Stockholder's Equity - Initial Public Offering and Reorganization Transactions (Details) $ / shares in Units, $ in Billions	Apr. 08, 2019 USD ($) $ / shares shares
Class A Common Stock | Initial Public Offering
Subsidiary, Sale of Stock [Line Items]
Issuance of common stock from equity incentive plans (in shares) | shares	46,000,000
Public offering price (in dollars per share) | $ / shares	$ 27.00
Class A Common Stock | Underwriter
Subsidiary, Sale of Stock [Line Items]
Issuance of common stock from equity incentive plans (in shares) | shares	6,000,000
Tradeweb Markets LLC
Subsidiary, Sale of Stock [Line Items]
Public offering price (in dollars per share) | $ / shares	$ 27.00
Net proceeds | $	$ 1.2