Stockholder's Equity - Redemptions and Exchange of LLC Interests (Details) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended	3 Months Ended
	Apr. 08, 2019	Oct. 31, 2019	Mar. 31, 2020	Dec. 31, 2019
LLC units | October 2019 Follow-On Offering
Subsidiary, Sale of Stock [Line Items]
Stock surrendered		19,835,666
LLC units | Redemptions and Exchanges of LLC Interests [Member]
Subsidiary, Sale of Stock [Line Items]
Number of LLC Units received from the exchange transaction			1,920,941
Class A common stock
Subsidiary, Sale of Stock [Line Items]
Issuance of common stock from equity incentive plans (in shares)			2,341,171
Class A common stock | October 2019 Follow-On Offering
Subsidiary, Sale of Stock [Line Items]
Issuance of common stock from equity incentive plans (in shares)				19,881,059
Weighted Average Share Price		$ 42.00
Net proceeds		$ 810.0
Stock surrendered		45,393
Class A common stock | Redemptions and Exchanges of LLC Interests [Member]
Subsidiary, Sale of Stock [Line Items]
Issuance of common stock from equity incentive plans (in shares)			1,920,941
Class D common stock | Redemptions and Exchanges of LLC Interests [Member]
Subsidiary, Sale of Stock [Line Items]
Stock surrendered			981,941
Class B common stock
Subsidiary, Sale of Stock [Line Items]
Issuance of common stock from equity incentive plans (in shares)	96,933,192
Class C common stock | Redemptions and Exchanges of LLC Interests [Member]
Subsidiary, Sale of Stock [Line Items]
Stock surrendered			939,000
Tradeweb Markets LLC
Subsidiary, Sale of Stock [Line Items]
Weighted Average Share Price	$ 27.00
Net proceeds	$ 1,200.0
Ownership interest	64.30%		74.50%
Equity interest of noncontrolling shareholders in consolidated entity			25.50%
Tradeweb Markets LLC | Public Investors
Subsidiary, Sale of Stock [Line Items]
Equity interest of noncontrolling shareholders in consolidated entity			31.40%
Tradeweb Markets LLC | Bank Stockholders
Subsidiary, Sale of Stock [Line Items]
Equity interest of noncontrolling shareholders in consolidated entity			15.20%
Tradeweb Markets Inc | Public Investors
Subsidiary, Sale of Stock [Line Items]
Voting power percentage			4.60%
Tradeweb Markets Inc | Bank Stockholders
Subsidiary, Sale of Stock [Line Items]
Voting power percentage			17.80%
Tradeweb Markets Inc | Class A common stock | Public Investors
Subsidiary, Sale of Stock [Line Items]
Number of share owned			70,670,440
Tradeweb Markets Inc | Class D common stock | Bank Stockholders
Subsidiary, Sale of Stock [Line Items]
Number of share owned			26,730,623
Tradeweb Markets Inc | Class C common stock | Bank Stockholders
Subsidiary, Sale of Stock [Line Items]
Number of share owned			7,389,983
Tradeweb Markets LLC
Subsidiary, Sale of Stock [Line Items]
Weighted Average Share Price	$ 27.00
Net proceeds	$ 1,200.0
Refinitiv | Tradeweb Markets LLC
Subsidiary, Sale of Stock [Line Items]
Ownership interest			53.30%
Refinitiv | Tradeweb Markets Inc
Subsidiary, Sale of Stock [Line Items]
Ownership interest			77.60%
Refinitiv | Tradeweb Markets Inc | Class D common stock
Subsidiary, Sale of Stock [Line Items]
Number of share owned			22,988,329
Refinitiv | Tradeweb Markets Inc | Class B common stock
Subsidiary, Sale of Stock [Line Items]
Number of share owned			96,933,192