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Investments - Equity Investment Ownership (Details)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Research Opportunities Fund
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	23.00%	28.00%	26.00%
Core Bond Fund
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	36.00%
High Yield Fund
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage			48.00%
Minimum | Research Opportunities Fund
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	20.00%
Maximum | Research Opportunities Fund
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%

X

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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