Income Taxes Income Taxes - Gross Unrecognized Tax Benefits (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
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits, Beginning Balance	$ 538	$ 596	$ 749	$ 741
Decreases related to positions taken on items from prior years	(2)	(19)	(167)	(44)
Increases related to positions taken on items from prior years	9	3	77	74
Increases related to positions taken in the current year	28	49	54	9
Settlement of uncertain tax positions with tax authorities	1	(6)	(9)	(13)
Unrecognized Tax Benefits, Impact of Internal Reorganizations	0	0	(278)	0
Decreases due to expiration of statutes of limitations	(5)	(86)	0	(5)
Exchange (gain) loss	1	1	0	(13)
Unrecognized Tax Benefits, Ending Balance	741	538	426	749
Total unrecognized tax benefits that, if recognized, would impact the effective tax rate	51	131	188	45
Total amount of interest and penalties (benefit) recognized in Provision for income taxes on continuing operations	1	(27)	(4)	11
Total accrual for interest and penalties associated with unrecognized tax benefits	47	40	$ 24	$ 45
Successor Period [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits, Beginning Balance	$ 709
Unrecognized Tax Benefits, Ending Balance		$ 709