Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenues:
Commissions	$ 420,969	$ 378,487	$ 850,489	$ 786,344
Principal transactions	90,432	84,988	174,662	176,906
Fees from related parties	7,221	5,934	13,016	12,233
Data, software and post-trade	18,741	15,370	36,651	30,469
Interest income	7,813	4,940	11,478	7,615
Other revenues	6,011	1,324	9,642	2,250
Total revenues	551,187	491,043	1,095,938	1,015,817
Expenses:
Compensation and employee benefits	290,071	252,250	578,071	530,097
Equity-based compensation and allocations of net income to limited partnership units and FPUs	43,752	45,602	55,893	84,991
Total compensation and employee benefits	333,823	297,852	633,964	615,088
Occupancy and equipment	45,109	34,365	91,111	71,512
Fees to related parties	6,457	5,882	9,384	9,933
Professional and consulting fees	23,347	20,001	43,352	37,909
Communications	29,974	30,729	60,385	62,128
Selling and promotion	21,491	17,855	39,893	34,080
Commissions and floor brokerage	16,791	15,345	31,409	29,260
Interest expense	14,985	10,028	28,183	19,396
Other expenses	21,765	14,548	45,780	31,886
Total expenses	513,742	446,605	983,461	911,192
Other income (losses) , net:
Gains (losses) on divestitures and sale of investments	(1,619)		18,435
Gains (losses) on equity method investments	738	1,011	1,521	3,635
Other income (loss)	194	1,481	21,396	32,892
Total other income (losses), net	(687)	2,492	41,352	36,527
Income (loss) from continuing operations before income taxes	36,758	46,930	153,829	141,152
Provision (benefit) for income taxes	14,993	14,571	44,890	36,121
Consolidated net income (loss) from continuing operations	21,765	32,359	108,939	105,031
Consolidated net income (loss) from discontinued operations, net of tax		17,631		42,390
Consolidated net income (loss)	21,765	49,990	108,939	147,421
Less: Net income (loss) from continuing operations attributable to noncontrolling interest in subsidiaries	8,154	12,358	33,460	41,032
Less: Net income (loss) from discontinued operations attributable to noncontrolling interest in subsidiaries		2,429		12,412
Net income (loss) available to common stockholders	13,611	35,203	75,479	93,977
Basic earnings (loss) per share from continuing operations
Net income (loss) from continuing operations available to common stockholders	$ 13,611	$ 20,001	$ 75,479	$ 63,999
Basic earnings (loss) per share from continuing operations	$ 0.04	$ 0.06	$ 0.22	$ 0.20
Basic weighted-average shares of common stock outstanding	341,272	321,199	339,845	314,501
Fully diluted earnings (loss) per share from continuing operations
Net income (loss) from continuing operations for fully diluted shares	$ 21,010	$ 20,001	$ 100,195	$ 87,517
Fully diluted earnings (loss) per share from continuing operations	$ 0.04	$ 0.06	$ 0.21	$ 0.20
Fully diluted weighted-average shares of common stock outstanding	522,984	322,720	467,232	429,070