| Document and Entity Information | Mar. 09, 2021 |
| Cover [Abstract] | |
| Amendment Flag | false |
| Entity Central Index Key | 0001758730 |
| Document Type | 8-K |
| Document Period End Date | Mar. 9, 2021 |
| Entity Registrant Name | Tradeweb Markets Inc. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-38860 |
| Entity Tax Identification Number | 83-2456358 |
| Entity Address, Address Line One | 1177 Avenue of the Americas |
| Entity Address, City or Town | New York |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10036 |
| City Area Code | (646) |
| Local Phone Number | 430-6000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Class A common stock, par value $0.00001 |
| Trading Symbol | TW |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
