Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues
Investment management fees	$ 264,865	$ 300,663	$ 260,557
Distribution and service fees	67,066	91,950	78,965
Administration and transfer agent fees	48,247	56,016	48,185
Other income and fees	1,799	1,969	1,508
Total revenues	381,977	450,598	389,215
Operating Expenses
Employment expenses	137,095	139,809	131,768
Distribution and other asset-based expenses	89,731	123,665	97,786
Other operating expenses	63,901	46,531	38,321
Restructuring and severance	0	294	203
Depreciation and other amortization	3,443	2,763	2,422
Amortization expense	3,295	3,778	4,413
Total operating expenses	301,599	319,878	275,711
Operating Income	80,378	130,720	113,504
Other Income (Expense)
Realized and unrealized (loss) gain on investments, net	(862)	914	2,350
Other income, net	898	891	74
Total other (expense) income, net	(26,650)	(2,843)	5,939
Interest Income (Expense)
Interest expense	(523)	(537)	(782)
Interest and dividend income	1,261	1,706	664
Total interest income, net	13,915	8,437	2,465
Income Before Income Taxes	67,643	136,314	121,908
Income tax expense	36,972	39,349	44,778
Net Income	30,671	96,965	77,130
Noncontrolling interests	4,435	735	(1,940)
Net Income Attributable to Common Stockholders	$ 35,106	$ 97,700	$ 75,190
Earnings per share—Basic (in $ per share)	$ 3.99	$ 10.75	$ 9.18
Earnings per Share—Diluted (in $ per share)	3.92	10.51	8.92
Cash Dividends Declared per Share (in $ per share)	$ 1.8	$ 1.35	$ 0
Weighted Average Shares Outstanding—Basic (in shares)	8,797	9,091	8,188
Weighted Average Shares Outstanding—Diluted (in shares)	8,960	9,292	8,433
Consolidated Sponsored Investment Products [Member]
Operating Expenses
Other operating expenses	$ 4,134	$ 3,038	$ 798
Other Income (Expense)
Realized and unrealized (loss) gain on investments, net	(23,181)	(4,648)	3,515
Interest Income (Expense)
Interest and dividend income	11,504	7,268	2,583
Consolidated Investment Product [Member]
Other Income (Expense)
Realized and unrealized (loss) gain on investments, net	(3,505)	0	0
Interest Income (Expense)
Interest and dividend income	$ 1,673	$ 0	$ 0