Non-Controlling Interests (Details) $ in Thousands		3 Months Ended
	Apr. 08, 2019 shares	Mar. 31, 2020 USD ($) shares
Non-Controlling Interests
Net income attributable to Tradeweb Markets Inc.		$ 43,928
Change in non-controlling interests as a result of ownership changes		45,443
Net transfers (to) from non-controlling interests		45,443
Change from net income attributable to Tradeweb Markets Inc. and transfers (to) from non-controlling interests		$ 89,371
Class A common stock
Non-Controlling Interests
Conversion ratio		1
Class B common stock
Non-Controlling Interests
Conversion ratio		1
Tradeweb Markets LLC
Non-Controlling Interests
Number of LLC Interests held by Tradeweb Markets Inc. | shares	142,933,192	167,603,632
Number of LLC Interests held by non-controlling interests | shares		57,261,214
Total LLC Interests outstanding | shares		224,864,846
Number of LLC Interests held by Tradeweb Markets Inc.	64.30%	74.50%
Equity interest of noncontrolling shareholders in consolidated entity		25.50%
Total LLC Interests outstanding		100.00%