Investment Securities - Investment securities (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Available for sale securities:
Available for sale securities	$ 195,070	$ 123,376
Trading securities:
Trading securities	262,912	175,365
Equity method securities
Equity method securities	43,845	30,009
Total investment securities	501,827	328,750
Cerficates of deposit
Available for sale securities:
Available for sale securities	10,001
Commercial paper
Available for sale securities:
Available for sale securities	4,985
Mortgage-backed securities
Trading securities:
Trading securities	12	13
Corporate bonds
Available for sale securities:
Available for sale securities	34,147
Trading securities:
Trading securities	16,098
Common Stock
Trading securities:
Trading securities	110	101
Consolidated Sponsored Funds
Trading securities:
Trading securities	215,116	145,710
Sponsored funds
Available for sale securities:
Available for sale securities	145,937	122,806
Trading securities:
Trading securities	30,945	29,541
Equity method securities
Equity method securities	40,154	26,775
Sponsored privately offered funds
Available for sale securities:
Available for sale securities		570
Trading securities:
Trading securities	631
Equity method securities
Equity method securities	$ 3,691	$ 3,234

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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