Geographic Information and Business Segments - Segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Total revenue	$ 2,293,373	$ 2,364,812	$ 2,811,485
Income (loss) before income taxes and noncontrolling interest	325,131	556,798	996,904
Operating Segments | Market Making
Segment Reporting Information [Line Items]
Total revenue	1,843,523	1,812,839	2,203,046
Income (loss) before income taxes and noncontrolling interest	315,602	480,559	925,968
Operating Segments | Execution Services
Segment Reporting Information [Line Items]
Total revenue	446,542	514,241	600,215
Income (loss) before income taxes and noncontrolling interest	10,440	41,342	70,019
Segment Reconciling Items | Corporate
Segment Reporting Information [Line Items]
Total revenue	3,308	37,732	8,224
Income (loss) before income taxes and noncontrolling interest	$ (911)	$ 34,897	$ 917