Financial Instruments Cash Flow Hedges Included in AOCI (Details) - USD ($) $ in Millions	4 Months Ended	8 Months Ended	12 Months Ended
	Dec. 31, 2017	Aug. 31, 2017	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Remaining Maturity			2 years
After-tax net loss to be reclassified from AOCL into earnings over the next twelve months			$ 1
Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Beginning Balance	$ (3)	$ 7	(26)	$ (2)
Additions and revaluations of derivatives designated as cash flow hedges	(2)	3	16	(19)
Clearance of hedge results to earnings	0	(13)	12	(5)
Ending Balance	(2)	(3)	$ 2	$ (26)
Cash Flow Hedging [Member] | Successor Period [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Beginning Balance	$ 0
Ending Balance		$ 0