Revenues from Contracts with Customers (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 614,489,000	$ 600,510,000	$ 498,544,000
Total revenue	2,811,485,000	3,239,331,000	1,517,492,000
Revenue related to performance obligation	51,500,000	57,300,000
Impairment losses on receivables	0
Deferred revenue related to contracts with customers	9,200,000	9,300,000
Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue	2,737,230,000	3,165,034,000	1,451,305,000
Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue	74,255,000	74,297,000	66,187,000
Commissions, net
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	474,710,000	458,151,000	380,927,000
Workflow technology
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	98,486,000	101,211,000	82,610,000
Analytics
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	41,293,000	41,148,000	35,007,000
Other sources of revenue
Disaggregation of Revenue [Line Items]
Other sources of revenue	2,196,996,000	2,638,821,000	1,018,948,000
Operating Segments | Market Making
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	40,955,000	52,453,000	23,526,000
Total revenue	2,203,046,000	2,593,342,000	1,028,094,000
Operating Segments | Market Making | Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue	2,203,046,000	2,593,342,000	1,028,094,000
Operating Segments | Market Making | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue	0	0	0
Operating Segments | Market Making | Commissions, net
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	40,955,000	52,453,000	23,526,000
Operating Segments | Market Making | Workflow technology
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0
Operating Segments | Market Making | Analytics
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0
Operating Segments | Market Making | Other sources of revenue
Disaggregation of Revenue [Line Items]
Other sources of revenue	2,162,091,000	2,540,889,000	1,004,568,000
Operating Segments | Execution Services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	573,534,000	548,057,000	475,018,000
Total revenue	600,215,000	650,143,000	491,736,000
Operating Segments | Execution Services | Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue	525,960,000	575,846,000	425,549,000
Operating Segments | Execution Services | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue	74,255,000	74,297,000	66,187,000
Operating Segments | Execution Services | Commissions, net
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	433,755,000	405,698,000	357,401,000
Operating Segments | Execution Services | Workflow technology
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	98,486,000	101,211,000	82,610,000
Operating Segments | Execution Services | Analytics
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	41,293,000	41,148,000	35,007,000
Operating Segments | Execution Services | Other sources of revenue
Disaggregation of Revenue [Line Items]
Other sources of revenue	26,681,000	102,086,000	16,718,000
Corporate
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0
Total revenue	8,224,000	(4,154,000)	(2,338,000)
Corporate | Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue	8,224,000	(4,154,000)	(2,338,000)
Corporate | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue	0	0	0
Corporate | Commissions, net
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0
Corporate | Workflow technology
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0
Corporate | Analytics
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0
Corporate | Other sources of revenue
Disaggregation of Revenue [Line Items]
Other sources of revenue	$ 8,224,000	$ (4,154,000)	$ (2,338,000)