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Pension and Savings Plans Textuals (Details) | 3 Months Ended | 9 Months Ended | 12 Months Ended | 21 Months Ended
--- | --- | --- | --- | ---
Apr. 01, 2017 USD ($) years plan | Dec. 31, 2017 USD ($) | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($) | Dec. 31, 2018 USD ($)
Successor |  |  |  |  |  |  |
Defined Contribution Plans [Abstract] |  |  |  |  |  |  |
Number of 401(k) plans | plan | 2 |  |  |  |  |  |
Paid discretionary contributions to defined contribution pension plans, company match |  | $ (25,500,000) |  | $ 30,300,000 |  |  |
Additional discretionary contributions to defined contribution pension plans, performance feature |  |  |  | $ 8,500,000 |  |  |
Successor | Pension Plan |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |
Retirees Affected by Pension Settlement |  | 1,950 |  |  |  |  |
Percentage of company's qualified pension plans on a GAAP accounting basis |  |  |  | 80.00% |  |  | 80.00%
Expected long-term return on plan assets | 5.65% | 5.90% |  | 5.65% | 4.20% |  |
Defined Benefit Plan, Accumulated Benefit Obligation |  |  |  | $ 795,900,000 |  |  | $ 795,900,000
Payment for Pension and Other Postretirement Benefits |  |  |  | 62,000,000 |  |  |
Defined Contribution Plans [Abstract] |  |  |  |  |  |  |
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement |  | $ 71,400,000 |  |  |  |  |
Pension obligations |  | $ 2,100,000 |  | $ 0 |  |  |
Successor | Equity Securities |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage |  | 27.00% |  |  | 27.00% |  |
Successor | Fixed Income Investments |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage |  | 73.00% |  | 100.00% | 73.00% |  | 100.00%
Successor | Real Estate |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage |  | 2.00% |  | 1.00% | 2.00% |  | 1.00%
Predecessor |  |  |  |  |  |  |
Defined Contribution Plans [Abstract] |  |  |  |  |  |  |
Paid discretionary contributions to defined contribution pension plans, company match | $ (5,500,000) |  |  |  |  | $ (19,200,000) |
Additional discretionary contributions to defined contribution pension plans, performance feature | $ 0 |  |  |  |  | $ 0 |
Predecessor | Pension Plan |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |
Expected long-term return on plan assets | 5.90% |  |  |  |  | 6.00% |
Percentage of actuarial gains and losses amortized | 5.00% |  |  |  |  |  |
Defined Benefit Plan, Amortization Period | years | 5 |  |  |  |  |  |
Defined Benefit Plan, Accumulated Benefit Obligation |  | $ 874,600,000 |  |  | $ 874,600,000 |  |
Defined Contribution Plans [Abstract] |  |  |  |  |  |  |
Pension obligations | $ 0 |  |  |  |  | $ 0 |
Scenario, Forecast |  |  |  |  |  |  |
Defined Contribution Plans [Abstract] |  |  |  |  |  |  |
Additional discretionary contributions to defined contribution pension plans, performance feature |  |  | $ 8,900,000 |  |  |  |
Australia | Successor |  |  |  |  |  |  |
Defined Contribution Plans [Abstract] |  |  |  |  |  |  |
Paid discretionary contributions to defined contribution pension plans, company match |  |  |  | $ 31,600,000 |  |  | $ 19,900,000
Additional discretionary contributions to defined contribution pension plans, performance feature |  | $ 0 |  | $ 3,000,000 |  |  |
Australia | Predecessor |  |  |  |  |  |  |
Defined Contribution Plans [Abstract] |  |  |  |  |  |  |
Paid discretionary contributions to defined contribution pension plans, company match | $ 6,100,000 |  |  |  |  | $ 23,900,000 |
Australia | Scenario, Forecast |  |  |  |  |  |  |
Defined Contribution Plans [Abstract] |  |  |  |  |  |  |
Additional discretionary contributions to defined contribution pension plans, performance feature |  |  | $ 2,300,000 |  |  |  |

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