Geographic Information and Business Segments - Segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Total revenue	$ 2,811,485	$ 3,239,331	$ 1,517,492
Income (loss) before income taxes and noncontrolling interest	996,904	1,382,837	(115,982)
Operating Segments | Market Making
Segment Reporting Information [Line Items]
Total revenue	2,203,046	2,593,342	1,028,094
Income (loss) before income taxes and noncontrolling interest	925,968	1,241,313	109,190
Operating Segments | Execution Services
Segment Reporting Information [Line Items]
Total revenue	600,215	650,143	491,736
Income (loss) before income taxes and noncontrolling interest	70,019	174,617	(126,931)
Segment Reconciling Items | Corporate
Segment Reporting Information [Line Items]
Total revenue	8,224	(4,154)	(2,338)
Income (loss) before income taxes and noncontrolling interest	$ 917	$ (33,093)	$ (98,241)