Acquisitions and Equity Investments - Additional Information (Detail) - USD ($) $ in Thousands			3 Months Ended	9 Months Ended
	Apr. 09, 2021	Nov. 30, 2020	Sep. 30, 2022	Sep. 30, 2022	May 01, 2022	Apr. 01, 2022	Dec. 31, 2021
Business Acquisition [Line Items]
Contingent consideration payable			$ 1,600	$ 1,600
Goodwill			154,789	154,789			$ 154,789
Contingent consideration paid			12,230	12,230			$ 41,090
RFQ hub Holdings LLC [Member]
Business Acquisition [Line Items]
Recorded investments					$ 34,400
Proportionate share in net earnings			900	1,100
RFQ hub Holdings LLC [Member] | Prepaid Expenses and Other Assets [Member]
Business Acquisition [Line Items]
Recorded investments			35,500	35,500
Muni Brokers L L C [Member]
Business Acquisition [Line Items]
Cash consideration	$ 17,100
Amortizable intangible assets	32,000
Contingent consideration payable			$ 12,200	$ 12,200
Goodwill	$ 7,400
Business combination, contingent consideration payment period	2 years
Contingent consideration paid					$ 8,300
Muni Brokers L L C [Member] | Accounts Payable, Accrued Expenses and Other Liabilities [Member]
Business Acquisition [Line Items]
Cash consideration	$ 17,100
Contingent consideration payable	22,500
Accounting purchase price	39,600
Regulatory Services GmbH of Deutsche Borse Group [Member]
Business Acquisition [Line Items]
Cash consideration		$ 22,500
Amortizable intangible assets		$ 37,400
Business combination, contingent consideration payment period		18 months
Contingent consideration paid						$ 17,900
Maximum [Member]
Business Acquisition [Line Items]
Business combination, contingent consideration payment period				24 months
Maximum [Member] | Muni Brokers L L C [Member]
Business Acquisition [Line Items]
Contingent consideration payable	$ 25,000
Maximum [Member] | Muni Brokers L L C [Member] | Customer Relationships and Technology [Member]
Business Acquisition [Line Items]
Useful lives	15 years
Maximum [Member] | Regulatory Services GmbH of Deutsche Borse Group [Member]
Business Acquisition [Line Items]
Contingent consideration payable		$ 24,600
Minimum [Member]
Business Acquisition [Line Items]
Business combination, contingent consideration payment period				18 months
Minimum [Member] | Muni Brokers L L C [Member] | Customer Relationships and Technology [Member]
Business Acquisition [Line Items]
Useful lives	1 year