Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenues:
Commissions	$ 435,220	$ 455,855
Principal transactions	98,763	113,311
Fees from related parties	3,785	5,521
Data, software and post-trade	21,986	19,398
Interest and dividend income	3,038	4,161
Other revenues	4,784	4,921
Total revenues	567,576	603,167
Expenses:
Compensation and employee benefits	308,162	344,928
Equity-based compensation and allocations of net income to limited partnership units and FPUs	33,495	42,204
Total compensation and employee benefits	341,657	387,132
Occupancy and equipment	48,133	51,074
Fees to related parties	5,291	5,435
Professional and consulting fees	16,140	19,956
Communications	29,804	30,521
Selling and promotion	7,488	18,699
Commissions and floor brokerage	17,929	19,277
Interest expense	17,853	17,506
Other expenses	16,089	17,531
Total expenses	500,384	567,131
Other income (losses), net:
Gains (losses) on equity method investments	1,466	1,023
Other income (loss)	5,406	(6,015)
Total other income (losses), net	6,872	(4,992)
Income (loss) from operations before income taxes	74,064	31,044
Provision (benefit) for income taxes	14,939	10,875
Consolidated net income (loss)	59,125	20,169
Less: Net income (loss) attributable to noncontrolling interest in subsidiaries	16,034	6,495
Net income (loss) available to common stockholders	43,091	13,674
Basic earnings (loss) per share
Net income (loss) available to common stockholders	$ 43,091	$ 13,674
Basic earnings (loss) per share	$ 0.12	$ 0.04
Basic weighted-average shares of common stock outstanding	374,318	358,001
Fully diluted earnings (loss) per share
Net income (loss) for fully diluted shares	$ 62,248	$ 19,325
Fully diluted earnings (loss) per share	$ 0.11	$ 0.04
Fully diluted weighted-average shares of common stock outstanding	557,068	538,442