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Derivatives and Fair Value Measurements - Gains and Losses on Hedging Derivatives (Details) - Designated as Hedging Instrument - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended | 9 Months Ended
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Sep. 30, 2018 | Sep. 30, 2017 | Apr. 01, 2017 | Sep. 30, 2017 | Sep. 30, 2018
Successor |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
(Loss) gain realized in income on derivatives | $ (1.8) | $ 7.3 |  | $ 7.0 | $ (6.5)
Unrealized gain (loss) recognized in income on non-designated derivatives | 0.3 | (1.7) |  | 1.5 | (1.4)
Total (loss) gain recognized in income | (1.5) | 5.6 |  | 8.5 | (7.9)
Successor | Foreign currency option contract | Operating costs and expenses |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
(Loss) gain realized in income on derivatives | (1.8) | 7.3 |  | 7.0 | (6.5)
Unrealized gain (loss) recognized in income on non-designated derivatives | 0.3 | (1.7) |  | 1.5 | (1.4)
Total (loss) gain recognized in income | $ (1.5) | $ 5.6 |  | $ 8.5 | $ (7.9)
Predecessor |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Loss reclassified from other comprehensive loss into income |  |  | $ (27.6) |  |
Total (loss) gain recognized in income |  |  | (27.6) |  |
Predecessor | Commodity swap contracts | Operating costs and expenses |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Loss reclassified from other comprehensive loss into income |  |  | (11.0) |  |
Total (loss) gain recognized in income |  |  | (11.0) |  |
Predecessor | Foreign currency option contract | Operating costs and expenses |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Loss reclassified from other comprehensive loss into income |  |  | (16.6) |  |
Total (loss) gain recognized in income |  |  | $ (16.6) |  |

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- Definition Amount of increase (decrease) in the fair value of derivatives recognized in the income statement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5618551-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (a),(c),(d),(e) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959 + 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 The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4D -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624177-113959 + Details
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- Definition The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959 + Details
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- Definition Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959 + Details
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