Accumulated Other Comprehensive Income (Loss) Components of Comprehensive Income (Loss), After-tax (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Apr. 01, 2017	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Reclassification for realized losses on cash flow hedges (net of respective net tax provision of $0.0, $0.0, $0.0, and $9.1) included in net (loss) income	$ 18.6	$ 0.0	$ 0.0	$ 0.0
Other Comprehensive Income Reclassification Adjustment Net Of Tax	23.0		(8.7)
Foreign currency translation adjustment	5.5	1.4	0.2	(5.9)
Other Comprehensive Income Loss Current Period Change Net Of Tax	5.5		0.2	38.7
Other Comprehensive Income (Loss), Fresh Start Reporting Adjustments	448.5
Accumulated Other Comprehensive Income (Loss), Net of Tax	0.0		31.6	40.1	$ (477.0)
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Translation Adjustment Functional to Reporting Currency, Gain (Loss), Reclassified to Earnings, Net of Tax	0.0		0.0
Foreign currency translation adjustment	5.5	1.4	0.2	(5.9)
Other Comprehensive Income (Loss), Fresh Start Reporting Adjustments	142.7
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	0.0	1.4	(4.3)	(4.5)	(148.2)
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax	5.8		0.0
HIDE ROW	0.0	0.0	0.0	0.0
Other Comprehensive Income (Loss), Fresh Start Reporting Adjustments	250.5
Accumulated Other Comprehensive Income Loss Acturial Loss Associated With Postretirement Plans And Workers Compensation Obligation Net Of Tax	0.0	0.0	0.0	0.0	(256.3)
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, after Tax	(1.4)		(8.7)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), after Tax	0.0	0.0	0.0	44.6
Other Comprehensive Income (Loss), Fresh Start Reporting Adjustments	(20.3)
Accumulated Other Comprehensive Income Loss Prior Service Cost Credit Arising During Period Net of tax	0.0	0.0	35.9	44.6	21.7
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other Comprehensive Income, Derivatives Qualifying As Hedges, Net Unamortized (Gain) Loss Arising During Period, Net of Tax	0.0	0.0	0.0	0.0
Other Comprehensive Income (Loss), Fresh Start Reporting Adjustments	75.6
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	0.0	0.0	0.0	0.0	$ (94.2)
AOCI Attributable to Parent
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Foreign currency translation adjustment	$ 5.5	1.4	0.2	(5.9)
Other Comprehensive Income Loss Current Period Change Net Of Tax		1.4
Accumulated Other Comprehensive Income (Loss), Net of Tax		$ 1.4	$ 31.6	$ 40.1