Condensed Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Revenues
Investment management fees	$ 74,537	$ 64,475	$ 146,329	$ 122,252
Distribution and service fees	23,940	19,324	46,378	36,685
Administration and transfer agent fees	13,942	12,061	27,015	22,756
Other income and fees	330	280	898	615
Total revenues	112,749	96,140	220,620	182,308
Operating Expenses
Employment expenses	35,481	32,878	70,510	65,289
Distribution and administration expenses	39,222	24,252	66,959	45,880
Other operating expenses	13,130	10,283	23,664	19,240
Other operating expenses of consolidated sponsored investment products	797	132	1,128	316
Restructuring and severance				203
Depreciation and other amortization	670	597	1,327	1,172
Amortization expense	947	1,116	1,904	2,226
Total operating expenses	90,247	69,258	165,492	134,326
Operating Income	22,502	26,882	55,128	47,982
Other Income (Expense)
Realized and unrealized gain (loss) on investments, net	905	(223)	2,751	602
Realized and unrealized gain (loss) on investments of consolidated sponsored investment products, net	6,444	(3,156)	6,480	(2,784)
Other income (expense), net	189	(11)	340	(29)
Total other income (expense), net	7,538	(3,390)	9,571	(2,211)
Interest Income (Expense)
Interest expense	(125)	(206)	(263)	(427)
Interest and dividend income	344	203	727	300
Interest and dividend income of investments of consolidated sponsored investment products	1,639	612	2,512	1,092
Total interest income, net	1,858	609	2,976	965
Income Before Income Taxes	31,898	24,101	67,675	46,736
Income tax expense	12,106	9,318	26,116	17,768
Net Income	19,792	14,783	41,559	28,968
Noncontrolling interests	(249)	602	(78)	377
Net Income Attributable to Common Stockholders	$ 19,543	$ 15,385	$ 41,481	$ 29,345
Earnings per share-Basic	$ 2.14	$ 1.97	$ 4.55	$ 3.75
Earnings per share-Diluted	$ 2.10	$ 1.91	$ 4.44	$ 3.64
Cash dividends declared per share	$ 0.45	$ 0.00	$ 0.45	$ 0.00
Weighted Average Shares Outstanding-Basic (in thousands)	9,133	7,821	9,125	7,821
Weighted Average Shares Outstanding-Diluted (in thousands)	9,325	8,058	9,343	8,073