Income Taxes Schedule of Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	11 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2017	Dec. 13, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent				7.83%		7.83%
Irish or Swiss Income Tax rate at 12.5% and 7.83%, respectively	$ 2		$ (299)		$ 216	$ 208
Impact of Emergence and Fresh Start Accounting	0		(495)		0	0
Change in Valuation Allowance Attributed to Emergence and Fresh Start Accounting	0		463		0	0
Tax on Operating Earnings Subject to Rates Different than the Irish or Swiss Federal Income Tax Rate	(65)		197		(387)	123
U.S. Tax Reform - Remeasure of U.S. Deferred Tax Assets	0		0		0	(249)
Change in Valuation Allowance Attributed to U.S. Tax Reform	0		0		0	301
Change in Valuation Allowance	56	$ 73	17		166	(459)
Change in Uncertain Tax Positions	(2)		(18)		(29)	(61)
Provision for Income Taxes	$ (9)		$ (135)		$ (34)	$ (137)