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Fair Value Measurements - Quantitative Information used in Valuing Level 3 Liabilities (Details) - Significant Unobservable Inputs (Level 3) - Affiliate equity repurchase obligations - Discounted cash flow $ in Millions | Sep. 30, 2020 USD ($) | Dec. 31, 2019 USD ($)
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Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Fair Value | $ 69.9 | $ 19.8
Growth rates | Minimum |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Affiliate equity repurchase obligations, measurement input | (0.01) | (0.09)
Growth rates | Maximum |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Affiliate equity repurchase obligations, measurement input | 0.08 | 0.07
Growth rates | Weighted Average |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Affiliate equity repurchase obligations, measurement input | 0.07 | 0.05
Discount rates | Minimum |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Affiliate equity repurchase obligations, measurement input | 0.14 | 0.14
Discount rates | Maximum |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Affiliate equity repurchase obligations, measurement input | 0.16 | 0.17
Discount rates | Weighted Average |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Affiliate equity repurchase obligations, measurement input | 0.15 | 0.15

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