Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2020	Dec. 31, 2018
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	$ 0	$ (18)	$ (1)
Other comprehensive income before reclassifications, net of tax	(1)	(8)	(26)
Ending Balance	(1)		(27)	$ (18)
Beginning Balance Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax	0	(1)	0
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	0	0	0
Ending Balance Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax	0		0	(1)
Beginning Balance Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	0	(17)	(3)
Foreign currency translation adjustments	(3)	(8)	(8)	(8)
Ending Balance Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	(3)		(11)	(17)
Beginning Balance Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax,	0	0	2
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, Tax, Parent	2	0	(18)
Ending Balance Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	$ 2		$ (16)	$ 0
Elimination of Predecessor AOCI		26
Pension and Other Postretirement Plans Costs
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Elimination of Predecessor AOCI		1
Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Elimination of Predecessor AOCI		25
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Elimination of Predecessor AOCI		$ 0