Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues
Investment management fees	$ 235,230	$ 264,865	$ 300,663
Distribution and service fees	48,250	67,066	91,950
Administration and transfer agent fees	38,261	48,247	56,016
Other income and fees	813	1,799	1,969
Total revenues	322,554	381,977	450,598
Operating Expenses
Employment expenses	135,641	137,095	139,809
Distribution and other asset-based expenses	69,049	89,731	123,665
Restructuring and severance	4,270	0	294
Depreciation and other amortization	3,092	3,443	2,763
Amortization expense	2,461	3,295	3,778
Total operating expenses	271,740	301,599	319,878
Operating Income	50,814	80,378	130,720
Other Income (Expense)
Other income, net	1,089	898	891
Total other income (expense), net	8,819	(26,650)	(2,843)
Interest Income (Expense)
Total interest income, net	10,174	13,915	8,437
Income Before Income Taxes	69,807	67,643	136,314
Income tax expense	21,044	36,972	39,349
Net Income	48,763	30,671	96,965
Noncontrolling interests	(261)	4,435	735
Net Income Attributable to Common Stockholders	$ 48,502	$ 35,106	$ 97,700
Earnings per share—Basic (in $ per share)	$ 6.34	$ 3.99	$ 10.75
Earnings per Share—Diluted (in $ per share)	6.20	3.92	10.51
Cash Dividends Declared per Share (in $ per share)	$ 1.8	$ 1.8	$ 1.35
Weighted Average Shares Outstanding—Basic (in shares)	7,648	8,797	9,091
Weighted Average Shares Outstanding—Diluted (in shares)	7,822	8,960	9,292
Parent [Member]
Operating Expenses
Other operating expenses	$ 50,274	$ 63,901	$ 46,531
Other Income (Expense)
Realized and unrealized gain (loss) on investments, net	4,982	(862)	914
Interest Income (Expense)
Interest expense	(679)	(523)	(537)
Interest and dividend income	1,743	1,261	1,706
Consolidated Sponsored Investment Products [Member]
Operating Expenses
Other operating expenses	3,009	4,134	3,038
Other Income (Expense)
Realized and unrealized gain (loss) on investments, net	3,818	(23,181)	(4,648)
Interest Income (Expense)
Interest and dividend income	7,509	11,504	7,268
Consolidated Investment Product [Member]
Revenues
Total revenues	11,823
Operating Expenses
Other operating expenses	3,944	0	0
Other Income (Expense)
Realized and unrealized gain (loss) on investments, net	(1,070)	(3,505)	0
Interest Income (Expense)
Interest expense	(11,292)	(484)	0
Interest and dividend income	12,893	$ 2,157	$ 0
Net Income Attributable to Common Stockholders	$ (3,413)