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Fair Value Measurements - Changes in Level 3 Liabilities (Details) - Significant Unobservable Inputs (Level 3) - Affiliate equity purchase obligations - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
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Jun. 30, 2021 | Jun. 30, 2020 | Jun. 30, 2021 | Jun. 30, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |
Balance, beginning of period | $ 66.1 | $ 115.1 | $ 22.0 | $ 19.8
Net realized and unrealized (gains) losses | 1.3 | (2.4) | 2.2 | (3.9)
Purchases and issuances | 12.3 | 13.0 | 83.0 | 207.0
Settlements and reductions | (31.8) | (52.4) | (59.3) | (149.6)
Balance, end of period | 47.9 | 73.3 | 47.9 | 73.3
Net change in unrealized (gains) losses relating to instruments still held at the reporting date | $ 0.0 | $ 0.0 | $ 0.0 | $ 0.0

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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 gain (loss) recognized in income from liability measured at fair value on recurring basis using unobservable input (level 3) and still held. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=123874694&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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258 + Details
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