Investment Securities - Fair value of investment securities (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Fair value of investments
Available-for-sale Securities	$ 120,756	$ 123,376
Trading Securities	164,561	175,365
Equity method securities	23,986	30,009
Total investment securities	309,303	328,750
Total Estimated Fair Value
Fair value of investments
Total investment securities	309,303	328,750
Sponsored funds
Fair value of investments
Available-for-sale Securities	120,756	122,806
Trading Securities	30,555	29,541
Equity method securities	20,441	26,775
Sponsored funds \| Total Estimated Fair Value
Fair value of investments
Available-for-sale Securities	120,756	122,806
Trading Securities	30,555	29,541
Equity method securities	20,441	26,775
Sponsored privately offered funds
Fair value of investments
Available-for-sale Securities		570
Trading Securities	614
Equity method securities	3,545	3,234
Sponsored privately offered funds \| Total Estimated Fair Value
Fair value of investments
Available-for-sale Securities		570
Trading Securities	614
Equity method securities	3,545	3,234
Mortgage-backed securities
Fair value of investments
Trading Securities	12	13
Mortgage-backed securities \| Total Estimated Fair Value
Fair value of investments
Trading Securities	12	13
Common Stock
Fair value of investments
Trading Securities	104	101
Common Stock \| Total Estimated Fair Value
Fair value of investments
Trading Securities	104	101
Consolidated Sponsored Funds
Fair value of investments
Trading Securities	133,276	145,710
Consolidated Sponsored Funds \| Total Estimated Fair Value
Fair value of investments
Trading Securities	133,276	145,710
Level 1
Fair value of investments
Total investment securities	266,801	280,070
Level 1 \| Sponsored funds
Fair value of investments
Available-for-sale Securities	120,756	122,806
Trading Securities	30,555	29,541
Equity method securities	20,441	26,775
Level 1 \| Common Stock
Fair value of investments
Trading Securities	104	101
Level 1 \| Consolidated Sponsored Funds
Fair value of investments
Trading Securities	94,945	100,847
Level 2
Fair value of investments
Total investment securities	38,343	44,876
Level 2 \| Mortgage-backed securities
Fair value of investments
Trading Securities	12	13
Level 2 \| Consolidated Sponsored Funds
Fair value of investments
Trading Securities	38,331	44,863
Other Assets Not Held at Fair Value
Fair value of investments
Total investment securities	4,159	3,804
Other Assets Not Held at Fair Value \| Sponsored privately offered funds
Fair value of investments
Available-for-sale Securities		570
Trading Securities	614
Equity method securities	$ 3,545	$ 3,234

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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-Publisher FASB
-Name Accounting Standards Codification
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+ References

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Amount of investments in debt and equity securities, including, but not limited to, held-to-maturity, trading and available-for-sale expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer.

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Amount of investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading.

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