Investment Securities - Fair value of investment securities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Fair value of investments
Cash equivalents	$ 156,835	$ 196,931
Available for sale securities	265,388	250,764
Trading debt securities	119,999	118,222
Equity securities	211,841	200,309
Total investment securities	649,052	617,135
Money market funds
Fair value of investments
Cash equivalents	119,874	121,759
U.S. government sponsored enterprise note
Fair value of investments
Cash equivalents	895	895
Certificates of deposit
Fair value of investments
Available for sale securities		5,001
Commercial paper
Fair value of investments
Cash equivalents	36,066	74,277
Available for sale securities	8,305	7,970
Trading debt securities	1,175	1,993
Corporate bonds
Fair value of investments
Available for sale securities	257,083	218,121
Trading debt securities	77,739	77,250
U.S. treasury bills
Fair value of investments
Available for sale securities		19,672
Trading debt securities	5,913	5,884
Fixed income securities: Mortgage-backed securities
Fair value of investments
Trading debt securities	7	7
Common Stock
Fair value of investments
Equity securities	30,680	21,204
Consolidated Sponsored Funds
Fair value of investments
Trading debt securities	35,165	33,088
Equity securities	27,883	24,879
Sponsored funds
Fair value of investments
Equity securities	152,481	153,548
Equity method securities	51,824	47,840
Sponsored privately offered funds
Fair value of investments
Equity securities	797	678
Level 1
Fair value of investments
Cash equivalents	119,874	121,759
Total investment securities	262,848	247,459
Level 1 \| Money market funds
Fair value of investments
Cash equivalents	119,874	121,759
Level 1 \| Common Stock
Fair value of investments
Equity securities	30,660	21,192
Level 1 \| Consolidated Sponsored Funds
Fair value of investments
Equity securities	27,883	24,879
Level 1 \| Sponsored funds
Fair value of investments
Equity securities	152,481	153,548
Equity method securities	51,824	47,840
Level 2
Fair value of investments
Cash equivalents	36,961	75,172
Total investment securities	385,387	368,986
Level 2 \| U.S. government sponsored enterprise note
Fair value of investments
Cash equivalents	895	895
Level 2 \| Certificates of deposit
Fair value of investments
Available for sale securities		5,001
Level 2 \| Commercial paper
Fair value of investments
Cash equivalents	36,066	74,277
Available for sale securities	8,305	7,970
Trading debt securities	1,175	1,993
Level 2 \| Corporate bonds
Fair value of investments
Available for sale securities	257,083	218,121
Trading debt securities	77,739	77,250
Level 2 \| U.S. treasury bills
Fair value of investments
Available for sale securities		19,672
Trading debt securities	5,913	5,884
Level 2 \| Fixed income securities: Mortgage-backed securities
Fair value of investments
Trading debt securities	7	7
Level 2 \| Consolidated Sponsored Funds
Fair value of investments
Trading debt securities	35,165	33,088
Level 3
Fair value of investments
Total investment securities	20	12
Level 3 \| Common Stock
Fair value of investments
Equity securities	20	12
Other Assets Held at Net Value
Fair value of investments
Total investment securities	797	678
Other Assets Held at Net Value \| Sponsored privately offered funds
Fair value of investments
Equity securities	$ 797	$ 678

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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-Publisher FASB
-Name Accounting Standards Codification
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Amount of short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ References

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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No definition available.

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Amount of investment in marketable security, classified as current.

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Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading).

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