Goodwill and Identifiable Intangible Assets (Details) (USD $)	3 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2014	Dec. 31, 2013
Goodwill and Identifiable Intangible Assets
Goodwill	$ 106,970,000	$ 106,970,000	$ 106,970,000
Mutual fund management advisory contracts	42,753,000	42,753,000	38,699,000
Mutual fund management subadvisory contracts	8,400,000	8,400,000	16,300,000
Total identifiable intangible assets	51,153,000	51,153,000	54,999,000
Total goodwill and identifiable intangible assets	158,123,000	158,123,000	161,969,000
Deferred tax liability	6,000,000	6,000,000
Impairment charge	7,900,000	7,900,000
Reduction of associated deferred tax liability	2,900,000	2,900,000
Intangible asset related to the fund adoption transaction agreement with Emerging Managers Group, L.P.	$ 4,100,000	$ 4,100,000