Earnings Per Share (Details) - USD ($)		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Denominator:
Weighted average shares of Class A and Class B common stock outstanding - Basic (in shares)	[1],[2]	187,774,170	142,935,206	177,257,994
Weighted average shares of Class A and Class B common stock outstanding - Diluted (in shares)	[1],[2]	194,955,695	151,362,643	185,026,108
Earnings per share - Basic (in dollars per share)		$ 0.20	$ 0.21	$ 0.63
Earnings per share - Diluted (in dollars per share)		$ 0.19	$ 0.20	$ 0.60
Weighted-average shares (in shares)		179,508	247,491	264,882	126,667
Potential Dilutive
Denominator:
Weighted-average shares (in shares)		39,513,246		48,397,598
Tradeweb Markets Inc
Numerator:
IPO net income		$ 36,812,000	$ 29,612,000	$ 111,236,000	$ 42,440,000
Denominator:
Weighted average shares of Class A and Class B common stock outstanding - Basic (in shares)		187,774,170	142,935,206	177,257,994	142,934,221	[1],[2]
Weighted average shares of Class A and Class B common stock outstanding - Diluted (in shares)		194,955,695	151,362,643	185,026,108	151,158,760	[1],[2]
Earnings per share - Basic (in dollars per share)		$ 0.20	$ 0.21	$ 0.63	$ 0.30	[1],[2]
Earnings per share - Diluted (in dollars per share)		$ 0.19	$ 0.20	$ 0.60	$ 0.28	[1],[2]
Tradeweb Markets Inc | PRSU
Denominator:
Dilutive effect (in shares)		2,584,192	2,492,381	2,371,727	2,355,938
Tradeweb Markets Inc | Options
Denominator:
Dilutive effect (in shares)		4,402,391	5,935,056	5,264,106	5,868,601
Tradeweb Markets Inc | RSU
Denominator:
Dilutive effect (in shares)		194,942	0	132,281	0
Tradeweb Markets LLC
Numerator:
IPO net income					$ 42,352
Denominator:
Weighted average shares of Class A and Class B common stock outstanding - Basic (in shares)	[1],[3]				222,222,197
Weighted average shares of Class A and Class B common stock outstanding - Diluted (in shares)	[1],[3]				223,320,457
Earnings per share - Basic (in dollars per share)	[1],[3]				$ 0.19
Earnings per share - Diluted (in dollars per share)	[1],[3]				$ 0.19
Tradeweb Markets LLC | PRSU
Denominator:
Dilutive effect (in shares)					1,098,260

[1] In April 2019, the Company completed the Reorganization Transactions and the IPO, which, among other things, resulted in Tradeweb Markets Inc. becoming the successor of Tradeweb Markets LLC for financial reporting purposes. As a result, earnings per share information for the pre-IPO period is not comparable to the earnings per share information for the post-IPO period. Therefore, earnings per share information is being presented separately for the pre-IPO and post-IPO periods. See Note 15 – Earnings Per Share for additional information.

[2] Presents information for Tradeweb Markets Inc. (post-IPO period).

[3] Presents information for Tradeweb Markets LLC (pre-IPO period).