Amortization period for pushdown accounting adjustments.

No definition available.

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
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-Section 50
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482099/360-10-50-1

+ Details

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Period Type:	instant

- Definition

The aggregate amount of recurring noncash expense charged against earnings in the period to allocate the cost of assets over their estimated remaining economic lives.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Subparagraph (b)
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-URI https://asc.fasb.org/1943274/2147476148/220-40-50-6

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 7A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-7A

+ Details

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Period Type:	duration

- 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.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Details

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Balance Type:
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- Details

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- Details

Name:	us-gaap_BusinessAcquisitionAxis=tw_R8FinMember
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- Details

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- Details

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- Details

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Significant Accounting Policies - Furniture, Equipment, Purchased Software, Leasehold Improvements and Software Development Costs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Software Development
Furniture, Equipment, Purchased Software and Leasehold Improvements
Accumulated depreciation and amortization	$ 411.5		$ 387.1
Useful life of intangible assets	3 years
Amortization of pushdown accounting allocation	9 years
Amortization expense	$ 24.4	$ 22.0
Software Development \| ICD Acquisition
Furniture, Equipment, Purchased Software and Leasehold Improvements
Useful life of intangible assets	8 years
Software Development \| R8Fin
Furniture, Equipment, Purchased Software and Leasehold Improvements
Useful life of intangible assets	7 years
Software Development \| Yieldbroker Acquisition
Furniture, Equipment, Purchased Software and Leasehold Improvements
Useful life of intangible assets	1 year
Software Development \| NFI Acquisition
Furniture, Equipment, Purchased Software and Leasehold Improvements
Useful life of intangible assets	1 year
Furniture, Equipment, Purchased Software and Leasehold Improvements
Furniture, Equipment, Purchased Software and Leasehold Improvements
Accumulated depreciation and amortization	$ 101.7		$ 96.7
Depreciation expense	$ 7.2	$ 6.1
Minimum
Furniture, Equipment, Purchased Software and Leasehold Improvements
Useful life of intangible assets	4 years
Minimum \| Furniture, Equipment, Purchased Software and Leasehold Improvements
Furniture, Equipment, Purchased Software and Leasehold Improvements
Useful life	3 years
Maximum
Furniture, Equipment, Purchased Software and Leasehold Improvements
Useful life of intangible assets	15 years
Maximum \| Furniture, Equipment, Purchased Software and Leasehold Improvements
Furniture, Equipment, Purchased Software and Leasehold Improvements
Useful life	7 years