Income Taxes (Reconciliation Of Provision For Income Taxes) (Details)	3 Months Ended		4 Months Ended	5 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Apr. 30, 2021	Sep. 30, 2021	Sep. 30, 2020
Successor [Member]
Consolidated tax provision at federal statutory rate	21.00%			21.00%
State income tax provisions, net of federal income tax expense (benefit)				2.80%
Changes in certain deferred tax balances	2.00%
Tax reserve adjustment	(0.10%)			0.20%
Federal research and development tax credit	0.30%			(0.50%)
All other, net	(3.50%)			1.20%
Effective tax rate	19.70%			24.70%
Predecessor [Member]
Consolidated tax provision at federal statutory rate		21.00%	21.00%		21.00%
State income tax provisions, net of federal income tax expense (benefit)		(792.50%)	0.50%		11.50%
Changes in certain deferred tax balances		1317.20%			(13.90%)
Interest expense deduction		(1592.10%)			22.60%
Restructuring cost		694.10%	0.30%		(10.30%)
Loss on disposal of Northwest Operations					(8.10%)
Tax reserve adjustment					(0.70%)
Fresh start and reorganization adjustments			(24.90%)
Shared-based payments					(0.30%)
Federal research and development tax credit					(0.50%)
All other, net		16.20%			(0.70%)
Effective tax rate		(336.10%)	(3.10%)		20.60%