Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenues
Commissions	$ 203,652	$ 174,199	$ 155,444
Information and post-trade services	25,377	7,435	7,199
Technology products and services	6,331	4,988	5,085
Investment income	420	1,057	1,228
Other	2,953	3,161	2,918
Total revenues	238,733	190,840	171,874
Expenses
Employee compensation and benefits	64,406	54,678	52,443
Depreciation and amortization	14,123	6,758	5,206
Technology and communications	16,037	12,523	10,619
Professional and consulting fees	18,220	12,150	9,006
Occupancy	5,173	2,446	2,337
Marketing and advertising	4,632	5,169	4,491
General and administrative	8,862	7,746	6,322
Total expenses	131,453	101,470	90,424
Income before income taxes from continuing operations	107,280	89,370	81,450
Provision for income taxes	38,717	27,586	32,003
Net income from continuing operations	68,563	61,784	49,447
(Loss) from discontinued operations, net of income taxes	(189)	(1,715)	(1,743)
Gain on the sale of discontinued operations, net of tax benefit	7,642
Net income	$ 76,016	$ 60,069	$ 47,704
Basic earnings per common share
Income from continuing operations	$ 1.86	$ 1.69	$ 1.34
Income (loss) from discontinued operations	$ 0.20	$ (0.04)	$ (0.05)
Net income per common share	$ 2.06	$ 1.65	$ 1.29
Diluted earnings per common share
Income from continuing operations	$ 1.81	$ 1.64	$ 1.25
Income (loss) from discontinued operations	$ 0.20	$ (0.05)	$ (0.05)
Net income per common share	$ 2.01	$ 1.59	$ 1.20
Cash dividends declared per common share	$ 0.52	$ 1.74	$ 0.36
Weighted average shares outstanding
Basic	36,886	36,516	37,006
Diluted	37,888	37,816	39,608