Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenues:
Commissions	$ 1,541,900	$ 1,567,668	$ 1,645,818
Principal transactions	327,761	351,633	321,923
Fees from related parties	14,856	25,754	29,442
Data, software and post-trade	89,963	81,920	73,166
Interest and dividend income	21,977	12,332	18,319
Other revenues	18,907	17,454	15,938
Total revenues	2,015,364	2,056,761	2,104,606
Expenses:
Compensation and employee benefits	1,271,340	1,132,557	1,127,041
Equity-based compensation and allocations of net income to limited partnership units and FPUs	256,164	183,545	170,625
Total compensation and employee benefits	1,527,504	1,316,102	1,297,666
Occupancy and equipment	188,322	192,837	186,111
Fees to related parties	24,030	23,618	19,778
Professional and consulting fees	67,884	74,072	93,071
Communications	117,502	121,646	120,037
Selling and promotion	38,048	38,234	81,829
Commissions and floor brokerage	64,708	59,376	63,617
Interest expense	69,329	76,607	60,246
Other expenses	80,888	89,045	118,671
Total expenses	2,178,215	1,991,537	2,041,026
Other income (losses), net:
Gains (losses) on divestitures and sale of investments	312,941	394	18,421
Gains (losses) on equity method investments	6,706	5,023	4,115
Other income (loss)	19,705	1,580	30,511
Total other income (losses), net	339,352	6,997	53,047
Income (loss) from operations before income taxes	176,501	72,221	116,627
Provision (benefit) for income taxes	23,013	21,303	49,811
Consolidated net income (loss)	153,488	50,918	66,816
Less: Net income (loss) attributable to noncontrolling interest in subsidiaries	29,481	5,856	22,915
Net income (loss) available to common stockholders	124,007	45,062	43,901
Basic earnings (loss) per share
Net income (loss) available to common stockholders	$ 124,007	$ 45,062	$ 43,901
Basic earnings (loss) per share (in dollars per share)	$ 0.33	$ 0.12	$ 0.13
Basic weighted-average shares of common stock outstanding (in shares)	379,215	361,736	344,332
Fully diluted earnings (loss) per share
Net income (loss) for fully diluted shares	$ 173,995	$ 64,787	$ 58,871
Fully diluted earnings (loss) per share (in dollars per share)	$ 0.32	$ 0.12	$ 0.12
Fully diluted weighted-average shares of common stock outstanding (in shares)	540,020	546,848	472,187