Consolidated Company-Sponsored Investment Funds (Change in Carrying Value Associated with Level 3 Financial Instruments) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Fair value measurement Level 3 reconciliation [Abstract]
Balance as of beginning of period	$ 117	$ 5,028	$ 1,071	$ 5,023
Purchases	0	0	0	0
Sales	0	0	0	0
Realized gains (losses), net	0	0	0	0
Unrealized (losses) gains, net	0	(3,958)	(954)	(3,953)
Balance as of end of period	117	1,070	117	1,070
Company-sponsored investment funds
Fair value measurement Level 3 reconciliation [Abstract]
Balance as of beginning of period	5,871	2,797	2,264	5,741
Deconsolidated funds	0	0	0	(6,697)
Transfers (out) in	(406)	(35)	(82)	378
Purchases	1,247	346	7,381	5,358
Sales	(197)	(1,148)	(2,820)	(3,045)
Realized gains (losses), net	2	5	(97)	1
Unrealized (losses) gains, net	(25)	52	(158)	269
Accrued discounts	2	1	6	13
Balance as of end of period	$ 6,494	$ 2,018	$ 6,494	$ 2,018

Amount of unrealized (holding) gain (loss) which is included in the statement of income (or changes in net assets) related to those assets still held at the reporting date for which fair value is measured on a recurring basis using significant unobservable inputs (Level 3).

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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 the income statement for 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 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.

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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.

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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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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
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