Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues:
Trading income, net	$ 203,907	$ 156,706	$ 479,644	$ 509,542
Interest and dividends income	20,430	5,271	30,933	14,961
Commissions, net and technology services	43,351	2,931	49,237	7,224
Other, net	3,598	(102)	3,647	(102)
Total revenue	271,286	164,806	563,461	531,625
Operating Expenses:
Brokerage, exchange and clearance fees, net	64,584	52,118	170,253	167,416
Communication and data processing	45,998	17,903	83,190	53,578
Employee compensation and payroll taxes	72,341	20,816	111,053	64,182
Payments for order flow	12,071		12,071
Interest and dividends expense	31,242	15,615	58,456	43,249
Operations and administrative	24,183	5,543	38,107	16,198
Depreciation and amortization	15,602	7,158	29,157	22,685
Amortization of purchased intangibles and acquired capitalized software	6,440	53	6,546	159
Debt issue costs related to debt refinancing	4,869		9,351
Transaction advisory fees and expenses	15,677		24,188	155
Reserve for legal matter			(2,176)
Charges related to share-based compensation at IPO	181	333	545	1,444
Financing interest expense on long-term borrowings	24,593	7,393	40,141	21,569
Total operating expenses	317,781	126,932	580,882	390,635
Income (loss) before income taxes and noncontrolling interest	(46,495)	37,874	(17,421)	140,990
Provision for (benefit from) income taxes	(6,505)	4,851	(2,918)	17,325
Net income (loss)	(39,990)	33,023	(14,503)	123,665
Noncontrolling interest	26,472	(25,997)	6,466	(97,913)
Net income (loss) available for common stockholders	$ (13,518)	$ 7,026	$ (8,037)	$ 25,752
Earnings (loss) per share
Basic (in dollars per share)	$ (0.17)	$ 0.18	$ (0.17)	$ 0.66
Diluted (in dollars per share)	$ (0.17)	$ 0.18	$ (0.17)	$ 0.66
Weighted average common shares outstanding
Basic (in shares)	79,199,142	38,351,465	53,520,346	38,264,139
Diluted (in shares)	79,199,142	38,351,465	53,520,346	38,264,139
Comprehensive income
Net income (loss)	$ (39,990)	$ 33,023	$ (14,503)	$ 123,665
Other comprehensive income (loss)
Foreign currency translation adjustment, net of taxes	2,558	519	8,300	1,783
Comprehensive income (loss)	(37,432)	33,542	(6,203)	125,448
Less: Comprehensive income (loss) attributable to non-controlling interests	25,122	(26,370)	1,014	(99,195)
Comprehensive income (loss) attributable to common stockholders	$ (12,310)	$ 7,172	$ (5,189)	$ 26,253