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Fair Value Measurements - Changes in Level 3 Financial Assets and Liabilities (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016
Contingent Payment Arrangements |  |  |
Changes in level 3 assets and liabilities |  |  |
Balance, beginning of period |  | $ 8.6 | $ 10.2
Net realized and unrealized (gains) losses(1) | [1] | 7.6 | (1.6)
Purchases and issuances(2) | [2] | 0.0 | 0.0
Settlements and reductions |  | (6.8) | 0.0
Balance, end of period |  | 9.4 | 8.6
Net change in unrealized (gains) losses relating to instruments still held at the reporting date |  | 2.8 | (1.6)
Affiliate Equity Obligations |  |  |
Changes in level 3 assets and liabilities |  |  |
Balance, beginning of period |  | 12.1 | 62.3
Net realized and unrealized (gains) losses(1) | [1] | 5.5 | 3.1
Purchases and issuances(2) | [2] | 206.1 | 69.1
Settlements and reductions |  | (174.5) | (122.4)
Balance, end of period |  | 49.2 | 12.1
Net change in unrealized (gains) losses relating to instruments still held at the reporting date |  | $ 0.0 | $ 0.0
[1] | Accretion and changes in the expected value of the Company’s contingent payment arrangements and Affiliate equity obligations are recorded in Imputed interest expense and contingent payment arrangements.
[2] | Includes transfers from Redeemable non-controlling interests and other activity.

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- Definition -- None. No documentation exists for this element. -- + References No definition available. + Details
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- Definition Represents total realized gains or losses for the period, arising from assets and liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in earnings or other comprehensive income. + References No definition available. + Details
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- Definition Represents assets and liabilities measured at fair value using significant unobservable inputs (Level 3) which are required for reconciliation purposes of beginning and ending balances. + References No definition available. + Details
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- Definition Represents settlements and reductions which have taken place during the period in relation to assets and liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3). + References No definition available. + Details
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- Definition Represents total unrealized gains or losses for the period, arising from assets and liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in earnings or other comprehensive income. + References No definition available. + Details
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- Details
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- Details
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