CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues
Trading revenues, net	$ 803,181	$ 837,357	$ 628,304
Commissions and fees	376,673	437,022	275,474
Interest, net	(2,128)	621	(537)
Investment income and other, net	421,384	41,232	124,095
Total revenues	1,599,110	1,316,232	1,027,336
Expenses
Employee compensation and benefits	405,609	437,269	349,192
Execution and clearance fees	265,186	305,177	246,414
Communications and data processing	139,263	150,595	123,552
Depreciation and amortization	90,231	81,448	55,570
Payments for order flow	61,741	70,183	35,711
Debt interest expense	36,755	32,456	34,938
Collateralized financing interest	34,678	27,860	9,847
Occupancy and equipment rentals	30,128	32,707	24,812
Professional fees	27,055	25,596	46,662
Business development	8,479	9,763	4,609
Debt extinguishment charges	25,006	9,552	13,209
Writedown of assets and other real estate related charges	56,642	8,625	14,748
Other	38,375	39,814	43,094
Total expenses	1,219,148	1,231,045	1,002,358
Income from continuing operations before income taxes	379,962	85,187	24,978
Income tax expense (benefit)	130,858	22,753	(101,114)
Income from continuing operations, net of tax	249,104	62,434	126,092
(Loss) income from discontinued operations, net of tax	0	(1,332)	80
Net income	249,104	61,102	126,172
Net loss allocated to preferred and participating units	0	0	(21,565)
Net income attributable to common shareholders	$ 249,104	$ 61,102	$ 147,737
Basic earnings per share from continuing operations (in dollars per share)	$ 2.48	$ 0.55	$ 1.84
Diluted earnings per share from continuing operations (in dollars per share)	2.42	0.54	1.82
Basic loss per share from discontinued operations (in dollars per share)	0.00	(0.01)	0.00
Diluted loss per share from discontinued operations (in dollars per share)	0.00	(0.01)	0.00
Basic earnings per share (in dollars per share)	2.48	0.54	1.84
Diluted earnings per share (in dollars per share)	$ 2.42	$ 0.52	$ 1.82
Shares used in computation of basic earnings (loss) per share	100,437	112,854	80,143
Shares used in computation of diluted earnings (loss) per share	102,922	116,534	81,015