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Derivatives and Fair Value Measurements - Textuals (Details) $ in Millions | 3 Months Ended | 6 Months Ended | 9 Months Ended |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Sep. 30, 2017 USD ($) | Apr. 01, 2017 USD ($) | Sep. 30, 2017 USD ($) | Sep. 30, 2018 USD ($) | Jun. 30, 2019 $ / $ | Mar. 31, 2019 $ / $ | Dec. 31, 2018 $ / $ | Oct. 15, 2018 AUD ($) | Sep. 30, 2018 AUD ($) | Dec. 31, 2017 USD ($)
Successor | Foreign currency option contract |  |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |  |
Derivative, notional amount |  |  |  |  |  |  |  |  | $ 675.0 |
Successor | Fair Value, Measurements, Recurring |  |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |  |
Derivative Assets (Liabilities), at Fair Value, Net |  |  |  | $ 10,200,000 |  |  |  |  |  | $ 4,200,000
Successor | Fair Value, Measurements, Recurring | Foreign currency option contract |  |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |  |
Derivative Assets (Liabilities), at Fair Value, Net |  |  |  | 200,000 |  |  |  |  |  | $ 4,200,000
Predecessor | Foreign currency option contract |  |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |  |
Transfers Between Hierarchy Levels | $ 0 | $ 0 | $ 0 | $ 0 |  |  |  |  |  |
Scenario, Forecast | Lower rate | Foreign currency option contract |  |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |  |
Derivative, Exchange Rate Cap | $ / $ |  |  |  |  | 0.76 | 0.79 | 0.79 |  |  |
Scenario, Forecast | Higher rate | Foreign currency option contract |  |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |  |
Derivative, Exchange Rate Cap | $ / $ |  |  |  |  |  | 0.82 | 0.82 |  |  |
Subsequent Event [Member] | Foreign currency option contract |  |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |  |
Derivative, notional amount |  |  |  |  |  |  |  | $ 275.0 |  |
Premium Costs |  |  |  |  |  |  |  | $ 0.8 |  |

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- Definition Aggregate notional amount specified by the derivative(s). Expressed as an absolute value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
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- Definition Fair values as of the balance sheet date of the net amount of all assets and liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 + Details
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