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Fair Value Measurements - Quantitative Information About Level 3 (Details) - Discounted cash flow - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016
Contingent payment arrangements |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Fair value liabilities | $ 9.4 | $ 8.6
Contingent payment arrangements | Minimum |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Growth rates | 7.00% | 3.00%
Discount rates | 15.00% | 14.00%
Contingent payment arrangements | Maximum |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Growth rates | 8.00% | 8.00%
Discount rates | 16.00% | 15.00%
Affiliate equity obligations |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Fair value liabilities | $ 49.2 | $ 12.1
Affiliate equity obligations | Minimum |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Growth rates | 0.00% | 4.00%
Discount rates | 12.00% | 15.00%
Affiliate equity obligations | Maximum |  |
Quantitative information for Level 3 Fair Value Measurements Liabilities |  |
Growth rates | 11.00% | 10.00%
Discount rates | 16.00% | 16.00%

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- Definition Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
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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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- Definition Fair value of financial and nonfinancial obligations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
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