Income Taxes Textuals (Details) $ in Millions, $ in Millions		3 Months Ended	9 Months Ended	12 Months Ended
	Apr. 01, 2017 USD ($)	Apr. 01, 2017 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2018 AUD ($)	Jan. 01, 2018 USD ($)	Dec. 22, 2017
Successor
Investments, Owned, Federal Income Tax Note [Line Items]
Global intangible low-taxed income			$ 0.0	$ 68.2
Alternative Minimum Tax Refund			91.1
Remeasurement due to the Tax Cuts and Jobs Act			473.5	9.5
Executive Compensation Tax Deduction			0.5
Unrecognized Tax Benefits, Interest and penalties on Income Taxes Expense			4.8	0.4
Change In Unrecognized Tax Benefit				1.3
Operating Loss Carryforwards							$ 3,700.0
Deferred Income Taxes and Tax Credits			(99.6)	35.5
Deferred Tax Assets, Operating Loss Carryforwards, Domestic				3,200.0
Tax Credit Carryforward, Amount				1,700.0
Deferred Tax Assets, Operating Loss Carryforwards, Domestic, Net				672.6
Deferred Tax Assets, Operating Loss Carryforwards, State and Local				84.4
Deferred Tax Assets, Tax Credit Carryforwards, Foreign				1.6			262.0
Tax Basis of Investments, Gross, Unrealized Depreciation							543.1
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax				45.5			91.1
Valuation Allowance Release			85.6	5.5
Deferred Tax Assets, Tax Credit Carryforwards, General Business				112.8			112.8
Deferred Tax Assets, Capital Loss Carryforwards							$ 205.7
Deferred Tax Assets, Operating Loss Carryforwards, Foreign				14.2
Changes in deferred tax asset valuation allowance				$ (296.5)
Tax Rate, Australia				30.00%		30.00%
Net Unrecognized Tax Benefit			12.7	$ 14.0
Unrecognized Tax Benefits, Interest on Income Taxes Accrued			5.0	5.4
Income tax provision (benefit)			(161.0)	18.4
Valuation allowance, income tax			(2,432.5)	(2,094.3)
Successor | Australia
Investments, Owned, Federal Income Tax Note [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Foreign, Net				795.4
Deferred Tax Assets, Operating Loss Carryforwards, Foreign						$ 3,300.0
Successor | US Deferred Tax Assets
Investments, Owned, Federal Income Tax Note [Line Items]
Valuation allowance, income tax				(900.0)
Successor | Australia Deferred Tax Assets
Investments, Owned, Federal Income Tax Note [Line Items]
Valuation allowance, income tax				(1,200.0)
Successor | Maximum
Investments, Owned, Federal Income Tax Note [Line Items]
Executive Compensation Tax Deduction				1.0
Operating Loss Carryforwards				$ 62.0
Successor | Non-U.S.
Investments, Owned, Federal Income Tax Note [Line Items]
Deferred Income Taxes and Tax Credits			260.4
Successor | Before Corporate Tax Rate Change
Investments, Owned, Federal Income Tax Note [Line Items]
Federal Corporate Tax Rate								35.00%
Successor | After Corporate Tax Rate Change
Investments, Owned, Federal Income Tax Note [Line Items]
Federal Corporate Tax Rate								21.00%
Predecessor
Investments, Owned, Federal Income Tax Note [Line Items]
Cancellation of Debt Income	$ 8,500.0
Global intangible low-taxed income		$ 0.0			$ 0.0
Remeasurement due to the Tax Cuts and Jobs Act		0.0			0.0
Unrecognized Tax Benefits, Interest and penalties on Income Taxes Expense		2.1			0.4
Operating Loss Carryforwards			$ 4,600.0
Deferred Income Taxes and Tax Credits		(262.3)			(97.0)
Income tax provision (benefit)		$ (263.8)			$ (94.5)
Predecessor | Third-party Lender
Investments, Owned, Federal Income Tax Note [Line Items]
Cancellation of Debt Income	3,900.0
Predecessor | Related Party Lender
Investments, Owned, Federal Income Tax Note [Line Items]
Cancellation of Debt Income	$ 4,600.0