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Fair Value Measurements - Changes in Level 3 Assets and Liabilities (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2017 | Sep. 30, 2016 | Sep. 30, 2017 | Sep. 30, 2016
Contingent Payment Arrangements |  |  |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |
Balance, beginning of period |  | $ 7.8 | $ 8.0 | $ 8.6 | $ 10.2
Net realized and unrealized (gains) losses | [1] | 0.3 | 0.2 | 2.3 | (2.0)
Purchases and issuances |  | 0.0 | 0.0 | 0.0 | 0.0
Settlements and reductions |  | 0.0 | 0.0 | (2.8) | 0.0
Balance, end of period |  | 8.1 | 8.2 | 8.1 | 8.2
Net change in unrealized (gains) losses relating to instruments still held at the reporting date | [1] | 0.3 | 0.2 | 2.3 | (2.0)
Affiliate Equity Obligations |  |  |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |
Balance, beginning of period |  | 70.7 | 27.0 | 12.1 | 62.3
Net realized and unrealized (gains) losses | [1] | (0.2) | 0.1 | (0.2) | 0.1
Purchases and issuances |  | 11.1 | 8.4 | 161.5 | 48.2
Settlements and reductions |  | (35.9) | (8.8) | (127.7) | (83.9)
Balance, end of period |  | 45.7 | 26.7 | 45.7 | 26.7
Net change in unrealized (gains) losses relating to instruments still held at the reporting date |  | $ 0.0 | $ 0.0 | $ 0.0 | $ 0.0
[1] | Accretion and changes in the expected value of the Company’s contingent payment arrangements are recorded in Imputed interest expense and contingent payment arrangements.

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- Definition Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Purchases And Issuances + References No definition available. + Details
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- Definition Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Settlements And Reductions + References No definition available. + Details
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- Definition Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings and Other Comprehensive Income (Loss) + References No definition available. + Details
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- Definition Amount of unrealized (holding) gain (loss) which is included in the statement of income (or changes in net assets) related to those liabilities still held at the reporting date for which fair value is measured on a recurring basis using significant unobservable inputs (Level 3). + 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 (d) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
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- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
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- Definition Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + 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 (c) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
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