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Fair Value Measurements - Assets and Liabilities Measured on a Recurring Basis (Details) - Fair Value Measured on a Recurring Basis - USD ($) $ in Millions | Sep. 30, 2020 | Dec. 31, 2019
--- | --- | ---
Financial Assets |  |
Investments in marketable securities | $ 68.2 | $ 59.4
Derivative financial instruments | 2.6 | 7.9
Financial Liabilities |  |
Affiliate equity repurchase obligations | 69.9 | 19.8
Derivative financial instruments | 4.0 | 1.0
Quoted Prices in Active Markets for Identical Assets (Level 1) |  |
Financial Assets |  |
Investments in marketable securities | 27.5 | 24.4
Derivative financial instruments | 0.0 | 0.0
Financial Liabilities |  |
Affiliate equity repurchase obligations | 0.0 | 0.0
Derivative financial instruments | 0.0 | 0.0
Significant Other Observable Inputs (Level 2) |  |
Financial Assets |  |
Investments in marketable securities | 40.7 | 35.0
Derivative financial instruments | 2.6 | 7.9
Financial Liabilities |  |
Affiliate equity repurchase obligations | 0.0 | 0.0
Derivative financial instruments | 4.0 | 1.0
Significant Unobservable Inputs (Level 3) |  |
Financial Assets |  |
Investments in marketable securities | 0.0 | 0.0
Derivative financial instruments | 0.0 | 0.0
Financial Liabilities |  |
Affiliate equity repurchase obligations | 69.9 | 19.8
Derivative financial instruments | $ 0.0 | $ 0.0

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