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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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Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan.

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