Consolidated Company-Sponsored Investment Funds - Change in Carrying Value Associated with Level 3 Financial Instruments (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Fair value measurement Level 3 reconciliation [Abstract]
Balance as of beginning of period	$ 118	$ 115	$ 119	$ 142
Purchases	0	0	0	0
Sales	0	0	0	0
Realized gains (losses), net	0	0	0	0
Unrealized gains (losses), net	(4)	2	(5)	(25)
Balance as of end of period	114	117	114	117
Company-sponsored investment funds
Fair value measurement Level 3 reconciliation [Abstract]
Balance as of beginning of period	534	10,261	854	8,373
Deconsolidated funds	(135)	0	(135)	0
Transfers (out) in	340	(89)	571	(186)
Purchases	13	5,680	46	7,791
Sales	(82)	(4,065)	(444)	(4,349)
Realized gains (losses), net	(14)	21	(14)	23
Unrealized gains (losses), net	(138)	20	(362)	169
Accrued discounts	(1)	6	1	13
Balance as of end of period	$ 517	$ 11,834	$ 517	$ 11,834

Amount of unrealized gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3) and still held.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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Amount of increase (decrease) of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

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-Publisher FASB
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Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
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-Section 50
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Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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-Publisher FASB
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Amount of transfer of financial instrument classified as an asset into (out of) level 3 of the fair value hierarchy.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of accretion (amortization) of purchase discount (premium) on nonoperating securities.

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-Publisher FASB
-Name Accounting Standards Codification
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