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Investments in Marketable Securities - Additional Information (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2020 | Jun. 30, 2019 | Jun. 30, 2020 | Jun. 30, 2019 | Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract] |  |  |  |  |
Proceeds received from sales of marketable securities | $ 37.9 | $ 3.4 | $ 64.1 | $ 18.5 |
Net realized gains (losses) on sale of marketable securities | 0.9 | $ 0.2 | (0.1) | $ 0.7 |
Variable Interest Entity, Primary Beneficiary |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |
Fair value of deconsolidated investment in affiliate | $ 37.6 |  | $ 37.6 |  | $ 38.1

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- Definition Marketable Securities, Fair Value, Deconsolidation + References No definition available. + Details
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