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Acquisitions - Additional Information (Detail) - USD ($) $ in Millions |  | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jul. 30, 2021 | Sep. 30, 2021 | Dec. 31, 2020
Business Acquisition [Line Items] |  |  |
Total consideration transferred |  |  | $ 9.6
Goodwill acquired during period net of assets acquired |  |  | $ 2.8
Futures Exchange Group |  |  |
Business Acquisition [Line Items] |  |  |
Payments to acquire businesses | $ 4.9 |  |
Total consideration transferred |  | $ 4.9 |

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- Definition Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 30 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=116859721&loc=d3e6613-128477 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=120321790&loc=d3e6927-128479 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 30 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=116859721&loc=d3e6578-128477 + Details
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