accounting Adjustment Amortization period for pushdown accounting adjustments. Earnings Per Share Earnings Per Share [Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Entity Shell Company Entity Shell Company Business Segment and Geographic Information Segment Reporting Information [Line Items] Recent Accounting Pronouncements – Adopted New Accounting Pronouncements, Policy [Policy Text Block] Employee equity compensation payable Equity Compensation Payable Equity compensation payable to employees. Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Required Financial Resources Futures Commission Merchant, Commodity Exchange Act, Required Net Capital Continuing LLC Owners Continuing L L C Owners [Member] Represents information pertaining to Continuing LLC Owners. Class P-1 (C) Common Class P1c Shares [Member] Class P-1(C) shares.