Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2019	Feb. 14, 2020	Jun. 28, 2019
Document Type	10-K/A
Document Period End Date	Dec. 31, 2019
Entity Registrant Name	Tradeweb Markets Inc.
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Interactive Data Current	Yes
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Public Float			$ 4.5
Entity Central Index Key	0001758730
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	true
Amendment Description	This Amendment on Form 10-K/A (the "Amended Report") amends and restates the Annual Report on Form 10-K for the year ended December 31, 2019 (the "Original Report") filed by Tradeweb Markets Inc. (the "Company") on February 21, 2020. The Company discovered that, due to a clerical error, the Original Report was inadvertently filed in lieu of the final version of the Company's Annual Report on Form 10-K. This Amended Report is the final version of the Company's Annual Report on Form 10-K for the year ended December 31, 2019 (including exhibits) that was originally intended to be filed and corrects clerical errors included in the Original Report.  Among others, these include:the inclusion of an inadvertently omitted paragraph under Part I, Item 3 "Legal Proceedings - IDC Matter;"conforming changes to the figures for total assets and total equity/members' capital as of December 31, 2019 in Part II, Item 6 "Selected Financial Data" corresponding to the amounts presented in the Consolidated Statement of Financial Condition as of December 31, 2019;the inclusion of an inadvertently omitted subsection entitled "Credit Risk" under Part II, Item 7A "Quantitative and Qualitative Disclosures About Market Risk;"the deletion of "(Unaudited)" from the heading of the Consolidated Statements of Changes in Equity in Part II, Item 8 "Financial Statements and Supplementary Data;"the deletion of "(Unaudited)" from the heading of the Table of Contents for the Notes to Consolidated Financial Statements in Part II, Item 8 "Financial Statements and Supplementary Data;"a correction to the amount of the recorded right-of-use assets in "Note 2 - Summary of Significant Accounting Policies - Recent Accounting Pronouncements - Adopted" to the Company's audited consolidated financial statements;a correction to the amount of the software development costs capitalized for the year ended December 31, 2019 in "Note 8 - Software Development Costs" to the Company's audited consolidated financial statements; andcorrections to the amount of an assumed deferred tax benefit and the amount of uncertain tax positions as of December 31, 2019 in "Note 9 - Income Taxes" to the Company's audited consolidated financial statements. Previously reported amounts in the Company's audited consolidated financial statements included in the Original Report did not include any clerical errors and are identical to corresponding amounts in the Company's audited consolidated financial statements included in this Amended Report, other than the corrections to the notes to the financial statements described above.  Unless expressly noted otherwise, the disclosures in this Amended Report continue to speak as of the date of the Original Report, and do not reflect events occurring after the filing of the Original Report.
Class A common stock
Entity Common Stock, Shares Outstanding		70,212,713
Class B common stock
Entity Common Stock, Shares Outstanding		96,933,192
Class C common stock
Entity Common Stock, Shares Outstanding		7,389,983
Class D common stock
Entity Common Stock, Shares Outstanding		49,873,346