Condensed Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Revenues
Investment management fees	$ 64,475	$ 44,878	$ 122,252	$ 86,725
Distribution and service fees	19,324	13,587	36,685	26,308
Administration and transfer agent fees	12,061	8,023	22,756	15,425
Other income and fees	280	330	615	758
Total revenues	96,140	66,818	182,308	129,216
Operating Expenses
Employment expenses	32,878	25,507	65,289	51,825
Distribution and administration expenses	24,252	15,796	45,880	34,719
Other operating expenses	10,283	9,035	19,240	16,928
Other operating expenses of consolidated sponsored investment products	132		316
Restructuring and severance		794	203	794
Depreciation and other amortization	597	436	1,172	759
Amortization expense	1,116	997	2,226	1,985
Total operating expenses	69,258	52,565	134,326	107,010
Operating Income	26,882	14,253	47,982	22,206
Other Income (Expense)
Realized and unrealized (loss) gain on trading securities, net	(223)	(214)	602	1,010
Realized and unrealized loss on investments of consolidated sponsored investment products, net	(3,156)		(2,784)
Other expense, net	(11)		(29)
Total other (expense) income, net	(3,390)	(214)	(2,211)	1,010
Interest Income (Expense)
Interest expense	(206)	(274)	(427)	(475)
Interest and dividend income	203	171	300	277
Interest and dividend income of investments of consolidated sponsored investment products	612		1,092
Total interest income (expense), net	609	(103)	965	(198)
Income Before Income Taxes	24,101	13,936	46,736	23,018
Income tax expense	9,318	5,569	17,768	9,201
Net Income	14,783	8,367	28,968	13,817
Noncontrolling interests	602		377
Allocation of earnings to preferred stockholders				(64)
Net Income Attributable to Common Stockholders	$ 15,385	$ 8,367	$ 29,345	$ 13,753
Earnings per share - Basic	$ 1.97	$ 1.08	$ 3.75	$ 1.81
Earnings per share - Diluted	$ 1.91	$ 1.04	$ 3.64	$ 1.71
Weighted Average Shares Outstanding - Basic (in thousands)	7,821	7,763	7,821	7,615
Weighted Average Shares Outstanding - Diluted (in thousands)	8,058	8,081	8,073	8,023