Revenue Recognition (Changes In Contract Assets And Contract Liabilities) (Details) - USD ($) $ in Millions	4 Months Ended	5 Months Ended	9 Months Ended
	Apr. 30, 2021	Sep. 30, 2021	Sep. 30, 2020
Contract current assets, Beginning balance			$ 37
Contract current assets, Revenue recognized included in opening contract balance			(27)
Contract current assets, Cash received, excluding amounts recognized as revenue
Contract current assets, Credits granted, excluding amounts recognized as revenue			3
Contract current assets, Reclassified between current and concurrent
Contract current assets, Ending balance			13
Contract noncurrent assets, Beginning balance			8
Contract noncurrent assets, Revenue recognized included in opening contract balance
Contract noncurrent assets, Cash received, excluding amounts recognized as revenue
Contract noncurrent assets, Credits granted, excluding amounts recognized as revenue
Contract noncurrent assets, Reclassified between current and concurrent
Contract noncurrent assets, Ending balance			8
Contract current liabilities, Beginning balance			41
Contract current liabilities, Revenue recognized included in opening contract balance			(47)
Contract current liabilities, Cash received, excluding amounts recognized as revenue			64
Contract current liabilities, Credits granted, excluding amounts recognized as revenue
Contract current liabilities, Reclassified between current and concurrent			1
Contract current liabilities, Ending balance			59
Contract noncurrent liabilities, Beginning balance			21
Contract noncurrent liabilities, Revenue recognized included in opening contract balance			(10)
Contract noncurrent liabilities, Cash received, excluding amounts recognized as revenue			9
Contract noncurrent liabilities, Credits granted, excluding amounts recognized as revenue
Contract noncurrent liabilities, Reclassified between current and concurrent			(1)
Contract noncurrent liabilities, Ending balance			$ 19
Successor [Member]
Contract current assets, Beginning balance
Contract current assets, Revenue recognized included in opening contract balance
Contract current assets, Credits granted, excluding amounts recognized as revenue
Contract current assets, Reclassified between current and concurrent
Contract current assets, Ending balance
Contract noncurrent assets, Beginning balance
Contract noncurrent assets, Revenue recognized included in opening contract balance
Contract noncurrent assets, Credits granted, excluding amounts recognized as revenue
Contract noncurrent assets, Reclassified between current and concurrent
Contract noncurrent assets, Ending balance
Contract current liabilities, Beginning balance		15
Contract current liabilities, Revenue recognized included in opening contract balance		(13)
Contract current liabilities, Credits granted, excluding amounts recognized as revenue		17
Contract current liabilities, Reclassified between current and concurrent		1
Contract current liabilities, Ending balance	15	20
Contract noncurrent liabilities, Beginning balance		1
Contract noncurrent liabilities, Revenue recognized included in opening contract balance		(1)
Contract noncurrent liabilities, Credits granted, excluding amounts recognized as revenue		9
Contract noncurrent liabilities, Reclassified between current and concurrent		(1)
Contract noncurrent liabilities, Ending balance	1	8
Predecessor [Member]
Contract current assets, Beginning balance	6	2
Contract current assets, Revenue recognized included in opening contract balance	(4)
Contract current assets, Cash received, excluding amounts recognized as revenue
Contract current assets, Ending balance	2
Contract current assets, Ending balance after adjustments
Contract noncurrent assets, Beginning balance	9	9
Contract noncurrent assets, Revenue recognized included in opening contract balance
Contract noncurrent assets, Cash received, excluding amounts recognized as revenue
Contract noncurrent assets, Ending balance	9
Contract noncurrent assets, Ending balance after adjustments
Contract current liabilities, Beginning balance	58	57
Contract current liabilities, Revenue recognized included in opening contract balance	(23)
Contract current liabilities, Cash received, excluding amounts recognized as revenue	22
Contract current liabilities, Ending balance	57
Contract current liabilities, Ending balance after adjustments	15
Contract noncurrent liabilities, Beginning balance	20	19
Contract noncurrent liabilities, Revenue recognized included in opening contract balance	(3)
Contract noncurrent liabilities, Cash received, excluding amounts recognized as revenue	2
Contract noncurrent liabilities, Ending balance	19
Contract noncurrent liabilities, Ending balance after adjustments	1
Fresh Start Adjustments [Member] | Predecessor [Member]
Contract current assets, Beginning balance		(2)
Contract current assets, Ending balance	(2)
Contract noncurrent assets, Beginning balance		(9)
Contract noncurrent assets, Ending balance	(9)
Contract current liabilities, Beginning balance		(42)
Contract current liabilities, Ending balance	(42)
Contract noncurrent liabilities, Beginning balance		$ (18)
Contract noncurrent liabilities, Ending balance	$ (18)