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Investments in Marketable Securities - Additional Information (Details) - USD ($) $ in Millions | Mar. 31, 2021 | Dec. 31, 2020
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Variable Interest Entity, Primary Beneficiary |  |
Investments in and Advances to Affiliates [Line Items] |  |
Marketable securities, consolidated Affiliate sponsored investment products | $ 77.8 | $ 52.3

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- Definition Marketable Securities, Fair Value + References No definition available. + Details
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Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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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. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |