Non-Controlling Interests - Summary of Equity Changes Due to Changes in Corporation Ownership (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Noncontrolling Interest [Abstract]
Net income attributable to Tradeweb Markets Inc.	$ 67,859	$ 43,928
Increase in Tradeweb Markets Inc.'s additional paid-in capital as a result of ownership changes in TWM LLC	80,665	45,436
Net transfers (to) from non-controlling interests	80,665	45,436
Change from net income attributable to Tradeweb Markets Inc. and transfers (to) from non-controlling interests	$ 148,524	$ 89,364