Goodwill and Identifiable Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2014	Dec. 31, 2015
Goodwill and identifiable intangible assets
Goodwill	$ 106,970		$ 106,970		$ 106,970
Other	200		200
Total identifiable intangible assets	41,599		41,599		51,148
Total goodwill and identifiable intangible assets	148,569		148,569		158,118
Write down of impaired assets			9,749	$ 7,900
Mutual fund management advisory contracts
Goodwill and identifiable intangible assets
Mutual fund contracts	38,699		38,699		42,748
Mutual fund management subadvisory contracts
Goodwill and identifiable intangible assets
Mutual fund contracts	2,700		$ 2,700		$ 8,400
Write down of impaired assets	$ 4,000	$ 5,700
Reduction of deferred tax liability		$ 2,100