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Fair Value Measurements - Quantitative Information used in Valuing Level 3 Liabilities (Details) - Discounted Cash Flow $ in Millions | Sep. 30, 2018 USD ($) | Dec. 31, 2017 USD ($)
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Contingent Payment Arrangements | Growth rates |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Contingent payment arrangements, measurement input | 0.07 |
Contingent Payment Arrangements | Growth rates | Minimum |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Contingent payment arrangements, measurement input |  | 0.07
Contingent Payment Arrangements | Growth rates | Maximum |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Contingent payment arrangements, measurement input |  | 0.08
Contingent Payment Arrangements | Discount rates |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Contingent payment arrangements, measurement input | 0.15 |
Contingent Payment Arrangements | Discount rates | Minimum |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Contingent payment arrangements, measurement input |  | 0.15
Contingent Payment Arrangements | Discount rates | Maximum |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Contingent payment arrangements, measurement input |  | 0.16
Affiliate Equity Obligations | Growth rates | Minimum |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Affiliate equity repurchase obligations, measurement input | 0.04 | 0.00
Affiliate Equity Obligations | Growth rates | Maximum |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Affiliate equity repurchase obligations, measurement input | 0.09 | 0.11
Affiliate Equity Obligations | Discount rates | Minimum |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Affiliate equity repurchase obligations, measurement input | 0.14 | 0.12
Affiliate Equity Obligations | Discount rates | Maximum |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Affiliate equity repurchase obligations, measurement input | 0.16 | 0.16
Significant Unobservable Inputs (Level 3) | Contingent Payment Arrangements |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Fair value liabilities | $ 4.3 | $ 9.4
Significant Unobservable Inputs (Level 3) | Affiliate Equity Obligations |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Fair value liabilities | $ 28.7 | $ 49.2

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- Definition Fair value of financial and nonfinancial obligations. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258 + Details
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