Business combination period of contingent consideration payable.

No definition available.

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Namespace Prefix:	mktx_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- 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.

+ Details

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Data Type:	xbrli:stringItemType
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Period Type:	duration

- Definition

Amount of liability recognized arising from contingent consideration in a business combination, expected to be settled beyond one year or the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 25
-Paragraph 6
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Balance Type:	credit
Period Type:	instant

- Definition

The amount of identifiable intangible assets recognized as of the acquisition date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 55
-Paragraph 37
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-URI http://asc.fasb.org/extlink&oid=121647850&loc=d3e4845-128472

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)(1)
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- Details

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Balance Type:
Period Type:

- Details

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- Details

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Balance Type:
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- Details

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Acquisitions - Additional Information (Detail) - USD ($) $ in Millions	Apr. 09, 2021	Nov. 30, 2020
Regulatory Services GmbH of Deutsche Borse Group [Member]
Business Acquisition [Line Items]
Cash consideration		$ 22.5
Amortizable intangible assets		$ 37.4
Business combination, contingent consideration payment period		18 months
Regulatory Services GmbH of Deutsche Borse Group [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Contingent consideration payable		$ 24.6
MuniBrokers LLC [Member] \| Subsequent Event [Member]
Business Acquisition [Line Items]
Cash consideration	$ 17.0
Business combination, contingent consideration payment period	2 years
MuniBrokers LLC [Member] \| Maximum [Member] \| Subsequent Event [Member]
Business Acquisition [Line Items]
Contingent consideration payable	$ 25.0