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Significant Accounting Policies - Useful Lives of Assets (Details) - Tradeweb Markets LLC	12 Months Ended
	Dec. 31, 2018
Furniture, Equipment, Purchased Software and Leasehold Improvements | Minimum
Furniture, Equipment, Purchased Software and Leasehold Improvements
Property, Plant and Equipment, Useful Life	3 years
Furniture, Equipment, Purchased Software and Leasehold Improvements | Maximum
Furniture, Equipment, Purchased Software and Leasehold Improvements
Property, Plant and Equipment, Useful Life	7 years
Software Development Costs
Furniture, Equipment, Purchased Software and Leasehold Improvements
Property, Plant and Equipment, Useful Life	3 years
Amortization of pushdown accounting allocation	9 years

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- Definition

Amortization period for pushdown accounting adjustments.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

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