Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues:
Commissions	$ 409,082	$ 351,969	$ 1,259,571	$ 1,138,313
Principal transactions	75,536	73,360	250,198	250,266
Fees from related parties	8,208	6,821	21,224	19,054
Data, software and post-trade	18,364	16,547	55,015	47,016
Interest income	3,976	2,870	15,454	10,485
Other revenues	5,971	4,075	15,613	6,325
Total revenues	521,137	455,642	1,617,075	1,471,459
Expenses:
Compensation and employee benefits	278,544	221,575	856,615	751,672
Equity-based compensation and allocations of net income to limited partnership units and FPUs	40,330	34,901	96,223	119,892
Total compensation and employee benefits	318,874	256,476	952,838	871,564
Occupancy and equipment	44,709	39,148	135,820	110,660
Fees to related parties	7,123	5,644	16,507	15,577
Professional and consulting fees	21,262	22,329	64,614	60,238
Communications	29,882	29,078	90,267	91,206
Selling and promotion	20,320	16,146	60,213	50,226
Commissions and floor brokerage	15,831	15,082	47,240	44,342
Interest expense	15,258	10,722	43,441	30,118
Other expenses	42,757	14,882	88,537	46,768
Total expenses	516,016	409,507	1,499,477	1,320,699
Other income (losses) , net:
Gains (losses) on divestitures and sale of investments			18,435
Gains (losses) on equity method investments	1,530	1,327	3,051	4,962
Other income (loss)	2,095	15,123	23,491	48,015
Total other income (losses), net	3,625	16,450	44,977	52,977
Income (loss) from continuing operations before income taxes	8,746	62,585	162,575	203,737
Provision (benefit) for income taxes	6,186	23,019	51,076	59,140
Consolidated net income (loss) from continuing operations	2,560	39,566	111,499	144,597
Consolidated net income (loss) from discontinued operations, net of tax		122,738		165,128
Consolidated net income (loss)	2,560	162,304	111,499	309,725
Less: Net income (loss) from continuing operations attributable to noncontrolling interest in subsidiaries	6,089	7,956	39,549	48,988
Less: Net income (loss) from discontinued operations attributable to noncontrolling interest in subsidiaries		34,062		46,474
Net income (loss) available to common stockholders	(3,529)	120,286	71,950	214,263
Basic earnings (loss) per share from continuing operations
Net income (loss) from continuing operations available to common stockholders	$ (3,529)	$ 31,610	$ 71,950	$ 95,609
Basic earnings (loss) per share from continuing operations	$ (0.01)	$ 0.10	$ 0.21	$ 0.30
Basic weighted-average shares of common stock outstanding	346,060	327,932	341,940	319,027
Fully diluted earnings (loss) per share from continuing operations
Net income (loss) from continuing operations for fully diluted shares	$ (3,529)	$ 44,708	$ 108,378	$ 95,609
Fully diluted earnings (loss) per share from continuing operations	$ (0.01)	$ 0.10	$ 0.21	$ 0.30
Fully diluted weighted-average shares of common stock outstanding	346,060	437,087	523,218	320,737