Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Revenues:
Trading income, net	$ 156,706	$ 206,832	$ 509,542	$ 590,554
Interest and dividends income	5,271	6,425	14,961	21,022
Technology services	2,931	2,545	7,224	7,733
Other revenues (losses)	(102)		(102)
Total revenue	164,806	215,802	531,625	619,309
Operating Expenses:
Brokerage, exchange and clearance fees, net	52,118	61,814	167,416	179,453
Communication and data processing	17,903	16,110	53,578	51,602
Employee compensation and payroll taxes	20,816	24,736	64,182	66,801
Interest and dividends expense	15,615	12,827	43,249	39,234
Operations and administrative	5,543	4,857	16,353	20,017
Depreciation and amortization	7,158	8,176	22,685	26,025
Amortization of purchased intangibles and acquired capitalized software	53	53	159	159
Charges related to share-based compensation at IPO	333	1,107	1,444	45,301
Financing interest expense on long term borrowings	7,393	7,205	21,569	22,066
Total operating expenses	126,932	136,885	390,635	450,658
Income before income taxes and noncontrolling interest	37,874	78,917	140,990	168,651
Provision for income taxes	4,851	9,378	17,325	14,103
Net income	33,023	69,539	123,665	154,548
Noncontrolling interest	(25,997)	(57,233)	(97,913)	(141,768)
Net income available for common stockholders	$ 7,026	$ 12,306	$ 25,752	$ 12,780
Earnings per share
Basic (in dollars per share)	$ 0.18	$ 0.36	$ 0.66	$ 0.37
Diluted (in dollars per share)	$ 0.18	$ 0.35	$ 0.66	$ 0.37
Weighted average common shares outstanding
Basic (in shares)	38,351,465	34,305,052	38,264,139	34,305,052
Diluted (in shares)	38,351,465	34,738,733	38,264,139	34,641,497
Comprehensive income
Net income	$ 33,023	$ 69,539	$ 123,665	$ 154,548
Other comprehensive income (loss)
Foreign exchange translation adjustment, net of taxes	519	3,596	1,783	595
Comprehensive income	33,542	73,135	125,448	155,143
Less: Comprehensive income attributable to non-controlling interests	(26,370)	(59,931)	(99,195)	(141,053)
Comprehensive income attributable to common stockholders	$ 7,172	$ 13,204	$ 26,253	$ 14,090